Nguyen, LN, Commault, AS, Kahlke, T, Ralph, PJ, Semblante, GU, Johir, MAH & Nghiem, LD 2020, 'Genome sequencing as a new window into the microbial community of membrane bioreactors - A critical review.', Science of the Total Environment, vol. 704, pp. 135279-135279.View/Download from: Publisher's site
Recent developed sequencing techniques have resulted in a new and unprecedented way to study biological wastewater treatment, in which most organisms are uncultivable. This review provides (i) an insight on state-of-the-art sequencing techniques and their limitations; (ii) a critical assessment of the microbial community in biological reactor and biofouling layer in a membrane bioreactor (MBR). The data from high-throughput sequencing has been used to infer microbial growth conditions and metabolisms of microorganisms present in MBRs at the time of sampling. These data shed new insight to two fundamental questions about a microbial community in the MBR process namely the microbial composition (who are they?) and the functions of each specific microbial assemblage (what are their function?). The results to date also highlight the complexity of the microbial community growing on MBRs. Environmental conditions are dynamic and diverse, and can influence the diversity and structural dynamics of any given microbial community for wastewater treatment. The benefits of understanding the structure of microbial communities on three major aspects of the MBR process (i.e. nutrient removal, biofouling control, and micropollutant removal) were symmetrically delineated. This review also indicates that the deployment of microbial community analysis for a practical engineering context, in terms of process design and system optimization, can be further realized.
Ryu, S, Naidu, G, Johir, MAH, Choi, Y, Jeong, S & Vigneswaran, S 2019, 'Acid mine drainage treatment by integrated submerged membrane distillation–sorption system', Chemosphere, vol. 218, pp. 955-965.View/Download from: Publisher's site
Acid mine drainage (AMD), an acidic effluent characterized by high concentrations of sulfate and heavy metals, is an environmental and economic concern. The performance of an integrated submerged direct contact membrane distillation (DCMD) – zeolite sorption system for AMD treatment was evaluated. The results showed that modified (heat treated) zeolite achieved 26–30% higher removal of heavy metals compared to natural untreated zeolite. Heavy metal sorption by heat treated zeolite followed the order of Fe > Al > Zn > Cu > Ni and the data fitted well to Langmuir and pseudo second order kinetics model. Slight pH adjustment from 2 to 4 significantly increased Fe and Al removal rate (close to 100%) due to a combination of sorption and partial precipitation. An integrated system of submerged DCMD with zeolite for AMD treatment enabled to achieve 50% water recovery in 30 h. The integrated system provided a favourable condition for zeolite to be used in powder form with full contact time. Likewise, heavy metal removal from AMD by zeolite, specifically Fe and Al, mitigated membrane fouling on the surface of the hollow fiber submerged membrane. The integrated system produced high quality fresh water while concentrating sulfuric acid and valuable heavy metals (Cu, Zn and Ni).
Jo, Y, Johir, MAH, Cho, Y, Naidu, G, Rice, SA, McDougald, D, Kandasamy, J, Vigneswaran, S & Sun, S 2019, 'A comparative study on nitric oxide and hypochlorite as a membrane cleaning agent to minimise biofilm growth in a membrane bioreactor (MBR) process', Biochemical Engineering Journal, vol. 148, pp. 9-15.View/Download from: Publisher's site
© 2019 Elsevier B.V. Reverse osmosis concentrates (ROC) produced from water reclamation plants can threaten the environment if it is not appropriately treated before discharge. A membrane bioreactor (MBR) process to treat ROC was used in this project. In an MBR, fouling is an essential and inevitable phenomenon which leads to higher operational and capital costs. A comparative study on chemical cleaning, such as sodium hypochlorite (NaOCl) and nitric oxide (NO), was experimentally evaluated together with the influence of filtration flux. Exposure to a low concentration of NO reduced biofilms in an MBR system. NO treatment delayed the formation of new biofilm biomass on the membrane. NO also showed good performance in reducing membrane fouling and had no adverse effect on activated sludge and the environment. In MBR, the bacterial community was dominated by Proteobacteria (61%), with Alpha and Beta-proteobacteria representing approximately 54% of the community. After NO treatment, the relative abundance of the Proteobacteria decreased to 44%, and this was also reflected in a reduction in Alpha and Beta-proteobacteria, to 30% and 5% respectively. Thus, NO treatment resulted in the decrease of the relative biofilms associated with reduced MBR performance.
Ryu, S, Naidu, G, Hasan Johir, MA, Choi, Y, Jeong, S & Vigneswaran, S 2019, 'Acid mine drainage treatment by integrated submerged membrane distillation-sorption system.', Chemosphere, vol. 218, pp. 955-965.View/Download from: Publisher's site
Acid mine drainage (AMD), an acidic effluent characterized by high concentrations of sulfate and heavy metals, is an environmental and economic concern. The performance of an integrated submerged direct contact membrane distillation (DCMD) - zeolite sorption system for AMD treatment was evaluated. The results showed that modified (heat treated) zeolite achieved 26-30% higher removal of heavy metals compared to natural untreated zeolite. Heavy metal sorption by heat treated zeolite followed the order of Fe > Al > Zn > Cu > Ni and the data fitted well to Langmuir and pseudo second order kinetics model. Slight pH adjustment from 2 to 4 significantly increased Fe and Al removal rate (close to 100%) due to a combination of sorption and partial precipitation. An integrated system of submerged DCMD with zeolite for AMD treatment enabled to achieve 50% water recovery in 30 h. The integrated system provided a favourable condition for zeolite to be used in powder form with full contact time. Likewise, heavy metal removal from AMD by zeolite, specifically Fe and Al, mitigated membrane fouling on the surface of the hollow fiber submerged membrane. The integrated system produced high quality fresh water while concentrating sulfuric acid and valuable heavy metals (Cu, Zn and Ni).
Ahmed, MB, Hasan Johir, MA, Zhou, JL, Ngo, HH, Nghiem, LD, Richardson, C, Moni, MA & Bryant, MR 2019, 'Activated carbon preparation from biomass feedstock: Clean production and carbon dioxide adsorption', Journal of Cleaner Production, vol. 225, pp. 405-413.View/Download from: Publisher's site
© 2019 Elsevier Ltd The current methods used for the production of activated carbon (AC) are often chemical and energy intensive and produce significant amount of chemical waste. Thus, clean production of AC is important to reduce its overall production cost and to limit the adverse effect on the environment. Therefore, the main aim of this study is to develop a clean method for AC production from woody biomass with low chemical consumption. Herein, this study reports a facile strategy for reducing chemical usages in the production of high-performance AC, by introducing a crucial pre-pyrolysis step before chemical activation of biomass. The ACs prepared were characterised using scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen and carbon dioxide gas adsorption measurements. All these characterisations indicated that produced ACs have similar physicochemical properties. The strategy reduced chemical use by 70% and produced high-performance ultra-microporous ACs with excellent carbon dioxide adsorption capacity (4.22–5.44 mmol m −2 ). The facile pre-pyrolysis method is recommended for further research as a cleaner activated carbon preparation method from biomass feedstock.
Nguyen, LN, Nguyen, AQ, Johir, MAH, Guo, W, Ngo, HH, Chaves, AV & Nghiem, LD 2019, 'Application of rumen and anaerobic sludge microbes for bio harvesting from lignocellulosic biomass.', Chemosphere, vol. 228, pp. 702-708.View/Download from: Publisher's site
This study investigated the production of biogas, volatile fatty acids (VFAs), and other soluble organic from lignocellulosic biomass by two microbial communities (i.e. rumen fluid and anaerobic sludge). Four types of abundant lignocellulosic biomass (i.e. wheat straw, oaten hay, lurence hay and corn silage) found in Australia were used. The results show that rumen microbes produced four-time higher VFAs level than that of anaerobic sludge reactors, indicating the possible application of rumen microorganism for VFAs generation from lignocellulosic biomass. VFA production in the rumen fluid reactors was probably due to the presence of specific hydrolytic and acidogenic bacteria (e.g. Fibrobacter and Prevotella). VFA production corroborated from the observation of pH drop in the rumen fluid reactors indicated hydrolytic and acidogenic inhibition, suggesting the continuous extraction of VFAs from the reactor. Anaerobic sludge reactors on the other hand, produced more biogas than that of rumen fluid reactors. This observation was consistent with the abundance of methanogens in anaerobic sludge inoculum (3.98% of total microbes) compared to rumen fluid (0.11%). VFA production from lignocellulosic biomass is the building block chemical for bioplastic, biohydrogen and biofuel. The results from this study provide important foundation for the development of engineered systems to generate VFAs from lignocellulosic biomass.
