Can supervise: YES
Khan, MA, Ngo, HH, Guo, W, Liu, Y, Nghiem, LD, Chang, SW, Nguyen, DD, Zhang, S, Luo, G & Jia, H 2019, 'Optimization of hydraulic retention time and organic loading rate for volatile fatty acid production from low strength wastewater in an anaerobic membrane bioreactor.', Bioresource Technology, vol. 271, pp. 100-108.View/Download from: UTS OPUS or Publisher's site
This study aims to investigate the production of volatile fatty acids (VFAs) from low strength wastewater at various hydraulic retention time (HRT) and organic loading rate (OLR) in a continuous anaerobic membrane bioreactor (AnMBR) using glucose as carbon source. This experiment was performed without any selective inhibition of methanogens and the reactor pH was maintained at 7.0 ± 0.1. 48, 24, 18, 12, 8 and 6 h-HRTs were applied and the highest VFA concentration was recorded at 8 h with an overall VFA yield of 48.20 ± 1.21 mg VFA/100 mg CODfeed. Three different ORLs were applied (350, 550 and 715 mg CODfeed) at the optimum 8 h-HRT. The acetic and propanoic acid concentration maximums were (1.1845 ± 0.0165 and 0.5160 ± 0.0141 mili-mole/l respectively) at 550 mg CODfeed. The isobutyric acid concentration was highest (0.3580 ± 0.0407 mili-mole/l) at 715 mg CODfeed indicating butyric-type fermentation at higher organic loading rate.
Thi, KLN, Huu, HN, Guo, W, Chang, SW, Dinh, DN, Long, DN, Liu, Y, Ni, B & Hai, F 2019, 'Insight into greenhouse gases emissions from the two popular treatment technologies in municipal wastewater treatment processes', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 671, pp. 1302-1313.View/Download from: UTS OPUS or Publisher's site
Ye, Y, Ngo, HH, Guo, W, Chang, SW, Dinh, DN, Liu, Y, Long, DN, Zhang, X & Wang, J 2019, 'Effect of organic loading rate on the recovery of nutrients and energy in a dual-chamber microbial fuel cell', BIORESOURCE TECHNOLOGY, vol. 281, pp. 367-373.View/Download from: UTS OPUS or Publisher's site
Hao, Q, Liu, Y, Chen, T, Guo, Q, Wei, W & Ni, B-J 2019, 'Bi2O3@Carbon Nanocomposites for Solar-Driven Photocatalytic Degradation of Chlorophenols', ACS Applied Nano Materials.View/Download from: UTS OPUS or Publisher's site
Li, X, Liu, Y, Xu, Q, Liu, X, Huang, X, Yang, J, Wang, D, Wang, Q, Liu, Y & Yang, Q 2019, 'Enhanced methane production from waste activated sludge by combining calcium peroxide with ultrasonic: Performance, mechanism, and implication', BIORESOURCE TECHNOLOGY, vol. 279, pp. 108-116.View/Download from: UTS OPUS or Publisher's site
Liu, X, Xu, Q, Wang, D, Wu, Y, Yang, Q, Liu, Y, Wang, Q, Li, X, Li, H, Zeng, G & Yang, G 2019, 'Unveiling the mechanisms of how cationic polyacrylamide affects short-chain fatty acids accumulation during long-term anaerobic fermentation of waste activated sludge', WATER RESEARCH, vol. 155, pp. 142-151.View/Download from: UTS OPUS or Publisher's site
Liu, X, Xu, Q, Wang, D, Yang, Q, Wu, Y, Li, Y, Fu, Q, Yang, F, Liu, Y, Ni, B-J, Wang, Q & Li, X 2019, 'Thermal-alkaline pretreatment of polyacrylamide flocculated waste activated sludge: Process optimization and effects on anaerobic digestion and polyacrylamide degradation', BIORESOURCE TECHNOLOGY, vol. 281, pp. 158-167.View/Download from: UTS OPUS or Publisher's site
Liu, X, Xu, Q, Wang, D, Yang, Q, Wu, Y, Yang, J, Liu, Y, Wang, Q, Ni, B-J, Li, X, Li, H & Yang, G 2019, 'Enhanced Short-Chain Fatty Acids from Waste Activated Sludge by Heat-CaO2 Advanced Thermal Hydrolysis Pretreatment: Parameter Optimization, Mechanisms, and Implications', ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 7, no. 3, pp. 3544-3555.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Ngo, HH, Guo, W, Peng, L, Wang, D & Ni, B 2019, 'The roles of free ammonia (FA) in biological wastewater treatment processes: A review.', Environment international, vol. 123, pp. 10-19.View/Download from: UTS OPUS or Publisher's site
Free ammonia (FA) can pose inhibitory and/or biocidal effects on a variety of microorganisms involved in different biological wastewater treatment process, which is widely presented in wastewater treatment plants (WWTPs) due to the high levels of ammonium in the systems. This review article gives the up-to-date status on several essential roles of FA in biological wastewater treatment processes: the impacts of FA, mechanisms of FA roles, modeling of FA impacts, and implications of FA for wastewater treatment. Specifically, the impacts of FA on both wastewater and sludge treatment lines were firstly summarized, including nitrification, denitrification, anaerobic ammonium oxidation (Anammox), enhanced biological phosphorus removal and anaerobic processes. The involved mechanisms were then analyzed, which indicated FA inhibition can slow specific microbial activities or even reconfigure the microbial community structure, likely due to negative impacts of FA on intracellular pH, specific enzymes and extracellular polymeric substances (EPS), thus causing cell inactivation/lysis. Mathematical models describing the impact of FA on both wastewater and sludge treatment processes were also explored to facilitate process optimization. Finally, the key implications of FA were identified, that is FA can be leveraged to substantially enhance the biodegradability of secondary sludge, which would further improve biological nutrient removal and enhance renewable energy production.
Pan, Y, Liu, Y, Peng, L, Ngo, HH, Guo, W, Wei, W, Wang, D & Ni, B-J 2019, 'Substrate Diffusion within Biofilms Significantly Influencing the Electron Competition during Denitrification.', Environmental science & technology, vol. 53, no. 1, pp. 261-269.View/Download from: UTS OPUS or Publisher's site
A common and long-existing operational issue of wastewater denitrification is the unexpected accumulation of nitrite (NO2-) that could suppress the activity of various microorganisms involved in biological wastewater treatment process and nitrous oxide (N2O) that could emit as a potent greenhouse gas. Recently, it has been confirmed that the accumulation of these denitrification intermediates in biological wastewater treatment process is greatly influenced by the electron competition between the four denitrification steps. However, little is known about this in biofilm systems. In this work, we applied a mathematical model that links carbon oxidation and nitrogen reduction processes through a pool of electron carriers, to assess electron competition in denitrifying biofilms. Simulations were performed comprehensively at seven combinations of electron acceptor addition scheme (i.e., simultaneous addition of one, two or three among nitrate (NO3-), NO2-, and N2O) to compare the effect of electron competition on NO3-, NO2- and N2O reduction. Overall, the effects of substrate loading, biofilm thickness and effective diffusion coefficients on electron competition are not always intuitive. Model simulations show that electron competition was intensified due to the substrate load limitation (from 120 to 20 mg COD/L) and increasing biofilm thicknesses (from 0.1 to 1.6 mm) in most cases, where electrons were prioritized to nitrite reductase because of the insufficient electron donor availability in the biofilm. In contrast, increasing effective diffusion coefficients did not pose a significant effect on electron competition and only increased electrons distributed to nitrite reductase when both NO2- and N2O are added.
Pan, Y, Liu, Y, Wang, D & Ni, B-J 2019, 'Modeling effects of H2S on electron competition among nitrogen oxide reduction and N2O accumulation during denitrification', ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY, vol. 5, no. 3, pp. 533-542.View/Download from: Publisher's site
Peng, L, Huu, HN, Song, S, Xu, Y, Guo, W, Liu, Y, Wei, W, Chen, X, Wang, D & Ni, B-J 2019, 'Heterotrophic denitrifiers growing on soluble microbial products contribute to nitrous oxide production in anammox biofilm: Model evaluation', JOURNAL OF ENVIRONMENTAL MANAGEMENT, vol. 242, pp. 309-314.View/Download from: UTS OPUS or Publisher's site
Vo, HNP, Ngo, HH, Guo, W, Nguyen, TMH, Liu, Y, Liu, Y, Nguyen, DD & Chang, SW 2019, 'A critical review on designs and applications of microalgae-based photobioreactors for pollutants treatment.', The Science of the total environment, vol. 651, no. Pt 1, pp. 1549-1568.View/Download from: UTS OPUS or Publisher's site
The development of the photobioreactors (PBs) is recently noticeable as cutting-edge technology while the correlation of PBs' engineered elements such as modellings, configurations, biomass yields, operating conditions and pollutants removal efficiency still remains complex and unclear. A systematic understanding of PBs is therefore essential. This critical review study is to: (1) describe the modelling approaches and differentiate the outcomes; (2) review and update the novel technical issues of PBs' types; (3) study microalgae growth and control determined by PBs types with comparison made; (4) progress and compare the efficiencies of contaminants removal given by PBs' types and (5) identify the future perspectives of PBs. It is found that Monod model's shortcoming in internal substrate utilization is well fixed by modified Droop model. The corroborated data also remarks an array of PBs' types consisting of flat plate, column, tubular, soft-frame and hybrid configuration in which soft-frame and hybrid are the latest versions with higher flexibility, performance and smaller foot-print. Flat plate PBs is observed with biomass yield being 5 to 20 times higher than other PBs types while soft-frame and membrane PBs can also remove pharmaceutical and personal care products (PPCPs) up to 100%. Looking at an opportunity for PBs in sustainable development, the flat plate PBs are applicable in PB-based architectures and infrastructures indicating an encouraging revenue-raising potential.
Wang, D, Wang, Y, Liu, X, Xu, Q, Yang, Q, Li, X, Zhang, Y, Liu, Y, Wang, Q, Ni, BJ & Li, H 2019, 'Heat pretreatment assists free ammonia to enhance hydrogen production from waste activated sludge', Bioresource Technology, pp. 316-325.View/Download from: UTS OPUS or Publisher's site
© 2019 Elsevier Ltd Controlling free ammonia in an anaerobic fermenter at pertinent levels is reported recently to be an economically attractive and practically feasible approach to enhance hydrogen yield from waste activated sludge (WAS). This paper reports a new technology for WAS dark fermentation, i.e., using heat pretreatment (70 °C for 60 min) to assist free ammonia for further improving hydrogen yield. The experimental results showed that the accumulative hydrogen production from combined reactors was promoted from 12.3 to 19.2 mL/g VSS (volatile suspended solids), the maximum of which was 1.8, 2.7, and 7.1 times of that from sole free ammonia (131.9 mg NH 3 -N/L), sole heat, and blank reactors, respectively. Mechanism explorations showed that the combination strategy significantly enhanced WAS disintegration, providing more substrates for hydrogen production. Moreover, the combination suppressed activities of all microbes associated with anaerobic fermentation, but its inhibition to hydrogen consumers was much severer than that to other microbes.