Areerachakul, N, Sakulkhaemaruethai, S, Johir, MAH, Kandasamy, J & Vigneswaran, S 2019, 'Photocatalytic degradation of organic pollutants from wastewater using aluminium doped titanium dioxide', Journal of Water Process Engineering, vol. 27, pp. 177-184.View/Download from: Publisher's site
© 2018 Elsevier Ltd The objective of this research was to study the performance of batch and continuous recirculating reactor to photo-degrade dye and synthetic wastewater. Here, Aluminium (Al) was used as the doped metal. The commercially available TiO2 P-25 and Al (NO3)3 was used as a Ti-precursor and doping agent, respectively, via the impregnation method. Various parameters such as the concentration of the doping agent, and calcination temperature were studied. The TiO2 nanocrystal doped with Al was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analyzer (TGA). The photocatalytic performance of Al-doped nanoparticle was quantified by the degradation of methylene blue (MB) solution under a visible light irradiation condition. Its performance was compared against undoped-nano-TiO2. The results showed that Al(NO3)3 solution with a concentration of 0.25% and volume of 100 cm/ml, and calcined at 300 ๐C for 4 h, was the optimum condition of Al-doped nano-TiO2. Furthermore, the highest pseudo-first-order kinetic rate was 0.096 where the doped Al(NO3)3 of 0.75 w/v was used in the batch reactor. The Al-doped nano-TiO2 that was obtained has the potential for use as a photocatalyst for degradation organics pollutant from wastewater under the visible light irradiation. The highest removal of organic pollutants from synthetic wastewater was 75% using TiO2 P-25 alone at 2 g/L dosage. In addition, the removal of organic pollutant by TiO2/doped with Al was 80% at a dosage of 0.5 g/L and was 85% at a dosage of 1 g/L.
Ekanayake, D, Aryal, R, Johir, M, Loganathan, P, Bush, C, Kandasamy, J & Vigneswaran, S 2019, 'Interrelationship among the pollutants in stormwater in an urban catchment and first flush identification using UV spectroscopy.', Chemosphere, vol. 233, pp. 245-251.View/Download from: Publisher's site
Assessing urban stormwater quality by investigation and characterisation of pollutants is a prerequisite for its effective management, for reuse and safe discharge. The stochastic nature of rainfall, dry weather periods, topology, human activities and climatic conditions generate and wash-off pollutants differently from event to event. This study investigated the major physico-chemical pollutants in stormwater runoff collected from an urban catchment over a period of two years. The aim of this study was to explore the use of UV spectroscopy to identify the first flush. In this study, the variation of pollutants during the passage of a rain event and the relationships among the measured pollutants was analysed to help broaden the application of UV spectroscopy beyond the detection of organic matter. Correlation analysis and principal component analysis (PCA) were performed to identify the possible relationship among measured pollutants. Although correlation analysis revealed some relationships between pollutants, in general they were not strong enough and was not helpful. PCA biplots suggested a few groups and revealed that the two components model could explain nearly 72% of the variability between pollutants. Pollutants in the group that included dissolved organic carbon (DOC) behaved in a similar manner. UV spectroscopy was applied to identify the first flush by comparing the recorded spectrum of consecutive samples that were collected in an event. Analysis of the spectra was able to isolate the point when first flush ends for DOC and pollutants that behave similar to it.
Kalaruban, M, Loganathan, P, Nguyen, TV, Nur, T, Hasan Johir, MA, Nguyen, TH, Trinh, MV & Vigneswaran, S 2019, 'Iron-impregnated granular activated carbon for arsenic removal: Application to practical column filters.', Journal of Environmental Management, vol. 239, pp. 235-243.View/Download from: Publisher's site
Arsenic is a major drinking water contaminant in many countries causing serious health hazards, and therefore, attempts are being made to remove it so that people have safe drinking water supplies. The effectiveness of arsenic removal from As(V) solutions using granular activated carbon (GAC) (zero point of charge (ZPC) pH 3.2) and iron incorporated GAC (GAC-Fe) (ZPC pH 8.0) was studied at 25 ± 1 °C. The batch study confirmed that GAC-Fe had higher Langmuir adsorption capacity at pH 6 (1.43 mg As/g) than GAC (1.01 mg As/g). Adsorption data of GAC-Fe fitted the Freundlich model better than the Langmuir model, thus indicating the presence of heterogeneous adsorption sites. Weber and Morris plots of the kinetic adsorption data suggested intra-particle diffusion into meso and micro pores in GAC. The column adsorption study revealed that 2-4 times larger water volumes can be treated by GAC-Fe than GAC, reducing the arsenic concentration from 100 μg/L to the WHO guideline of 10 μg/L. The volume of water treated increased with a decrease in flow velocity and influent arsenic concentration. The study indicates the high potential of GAC-Fe to remove arsenic from contaminated drinking waters in practical column filters.
Nur, T, Loganathan, P, Ahmed, MB, Johir, MAH, Tien, VN & Vigneswaran, S 2019, 'Removing arsenic from water by coprecipitation with iron: Effect of arsenic and iron concentrations and adsorbent incorporation', CHEMOSPHERE, vol. 226, pp. 431-438.View/Download from: Publisher's site
Volpin, F, Heo, H, Johir, M, Cho, J, Phuntsho, S & Shon, HK 2019, 'Techno-economic feasibility of recovering phosphorus, nitrogen and water from dilute human urine via forward osmosis.', Water research, vol. 150, pp. 47-55.View/Download from: Publisher's site
Due to high phosphorus (P) and nitrogen (N) content, human urine has often proven to suitable raw material for fertiliser production. However, most of the urine diverting toilets or male urinals dilute the urine 2 to 10 times. This decreases the efficiency in the precipitation of P and stripping of N. In this work, a commercial fertiliser blend was used as forward osmosis (FO) draw solution (DS) to concentrate real diluted urine. During the concentration, the urea in the urine is recovered as it diffuses to the fertiliser. Additionally, the combination of concentrate PO43-, reverse Mg2+ flux from the DS and the Mg2+ presents in the flushing water, was able to recover the PO43- as struvite. With 50% concentrated urine, 93% P recovery was achieved without the addition of an external Mg2+. Concurrently, 50% of the N was recovered in the diluted fertiliser DS. An economic analysis was performed to understand the feasibility of this process. It was found that the revenue from the produced fertilisers could potentially offset the operational and capital costs of the system. Additionally, if the reduction in the downstream nutrients load is accounted for, the total revenue of the process would be over 5.3 times of the associated costs.
Nguyen, LN, Commault, AS, Johir, MAH, Bustamante, H, Aurisch, R, Lowrie, R & Nghiem, LD 2019, 'Application of a novel molecular technique to characterise the effect of settling on microbial community composition of activated sludge.', Journal of environmental management, vol. 251.View/Download from: Publisher's site
Activated sludge (AS) and return activated sludge (RAS) microbial communities from three full-scale municipal wastewater treatment plants (denoted plant A, B and C) were compared to assess the impact of sludge settling (i.e. gravity thickening in the clarifier) and profile microorganisms responsible for nutrient removal and reactor foaming. The results show that all three plants were dominated with microbes in the phyla of Proteobacteria, Bacteroidetes, Verrucomicrobia, Actinobacteria, Chloroflexi, Firmicutes, Nitrospirae, Spirochaetae, Acidobacteria and Saccharibacteria. AS and RAS shared above 80% similarity in the microbial community composition, indicating that sludge thickening does not significantly alter the microbial composition. Autotrophic and heterotrophic nitrifiers were present in the AS. However, the abundance of autotrophic nitrifiers was significantly lower than that of the heterotrophic nitrifiers. Thus, ammonium removal at these plants was achieved mostly by heterotrophic nitrification. Microbes that can cause foaming were at 3.2% abundance, and this result is well corroborated with occasional aerobic biological reactor foaming. By contrast, these microbes were not abundant (<2.1%) at plant A and C, where aerobic biological reactor foaming has not been reported.
Nguyen, LN, Johir, MAH, Commault, A, Bustamante, H, Aurisch, R, Lowrie, R & Nghiem, LD 2019, 'Impacts of mixing on foaming, methane production, stratification and microbial community in full-scale anaerobic co-digestion process.', Bioresource technology, vol. 281, pp. 226-233.View/Download from: Publisher's site
This study investigated the impact of mixing on key factors including foaming, substrate stratification, methane production and microbial community in three full scale anaerobic digesters. Digester foaming was observed at one plant that co-digested sewage sludge and food waste, and was operated without mixing. The lack of mixing led to uneven distribution of total chemical oxygen demand (tCOD) and volatile solid (VS) as well as methane production within the digester. 16S rRNA gene-based community analysis clearly differentiated the microbial community from the top and bottom. By contrast, foaming and substrate stratification were not observed at the other two plants with internal circulation mixing. The abundance of methanogens (Methanomicrobia) at the top was about four times higher than at the bottom, correlating to much higher methane production from the top verified by ex-situ biomethane assay, causing foaming. This result is consistent with foaming potential assessment of digestate samples from the digester.