Wang, D, Zhang, D, Xu, Q, Liu, Y, Wang, Q, Ni, B-J, Yang, Q, Li, X & Yang, F 2019, 'Calcium peroxide promotes hydrogen production from dark fermentation of waste activated sludge', CHEMICAL ENGINEERING JOURNAL, vol. 355, pp. 22-32.View/Download from: UTS OPUS or Publisher's site
Xu, Q, Liu, X, Yang, G, Wang, D, Wang, Q, Liu, Y, Li, X & Yang, Q 2019, 'Free nitrous acid-based nitrifying sludge treatment in a two-sludge system obtains high polyhydroxyalkanoates accumulation and satisfied biological nutrients removal', Bioresource Technology, pp. 16-24.View/Download from: UTS OPUS or Publisher's site
© 2019 Elsevier Ltd A novel strategy to achieve substantial polyhydroxyalkanoates (PHA) accumulation in waste activated sludge (WAS) was developed, which was conducted in a two-sludge system consisted of an anaerobic/anoxic/oxic reactor (AAO-SBR) and a nitrifying reactor (N-SBR), where the nitrifying-sludge was treated by free nitrous acid (FNA). Initially, 0.98 ± 0.09 and 1.46 ± 0.10 mmol-c/g VSS of PHA were respectively determined in the control-SBR and AAO-SBR. When 1/16 of nitrifying sludge was daily treated with 1.49 mg N/L FNA for 24 h, ∼46.5% of nitrite was accumulated in the N-SBR, ∼2.43 ± 0.12 mmol-c/g VSS of PHA was accumulated in WAS in AAO-SBR without deteriorating nutrient removal. However, nutrient removal of control-SBR was completely collapsed after implementing the same FNA treatment. Further investigations revealed that the activity and abundance of nitrite oxidizing bacteria (NOB) was decreased significantly after FNA treatment. Finally, sludge with high PHA level to generate more methane was confirmed.
Yang, J, Liu, X, Wang, D, Xu, Q, Yang, Q, Zerig, G, Li, X, Liu, Y, Gong, J, Ye, J & Li, H 2019, 'Mechanisms of peroxymonosulfate pretreatment enhancing production of short-chain fatty acids from waste activated sludge', WATER RESEARCH, vol. 148, pp. 239-249.View/Download from: Publisher's site
Ye, Y, Ngo, HH, Guo, W, Liu, Y, Chang, SW, Dinh, DN, Ren, J, Liu, Y & Zhang, X 2019, 'Feasibility study on a double chamber microbial fuel cell for nutrient recovery from municipal wastewater', CHEMICAL ENGINEERING JOURNAL, vol. 358, pp. 236-242.View/Download from: UTS OPUS or Publisher's site
Xu, X, Zhou, Z, Liu, Y, Wen, S, Guo, Z, Gao, L & Wang, F 2019, 'Optimising passivation shell thickness of single upconversion nanoparticles using a time-resolved spectrometer', APL PHOTONICS, vol. 4, no. 2.View/Download from: Publisher's site
Cheng, D, Ngo, HH, Guo, W, Liu, Y, Chang, SW, Nguyen, DD, Nghiem, LD, Zhou, J & Ni, B 2018, 'Anaerobic membrane bioreactors for antibiotic wastewater treatment: Performance and membrane fouling issues.', Bioresource technology, vol. 267, pp. 714-724.View/Download from: UTS OPUS or Publisher's site
Antibiotic wastewater has become a major concern due to the toxicity and recalcitrance of antibiotics. Anaerobic membrane bioreactors (AnMBRs) are considered alternative technology for treating antibiotic wastewater because of their advantages over the conventional anaerobic processes and aerobic MBRs. However, membrane fouling remains the most challenging issue in the AnMBRs' operation and this limits their application. This review critically discusses: (i) antibiotics removal and antibiotic resistance genes (ARGs) in different types of AnMBRs and the impact of antibiotics on membrane fouling and (ii) the integrated AnMBRs systems for fouling control and removal of antibiotics. The presence of antibiotics in AnMBRs could aggravate membrane fouling by influencing fouling-related factors (i.e., sludge particle size, extracellular polymeric substances (EPS), soluble microbial products (SMP), and fouling-related microbial communities). Conclusively, integrated AnMBR systems can be a practical technology for antibiotic wastewater treatment.
Do, MH, Ngo, HH, Guo, WS, Liu, Y, Chang, SW, Nguyen, DD, Nghiem, LD & Ni, BJ 2018, 'Challenges in the application of microbial fuel cells to wastewater treatment and energy production: A mini review.', The Science of the total environment, vol. 639, pp. 910-920.View/Download from: UTS OPUS or Publisher's site
Wastewater is now considered to be a vital reusable source of water reuse and saving energy. However, current wastewater has multiple limitations such as high energy costs, large quantities of residuals being generated and lacking in potential resources. Recently, great attention has been paid to microbial fuel cells (MFCs) due to their mild operating conditions where a variety of biodegradable substrates can serve as fuel. MFCs can be used in wastewater treatment facilities to break down organic matter, and they have also been analysed for application as a biosensor such as a sensor for biological oxygen which demands monitoring. MFCs represent an innovation technology solution that is simple and rapid. Despite the advantages of this technology, there are still practical barriers to consider including low electricity production, current instability, high internal resistance and costly materials used. Thus, many problems must be overcome and doing this requires a more detailed analysis of energy production, consumption, and application. Currently, real-world applications of MFCs are limited due to their low power density level of only several thousand mW/m2. Efforts are being made to improve the performance and reduce the construction and operating costs of MFCs. This paper explores several aspects of MFCs such as anode, cathode and membrane, and in an effort to overcome the practical challenges of this system.
Khan, MA, Ngo, HH, Guo, W, Liu, Y, Chang, SW, Nguyen, DD, Nghiem, LD & Liang, H 2018, 'Can membrane bioreactor be a smart option for water treatment?', Bioresource Technology Reports, vol. 4, pp. 80-87.View/Download from: UTS OPUS or Publisher's site
The gradual increase of organic and inorganic micropollutants in natural and drinking watercourses has posed a greater challenge for current water treatment technologies. Currently established water treatment processes such as activated sludge, microfiltration, reverse osmosis, adsorption, carbon nanotube etc. have a limited range of application, low energy recovery, and cost-intensive operation. Membrane bioreactor has already been utilized as a useful option to remove soluble organics, nutrients, and micropollutants from wastewater. Although currently established Membrane Bioreactors have few limitations, recent developments on this technology have improved its energy efficiency and reduced the operating and maintenance cost. Implementing these research findings in full-scale operation can make this process a favorable option in industrial wastewater treatment.
Peng, L, Ngo, HH, Guo, WS, Liu, Y, Wang, D, Song, S, Wei, W, Nghiem, LD & Ni, BJ 2018, 'A novel mechanistic model for nitrogen removal in algal-bacterial photo sequencing batch reactors.', Bioresource technology, vol. 267, pp. 502-509.View/Download from: UTS OPUS or Publisher's site
A comprehensive mathematical model was constructed to evaluate the complex substrate and microbial interaction in algal-bacterial photo sequencing batch reactors (PSBR). The kinetics of metabolite, growth and endogenous respiration of ammonia oxidizing bacteria, nitrite oxidizing bacteria and heterotrophic bacteria were coupled to those of microalgae and then embedded into widely-used activated sludge model series. The impact of light intensity was considered for microalgae growth, while the effect of inorganic carbon was considered for each microorganism. The integrated model framework was assessed using experimental data from algal-bacterial consortia performing sidestream nitritation/denitritation. The validity of the model was further evaluated based on dataset from PSBR performing mainstream nitrification. The developed model could satisfactorily capture the dynamics of microbial populations and substrates under different operational conditions (i.e. feeding, carbon dosing and illuminating mode, light intensity, influent ammonium concentration), which might serve as a powerful tool for optimizing the novel algal-bacterial nitrogen removal processes.
Cheng, DL, Ngo, HH, Guo, WS, Liu, YW, Zhou, JL, Chang, SW, Nguyen, DD, Bui, XT & Zhang, XB 2018, 'Bioprocessing for elimination antibiotics and hormones from swine wastewater.', Science of the Total Environment, vol. 621, pp. 1664-1682.View/Download from: UTS OPUS or Publisher's site
Antibiotics and hormones in swine wastewater have become a critical concern worldwide due to the severe threats to human health and the eco-environment. Removal of most detectable antibiotics and hormones, such as sulfonamides (SAs), SMs, tetracyclines (TCs), macrolides, and estrogenic hormones from swine wastewater utilizing various biological processes were summarized and compared. In biological processes, biosorption and biodegradation are the two major removal mechanisms for antibiotics and hormones. The residuals in treated effluents and sludge of conventional activated sludge and anaerobic digestion processes can still pose risks to the surrounding environment, and the anaerobic processes' removal efficiencies were inferior to those of aerobic processes. In contrast, membrane bioreactors (MBRs), constructed wetlands (CWs) and modified processes performed better because of their higher biodegradation of toxicants. Process modification on activated sludge, anaerobic digestion and conventional MBRs could also enhance the performance (e.g. removing up to 98% SMs, 88.9% TCs, and 99.6% hormones from wastewater). The hybrid process combining MBRs with biological or physical technology also led to better removal efficiency. As such, modified conventional biological processes, advanced biological technologies and MBR hybrid systems are considered as a promising technology for removing toxicants from swine wastewater.