Nguyen, LN, Labeeuw, L, Commault, AS, Emmerton, B, Ralph, PJ, Johir, MAH, Guo, W, Ngo, HH & Nghiem, LD 2019, 'Validation of a cationic polyacrylamide flocculant for the harvesting fresh and seawater microalgal biomass', Environmental Technology and Innovation, vol. 16.View/Download from: Publisher's site
© 2019 Elsevier B.V. A simple, efficient, and fast settling flocculation technique to harvest microalgal biomass was demonstrated using a proprietary cationic polyacrylamide flocculant for a freshwater (Chlorella vulgaris) and a marine (Phaeodactylum tricornutum) microalgal culture at their mid-stationary growth phase. The optimal flocculant doses were 18.9 and 13.7 mg/g of dry algal biomass for C. vulgaris and P. tricornutum, respectively (equivalent to 7 g per m3 of algal culture for both species). The obtained optimal dose was well corroborated with changes in cell surface charge, and culture solution optical density and turbidity. At the optimal dose, charge neutralization of 64 and 86% was observed for C. vulgaris and P. tricornutum algal cells, respectively. Algae recovery was independent of the culture solution pH in the range of pH 6 to 9. Algal biomass recovery was achieved of 100 and 90% for C vulgaris and P. tricornutum respectively, and over 98% medium recovery was achievable by simple decanting.
Ahmed, M, Johir, MAH, Khourshed, C, Zhou, J, Ngo, HH, Nghiem, D, Moni, M & Sun, L 2018, 'Sorptive removal of dissolved organic matter in biologically-treated effluent by functionalized biochar and carbon nanotubes: importance of sorbent functionality', Bioresource Technology.View/Download from: Publisher's site
The sorptive removal of dissolved organic matter (DOM) in biologically-treated effluent was studied by using multi-walled carbon nanotube (MWCNT), carboxylic functionalised MWCNT (MWCNT-COOH), hydroxyl functionalized MWCNT (MWCNT-OH) and functionalized biochar (fBC). DOM was dominated by hydrophilic fraction (79.6%) with a significantly lower hydrophobic fraction (20.4%). The sorption of hydrophobic DOM was not significantly affected by the sorbent functionality (∼10.4% variation) and sorption capacity followed the order of MWCNT > MWCNT-COOH > MWCNT-OH > fBC. In comparison, the sorption of hydrophilic fraction of DOM changed significantly (∼37.35% variation) with the change of sorbent functionality with adsorption capacity decreasing as MWCNT-OH > MWCNT-COOH > MWCNT > fBC. Furthermore, the affinity of adsorbents toward a hydrophilic compound (dinitrobenzene), a hydrophobic compound (pyrene) and humic acid was also evaluated to validate the proposed mechanisms. The results provided important insights on the type of sorbents which are most effective to remove different DOM fractions.
Ahmed, M, Zhou, J, Ngo, H, Johir, MAH & Kireesan, S 2018, 'Sorptive removal of phenolic endocrine disruptors by functionalized biochar:competitive interaction mechanism, removal efficacy and application in wastewater', Chemical Engineering Journal, vol. 335, pp. 801-811.View/Download from: Publisher's site
Sorptive removal of six phenolic endocrine disrupting chemicals (EDCs) estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), bisphenol A (BPA) and 4-tert-butylphenol (4tBP) by functionalized biochar (fBC) through competitive interactions was investigated. EDC sorption was pH dependent with the maximum sorption at pH 3.0-3.5 due to hydrogen bonds and π-π interactions as the principal sorptive mechanism. Sorption isotherm of the EDCs was fitted to the Langmuir model. Sorption capacities and distribution coefficient values followed the order E1 > E2 ≥ EE2 > BPA > 4tBP > E3. The findings suggested that EDC sorption occurred mainly through pseudo-second order and external mass transfer diffusion processes, by forming H-bonds along with π-π electron-donor-acceptor (EDA) interactions at different pH. The complete removal of ∼500 μg L-1 of each EDC from different water decreased in the order: deionised water > membrane bioreactor (MBR) sewage effluent > synthetic wastewater. The presence of sodium lauryl sulphonate and acacia gum in synthetic wastewater significantly suppressed sorption affinity of EDCs by 38-50%, hence requiring more fBC to maintain removal efficacy.
Ahmed, MB, Zhou, J, Ngo, HH, Johir, MAH, Sun, L, Asadullah, M & Belhaj, D 2018, 'Sorption of hydrophobic organic contaminants on functionalized biochar: protagonist role of π-π electron-donor-acceptor interactions and hydrogen bonds', Journal of Hazardous Materials.View/Download from: Publisher's site
The sorption of five potent endocrine disruptors as representative hydrophobic organic contaminants (HOCs) namely estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2) and bisphenol A (BPA) on functionalized biochar (fBC) was systematically examined, with a particular focus on the importance of π-electron-donor (phenanthrene: PHEN) and π-electron-acceptors (1,3-dinitrobenzene: DNB, p-amino benzoic acid: PABA) on sorption. Experimental results suggested that hydrogen-bond formation and π-π-electron-donor-acceptor (EDA) interactions were the dominant sorption mechanisms. The sorption of HOCs decreased as E1 > E2 > EE2 > E3 > BPA based on the Freundlich and Polanyi-Mane-models. The comparison of adsorption coefficient (Kd) normalized against hexadecane-water partition coefficient (KHW) between HOCs and PHEN indicated strong π-π-EDA interactions. π-π interactions among DNB, PHEN and HOCs were verified by the observed upfield frequency (Hz) shifts using proton nuclear magnetic resonance (1H NMR) which identified the specific direction of π-π interactions. UV-vis spectra showed charge-transfer bands for π-donors (PHEN and HOCs) with the model π-acceptor (DNB) also demonstrating the role of π-π EDA interactions. The role of π-electron-donor and π-electron-acceptor domains in fBC was identified at different solution pH.
Nur, T, Loganathan, P, Ahmed, MB, Johir, M, Kandasamy, J & Vigneswaran, S 2018, 'Struvite production using membrane-bioreactor wastewater effluent and seawater', Desalination, vol. 444, pp. 1-5.View/Download from: Publisher's site
© 2018 Elsevier B.V. Wastewater phosphorus (P) released into natural water bodies such as lakes and rivers, can cause water pollution as a result of eutrophication. If this P is effectively removed from wastewaters and economically recovered for use as fertilisers, not only can the water pollution be controlled, but also reduce the anticipated global shortage of P. This scarcity will result from the natural phosphate rock reserve being exhausted. Three experiments were conducted using membrane-bioreactor effluent (MBR, 35 mg PO 4 /L) and reverse osmosis concentrate (ROC, 10 mg PO 4 /L) waters to supply phosphate, and sea water (1530 mg Mg/L) to supply Mg for the production of struvite. The phosphate in the MBR and ROC was concentrated approximately 15 times by adsorption onto an ion exchange resin column followed by desorption. Struvite was precipitated by mixing the desorbed solution with seawater and NH 4 Cl. The chemical composition and mineral structure of the precipitates agreed with those of the reference struvite. When Ca in seawater (300 mg Ca/L) was removed before mixing the water with MBR or ROC, the purity of the struvite improved.
Nur, T, Loganathan, P, Johir, MAH, Kandasamy, J & Vigneswaran, S 2018, 'Removing rubidium using potassium cobalt hexacyanoferrate in the membrane adsorption hybrid system', Separation and Purification Technology, vol. 191, pp. 286-294.View/Download from: Publisher's site
© 2017 Elsevier B.V. Highly-priced rubidium (Rb) can be effectively extracted from seawater using potassium cobalt hexacyanoferrate (KCoFC) and ammonium molybdophosphate (AMP) adsorbents in the membrane adsorption hybrid system (MAHS). KCoFC ( < 0.075 mm), KCoFC (0.075–0.15 mm), and AMP ( < 0.075 mm) had Langmuir adsorption capacities of 145, 113, and 77 mg/g at pH 6.5–7.5, respectively. When KCoFC ( < 0.075 mm) at a dose of 0.2 g/L was initially added to 4 L of a solution containing 5 mg Rb/L in the MAHS and 25% of the initial dose was repeatedly added every hour, the amount of Rb removed remained steady at 90–96% for the experiment's 26 h duration. The removal of Rb by AMP under similar conditions was 80–82%. The cumulative Rb removed by KCoFC ( < 0.075 mm) in MAHS was only 33% reduced in the presence of high concentrations of other cations in synthetic seawater compared to that in solution containing only Rb. Approximately 30% of the adsorbed Rb was desorbed using 1 M KCl. When the desorbed solution was passed through a column containing resorcinol formaldehyde (RF), 35% of the Rb in the desorbed solution was adsorbed on RF. Furthermore 50% of the Rb adsorbed on RF was recovered by 1 M HCl leaching of the column. This sequence of concentration and separation of Rb in the presence of other cations in synthetic seawater is an efficient method for recovering pure Rb from real seawater and seawater reverse osmosis brine.