Chen, Y, Wu, Y, Wang, D, Li, H, Wang, Q, Liu, Y, Peng, L, Yang, Q, Li, X, Zeng, G & Chen, Y 2018, 'Understanding the mechanisms of how poly aluminium chloride inhibits short-chain fatty acids production from anaerobic fermentation of waste activated sludge', Chemical Engineering Journal, vol. 334, pp. 1351-1360.View/Download from: UTS OPUS or Publisher's site
© 2017 Elsevier B.V. Poly aluminum chloride (PAC) is accumulated in waste activated sludge at high levels. However, details of how PAC affects short-chain fatty acids (SCFA) production from anaerobic sludge fermentation has not been documented. This work therefore aims to fill this knowledge gap by analyzing the impact of PAC on the aggregate of sludge flocs, disruption of extracellular polymeric substances (EPS), and the bio-processes of hydrolysis, acidogenesis, and methanogenesis. The relationship between SCFA production and different aluminum species (i.e., Ala, Alb, and Alc) was also identified by controlling different OH/Al ratio and pH in different fermentation systems. Experimental results showed that with the increase of PAC addition from 0 to 40 mg Al per gram of total suspended solids, SCFA yield decreased from 212.2 to 138.4 mg COD/g volatile suspended solids. Mechanism exploration revealed that PAC benefited the aggregates of sludge flocs and caused more loosely- and tightly-bound extracellular polymeric substances remained in sludge cells. Besides, it was found that the hydrolysis, acidiogenesis, and methanogenesis processes were all inhibited by PAC. Although three types of Al species, i.e., Ala (Al monomers, dimer, and trimer), Alb (Al13(AlO4Al12(OH)24(H2O)7 + 12), and Alc (Al polymer molecular weight normally larger than 3000 Da), were co-existed in fermentation systems, their impacts on SCFA production were different. No correlation was found between SCFA and Ala, whereas SCFA production decreased with the contents of Alb and Alc. Compared with Alb, Alc was the major contributor to the decreased SCFA production (R2 = 0.5132 vs R2 = 0.98). This is the first report revealing the underlying mechanism of how PAC affects SCFA production and identifying the contribution of different Al species to SCFA inhibition.
Khan, MA, Ngo, HH, Guo, W, Liu, Y, Zhang, X, Guo, J, Chang, SW, Nguyen, DD & Wang, J 2018, 'Biohydrogen production from anaerobic digestion and its potential as renewable energy', Renewable Energy, vol. 129, pp. 754-768.View/Download from: UTS OPUS or Publisher's site
© 2017. The current demand-supply scenario for fossil fuels requires an alternative energy source with cleaner combustion products whilst production of hydrogen from anaerobic digestion involves the utilization of waste materials and zero emission of greenhouse gasses. However, large scale industrial application has yet not been implemented due to numerous challenges in its production, storage, and transportation. This review study demonstrates that production of hydrogen from anaerobic digestion is potentially a worthy alternative regarding energy density, environmental impact, and cost. Moreover, dependence on fossil fuel systems in the future could be minimized when biohydrogen production is feasible from renewable energy sources.
Liu, X, Xu, Q, Wang, D, Yang, Q, Wu, Y, Yang, J, Gong, J, Ye, J, Li, Y, Wang, Q, Liu, Y, Ni, B-J, Zeng, G & Li, X 2018, 'Revealing the Underlying Mechanisms of How Initial pH Affects Waste Activated Sludge Solubilization and Dewaterability in Freezing and Thawing Process', ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 6, no. 11, pp. 15822-15831.View/Download from: UTS OPUS or Publisher's site
Liu, X, Xu, Q, Wang, D, Zhao, J, Wu, Y, Liu, Y, Ni, B-J, Wang, Q, Zeng, G, Li, X & Yang, Q 2018, 'Improved methane production from waste activated sludge by combining free ammonia with heat pretreatment: Performance, mechanisms and applications', BIORESOURCE TECHNOLOGY, vol. 268, pp. 230-236.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Li, C, Lackner, S, Wagner, M & Horn, H 2018, 'The role of interactions of effective biofilm surface area and mass transfer in nitrogen removal efficiency of an integrated fixed-film activated sludge system', Chemical Engineering Journal, vol. 350, pp. 992-999.View/Download from: UTS OPUS or Publisher's site
© 2018 Elsevier B.V. A reaction-diffusion biofilm model was implemented to simulate the nitrification/denitrification performance of a lab-scale integrated fixed-film activated sludge (IFAS) reactor. The model was capable of representing the system performance, i.e. changes in organic load and decrease in sludge age. Furthermore, nitrification batch tests with sludge and carrier material could also be simulated successfully with the model. Model simulation revealed that the diffusive fluxes into biofilm depended strongly on substrate loading as well as sludge age. The microbial composition in the biofilm matrix was mainly influenced by the diffusive flux of chemical oxygen demand (COD) into biofilm. When COD removal started to switch to biofilm, heterotrophic bacteria quickly replaced the previously dominating autotrophic bacteria. Running a set of simulations with a range of effective biofilm surface area and different mass transfer coefficients revealed the strong influence of these two parameters on the IFAS performance. The analysis showed that both parameters were dominating factors for ammonium removal. The optimum mass transfer coefficient was in the range of 3–4 m d−1 and the effective biofilm surface was around 63–88% of the theoretical carrier surface.
Liu, Y, Ngo, HH, Guo, W, Peng, L, Chen, X, Wang, D, Pan, Y & Ni, B-J 2018, 'Modeling electron competition among nitrogen oxides reduction and N2 O accumulation in hydrogenotrophic denitrification.', Biotechnology and Bioengineering, vol. 115, no. 4, pp. 978-988.View/Download from: UTS OPUS or Publisher's site
Hydrogenotrophic denitrification is a novel and sustainable process for nitrogen removal, which utilizes hydrogen as electron donor, and carbon dioxide as carbon source. Recent studies have shown that nitrous oxide (N2 O), a highly undesirable intermediate and potent greenhouse gas, can accumulate during this process. In this work, a new mathematical model is developed to describe nitrogen oxides dynamics, especially N2 O, during hydrogenotrophic denitrification for the first time. The model describes electron competition among the four steps of hydrogenotrophic denitrification through decoupling hydrogen oxidation and nitrogen reduction processes using electron carriers, in contrast to the existing models that couple these two processes and also do not consider N2 O accumulation. The developed model satisfactorily describes experimental data on nitrogen oxides dynamics obtained from two independent hydrogenotrophic denitrifying cultures under various hydrogen and nitrogen oxides supplying conditions, suggesting the validity and applicability of the model. The results indicated that N2 O accumulation would not be intensified under hydrogen limiting conditions, due to the higher electron competition capacity of N2 O reduction in comparison to nitrate and nitrite reduction during hydrogenotrophic denitrification. The model is expected to enhance our understanding of the process during hydrogenotrophic denitrification and the ability to predict N2 O accumulation.
Peng, L, Dai, X, Liu, Y, Sun, J, Song, S & Ni, B-J 2018, 'Model-based assessment of estrogen removal by nitrifying activated sludge', CHEMOSPHERE, vol. 197, pp. 430-437.View/Download from: UTS OPUS or Publisher's site
Peng, L, Dai, X, Liu, Y, Wei, W, Sun, J, Xie, G-J, Wang, D, Song, S & Ni, B-J 2018, 'Kinetic assessment of simultaneous removal of arsenite, chlorate and nitrate under autotrophic and mixotrophic conditions', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 628-629, pp. 85-93.View/Download from: UTS OPUS or Publisher's site
Wang, D, Duan, Y, Yang, Q, Liu, Y, Ni, B-J, Wang, Q, Zeng, G, Li, X & Yuan, Z 2018, 'Free ammonia enhances dark fermentative hydrogen production from waste activated sludge', WATER RESEARCH, vol. 133, pp. 272-281.View/Download from: UTS OPUS or Publisher's site
Wang, D, Liu, B, Liu, X, Xu, Q, Yang, Q, Liu, Y, Zeng, G, Li, X & Ni, B-J 2018, 'How does free ammonia-based sludge pretreatment improve methane production from anaerobic digestion of waste activated sludge.', Chemosphere, vol. 206, pp. 491-501.View/Download from: UTS OPUS or Publisher's site
Previous studies reported that free ammonia (FA) pretreatment could improve methane production from anaerobic digestion of waste activated sludge (WAS) effectively. However, details of how FA pretreatment improves methane production are poorly understood. This study therefore aims to reveal the underlying mechanisms of FA pretreatment affecting anaerobic digestion of WAS through a series of batch tests using either real sludge or synthetic media as the digestion substrates at different pH values. At pH 8.5 level, with an increase of FA level from 18.5 to 92.5 mg/L (i.e., NH+ 4-N: 100-500 mg/L; pH 8.5) the maximum methane yield varied between 194.0 ± 3.9 and 196.9 ± 7.7 mL/g of VSS (25 °C, 1 atm). At pH 9.5 or 10 level, however, with an increase of initial FA level from 103.2 to 516.2 mg/L, the maximal methane yield increased linearly. The mechanism studies revealed that FA pretreatment at high levels not only accelerated the disintegration of WAS but also enhanced the biodegradability of WAS. Although pH in the digesters was adjusted to 7.0 ± 0.1, the high levels of NH+ 4-N added or released led to substantial levels of residual FA ranging from 4.4 to 11.6 mg/L. It was found that this level of FA inhibited homoacetogenesis and methanogenesis significantly, though hydrolysis, acidogenesis, and acetogenesis processes were unaffected largely. Further analyses showed that the inhibition constant of FA to substrate degradation was in the sequence of dextran > glucose > hydrogen > acetate, indicating the methanogenesis process was more sensitive to FA.
Wang, D, Liu, X, Zeng, G, Zhao, J, Liu, Y, Wang, Q, Chen, F, Li, X & Yang, Q 2018, 'Understanding the impact of cationic polyacrylamide on anaerobic digestion of waste activated sludge.', Water research, vol. 130, pp. 281-290.View/Download from: UTS OPUS or Publisher's site
Previous investigations showed that cationic polyacrylamide (cPAM), a flocculant widely used in wastewater pretreatment and waste activated sludge dewatering, deteriorated methane production during anaerobic digestion of sludge. However, details of how cPAM affects methane production are poorly understood, hindering deep control of sludge anaerobic digestion systems. In this study, the mechanisms of cPAM affecting sludge anaerobic digestion were investigated in batch and long-term tests using either real sludge or synthetic wastewaters as the digestion substrates. Experimental results showed that the presence of cPAM not only slowed the process of anaerobic digestion but also decreased methane yield. The maximal methane yield decreased from 139.1 to 86.7 mL/g of volatile suspended solids (i.e., 1861.5 to 1187.0 mL/L) with the cPAM level increasing from 0 to 12 g/kg of total suspended solids (i.e., 0-236.7 mg/L), whereas the corresponding digestion time increased from 22 to 26 d. Mechanism explorations revealed that the addition of cPAM significantly restrained the sludge solubilization, hydrolysis, acidogenesis, and methanogenesis processes. It was found that ∼46% of cAPM was degraded in the anaerobic digestion, and the degradation products significantly affected methane production. Although the theoretically biochemical methane potential of cPAM is higher than that of protein and carbohydrate, only 6.7% of the degraded cPAM was transformed to the final product, methane. Acrylamide, acrylic acid, and polyacrylic acid were found to be the main degradation metabolites, and their amount accounted for ∼50% of the degraded cPAM. Further investigations showed that polyacrylic acid inhibited all the solubilization, hydrolysis, acidogenesis, and methanogenesis processes while acrylamide and acrylic acid inhibited the methanogenesis significantly.