Sornalingam, K, McDonagh, A, Zhou, J, Johir, M & Ahmed, M 2018, 'Photocatalysis of estrone in water and wastewater: Comparison between Au-TiO2 nanocomposite and TiO2, and degradation by-products', Science of the Total Environment, vol. 610–611, pp. 521-530.View/Download from: Publisher's site
Gold-modified TiO2 (Au-TiO2) photocatalysts were utilised for the degradation of estrone (E1), a major endocrine disrupting chemical in water and wastewater. Au-TiO2 catalysts were synthesised by a deposition-precipitation method with gold loadings of 0–8% (wt%). The Au-TiO2 nanocomposite exhibited superior activity compared to P25 TiO2 under UVA (λ = 365 nm), cool white (λ > 420 nm) and green (λ = 523 nm) light emitting diodes (LEDs), for treating 1 mg l− 1 of E1. The 4 wt% Au loading was found to produce the best photocatalytic activity with a rate constant of 2.44 ± 0.36 h− 1, compared to 0.06 ± 0.01 h− 1 for P25 TiO2, under visible light. In total 4 by-products were identified, one from negative ionization mode (m/z = 269) and three from positive ionization mode (m/z = 287) during photocatalysis, which were also degraded with time by Au-TiO2. For different water matrices, the photodegradation rate of E1 decreased in the order: ultrapure water > synthetic wastewater ≈ wastewater effluent from membrane bio-reactor. Overall, 4 wt% Au-TiO2 demonstrated superior performance compared to P25 TiO2 in water and wastewater.
Naidu, G, Jeong, S, Johir, MAH, Fane, AG, Kandasamy, J & Vigneswaran, S 2017, 'Rubidium extraction from seawater brine by an integrated membrane distillation-selective sorption system.', Water Research, vol. 123, pp. 321-331.View/Download from: Publisher's site
The ultimate goal of seawater reverse osmosis (SWRO) brine management is to achieve minimal liquid discharge while recovering valuable resources. The suitability of an integrated system of membrane distillation (MD) with sorption for the recovery of rubidium (Rb+) and simultaneous SWRO brine volume reduction has been evaluated for the first time. Polymer encapsulated potassium copper hexacyanoferrate (KCuFC(PAN)) sorbent exhibited a good selectivity for Rb+ sorption with 10-15% increment at 55 °C (Langmuir Qmax = 125.11 ± 0.20 mg/g) compared to at 25 °C (Langmuir Qmax = 108.71 ± 0.20 mg/g). The integrated MD-KCuFC(PAN) system with periodic membrane cleaning, enabled concentration of SWRO brine to a volume concentration factor (VCF) of 2.9 (65% water recovery). A stable MD permeate flux was achieved with good quality permeate (conductivity of 15-20 μS/cm). Repeated cycles of MD-KCuFC(PAN) sorption with SWRO brine enabled the extraction of 2.26 mg Rb+ from 12 L of brine (equivalent to 1.9 kg of Rb/day, or 0.7 tonne/yr from a plant producing 10,000 m3/day brine). KCuFC(PAN) showed a high regeneration and reuse capacity. NH4Cl air stripping followed by resorcinol formaldehyde (RF) resin filtration enabled to recover Rb+ from the desorbed solution.
Shrestha, A, Naidu, G, Johir, MAH, Kandasamy, J & Vigneswaran, S 2017, 'Performance of flocculation titanium salts for seawater reverse osmosis pretreatment', Desalination and Water Treatment, vol. 98, pp. 92-97.View/Download from: Publisher's site
© 2017 Desalination Publications. All rights reserved. This study evaluated the performance of titanium tetrachloride (TiCl4) and titanium sulphate (Ti(SO4)2) as coagulants to remove organic matter and solids from actual seawater. The coagulant performances were evaluated at different doses in terms of turbidity, dissolved organic carbon (DOC), humics (UV254), zeta potential and pH of the solution. The performance of Ti-salts were compared to ferric chloride (FeCl3), a commonly used coagulant. The results showed that at pH of 8.0 (closely similar to seawater pH), TiCl4showed relatively better performance over FeCl3and Ti(SO4)2for the same coagulant dose of 20 mg/L. TiCl4achieved a 70% DOC and UV254removal. This was approximately two times higher than achieved by FeCl3and Ti(SO4)2. Based on a floc zeta potential evaluation, the difference in performance of the coagulants were attributed to the coagulation mechanism. The coagulation mechanisms of Ti-salts were mainly charge neutralization while FeCl3was adsorption mechanism.
Ahmed, M, Guo, W, Zhou, J, Johir, M & Ngo, H 2017, 'Competitive sorption affinity of sulfonamides and chloramphenicol antibiotics toward functionalized biochar for water and wastewater treatment', Bioresource Technology.View/Download from: Publisher's site
Competitive sorption of sulfamethazine (SMT), sulfamethoxazole (SMX), sulfathiazole (STZ) and chloramphenicol (CP) toward functionalized biochar (fBC) was highly pH dependent with maximum sorption at pH ∼4.0-4.25. Equilibrium data were well represented by the Langmuir and Freundlich models in the order STZ > SMX > CP > SMT. Kinetics data were slightly better fitted by the pseudo second-order model than pseudo first-order and intra-particle-diffusion models. Maximum sorptive interactions occurred at pH 4.0-4.25 through H-bonds formations for neutral sulfonamides species and through negative charge assisted H-bond (CAHB) formation for CP, in addition to π-π electron-donor-acceptor (EDA) interactions. EDA was the main mechanism for the sorption of positive sulfonamides species and CP at pH < 2.0. Sorption of negative sulfonamides species and CP at pH > 7.0 was regulated by H-bond formation and proton exchange with water by forming CAHB, respectively. The results suggested fBC to be highly efficient in removing antibiotics mixture.
Ahmed, M, zhou, J, Ngo, H, Guo, W, Johir, M & Kiressan, S 2017, 'Nano-Fe0 Immobilized onto Functionalized Biochar Gaining Excellent Stability during Sorption and Reduction of Chloramphenicol via Transforming to Reusable Magnetic Composite', Chemical Engineering Journal, vol. 322, pp. 571-581.View/Download from: Publisher's site
The widely used nanosized zero-valent iron (nZVI or nFe0) particles and their composite material lose reductive nature during application, and the stability of transformed composite material for repeatable application is not addressed to date. To shed light on this, nZVI was synthesized from scrap material and immobilized on functionalized biochar (fBC) to prepare nZVI-fBC composite. Comparative study between nZVI and nZVI-fBC composite on the removal of chlorinated antibiotic chloramphenicol from different water types was conducted. The results suggested that nZVI was solely responsible for reduction of chloramphenicol. Whereas nZVI-fBC could be applied once, within a few hours, for the reduction of chloramphenico (29–32.5%) and subsequently sorption (67.5–70.5%) by transforming to a fully magnetic composite (nFe3O4-fBC) gaining stability with synergistic sorption performance. In both cases, two reduction by-products were identified namely 2-chloro-N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 257) and dechlorinated N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 223). The complete removal of 3.1 µM L−1 of chloramphenicol in different water was faster by nZVI-fBC (∼12–15 h) than by stable nFe3O4-fBC composite (∼18 h). Both nZVI-fBC and nFe3O4-fBC composites removed chloramphenicol in the order: deionized water > lake water > synthetic wastewater. nFe3O4-fBC showed excellent reusability after regeneration, with the regenerated nFe3O4-fBC composite (after 6 cycles of application) showing significant performance for methylene blue removal (∼287 mg g−1). Therefore, the transformed nFe3O4-fBC composite is a promising and reusable sorbent for the efficient removal of organic contaminants.