Wang, D, Shuai, K, Xu, Q, Liu, X, Li, Y, Liu, Y, Wang, Q, Li, X, Zeng, G & Yang, Q 2018, 'Enhanced short-chain fatty acids production from waste activated sludge by combining calcium peroxide with free ammonia pretreatment', BIORESOURCE TECHNOLOGY, vol. 262, pp. 114-123.View/Download from: UTS OPUS or Publisher's site
Wang, Y, Zhao, J, Wang, D, Liu, Y, Wang, Q, Ni, B-J, Chen, F, Yang, Q, Li, X, Zeng, G & Yuan, Z 2018, 'Free nitrous acid promotes hydrogen production from dark fermentation of waste activated sludge', WATER RESEARCH, vol. 145, pp. 113-124.View/Download from: UTS OPUS or Publisher's site
Xu, Q, Liu, X, Fu, Y, Li, Y, Wang, D, Wang, Q, Liu, Y, An, H, Zhao, J, Wu, Y, Li, X, Yang, Q & Zeng, G 2018, 'Feasibility of enhancing short-chain fatty acids production from waste activated sludge after free ammonia pretreatment: Role and significance of rhamnolipid.', Bioresource technology, vol. 267, pp. 141-148.View/Download from: UTS OPUS or Publisher's site
This study reported a new, renewable and high-efficient strategy for anaerobic fermentation, i.e., using free ammonia (FA) to pretreat waste activated sludge (WAS) for 1 d and then combining with rhamnolipid (RL), by which the short-chain fatty acids (SCFA) production was remarkably improved. Experimental results showed the maximal SCFA production of 324.7 ± 13.9 mg COD/g VSS was achieved at 62.6 mg FA/L pretreatment combined with 0.04 g RL/g TSS, which was respectively 5.95-fold, 1.63-fold and 1.41-fold of that from control, FA pretreatment and RL pretreatment. Mechanism investigations revealed that FA + RL enhanced sludge solubilization and hydrolysis, providing more organics for subsequent SCFA production. It was also found that the combined method inhibited acidogenesis and methanogenesis, but the inhibition to methanogenesis was much severer than that to acidogenesis. Finally, the feasibility of NH4+-N and PO3-4-P, released in fermentation liquor, being recovered as magnesium ammonium phosphate (MAP) was confirmed.
Xu, Q, Liu, X, Wang, D, Wu, Y, Wang, Q, Liu, Y, Li, X, An, H, Zhao, J, Chen, F, Zhong, Y, Yang, Q & Zeng, G 2018, 'Free ammonia-based pretreatment enhances phosphorus release and recovery from waste activated sludge', CHEMOSPHERE, vol. 213, pp. 276-284.View/Download from: UTS OPUS or Publisher's site
Yang, G, Wang, D, Yang, Q, Zhao, J, Liu, Y, Wang, Q, Zeng, G, Li, X & Li, H 2018, 'Effect of acetate to glycerol ratio on enhanced biological phosphorus removal.', Chemosphere, vol. 196, pp. 78-86.View/Download from: UTS OPUS or Publisher's site
Enhanced biological phosphorus removal (EBPR) is a sustainable and promising technology for phosphorus removal from wastewater. The efficiency of this technology, however, is often discounted due to the insufficient carbon sources in influent. In this work, the effect of acetate to glycerol ratio on the EBPR performance was evaluated. The experimental results showed when the ratio of acetate to glycerol decreased from 100/0% to 50/50%, the EBPR efficiency increased from 90.2% to 96.2%. Further decrease of acetate to glycerol ratio to 0/100% decreased the efficiency of EBPR to 30.5%. Fluorescence in situ hybridization analysis demonstrated appropriate increase of glycerol benefited to increase the relative abundance of phosphate accumulating organisms. Further investigation revealed the proper addition of glycerol increased the amount of polyhydroxyalkanoates synthesis, and then produced sufficient energy for oxic luxury phosphorus in the subsequent oxic phase.
Ye, Y, Liu, W, Jiang, W, Kang, J, Ngo, HH, Guo, W & Liu, Y 2018, 'Defluoridation by magnesia-pullulan: Surface complexation modeling and pH neutralization of treated fluoride water by aluminum', JOURNAL OF THE TAIWAN INSTITUTE OF CHEMICAL ENGINEERS, vol. 93, pp. 625-631.View/Download from: UTS OPUS or Publisher's site
Ye, Y, Ngo, HH, Guo, W, Liu, Y, Chang, SW, Nguyen, DD, Liang, H & Wang, J 2018, 'A critical review on ammonium recovery from wastewater for sustainable wastewater management.', Bioresource technology, vol. 268, pp. 749-758.View/Download from: UTS OPUS or Publisher's site
The growing global population's demand for ammonium has triggered an increase in its supply, given that ammonium plays a crucial role in fertilizer production for the purpose of food security. Currently, ammonia used in fertilizer production is put through what is known as the industrial Haber Bosch process, but this approach is substantially expensive and requires much energy. For this reason, looking for effective methods to recover ammonium is important for environmental sustainability. One of the greatest opportunities for ammonium recovery occurs in wastewater treatment plants due to wastewater containing a large quantity of ammonium ions. The comprehensively and critically review studies on ammonium recovery conducted, have the potential to be applied in current wastewater treatment operations. Technologies and their ammonium recovery mechanisms are included in this review. Furthermore the economic feasibility of such processes is analysed. Possible future directions for ammonium recovery from wastewater are suggested.
Ye, Y, Yang, J, Jiang, W, Kang, J, Hu, Y, Ngo, HH, Guo, W & Liu, Y 2018, 'Fluoride removal from water using a magnesia-pullulan composite in a continuous fixed-bed column.', Journal of environmental management, vol. 206, pp. 929-937.View/Download from: UTS OPUS or Publisher's site
A magnesia-pullulan composite (MgOP) was previously shown to effectively remove fluoride from water. In the present study, a continuous fixed-bed column was used to examine the application of the composite at an industrial scale. The influencing parameters included bed mass (4.0, 6.0 and 8.0 g), influent flow rate (8, 16 and 32 mL/min), inlet fluoride concentration (5, 10 and 20 mg/L), reaction temperature (20, 30 and 40 °C), influent pH (4, 7 and 10) and other existing anions (HCO3-, SO42-, Cl- and NO3-), through which the breakthrough curves could be depicted for the experimental data analysis. The results indicated that MgOP is promising for fluoride removal with a defluoridation capacity of 16.6 mg/g at the bed mass of 6.0 g, influent flow rate of 16 mL/min and inlet fluoride concentration of 10 mg/L. The dynamics of the fluoride adsorption process were modeled using the Thomas and Yan models, in which the Yan model presented better predictions for the breakthrough curves than the Thomas model. Moreover, the concentration of magnesium in the effluent was monitored to determine Mg stability in the MgOP composite. Results indicated the effluent concentration of Mg2+ ions could be kept at a safe level. Calcination of fluoride-loaded MgOP effectively regenerated the material.
Zhang, C, Qin, Y, Xu, Q, Liu, X, Liu, Y, Ni, B-J, Yang, Q, Wang, D, Li, X & Wang, Q 2018, 'Free Ammonia-Based Pretreatment Promotes Short-Chain Fatty Acid Production from Waste Activated Sludge', ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 6, no. 7, pp. 9120-9129.View/Download from: UTS OPUS or Publisher's site
Zhao, J, Liu, Y, Wang, Y, Lian, Y, Wang, Q, Yang, Q, Wang, D, Xie, GJ, Zeng, G, Sun, Y, Li, X & Ni, BJ 2018, 'Clarifying the Role of Free Ammonia in the Production of Short-Chain Fatty Acids from Waste Activated Sludge Anaerobic Fermentation', ACS Sustainable Chemistry and Engineering, vol. 6, no. 11, pp. 14104-14113.View/Download from: UTS OPUS or Publisher's site
Copyright © 2018 American Chemical Society. Free ammonia (FA) could accumulate at high levels in the sludge anaerobic fermentation, especially under alkaline fermentation conditions, which might significantly affect the anaerobic fermentation. However, its role in the sludge fermentation process has not been revealed fundamentally. This work therefore aims to fill the knowledge gap through the integration of experimental and mathematical approaches. Experimental results showed that when the initial ammonium concentration increased from 20 to 300 mg/L, the maximal short-chain fatty acid (SCFA) yield from fermentation systems with different pH values varied from 91.2 to 296.7 mg of chemical oxygen demand/g volatile suspended solids (VSS). The increasing SCFA production was observed to correlate with the FA level rather than the ammonium level, suggesting that FA, instead of ammonium, is likely the true contributor to enhance SCFA production. Batch tests confirmed that ammonium in the fermentation-strength range (e.g., 0-300 mg/L) did not affect any process of sludge fermentation, but all the processes were affected significantly by FA, pH, or combined FA-pH. It was found that FA facilitated sludge disintegration but inhibited the processes of hydrolysis, acidification, and methanogenesis. When FA and alkaline conditions were combined, synergistic effects on all these processes were observed. The significant contribution of FA to SCFA production was finally confirmed by a sludge fermentation mathematical model proposed recently. The findings reported here revealed the actually existing, yet previously unrecognized contributor to the sludge fermentation, which help engineers better understand the role of FA in sludge anaerobic fermentation.
Zhao, J, Wang, D, Liu, Y, Ngo, HH, Guo, W, Yang, Q & Li, X 2018, 'Novel stepwise pH control strategy to improve short chain fatty acid production from sludge anaerobic fermentation.', Bioresource Technology, vol. 249, pp. 431-438.View/Download from: UTS OPUS or Publisher's site
This study reports an innovative strategy known as stepwise pH fermentation, developed to enhance the production of short chain volatile fatty acids (SCFA) from waste activated sludge (WAS) anaerobic fermentation. Experimental results confirmed the optimal pH for WAS disruption and acidification was 11 and 9, respectively, and corresponding optimal time was, respectively, 5 d and 2 d. In this scenario, the optimal SCFA yield was 2356 mg chemical oxygen demand (COD)/L, which was much higher than that derived from alkaline fermentation system. Investigation of the mechanism indicated that pH 11 could accelerate the disruption of WAS and inhibit the activities of methanogens; furthermore, pH 9 was beneficial to the activity of acid-producing bacteria, resulting in more SCFA production. Stepwise pH fermentation integrated with sodium chloride (NaCl) present in WAS had synergistic impacts on WAS anaerobic fermentation.