Ahmed, MB, Johir, MAH, Zhou, JL, Ngo, HH, Guo, W & Sornalingam, K 2017, 'Photolytic and Photocatalytic Degradation of Organic UV Filters in Contaminated Water', Current Opinion in Green and Sustainable Chemistry, vol. 6, pp. 85-92.View/Download from: Publisher's site
UV filters as emerging contaminants are of great concern and their wide detection in aquatic environments indicates their chemical stability and persistence. This review summarized the photolytic and photocatalytic degradation of UV filters in contaminated water. The findings indicated that limited research has been conducted on the photolysis and photocatalysis of UV filters. Photolysis of UV filters through UV irradiation in natural water was a slow process, which was accelerated by the presence of photosensitisers e.g. triplet state of chromaphoric dissolved organic matter (3CDOM*) and nutrients but reduced by salinity, dissolved organic matter (DOM) and divalent cations. UV Photocatalysis of 4-methylbenzylidene camphor and 2-phenylbenzimidazole-5-sulfonic acid was very effective with 100% removal within 30 min and 90 min using medicated TiO2/H2O2 and TiO2, respectively. The radiation source, type of catalyst and oxygen content were key factors. Future research should focus on improved understanding of photodegradation pathways and by-products of UV filters.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Johir, MAH & Sornalingam, K 2017, 'Single and competitive sorption properties and mechanism of functionalized biochar for removing sulfonamide antibiotics from water', Chemical Engineering Journal, vol. 311, pp. 348-358.View/Download from: Publisher's site
© 2016 Elsevier B.V.Single and competitive sorption of ionisable sulphonamides sulfamethazine, sulfamethoxazole and sulfathiazole on functionalized biochar was highly pH dependent. The equilibrium data were well represented by both Langmuir and Freundlich models for single solutes, and by the Langmuir model for competitive solutes. Sorption capacity and distribution coefficient values decreased as sulfathiazole > sulfamethoxazole > sulfamethazine. The sorption capacity of each antibiotic in competitive mode is about three times lower than in single solute sorption. The kinetics data were best described by the pseudo second-order (PSO) model for single solutes, and by PSO and intra-particle diffusion models for competitive solutes. Adsorption mechanism was governed by pore filling through diffusion process. The findings from pH shift, FTIR spectra and Raman band shift showed that sorption of neutral sulfonamide species occurred mainly due to strong H-bonds followed by π+-π electron-donor-acceptor (EDA), and by Lewis acid-base interaction. Moreover, EDA was the main mechanism for the sorption of positive sulfonamides species. The sorption of negative species was mainly regulated by proton exchange with water forming negative charge assisted H-bond (CAHB), followed by the neutralization of –OH groups by H+ released from functionalized biochar surface; in addition π-π electron-acceptor-acceptor (EAA) interaction played an important role.
MB Ahmed, JunLiang Zhou, Huu Hao Nog, Wenshan Guo, MAH Johir, K. Sornalingram & MS Rahman 2017, 'Chloramphenicol interaction with functionalized biochar in water: sorptive mechanism, molecular imprinting effect and repeatable application', Science of the Total Environment, vol. 609, pp. 885-895.View/Download from: Publisher's site
Biochar and functionalized biochar (fBC-1 and fBC-2) were prepared and applied to remove antibiotic chloramphenicol
from deionized water, lake water and synthetic wastewater. Results showed that chloramphenicol removal
on biochar was pH dependent and maximum sorption occurred at pH 4.0–4.5. The sorption data of
chloramphenicol fitted better with the Langmuir isotherm model than the Freundlich isotherm model with the
maximum Langmuir sorption capacity of 233 μM g−1 using fBC-2. Chloramphenicol sorption on fBC-2 followed
the trend: deionized water N lake water N synthetic wastewater. The presence of humic acid decreased the
sorption distribution coefficient (Kd) while the presence of low ionic strength and soil in solution increased Kd
value significantly. The mechanism of sorption on fBC mainly involved electron-donor-acceptor (EDA) interactions
at pH b 2.0; formation of charge assisted hydrogen bond (CAHB) and hydrogen bonds in addition to EDA
in the pH 4.0–4.5; and CAHB and EDA interactions at pH N 7.0. Additionally, solvent and thermal regeneration
of fBC-2 for repeatable applications showed excellent sorption of chloramphenicol under the same condition,
due to the creation of a molecular imprinting effect in fBC-2. Consequently, fBC-2 can be applied with excellent
reusability properties to remove chloramphenicol and other similar organic contaminants.
Qi, F, Dong, Z, Lamb, D, Naidu, R, Bolan, NS, Ok, YS, Liu, C, Khan, N, Johir, MAH & Semple, KT 2017, 'Effects of acidic and neutral biochars on properties and cadmium retention of soils', Chemosphere, vol. 180, pp. 564-573.View/Download from: Publisher's site
© 2017 Elsevier Ltd In this study, an acidic biochar and a neutral biochar were applied at 5 wt% into two soils for an 11-month incubation experiment. One Ferrosol soil (Ba) was slightly acidic with low organic matter and the other Dermosol soil (Mt) was slightly alkaline with high organic matter. The acidic (pH = 3.25) wood shaving (WS) biochar had no marked impact on nutrient levels, cation exchange capacity (CEC), pH and acid neutralization capacity (ANC) of either soil. By contrast, the neutral (pH = 7.00) chicken litter (CL) biochar significantly increased major soluble nutrients, pH, ANC of soil Ba. In terms of C storage, 87.9% and 69.5% WS biochar-C can be sequestrated as TOC by soil Ba and Mt, respectively, whereas only 24.0% of CL biochar-C stored in soil Ba and negligible amount in Mt as TOC. Biochars did not have significant effects on soil sorption capacity and sorption reversibility except that CL biochar increased sorption of soil Ba by around 25.4% and decreased desorption by around 50.0%. Overall, the studied acidic C rich WS biochar held little agricultural or remedial values but was favourable for C sequestration. The neutral mineral rich CL biochar may provide short-term agricultural benefit and certain sorption capacities of lower sorption capacity soils, but may be unlikely to result in heightened C sequestration in soils. This is the first study comprehensively examining functions of acidic and neutral biochars for their benefits as a soil amendment and suggests the importance of pre-testing biochars for target purposes prior to their large scale production.
Shanmuganathan, S, Loganathan, P, Kazner, C, Johir, MAH & Vigneswaran, S 2017, 'Submerged membrane filtration adsorption hybrid system for the removal of organic micropollutants from a water reclamation plant reverse osmosis concentrate', Desalination, vol. 401, pp. 134-141.View/Download from: Publisher's site
© 2016 Elsevier B.V. Reverse osmosis (RO) is a widespread water treatment process utilised in water reuse applications. However, the improper discharge of RO concentrate (ROC) containing organic micropollutants such as pharmaceuticals into the environment may cause potential health risks to non-target species and particularly those in aquatic environments. A study was conducted using a submerged membrane-filtration/granular activated carbon (GAC) adsorption hybrid system to remove organic micropollutants from a water treatment plant ROC by initially adding 10 g GAC /L of membrane reactor volume with 10% daily GAC replacement. The percentage of dissolved organic carbon removal varied from 60% to 80% over an operation lasting 10 days. Removal of organic micropollutants was almost complete for virtually all compounds. Of the 19 micropollutants tested, only two remained (the less hydrophobic DEET 27 ng/L and the hydrophilic sulfamethoxazole 35 ng/L) below 80% removal on day 1, while five of the most hydrophobic micropollutants were detectable in very small concentrations ( < 5–10 ng/L) with > 89%– > 99% being removed. High percentages of micropollutants were removed probably because of their high hydrophobicity or they had positive or neutral charges and therefore they were electrostatically adsorbed to the negatively charged GAC.
Naidu, G, Loganathan, P, Jeong, S, Johir, MAH, Vu, HPT, Kandasamy, J & Vigneswaran, S 2016, 'Rubidium extraction using an organic polymer encapsulated potassium copper hexacyanoferrate sorbent', CHEMICAL ENGINEERING JOURNAL, vol. 306, pp. 31-42.View/Download from: Publisher's site
Johir, MAH, Nguyen, TT, Mahatheva, K, Pradhan, M, Ngo, HH, Guo, W & Vigneswaran, S 2016, 'Removal of phosphorus by a high rate membrane adsorption hybrid system', Bioresource Technology, vol. 201, pp. 365-369.View/Download from: Publisher's site
© 2015 Elsevier Ltd. Membrane adsorption hybrid system (MAHS) was evaluated for the removal of phosphate from a high rate membrane bioreactor (HR-MBR) effluent. The HR-MBR was operated at permeate flux of 30L/m2 h. The results indicated that the HR-MBR could eliminate 93.1±1.5% of DOC while removing less than 53% phosphate (PO4-P). Due to low phosphate removal by HR-MBR, a post-treatment of strong base anion exchange resin (Dowex*21K-XLT), and zirconium (IV) hydroxide were used as adsorbent in MAHS for further removal of phosphate from HR-MBR effluent. It was found that the MAHS enabled to eliminate more than 85% of PO4-P from HR-MBR effluent. Hence, HR-MBR followed by MAHS lead to simultaneous removal of organics and phosphate in a reliable manner. The experiments were conducted only for a short period to investigate the efficiency of these resins/adsorbents on the removal of phosphorus and high rate MBR for organic removal.