Liu, Y, Ngo, HH, Guo, W, Zhou, J, Peng, L, Wang, D, Chen, X, Sun, J & Ni, B-J 2017, 'Optimizing sulfur-driven mixotrophic denitrification process: System performance and nitrous oxide emission', CHEMICAL ENGINEERING SCIENCE, vol. 172, pp. 414-422.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Zhang, Y, Zhao, Z, Ngo, HH, Guo, W, Zhou, J, Peng, L & Ni, B-J 2017, 'A modeling approach to direct interspecies electron transfer process in anaerobic transformation of ethanol to methane.', Environmental Science and Pollution Research, vol. 24, no. 1, pp. 855-863.View/Download from: UTS OPUS or Publisher's site
Recent studies have shown that direct interspecies electron transfer (DIET) plays an important part in contributing to methane production from anaerobic digestion. However, so far anaerobic digestion models that have been proposed only consider two pathways for methane production, namely, acetoclastic methanogenesis and hydrogenotrophic methanogenesis, via indirect interspecies hydrogen transfer, which lacks an effective way for incorporating DIET into this paradigm. In this work, a new mathematical model is specifically developed to describe DIET process in anaerobic digestion through introducing extracellular electron transfer as a new pathway for methane production, taking anaerobic transformation of ethanol to methane as an example. The developed model was able to successfully predict experimental data on methane dynamics under different experimental conditions, supporting the validity of the developed model. Modeling predictions clearly demonstrated that DIET plays an important role in contributing to overall methane production (up to 33 %) and conductive material (i.e., carbon cloth) addition would significantly promote DIET through increasing ethanol conversion rate and methane production rate. The model developed in this work will potentially enhance our current understanding on syntrophic metabolism via DIET.
Chen, C, Guo, WS, Ngo, HH, Liu, Y, Du, B, Wei, Q, Wei, D, Nguyen, DD & Chang, SW 2017, 'Evaluation of a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) for municipal wastewater treatment', RENEWABLE ENERGY, vol. 111, pp. 620-627.View/Download from: UTS OPUS or Publisher's site
Chen, X, Liu, Y, Peng, L & Ni, B-J 2017, 'Perchlorate, nitrate, and sulfate reduction in hydrogen-based membrane biofilm reactor: Model-based evaluation', CHEMICAL ENGINEERING JOURNAL, vol. 316, pp. 82-90.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Ngo, HH, Guo, W, Sun, J, Wang, D, Peng, L & Ni, B-J 2017, 'Modeling aerobic biotransformation of vinyl chloride by vinyl chloride-assimilating bacteria, methanotrophs and ethenotrophs.', Journal of Hazardous Materials, vol. 332, pp. 97-103.View/Download from: UTS OPUS or Publisher's site
Recent studies have investigated the potential of enhanced groundwater Vinyl Chloride (VC) remediation in the presence of methane and ethene through the interactions of VC-assimilating bacteria, methanotrophs and ethenotrophs. In this study, a mathematical model was developed to describe aerobic biotransformation of VC in the presence of methane and ethene for the first time. It examines the metabolism of VC by VC-assimilating bacteria as well as cometabolism of VC by both methanotrophs and ethenotrophs, using methane and ethene respectively, under aerobic conditions. The developed model was successfully calibrated and validated using experimental data from microcosms with different experimental conditions. The model satisfactorily describes VC, methane and ethene dynamics in all microcosms tested. Modeling results describe that methanotrophic cometabolism of ethene promotes ethenotrophic VC cometabolism, which significantly enhances aerobic VC degradation in the presence of methane and ethene. This model is expected to be a useful tool to support effective and efficient processes for groundwater VC remediation.
Peng, L, Kassotaki, E, Liu, Y, Sun, J, Dai, X, Pijuan, M, Rodriguez-Roda, I, Buttiglieri, G & Ni, BJ 2017, 'Modelling cometabolic biotransformation of sulfamethoxazole by an enriched ammonia oxidizing bacteria culture', Chemical Engineering Science, vol. 173, pp. 465-473.View/Download from: UTS OPUS or Publisher's site
© 2017 Elsevier Ltd Antibiotics such as sulfamethoxazole (SFX) are environmentally hazardous after being released into the aquatic environment and challenges remain in the development of engineered prevention strategies. In this work, a mathematical model was developed to describe and evaluate cometabolic biotransformation of SFX and its transformation products (TPs) in an enriched ammonia oxidizing bacteria (AOB) culture. The growth-linked cometabolic biodegradation by AOB, non-growth transformation by AOB and non-growth transformation by heterotrophs were considered in the model framework. The production of major TPs comprising 4-Nitro-SFX, Desamino-SFX and N 4 -Acetyl-SFX was also specifically modelled. The validity of the model was demonstrated through testing against literature reported data from extensive batch tests, as well as from long-term experiments in a partial nitritation sequencing batch reactor (SBR) and in a combined SBR + membrane aerated biofilm reactor performing nitrification/denitrification. Modelling results revealed that the removal efficiency of SFX increased with the increase of influent ammonium concentration, whereas the influent organic matter, hydraulic retention time and solid retention time exerted a limited effect on SFX biodegradation with the removal efficiencies varying in a narrow range. The variation of influent SFX concentration had no impact on SFX removal efficiency. The established model framework enables interpretation of a range of experimental observations on SFX biodegradation and helps to identify the optimal conditions for efficient removal.
Peng, L, Liu, Y, Sun, J, Wang, D, Dai, X & Ni, BJ 2017, 'Enhancing immobilization of arsenic in groundwater: A model-based evaluation', Journal of Cleaner Production, vol. 166, pp. 449-457.View/Download from: UTS OPUS or Publisher's site
© 2017 Elsevier Ltd The mobilization of arsenic (As) in aquatic environment (groundwater) can cause severe environmental and healthy issues. To develop remediation strategies, we proposed a comprehensive mathematical model to describe the As removal in a arsenite (As (III)) oxidizing and ferrous iron (Fe (II)) oxidizing denitrifying granular biofilm system. In the model framework, the growth-linked microbial oxidation of As (III) and Fe (II) was coupled to chemolithotrophic denitrification of one-step reduction of nitrate to nitrogen gas. Meanwhile, the precipitation of ferric iron (Fe (III)) and adsorption of arsenate (As (V)) onto the biogenic Fe (III) (hydr)oxides were also considered. The model was calibrated by comparing the model predictions against experimental data from batch experiments. The validity of the model was further demonstrated through testing against long-term experimental results from five independent bioreactors with different reactor configurations and operational conditions. Modeling results revealed that the granule size would exert a limited impact on arsenic and iron removal. Nevertheless, their removal efficiencies increased rapidly with the increase of hydraulic retention time (HRT) from 1 h to 12 h, but became independent of HRT as it further increased. The established model framework enables interpretation of a range of experimental observations on As and Fe removal and helps to identify the optimal conditions for enhanced arsenic remediation.
Peng, L, Sun, J, Liu, Y, Dai, X & Ni, B-J 2017, 'Nitrous Oxide Production in a Granule-based Partial Nitritation Reactor: A Model-based Evaluation.', Scientific Reports, vol. 7, pp. 1-9.View/Download from: UTS OPUS or Publisher's site
Sustainable wastewater treatment has been attracting increasing attentions over the past decades. However, the production of nitrous oxide (N2O), a potent GHG, from the energy-efficient granule-based autotrophic nitrogen removal is largely unknown. This study applied a previously established N2O model, which incorporated two N2O production pathways by ammonia-oxidizing bacteria (AOB) (AOB denitrification and the hydroxylamine (NH2OH) oxidation). The two-pathway model was used to describe N2O production from a granule-based partial nitritation (PN) reactor and provide insights into the N2O distribution inside granules. The model was evaluated by comparing simulation results with N2O monitoring profiles as well as isotopic measurement data from the PN reactor. The model demonstrated its good predictive ability against N2O dynamics and provided useful information about the shift of N2O production pathways inside granules for the first time. The simulation results indicated that the increase of oxygen concentration and granule size would significantly enhance N2O production. The results further revealed a linear relationship between N2O production and ammonia oxidation rate (AOR) (R2 = 0.99) under the conditions of varying oxygen levels and granule diameters, suggesting that bulk oxygen and granule size may exert an indirect effect on N2O production by causing a change in AOR.
Sun, J, Dai, X, Liu, Y, Peng, L & Ni, BJ 2017, 'Sulfide removal and sulfur production in a membrane aerated biofilm reactor: Model evaluation', Chemical Engineering Journal, vol. 309, pp. 454-462.View/Download from: UTS OPUS or Publisher's site
© 2016 Elsevier B.V. Sulfide removal from wastewater is essential, in view of the toxic, malodor and corrosive property of sulfide. The oxidation of sulfide by chemolithotrophic sulfide oxidation bacteria can produce elemental sulfur, an important chemical material. A membrane aerated biofilm reactor (MABR) has been successfully implemented and demonstrated for enhanced sulfide oxidation and sulfur production, owning to its counter-diffusion design of oxygen supply. In this work, a mathematical model was developed to evaluate the sulfide oxidation and sulfur production in the MABR in the presence of residual organics in the influent. The model was calibrated and validated using the experimental data from the long-term operation of the sulfide-oxidation MABR at different operational stages. The results suggested that the developed model could satisfactorily describe sulfide oxidation, sulfur production, sulfate accumulation and organics conversion in the MABR. The modelling results indicated that with the optimal combinations of sulfide loading and oxygen pressure, over 90% of sulfide removal and over 75% of sulfur recovery could be achieved. The sulfide oxidation and sulfur production would also be affected by the biofilm area to reactor volume (A/V) ratio in the MABR, with high A/V ratio might deteriorate the sulfur production efficiency depending on the oxygen pressure applied. Further, the increase of volatile fatty acids in the wastewater would not affect the sulfide oxidation efficiency but could enhance the sulfur production efficiency by decreasing the amount of sulfur oxidized to sulfate.
Sun, J, Dai, X, Peng, L, Liu, Y, Wang, Q & Ni, B-J 2017, 'A biofilm model for assessing perchlorate reduction in a methane-based membrane biofilm reactor', CHEMICAL ENGINEERING JOURNAL, vol. 327, pp. 555-563.View/Download from: UTS OPUS or Publisher's site
Wang, D, Fu, Q, Xu, Q, Liu, Y, Hao Ngo, H, Yang, Q, Zeng, G, Li, X & Ni, B-J 2017, 'Free nitrous acid-based nitrifying sludge treatment in a two-sludge system enhances nutrient removal from low-carbon wastewater.', Bioresource Technology, vol. 244, no. Part 1, pp. 920-928.View/Download from: UTS OPUS or Publisher's site
A new method to enhance nutrient removal from low carbon-wastewater was developed. The method consists of a two-sludge system (i.e., an anaerobic-anoxic-oxic reactor coupled to a nitrifying reactor (N-SBR)) and a nitrifying-sludge treatment unit using free nitrous acid (FNA). Initially, 65.1±2.9% in total nitrogen removal and 69.6±3.4% in phosphate removal were obtained without nitrite accumulation. When 1/16 of the nitrifying sludge was daily treated with FNA at 1.1mgN/L for 24h, ∼28.5% of nitrite was accumulated in the N-SBR, and total nitrogen and phosphate removal increased to 72.4±3.2% and 76.7±2.9%, respectively. About 67.8% of nitrite was accumulated at 1.9mgN/L FNA, resulting in 82.9±3.8% in total nitrogen removal and 87.9±3.5% in phosphate removal. Fluorescence in-situ hybridization analysis showed that FNA treatment reduced the abundance of nitrite oxidizing bacteria (NOB), especially that of Nitrospira sp.
Wang, D, Liu, Y, Ngo, HH, Zhang, C, Yang, Q, Peng, L, He, D, Zeng, G, Li, X & Ni, B-J 2017, 'Approach of describing dynamic production of volatile fatty acids from sludge alkaline fermentation.', Bioresource Technology, vol. 238, pp. 343-351.View/Download from: UTS OPUS or Publisher's site
In this work, a mathematical model was developed to describe the dynamics of fermentation products in sludge alkaline fermentation systems for the first time. In this model, the impacts of alkaline fermentation on sludge disintegration, hydrolysis, acidogenesis, acetogenesis, and methanogenesis processes are specifically considered for describing the high-level formation of fermentation products. The model proposed successfully reproduced the experimental data obtained from five independent sludge alkaline fermentation studies. The modeling results showed that alkaline fermentation largely facilitated the disintegration, acidogenesis, and acetogenesis processes and severely inhibited methanogenesis process. With the pH increase from 7.0 to 10.0, the disintegration, acidogenesis, and acetogenesis processes respectively increased by 53%, 1030%, and 30% while methane production decreased by 3800%. However, no substantial effect on hydrolysis process was found. The model also indicated that the pathway of acetoclastic methanogenesis was more severely inhibited by alkaline condition than that of hydrogentrophic methanogenesis.
Wang, D, Wang, Y, Liu, Y, Ngo, HH, Lian, Y, Zhao, J, Chen, F, Yang, Q, Zeng, G & Li, X 2017, 'Is denitrifying anaerobic methane oxidation-centered technologies a solution for the sustainable operation of wastewater treatment Plants?', Bioresource Technology, vol. 234, pp. 456-465.View/Download from: UTS OPUS or Publisher's site
With the world's increasing energy crisis, society is growingly considered that the operation of wastewater treatment plants (WWTPs) should be shifted in sustainable paradigms with low energy input, or energy-neutral, or even energy output. There is a lack of critical thinking on whether and how new paradigms can be implemented in WWTPs based on the conventional process. The denitrifying anaerobic methane oxidation (DAMO) process, which uses methane and nitrate (or nitrite) as electron donor and acceptor, respectively, has recently been discovered. Based on critical analyses of this process, DAMO-centered technologies can be considered as a solution for sustainable operation of WWTPs. In this review, a possible strategy with DAMO-centered technologies was outlined and illustrated how this applies for the existing WWTPs energy-saving and newly designed WWTPs energy-neutral (or even energy-producing) towards sustainable operations.
Wang, Y, Wang, D, Liu, Y, Wang, Q, Chen, F, Yang, Q, Li, X, Zeng, G & Li, H 2017, 'Triclocarban enhances short-chain fatty acids production from anaerobic fermentation of waste activated sludge.', Water Research, vol. 127, pp. 150-161.View/Download from: UTS OPUS or Publisher's site
Triclocarban (TCC), one typical antibacterial agent being widely used in various applications, was found to be present in waste activated sludge at significant levels. To date, however, its effect on anaerobic fermentation of sludge has not been investigated. This work therefore aims to fill this knowledge gap. Experimental results showed that when TCC content in sludge increased from 26.7 ± 5.3 to 520.5 ± 12.6 mg per kilogram total suspended solids, the maximum concentration of short-chain fatty acids (SCFA) increased from 32.6 ± 2.5 to 228.2 ± 3.6 (without pH control) and from 211.7 ± 2.4 to 378.3 ± 3.2 mg COD/g VSS (initial pH 10), respectively. The large promotion of acetic acid was found to be the major reason for the enhancement of total SCFA production. Although a significant level of TCC was degraded in the fermentation process, SCFA was neither produced from TCC nor affected by its major intermediates at the relevant levels. It was found that TCC facilitated solubilization, acidogenesis, acetogenesis, and homoacetogenesis processes but inhibited methanogenesis process. Microbial analysis revealed that the increase of TCC increased the microbial community diversity, the abundances of SCFA (especially acetic acid) producers, and the activities of key enzymes relevant to acetic acid production.
Xu, Q, Li, X, Ding, R, Wang, D, Liu, Y, Wang, Q, Zhao, J, Chen, F, Zeng, G, Yang, Q & Li, H 2017, 'Understanding and mitigating the toxicity of cadmium to the anaerobic fermentation of waste activated sludge.', Water Research, vol. 124, pp. 269-279.View/Download from: UTS OPUS or Publisher's site
Cadmium (Cd) is present in significant levels in waste activated sludge, but its potential toxicities on anaerobic fermentation of sludge remain largely unknown. This work therefore aims to provide such support. Experimental results showed that the impact of Cd on short-chain fatty acids (SCFA) production from sludge anaerobic fermentation was dose-dependent. The presence of environmentally relevant level of Cd (e.g., 0.1 mg/g VSS) enhanced SCFA production by 10.6%, but 10 mg/g VSS of Cd caused 68.1% of inhibition. Mechanism exploration revealed that although all levels of Cd did not cause extra leakage of intracellular substrates, 0.1 mg/g VSS Cd increased the contents of both soluble and loosely-bound extracellular polymeric substances (EPS), thereby benefitting sludge solubilization. On the contrary, 10 mg/g VSS Cd decreased the levels of all EPS layers, which reduced the content of soluble substrates. It was also found that 0.1 mg/g VSS Cd benefited both the hydrolysis and acidogenesis but 10 mg/g VSS Cd inhibited all the hydrolysis, acidogenesis, and methanogenesis processes. Further investigations with microbial community and enzyme analysis showed that the pertinent presence of Cd enhanced the activities of protease, acetate kinase, and oxaloacetate transcarboxylase whereas 10 mg/g VSS Cd decreased the microbial diversity, the abundances of functional microbes, and the activities of key enzymes. Finally, one strategy that could effectively mitigate the adverse impact of high Cd levels on SCFA production was proposed and examined. This work provides insights into Cd-present sludge fermentation systems, and the findings obtained may guide engineers to manipulate sludge treatment systems in the future.
Ye, Y, Ngo, HH, Guo, W, Liu, Y, Li, J, Liu, Y, Zhang, X & Jia, H 2017, 'Insight into chemical phosphate recovery from municipal wastewater.', Science of the Total Environment, vol. 576, pp. 159-171.View/Download from: UTS OPUS or Publisher's site
Phosphate plays an irreplaceable role in the production of fertilizers. However, its finite availability may not be enough to satisfy increasing demands for the fertilizer production worldwide. In this scenario, phosphate recovery can effectively alleviate this problem. Municipal wastewater has received high priority to recover phosphate because its quantity is considerable. Therefore, phosphate recovery from municipal wastewater can bring many benefits such as relieving the burden of increasing production of fertilizers and reduction in occurrence of eutrophication caused by the excessive concentration of phosphate in the released effluent. The chemical processes are the most widely applied in phosphate recovery in municipal wastewater treatment because they are highly stable and efficient, and simple to operate. This paper compares chemical technologies for phosphate recovery from municipal wastewater. As phosphate in the influent is transferred to the liquid and sludge phases, a technical overview of chemical phosphate recovery in both phases is presented with reference to mechanism, efficiency and the main governing parameters. Moreover, an analysis on their applications at plant-scale is also presented. The properties of recovered phosphate and its impact on crops and plants are also assessed with a discussion on the economic feasibility of the technologies.
Zhao, J, Gui, L, Wang, Q, Liu, Y, Wang, D, Ni, B-J, Li, X, Xu, R, Zeng, G & Yang, Q 2017, 'Aged refuse enhances anaerobic digestion of waste activated sludge', WATER RESEARCH, vol. 123, pp. 724-733.View/Download from: Publisher's site
Zhao, J, Liu, Y, Wang, D, Chen, F, Li, X, Zeng, G & Yang, Q 2017, 'Potential impact of salinity on methane production from food waste anaerobic digestion.', Waste Management, vol. 67, pp. 308-314.View/Download from: UTS OPUS or Publisher's site
Previous studies have demonstrated that the presence of sodium chloride (NaCl) inhibited the production of methane from food waste anaerobic digestion. However, the details of how NaCl affects methane production from food waste remain unknown by now and the efficient approach to mitigate the impact of NaCl on methane production was seldom reported. In this paper, the details of how NaCl affects methane production was first investigated via a series of batch experiments. Experimental results showed the effect of NaCl on methane production was dosage dependent. Low level of NaCl improved the hydrolysis and acidification but inhibited the process of methanogenesis whereas high level of NaCl inhibit both steps of acidification and methanogenesis. Then an efficient approach, i.e. co-digestion of food waste and waste activated sludge, to mitigate the impact of NaCl on methane production was reported. Finally, the mechanisms of how co-digestion mitigates the effect on methane production caused by NaCl in co-digestion system were revealed. These findings obtained in this work might be of great importance for the operation of methane recovery from food waste in the presence of NaCl.