Johir, MAH, Pradhan, M, Loganathan, P, Kandasamy, J & Vigneswaran, S 2016, 'Phosphate adsorption from wastewater using zirconium (IV) hydroxide: Kinetics, thermodynamics and membrane filtration adsorption hybrid system studies', JOURNAL OF ENVIRONMENTAL MANAGEMENT, vol. 167, pp. 167-174.View/Download from: Publisher's site
Johir, MAH, Shim, WG, Pradhan, M, Vigneswaran, S & Kandasamy, J 2016, 'Benefit of adding adsorbent in submerged membrane microfiltration treatment of wastewater', Desalination and Water Treatment, vol. 57, no. 44, pp. 20683-20693.View/Download from: Publisher's site
In this study, the effect of coupling ion-exchange resin (purolite) and powdered activated carbon (PAC) in a submerged membrane reactor was investigated in terms of (i) removal of different classes of organic matter and (ii) reduction of membrane fouling. The degree of fouling in a membrane hybrid system was modelled in terms of transmembrane pressure development and organic removal efficiency using a simple semi-empirical model. Among these three absorbents, PAC was the most effective with higher removal efficiency for DOC (almost 100% reduction of hydrophobic organic compounds). Excitation–emission matrix analysis and LC–OCD were employed for the detailed organic characterisation.
Phuntsho, S, Kim, JE, Johir, MAH, Hong, S, Li, Z, Ghaffour, N, Leiknes, T & Shon, HK 2016, 'Fertiliser drawn forward osmosis process: Pilot-scale desalination of mine impaired water for fertigation', JOURNAL OF MEMBRANE SCIENCE, vol. 508, pp. 22-31.View/Download from: Publisher's site
Vigneswaran, S, Kandasamy, J & Johir, MAH 2016, 'Sustainable Operation of Composting in Solid Waste Management', Procedia Environmental Sciences, vol. 35, pp. 408-415.View/Download from: Publisher's site
Rattananurak, W, Chang, J-S, Wattanachira, S, Johir, MAH & Vigneswaran, S 2015, 'A novel plate settler in immersed membrane bioreactor (iMBR) in reducing membrane fouling', DESALINATION AND WATER TREATMENT, vol. 55, no. 1, pp. 10-16.View/Download from: Publisher's site
Shanmuganathan, S, Johir, MAH, Tien, VN, Kandasamy, J & Vigneswaran, S 2015, 'Experimental evaluation of microfiltration-granular activated carbon (MF-GAC)/nano filter hybrid system in high quality water reuse', JOURNAL OF MEMBRANE SCIENCE, vol. 476, pp. 1-9.View/Download from: Publisher's site
Shrestha, A, Johir, MAH, Vigneswaran, S & Kandasamy, J 2015, 'A comparative study on in-line flocculation and spiral flocculation followed by media filtration as a pre-treatment of seawater', Desalination and Water Treatment, vol. 55, no. 4, pp. 892-900.View/Download from: Publisher's site
© 2014 Balaban Desalination Publications. All rights reserved. Abstract: In this study the efficiency of two different flocculation systems namely in-line flocculation and spiral flocculation followed by media filtration (sand or anthracite) have been investigated as a pre-treatment of seawater to reverse osmosis. The performances of these filtration systems were assessed in terms of turbidity removal, head loss development, ultra filter-modified fouling index (UF-MFI) and organic matters removal. Both systems showed 60–70% removal of turbidity. In-line flocculation and filtration showed 2–3 times higher head loss development than spiral flocculation filtration. These filtration systems helped to reduce the fouling potential (in terms of UF-MFI) by 50–73%, whereas dissolved organic carbon-removal efficiency was 30–45%. The fractionation of organic matter showed that both systems removed 70% of hydrophobic organic matters. The removals of hydrophilic organics were around 30–40%. Among the hydrophilic compounds, the removal of biopolymer and lower molecular weight neutrals and acid were higher than that of humic substances' and building blocks'.
Tijing, LD, Woo, Y, Johir, M, Choi, JS & Shon, H 2014, 'A novel dual-layer bicomponent electrospun nanofibrous membrane for desalination by direct contact membrane distillation', Chemical Engineering Journal, vol. 256, pp. 155-159.View/Download from: Publisher's site
In this study, a bicomponent nanofibrous composite membrane was fabricated by electrospinning and was tested for desalination by direct contact membrane distillation (DCMD). The nanofibrous membrane was composed of a dual-layered structure of poly(vinylidene fluoride-co-hexafluoropropylene) (PH) nanofibers and polyacrylonitrile (PAN) microfibers. Morphological characterization showed slightly beaded cylindrical PH nanofibers with porosity of about 90%. The contact angles of PH and PAN nano/microfibers were 150 degrees and 100 degrees, respectively. The nanofibrous membranes were tested by DCMD and a high water flux of 45 and 30 L m(-2) h(-1) was obtained for distilled water and 35 g L-1 NaCl solutions as feed, respectively using DL2 membrane (i.e., 25/75 PH/PAN thickness ratio). The present dual-layer membrane showed better flux performance compared to a commercial flat-sheet membrane. The results suggest the potential of the dual-layer nanofibrous membrane for DCMD applications
Nur, T, Johir, MAH, Loganathan, P, Nguyen, T, Vigneswaran, S & Kandasamy, J 2014, 'Phosphate removal from water using an iron oxide impregnated strong base anion exchange resin', Journal of Industrial and Engineering Chemistry, vol. 20, pp. 1301-1307.View/Download from: Publisher's site
Removing phosphate from water is important as it causes eutrophication, which in turn has a harmful effect on aquatic life, resulting in a reduction in biodiversity. On the other hand, recovery of phosphate from phosphorus containing wastewater is essential for developing an alternative source of phosphorus to overcome the global challenge of phosphorus scarcity. Phosphate removal from aqueous solutions was studied using an iron oxide impregnated strong base anion exchange resin, Purolite FerrIX A33E in batch and fixed-bed column experiments. Phosphate adsorption in the batch study satisfactorily fitted to the Langmuir isotherm with a maximum adsorption capacity of 48 mg P/g. In the column study, increase in inlet phosphate concentration (530 mg P/L), and filtration velocity (2.510 m/h) resulted in faster breakthrough times and increase in breakthrough adsorption capacities. Increase in bed height (3 19 cm) also increased adsorption capacity but the breakthrough time was slower. The breakthrough data were reasonably well described using the empirical models of BohartAdams, Thomas, and Yoon Nelson, except for high bed heights. Phosphate adsorbed was effectively desorbed using 1 M NaOH and the adsorbent was regenerated after each of three adsorption/desorption cycles by maintaining the adsorption capacity at >90% of the original value. Greater than 99.5% of the desorbed P was recovered by precipitation using CaCl2.
Nur, T, Shim, WG, Johir, MAH, Vigneswaran, S & Kandasamy, J 2014, 'Modelling of phosphorus removal by ion-exchange resin (Purolite FerrIX A33E) in fixed-bed column experiments', Desalination and Water Treatment, vol. 52, no. 4-6, pp. 784-790.View/Download from: Publisher's site
Phosphorus removal is important as it causes eutrophication that in turn has a harmful effect on fish and other aquatic life, resulting in a reduction in biodiversity as well as unfavourable human environmental health. In this study, phosphorus removal from aqueous solutions was studied using an ion-exchange resin (Purolite FerrIX A33E) in fixed-bed column experiments. The effects of adsorbent bed height (319 cm) on the breakthrough characteristics of the adsorption system were studied. An increase in bed height (319 cm) increased adsorption capacity but the breakthrough time was shorter. As the bed height increased, the detention time increased and the phosphate was in contact with the purolite ion-exchange resin for a longer time, resulting in more efficient removal of phosphate. The shape of breakthrough curve was steeper for a shorter bed height. A mathematical model (advection dispersion equation) was solved numerically to predict the dynamic behaviour of the columns. Finally, sensitivity analysis results apparently revealed that the dynamic adsorption behaviours of phosphate in Purolite FerrIX A33E were mainly controlled by the external mass transfer rather than the axial dispersion and the intra-particle diffusion.
Chanan, AP, Vigneswaran, S, Kandasamy, JK & Johir, M 2013, 'Need for a fresh look at phosphorus management in wastewater treatment: Trash to treasure', Sustainable Environment Research, vol. 23, no. 1, pp. 23-31.
Eutrophication of water bodies is a major, global environmental problem. It is now well understood that its main cause is excessive amounts of nutrients such as phosphorus. Stringent laws were therefore introduced across the world, requiring that the level of the P be significantly reduced. Consequently, the focus for wastewater treatment industry became the elimination of phosphorus in effluent stream. Treatment technologies capable of removing over 90% of phosphorus from wastewater have now been developed. However, these phosphorus removal options are likely to be ineffective in the future. The future would call for a shift to the primary goal of phosphorus removal to 'capturing and reusing' phosphorus. This paper calls for a re-think in developing phosphorus management programs. Discussing Fertigation as step-one in phosphorus reclamation, the paper will further elaborate phosphorus recovery opportunities such as ion-exchange that can be retrofitted to existing wastewater treatment plants.