Khan, MA, Ngo, HH, Guo, WS, Liu, Y, Nghiem, LD, Hai, FI, Deng, LJ, Wang, J & Wu, Y 2016, 'Optimization of process parameters for production of volatile fatty acid, biohydrogen and methane from anaerobic digestion', BIORESOURCE TECHNOLOGY, vol. 219, pp. 738-748.View/Download from: UTS OPUS or Publisher's site
Khan, MA, Ngo, HH, Guo, WS, Liu, YW, Zhou, JL, Zhang, J, Liang, S, Ni, BJ, Zhang, XB & Wang, J 2016, 'Comparing the value of bioproducts from different stages of anaerobic membrane bioreactors', Bioresource Technology, vol. 214, pp. 816-825.View/Download from: UTS OPUS or Publisher's site
Abstract The anaerobic digestion process in anaerobic membrane bioreactors is an effective way for waste management, energy sustainability and pollution control in the environment. This digestion process basically involves the production of volatile fatty acids and biohydrogen as intermediate products and methane as a final product. This paper compares the value of bioproducts from different stages of anaerobic membrane bioreactors through a thorough assessment. The value was assessed in terms of technical feasibility, economic assessment, environmental impact and impact on society. Even though the current research objective is more inclined to optimize the production of methane, the intermediate products could also be considered as economically attractive and environment friendly options. Hence, this is the first review study to correlate the idea into an anaerobic membrane bioreactor which is expected to guide future research pathways regarding anaerobic process and its bioproducts.
Chen, H, Liu, Y, Ni, B-J, Wang, Q, Wang, D, Zhang, C, Li, X & Zeng, G 2016, 'Full-scale evaluation of aerobic/extended-idle regime inducing biological phosphorus removal and its integration with intermittent sand filter to treat domestic sewage discharged from highway rest area', BIOCHEMICAL ENGINEERING JOURNAL, vol. 113, pp. 114-122.View/Download from: Publisher's site
Chen, X, Liu, Y, Peng, L, Yuan, Z & Ni, B-J 2016, 'Model-Based Feasibility Assessment of Membrane Biofilm Reactor to Achieve Simultaneous Ammonium, Dissolved Methane, and Sulfide Removal from Anaerobic Digestion Liquor', SCIENTIFIC REPORTS, vol. 6.View/Download from: UTS OPUS or Publisher's site
Gao, SH, Peng, L, Liu, Y, Zhou, X, Ni, BJ, Bond, PL, Liang, B & Wang, AJ 2016, 'Bioelectrochemical reduction of an azo dye by a Shewanella oneidensis MR-1 formed biocathode', International Biodeterioration and Biodegradation, vol. 115, pp. 250-256.View/Download from: Publisher's site
© 2016 Elsevier Ltd Presently there is great interest to develop pure culture cathodes in bioelectrochemical systems (BES) for achieving decolorization/reduction of azo dyes. In this study, we investigated the decolorization of a model azo dye, acid orange 7 (AO7) in a biocathode inoculated with a model electrogenic microorganism Shewanella oneidensis MR-1 (MR-1). The decolorization efficiency of AO7 reached 95.8 ± 4.6%, 86.4 ± 2.0%, and 77.8 ± 1.0% in 46 h in the biocathode fed with lactate, in the biocathode without lactate, and in the abiotic cathode respectively. Thus, enhanced decolorization of AO7 occurred in the biocathode, compared to the abiotic cathode, regardless of the presence of lactate. To further investigate the AO7 reduction mechanism and electron transfer between the electrode and S. oneidensis, the cathode potential was controlled such that hydrogen was not produced. In the absence of lactate, the AO7 decolorization efficiency (78.5 ± 0.8%) and sulfanilic acid (SA) production efficiency (70.9 ± 1.5%) in the biocathode were higher than the AO7 decolorization efficiency (63.7 ± 3.6%) and the SA production (56.1 ± 1.9%) efficiency in the abiotic cathode. This suggests that the reduction of AO7, with electrode as the sole electron donor, was enhanced by electron transfer between the cathode and the S. oneidensis formed biofilm on the cathode surface. This study demonstrated that S. oneidensis enhanced the capture of electrons from the cathode electrode for the reduction of the organic pollutant AO7.
Li, Y, Zhang, Y, Liu, Y, Zhao, Z, Zhao, Z, Liu, S, Zhao, H & Quan, X 2016, 'Enhancement of anaerobic methanogenesis at a short hydraulic retention time via bioelectrochemical enrichment of hydrogenotrophic methanogens', BIORESOURCE TECHNOLOGY, vol. 218, pp. 505-511.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Ngo, HH, Guo, W, Peng, L, Pan, Y, Guo, J, Chen, X & Ni, B-J 2016, 'Autotrophic nitrogen removal in membrane-aerated biofilms: Archaeal ammonia oxidation versus bacterial ammonia oxidation', CHEMICAL ENGINEERING JOURNAL, vol. 302, pp. 535-544.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Peng, L, Ngo, HH, Guo, W, Wang, D, Pan, Y, Sun, J & Ni, B-J 2016, 'Evaluation of Nitrous Oxide Emission from Sulfide- and Sulfur-Based Autotrophic Denitrification Processes', ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 50, no. 17, pp. 9407-9415.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Sun, J, Peng, L, Wang, D, Dai, X & Ni, B-J 2016, 'Assessment of Heterotrophic Growth Supported by Soluble Microbial Products in Anammox Biofilm using Multidimensional Modeling', SCIENTIFIC REPORTS, vol. 6.View/Download from: Publisher's site
Liu, Y, Tugtas, AE, Sharma, KR, Ni, B-J & Yuan, Z 2016, 'Sulfide and methane production in sewer sediments: Field survey and model evaluation', Water Research, vol. 89, pp. 142-150.View/Download from: UTS OPUS or Publisher's site
Sewer sediment processes have been reported to significantly contribute to overall sulfide and methane production in sewers, at a scale comparable to that of sewer biofilms. The physiochemical and biological characteristics of sewer sediments are heterogeneous; however, the variability of in-sediments sulfide and methane production rates among sewers has not been assessed to date. In this study, five sewer sediment samples were collected from two cities in Australia with different climatic conditions. Batch assays were conducted to determine the rates of sulfate reduction and methane production under different flow velocity (shear stress) conditions as well as under completely mixed conditions. The tests showed substantial and variable sulfate reduction and methane production activities among different sediments. Sulfate reduction and methane production from sewer sediments were confirmed to be areal processes, and were dependent on flow velocity/shear stress. Despite of the varying characteristics and reactions kinetics, the sulfate reduction and methane production processes in all sediments could be well described by a one-dimensional sewer sediment model recently developed based on results obtained from a laboratory sewer sediment reactor. Model simulations indicated that the in-situ contribution of sewer sediment emissions could be estimated without the requirement of measuring the specific sediment characteristics or the sediment depths.
Pan, Y, Ni, B-J, Liu, Y & Guo, J 2016, 'Modeling of the interaction among aerobic ammonium-oxidizing archaea/bacteria and anaerobic ammonium-oxidizing bacteria', CHEMICAL ENGINEERING SCIENCE, vol. 150, pp. 35-40.View/Download from: UTS OPUS or Publisher's site
Peng, L, Liu, Y & Ni, B-J 2016, 'Nitrous oxide production in completely autotrophic nitrogen removal biofilm process: A simulation study', CHEMICAL ENGINEERING JOURNAL, vol. 287, pp. 217-224.View/Download from: UTS OPUS or Publisher's site
Peng, L, Liu, Y, Gao, S-H, Chen, X & Ni, B-J 2016, 'Evaluating simultaneous chromate and nitrate reduction during microbial denitrification processes', WATER RESEARCH, vol. 89, pp. 1-8.View/Download from: UTS OPUS or Publisher's site
Peng, L, Sun, J, Liu, Y, Dai, X & Ni, B-J 2016, 'Nitrous Oxide Production in Co-Versus Counter-Diffusion Nitrifying Biofilms', SCIENTIFIC REPORTS, vol. 6.View/Download from: UTS OPUS or Publisher's site
Ye, Y, Huu, HN, Guo, W, Liu, Y, Zhang, X, Guo, J, Ni, B-J, Chang, SW & Dinh, DN 2016, 'Insight into biological phosphate recovery from sewage', BIORESOURCE TECHNOLOGY, vol. 218, pp. 874-881.View/Download from: UTS OPUS or Publisher's site
Zhao, J, Liu, Y, Ni, B, Wang, Q, Wang, D, Yang, Q, Sun, Y, Zeng, G & Li, X 2016, 'Combined Effect of Free Nitrous Acid Pretreatment and Sodium Dodecylbenzene Sulfonate on Short-Chain Fatty Acid Production from Waste Activated Sludge', SCIENTIFIC REPORTS, vol. 6.View/Download from: Publisher's site
Zhu, T, Zhang, Y, Bu, G, Quan, X & Liu, Y 2016, 'Producing nitrite from anodic ammonia oxidation to accelerate anammox in a bioelectrochemical system with a given anode potential', CHEMICAL ENGINEERING JOURNAL, vol. 291, pp. 184-191.View/Download from: UTS OPUS or Publisher's site
Chen, X, Guo, J, Xie, G-J, Liu, Y, Yuan, Z & Ni, B-J 2015, 'A new approach to simultaneous ammonium and dissolved methane removal from anaerobic digestion liquor: A model-based investigation of feasibility', WATER RESEARCH, vol. 85, pp. 295-303.View/Download from: UTS OPUS or Publisher's site
Feng, Y, Liu, Y & Zhang, Y 2015, 'Enhancement of sludge decomposition and hydrogen production from waste activated sludge in a microbial electrolysis cell with cheap electrodes', ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY, vol. 1, no. 6, pp. 761-768.View/Download from: Publisher's site
Liu, Y & Ni, B-J 2015, 'Appropriate Fe (II) Addition Significantly Enhances Anaerobic Ammonium Oxidation (Anammox) Activity through Improving the Bacterial Growth Rate', SCIENTIFIC REPORTS, vol. 5.View/Download from: Publisher's site
Liu, Y, Peng, L, Chen, X & Ni, B-J 2015, 'Mathematical Modeling of Nitrous Oxide Production during Denitrifying Phosphorus Removal Process', ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 49, no. 14, pp. 8595-8601.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Peng, L, Gao, S-H, Dai, X & Ni, B-J 2015, 'Mathematical modeling of microbial extracellular electron transfer by electrically active microorganisms', ENVIRONMENTAL SCIENCE-WATER RESEARCH & TECHNOLOGY, vol. 1, no. 6, pp. 747-752.View/Download from: Publisher's site
Liu, Y, Peng, L, Guo, J, Chen, X, Yuan, Z & Ni, B-J 2015, 'Evaluating the Role of Microbial Internal Storage Turnover on Nitrous Oxide Accumulation During Denitrification', SCIENTIFIC REPORTS, vol. 5.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Sharma, KR, Fluggen, M, O'Halloran, K, Murthy, S & Yuan, Z 2015, 'Online dissolved methane and total dissolved sulfide measurement in sewers', WATER RESEARCH, vol. 68, pp. 109-118.View/Download from: Publisher's site
Liu, Y, Sharma, KR, Ni, B-J, Fan, L, Murthy, S, Tyson, GQ & Yuan, Z 2015, 'Effects of nitrate dosing on sulfidogenic and methanogenic activities in sewer sediment', WATER RESEARCH, vol. 74, pp. 155-165.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Wang, Q, Zhang, Y & Ni, B-J 2015, 'Zero Valent Iron Significantly Enhances Methane Production from Waste Activated Sludge by Improving Biochemical Methane Potential Rather Than Hydrolysis Rate', SCIENTIFIC REPORTS, vol. 5.View/Download from: Publisher's site
Liu, Y, Zhang, Y & Ni, B-J 2015, 'Evaluating Enhanced Sulfate Reduction and Optimized Volatile Fatty Acids (VFA) Composition in Anaerobic Reactor by Fe (III) Addition', Environmental Science and Technology, vol. 49, no. 4, pp. 2123-2131.View/Download from: UTS OPUS or Publisher's site
Anaerobic reactors with ferric iron addition have been experimentally demonstrated to be able to simultaneously improve sulfate reduction and organic matter degradation during sulfate-containing wastewater treatment. In this work, a mathematical model is developed to evaluate the impact of ferric iron addition on sulfate reduction and organic carbon removal as well as the volatile fatty acids (VFA) composition in anaerobic reactor. The model is successfully calibrated and validated using independent long-term experimental data sets from the anaerobic reactor with Fe (III) addition under different operational conditions. The model satisfactorily describes the sulfate reduction, organic carbon removal and VFA production. Results show Fe (III) addition induces the microbial reduction of Fe (III) by iron reducing bacteria (IRB), which significantly enhances sulfate reduction by sulfate reducing bacteria (SRB) and subsequently changes the VFA composition to acetate-dominating effluent. Simultaneously, the produced Fe (II) from IRB can alleviate the inhibition of undissociated H2S on microorganisms through iron sulfide precipitation, resulting in further improvement of the performance. In addition, the enhancement on reactor performance by Fe (III) is found to be more significantly favored at relatively low organic carbon/SO42– ratio (e.g., 1.0) than at high organic carbon/SO42– ratio (e.g., 4.5). The Fe (III)-based process of this work can be easily integrated with a commonly used strategy for phosphorus recovery, with the produced sulfide being recovered and then deposited into conventional chemical phosphorus removal sludge (FePO4) to achieve FeS precipitation for phosphorus recovery while the required Fe (III) being acquired from the waste ferric sludge of drinking water treatment process, to enable maximum resource recovery/reuse while achieving high-rate sulfate removal.