Johir, M, Shanmuganathan, S, Vigneswaran, S & Kandasamy, JK 2013, 'Performance of submerged membrane bioreactor (SMBR) with and without the addition of the different particle sizes of GAC as suspended medium', Bioresource Technology, vol. 141, pp. 13-18.View/Download from: Publisher's site
In this study the effect of different particle sizes of granular activated carbon (GAC) on the performance of a submerged membrane bioreactor (SMBR) was investigated. The sizes of GAC used were 150300, 300600 and 6001200 µm. The SMBR was operated at a filtration flux of 20 L/m2 h. The removal of dissolved organic carbon (DOC) and chemical oxygen demand (COD) with the addition of GAC was 95%. The concentration of biopolymers, humic, building block and low molecular weight neutral and acids in the SMBR effluent was reduced by 20%, 6676%, 2050%, 3056%, respectively. It helped to reduce the sludge volume index (SVI) and transmembrane pressure (TMP) development by 3040% and 58%, respectively. However, the removal of View the MathML source and View the MathML source was relatively low of 3545% and 3443%, respectively. The SMBR effluent was rich in View the MathML source and was removed/recovered using hydrated ferric oxide (HFO). The removal of View the MathML source was almost 90%.
Johir, M, Vigneswaran, S, Kandasamy, JK & Sleigh, R 2013, 'Coupling Of Physico-chemical Treatment And Steel Membrane Filtration To Enhanced Organic Removal In Wastewater Treatment', Desalination And Water Treatment, vol. 51, no. 13-15, pp. 2695-2701.View/Download from: Publisher's site
In this study, the application of steel membrane filtration was tested with the pre-treated wastewater. The pre-treatment methods tested before membrane filtration application were flocculation using FeCl3, Powdered Activated Carbon (PAC) adsorption, purolite ion-exchange column and purolite ion-exchange column followed by flocculation (FeCl3). The effect of two different modes of membrane application (cross-flow and dead-end modes) was examined. The ability of these filters in removing organic matters and solids were examined. It was found that the decline of flux was slightly lower for dead-end mode of operation to that of cross-flow mode of operation. Pre-treatment increased the performance of membrane filtration. The flux decline of raw water (without pre-treatment) was 31-10%, whereas after pre-treatment, it was about 2.5-21%. Pre-treatment followed by microfiltration (MF) showed 68-91% removal efficiency of dissolved organic carbon
Johir, M, Vigneswaran, S, Kandasamy, JK, Benaim, R & Grasmick, A 2013, 'Effect of salt concentration on membrane bioreactor (MBR) performances: Detailed organic characterization', Desalination, vol. 322, no. 1, pp. 13-20.View/Download from: Publisher's site
The gradual increase of salt concentration (0 to 35 g-NaCl/L) on the performance of membrane bioreactor (MBR) was studied. The uptake rate of dissolved organic carbon and ammonia decreased from around 17.0 mg-DOC/g-MLVSS.d to 1.8 mg-DOC/g-MLVSS.d and from 8.2 mg-NH4-N/g-MLVSS.d to 0 mg-NH4-N/g-MLVSS.d respectively when salt concentration reached to 35 g-NaCl/L. Similarly the specific oxygen uptake rate (SOUR) reduced from 8 to 9 to around 0.3 mg-O2/g-MLVSS.h. The removal of bio-polymers, humic acids, building blocks and low molecular weight neutral decreased with increase in salt concentration. The concentration of dissolved organic nitrogen (DON) in bio-polymer increased from 0.05 to 3.31 mg/L when the salt concentration reached to 35 g-NaCl/L. This study provides good information for understanding the effect of continuous increase of salt concentration in treating saline wastewater in a MBR process.
Aryal, R, Johir, MH, Vigneswaran, S, Kandasamy, JK & Sleigh, R 2012, 'Performance Of A Stainless Steel Membrane In Membrane Bioreactor Process', Desalination and Water Treatment, vol. 41, no. 1-3, pp. 258-264.View/Download from: Publisher's site
Stainless steel membrane has recently emerged as a durable membrane for microfiltration. An aerobic membrane bioreactor (MBR) equipped with a tubular stainless steel membrane of pore size 0.3âÎ¼m was submerged in a wastewater reactor to treat municipal wastewater of about 1,000âmg/L COD. The membrane operational performance was tested at three different permeate flux (7.5, 10 and 15âL/m2âh [LMH]) for 2 days each. In all cases, the rate of transmembrane pressure (TMP) rise was very high at 30, 45 and 80âkPa for 7.5, 10 and 15âLMH, respectively. Different analytical techniques i.e. particle size distribution, UV spectrometry, fluorescent spectrometry and size exclusion chromatography were used to study the nature of mixed liquor and the fouling deposited on the membrane surface. Rapid rise of TMP and decrease in permeate flux was observed during the experiment. Analysis of the fouling indicated a negligible difference in nature of organics between it and the mixed liquor. Filtration flux test showed a high sludge cake and pore-blocking resistance of 4.4âÃâ1019 and 2.8âÃâ1016âmâ1, respectively, compared to a clean membrane resistance 5.4âÃâ1012âmâ1. The similar nature of organics in the mixed liquor and the foulant and recovery of flux after removal of the foulant after gentle washing in water, indicated a rapid sludge accumulation rather than the irreversible fouling.
Hong, S, Aryal, R, Vigneswaran, S, Johir, MH & Kandasamy, JK 2012, 'Influence of hydraulic retention time on the nature of foulant organics in a high rate membrane bioreactor', Desalination, vol. 287, no. 1, pp. 116-122.View/Download from: Publisher's site
The influence of hydraulic retention time (HRT) in a submerged hollow fibre membrane bioreactor was studied by conducting experiments at four different HRTs (4,2, 1.3 and 1 h) at room temperature of 25 Â°C. lt was found that a shorter HRT led to a higher development of trans-membrane pressure. The highest sludge cake and pore-blocking resistances of 4.02 x 1011 m-1 and 0.77 x 1011 m-1 respectively were noted for the shortest HRT (of 1 h) application. UV and fluorescence spectroscopy analyses showed that the nature of organics in the biomass and sludge cakes were different. The organic fraction analysis by liquid chromatography with organic carbon detector (LC-OCO) showed a significant amount of biopolymers and a lower amount of humics for longer HRT.
Johir, M, George, J, Vigneswaran, S, Kandasamy, JK, Sathasivan, AS & Grasmick, A 2012, 'Effect Of Imposed Flux On Fouling Behavior In High Rate Membrane Bioreactor', Bioresource Technology, vol. 122, pp. 42-49.View/Download from: Publisher's site
The influence of imposed flux and aeration rates on membrane fouling in a submerged membrane bioreactor was studied. The experiments were conducted at four imposed fluxes and three aeration rates. The effect of flux on the reduction of membrane fouling w
Johir, MH, Vigneswaran, S, Sathasivan, AS, Kandasamy, JK & Chang, C 2012, 'Effect Of Organic Loading Rate On Organic Matter And Foulant Characteristics In Membrane Bio-Reactor', Bioresource Technology, vol. 113, pp. 154-160.View/Download from: Publisher's site
In this study, the influence of organic loading rate (OLR) on the performance of a membrane bio-reactor (MBR) was investigated. The MBR was operated with 6 different OLRs between 0.5 and 3.0 kg COD/m3 d. The hydrodynamic parameters of the MBR were kept constant. The hydraulic retention time and sludge retention time were kept at 8 h and 40 d respectively. From the experimental investigation, it was found that the removal efficiency of DOC, COD and NH4-N decreased when OLRs were increased from 0.5 to 3.0 kg COD/m3 d. Higher OLRs of 2.75-3.0 kg COD/m3 d resulted in a higher transmembrane pressure development. The fractionation of organic matters showed more hydrophilic substances with higher OLRs. A detailed organic matter characterization of membrane foulant, soluble microbial product and extracellular polymeric substances showed that bio-polymers type substances together with humic acid and lower molecular neutral and acids were responsible for membrane fouling.