Liu, Y, Zhang, Y & Ni, B-J 2015, 'Zero valent iron simultaneously enhances methane production and sulfate reduction in anaerobic granular sludge reactors', WATER RESEARCH, vol. 75, pp. 292-300.View/Download from: UTS OPUS or Publisher's site
Peng, L, Chen, X, Xu, Y, Liu, Y, Gao, S-H & Ni, B-J 2015, 'Biodegradation of pharmaceuticals in membrane aerated biofilm reactor for autotrophic nitrogen removal: A model-based evaluation', JOURNAL OF MEMBRANE SCIENCE, vol. 494, pp. 39-47.View/Download from: Publisher's site
Peng, L, Liu, Y, Gao, S-H, Chen, X, Xin, P, Dai, X & Ni, B-J 2015, 'Evaluation on the Nanoscale Zero Valent Iron Based Microbial Denitrification for Nitrate Removal from Groundwater', SCIENTIFIC REPORTS, vol. 5.View/Download from: UTS OPUS or Publisher's site
Peng, L, Liu, Y, Gao, S-H, Dai, X & Ni, B-J 2015, 'Assessing chromate reduction by dissimilatory iron reducing bacteria using mathematical modeling', Chemosphere, vol. 139, pp. 334-339.View/Download from: UTS OPUS or Publisher's site
Chromate (Cr (VI)) is a ubiquitous contaminant in aquifers and soils, which can be reduced to its trivalent counterpart (Cr (III)), with the hazard being relieved. The coupling microbial and chemical reduction by dissimilatory iron reducing bacteria (IRB) is a promising approach for the reduction of Cr (VI) to Cr (III). In this work, three mathematical models with different Cr (VI) reduction pathways were proposed and compared based on their ability to predict the performance of an IRB-based stirred-flow reactor treating Cr (VI) contaminated medium and to provide insights into the possible chemical or microbial pathways for Cr (VI) reduction in the system. The Cr (VI) reduction was considered as chemical reaction between Fe (II) and Cr (VI), direct microbial reduction by IRB and combined biotic–abiotic reduction in these three models, respectively. Model evaluation results indicated that the model incorporating both chemical and microbial Cr (VI) reductions could well describe the system performance. In contrast, the other two single-pathway models were not capable of predicting the experimental data, suggesting that both chemical and microbial pathways contributed to Cr (VI) reduction by IRB. The validity of the two-pathway model was further confirmed by an independent experimental data set with different conditions. The results further revealed that the organic carbon availability and Cr (VI) loading rates for the IRB in the system determined the relative contributions of chemical and microbial pathways to overall Cr (VI) reduction.
Methane is a highly potent greenhouse gas and contributes significantly to climate change. Recent studies have shown significant methane production in sewers. The studies conducted so far have relied on manual sampling followed by off-line laboratory-based chromatography analysis. These methods are labor-intensive when measuring methane emissions from a large number of sewers, and do not capture the dynamic variations in methane production. In this study, we investigated the suitability of infrared spectroscopy-based on-line methane sensors for measuring methane in humid and condensing sewer air. Two such sensors were comprehensively tested in the laboratory. Both sensors displayed high linearity (R2 > 0.999), with a detection limit of 0.023% and 0.110% by volume, respectively. Both sensors were robust against ambient temperature variations in the range of 5 to 35°C. While one sensor was robust against humidity variations, the other was found to be significantly affected by humidity. However, the problem was solved by equipping the sensor with a heating unit to increase the sensor surface temperature to 35°C. Field studies at three sites confirmed the performance and accuracy of the sensors when applied to actual sewer conditions, and revealed substantial and highly dynamic methane concentrations in sewer air.
Liu, Y, Zhang, Y, Quan, X, Li, Y, Zhao, Z, Meng, X & Chen, S 2012, 'Optimization of anaerobic acidogenesis by adding Fe0 powder to enhance anaerobic wastewater treatment', Chemical Engineering Journal, vol. 192, pp. 179-185.View/Download from: UTS OPUS or Publisher's site
Acidogenesis is responsible to convert complex organics into volatile fatty acids (VFA), whose metabolic rate and production type have important effects on the whole anaerobic digestion. A novel strategy for enhancing anaerobic wastewater treatment via dosing Fe powder (40g) in an acidogenic reactor (2L) is described. The results showed that the hydrolysis/fermentation was accelerated by Fe dosing. As a result, the acidogenic performances in COD removal (45-56%) and VFA production (1170-1340mg/L) were less affected by shortened hydraulic retention time (HRT) from 6 to 2h. However, COD removal declined to 25% and VFA production decreased to 661mg/L in a reference reactor without Fe 0 dosing (A2). Besides, Fe 0 dosing optimized fermentation type, namely, the production of propionate was decreased, which was favorable for subsequent acetogenesis and methanogenesis. Fluorescence in situ hybridization (FISH) analysis indicated that Fe 0 dosing increased the abundance of acidogens, especially acetogens. The methanogenic reactor fed with the effluent of A1 had higher COD removal and treatment stability with almost no propionate detected. These results suggested that the enhancement of acidification by Fe 0 powder dosing was helpful to accelerate and improve anaerobic acidogenesis to create a favorable feeding condition for the subsequent treatment. © 2012 Elsevier B.V..
Liu, Y, Zhang, Y, Zhao, Z, Li, Y, Quan, X & Chen, S 2012, 'Enhanced azo dye wastewater treatment in a two-stage anaerobic system with Fe-0 dosing', BIORESOURCE TECHNOLOGY, vol. 121, pp. 148-153.View/Download from: UTS OPUS or Publisher's site
Zhang, Y, Liu, Y, Jing, Y, Zhao, Z & Quan, X 2012, 'Steady performance of a zero valent iron packed anaerobic reactor for azo dye wastewater treatment under variable influent quality', JOURNAL OF ENVIRONMENTAL SCIENCES, vol. 24, no. 4, pp. 720-727.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Zhang, Y, Quan, X, Chen, S & Zhao, H 2011, 'Applying an electric field in a built-in zero valent iron - Anaerobic reactor for enhancement of sludge granulation', WATER RESEARCH, vol. 45, no. 3, pp. 1258-1266.View/Download from: UTS OPUS or Publisher's site
Liu, Y, Zhang, Y, Quan, X, Zhang, J, Zhao, H & Chen, S 2011, 'Effects of an electric field and zero valent iron on anaerobic treatment of azo dye wastewater and microbial community structures', BIORESOURCE TECHNOLOGY, vol. 102, no. 3, pp. 2578-2584.View/Download from: UTS OPUS or Publisher's site
Zhang, J, Zhang, Y, Quan, X, Liu, Y, An, X, Chen, S & Zhao, H 2011, 'Bioaugmentation and functional partitioning in a zero valent iron-anaerobic reactor for sulfate-containing wastewater treatment', CHEMICAL ENGINEERING JOURNAL, vol. 174, no. 1, pp. 159-165.View/Download from: UTS OPUS or Publisher's site
Peng, L, Liu, Y, Sun, J & Ni, BJ 2017, 'Microbial remediation of chromium-contaminated wastes' in Handbook of Metal-Microbe Interactions and Bioremediation, pp. 689-706.View/Download from: Publisher's site
© 2017 by Taylor & Francis Group, LLC. Cr(VI) and Cr(III) are the two most ubiquitous forms of chromium. The remediation of chromium contaminant is primarily dependent on transformation from highly toxic and mobile Cr(VI) to insoluble Cr(III) with less toxicity. Biological Cr(VI) removal is not only a promising method but also a very complicated process. This chapter introduces various remediation processes, highlights important Cr(VI)-reducing microorganisms, and reveals underlying mechanisms for bacterial Cr(VI) resistance and reduction. The assessment of key factors limiting and influencing bacterial growth and chromium removal along with reviews on mathematical modeling tended to facilitate further application of microbial Cr(VI) removal in the bench scale, pilot scale, and in situ studies under a wide array of environmental conditions.