Kus, BG, Johir, MH, Kandasamy, JK, Vigneswaran, S, Shon, H, Sleigh, R & Moody, G 2012, 'Performance Of Granular Medium Filtration And Membrane Filtration In Treating Stormwater For Harvesting And Reuse', Desalination and Water Treatment, vol. 45, no. 1-3, pp. 120-127.View/Download from: Publisher's site
This paper discusses laboratory scale and pilot scale treatment systems used to in treat water from a stormwater canal in Carlton, Sydney. The laboratory scale pre-treatment systems investigated included flocculation, GAC filtration and fibre filter prior to laboratory scale steriflow stainless steel membrane filter. The results showed that these pre-treatments improved the quality of the filtrate as measured by the turbidity and TOC removal effi ciency. The use of pre-treatment improved the TOC removal efficiency from 10% to 90%. Among the three pretreatment methods, GAC filter resulted in the highest TOC removal efficiency (88%). Pilot scale experiments were also carried out using stainless steel membrane filtration and GAC filtration at Carlton, Sydney. Pilot scale experiments showed that the Steri-Flow membrane filter treatment without any pre-treatment achieved an effluent fi ltrate turbidity of between 0.79â0.99 NTU which were well below the 5 NTU ADWG (2004) limit . The influent raw stormwater had generally low concentrations of heavy metals. Following membrane filtration the concentration of all heavy metals were reduced to very low levels and well within the ADWG (2004)  limits. The membrane fi lter could not remove TOC in significant amounts. GAC adsorption used as post-treatment following Steri-flow membrane treatment effectively reduced the TOC influent feed levels. GAC filtration of stormwater provided a 70% removal of organics. It removed all types of organic. The GAC filter did not provide any further improvement to the turbidity level or heavy metal concentration following treatment with the Steri-flow membrane system.
Nur, T, Johir, MAH, Loganathan, P, Vigneswaran, S & Kandasamy, J 2012, 'Effectiveness of purolite A500PS and A520E ion exchange resins on the removal of nitrate and phosphate from synthetic water', Desalination and Water Treatment, vol. 47, no. 1-3, pp. 50-58.View/Download from: Publisher's site
Water pollution due to the excessive presence of nutrients (nitrogen and phosphorus) is a serious environmental worldwide problem, because both species are implicated in the eutrophication of receiving surface waters and elevated nitrate concentration in drinking water can be toxic to infants. The removal efficiencies of nitrate and phosphate from water spiked with different ratios and concentrations of these nutrients by two ion-exchange resins (Purolite A500PS and Purolite A520E) were studied in batch kinetics and equilibrium adsorption experiments. Both purolites were found to be selective towards nitrate removal at all ratios of nitrate to phosphate in solution. Purolite A520E showed higher (<85%) removal efficiency of nitrate than Purolite A500PS (about 65%) from a solution containing 20mgN/L as nitrate and 10mgP/L as phosphate at a resin dose of 1.5 g/L. However, Purolite A500PS showed higher (65%) removal of phosphate than Purolite A520E (48%). Langmuir and Freundlich isotherm models fitted well for the adsorption of nitrate on Purolite A520E (R2 = 0.950.96). However, the adsorption of nitrate on Purolite A500PS can be explained satisfactorily only by Freundlich model (R2 = 0.98). The adsorption of phosphate on the resins fitted well to Freundlich model (R2 = 0.90) for Purolite A500PS as well as for Purolite A520E (R2 = 0.90). The adsorption of phosphate and nitrate on both ion-exchange resins was much better described by pseudo-second-order kinetic model (R2P0.99) than by pseudo-first-order kinetic model (R2 = 0.250.94).
Johir, MH, Aryal, R, Vigneswaran, S, Kandasamy, JK & Grasmick, A 2011, 'Influence Of Supporting Media In Suspension On Membrane Fouling Reduction In Submerged Membrane Bioreactor (Smbr)', Journal Of Membrane Science, vol. 374, no. 1-2, pp. 121-128.View/Download from: Publisher's site
In this study, the SMBR was compared in terms of membrane fouling with and without the addition of suspended medium in the membrane reactor. The effectiveness of medium in suspension in submerged membrane bioreactor (SMBR) was evaluated at different filt
Johir, MH, George, J, Vigneswaran, S, Kandasamy, JK & Grasmick, A 2011, 'Removal and recovery of nutrients by ion exchange from high rate membrane bio-reactor (MBR) effluent', Desalination, vol. 275, no. 2, pp. 197-202.View/Download from: Publisher's site
In this study a membrane bioreactor (MBR) with ion-exchange as post-treatment was investigated for organic removal and nutrient recovery. The MBR was operated at a short HRT of 4 h in order to mainly remove organic carbon. This was followed by an ion-exchange process to remove and later recover the nitrogen and phosphorus from the MBR effluent. The increase in membrane resistance was reduced by 90% (from 0.061 to 0.006 m-1d-1) when the air scouring rate was increased from 0.5 to 1.5 m3/m2 membrane area h. The organic removal rate in terms of DOC was 85â90%. The bio-polymer in the molecular weight range of 24,500 Da was retained by the membrane of the MBR while humic type substances and lower molecular organic matter (molecular weight of 360â60 Da) were not effectively removed by the membrane. The ion-exchange process effectively removed the nutrients from the effluent of the MBR. The retention of PO4 3â and NO3 â by the two ion-exchange columns in series was 85% and 95% respectively. Over 95â98% phosphate and nitrate recovery was obtained during regeneration of columns with 1% NaCl of 20 bed volumes. This integrated process can remove pollutants and at the same time recover nutrients and thus open a new source for nitrogen and phosphorous.
Chinu, KJ, Johir, MH, Vigneswaran, S, Shon, H & Kandasamy, JK 2010, 'Assessment of pretreatment to microfiltration for desalination in terms of fouling index and molecular weight distribution', Desalination, vol. 250, no. 2, pp. 644-647.View/Download from: Publisher's site
In this study, different processes such as flocculation with ferric chloride (FeCl3) and deep bed filtration (sand filtration and dual media filtration) as a pre-treatment to microfiltration (MF) were used for seawater desalination. The performance of these pre-treatments was determined in terms of silt density index (SDI) and modified fouling index (MFI) and flux decline in MF. Flux decline of MF with seawater was 45% without any pre-treatment, 42% after pre-treatment of FeCl3 flocculation, 24% after pre-treatment of sand filtration with in-line coagulation and 22% after pre-treatment of dual media filtration (sand and anthracite), respectively. MFI and SDI also indicated that deep bed filtration with in-line flocculation was better pretreatment than flocculation alone. Detailed molecular weight distribution (MWD) of seawater organic matter was examined after different pretreatments. MWD of the initial seawater mainly ranged from 1510 Da to 130 Da. Deep bed filtration with in-line flocculation removed relatively large molecular weight of organic matter (1510â1180 Da), while the small molecular weights (less than 530 Da) were not removed.
Johir, MH, Vigneswaran, S & Kandasamy, JK 2010, 'Hybrid filtration method for pre-treatment of stormwater', Water Science And Technology, vol. 62, no. 12, pp. 2937-2943.View/Download from: Publisher's site
In this study the hybrid filtration process (combining fibre filter with deep bed dual media filtration) was investigated as pre-treatment to stormwater. This process was investigated in-terms of reduction in turbidity, dissolved organic carbon (DOC), colour, headloss development across the filters, suspended solids removal, organic matter removal, nutrients and heavy matter (such as iron, copper, lead, zinc) removal efficiency. A comparison was made between the hybrid filter with single media (sand) deep bed filter and fibre filter. It was found that the hybrid filtration system successfully removed turbidity (98%), colour (99%), suspended solids (99%), and DOC (55%). The removal efficiency of heavy metal was relatively low as the concentration of heavy metals present in stormwater was low. The removal efficiency of nitrate, nitrite and phosphorous (as orthophosphate) was 27, 35 and 72% respectively. Hybrid filtration processes showed a better reduction of Modified Fouling Index (MFI) value (from 15.500 s/l2 to 9 s/l2) compared with single media sand, anthracite and fibre filter which were 35 s/l2, 13 s/l2 and 14 s/l2 respectively when operated at FeCl3 dose of 15 mg/l.
Lee, J, Johir, MH, Chinu, KJ, Shon, H, Vigneswaran, S, Kandasamy, JK, Kim, CW & Shaw, K 2010, 'Novel pre-treatment method for seawater reverse osmosis: Fibre media filtration', Desalination, vol. 250, no. 2, pp. 557-561.View/Download from: Publisher's site
A high rate fibre filter was used as a pre-treatment to seawater reverse osmosis (SWRO) to reduce membrane fouling. Seawater was drawn from Chowder Bay where the Sydney Institute of Marine Science, Australia is located. A lab-scale fibre filter with a height of 1000 mm and a diameter of 30 mm was used in conjunction with in-line coagulation. The effect of operating the fibre filter with different packing densities (105, 115 kg/m3) and filtration velocities (40, 60 m/h) was investigated in terms of silt density index (SDI10), modified fouling index (MFI), pressure drop (ÎP), turbidity and molecular weight distribution (MWD). The use of in-line coagulation improved the performance of fibre filter as measured by the MFI and SDI. Regardless of filtration velocity and packing density the MFI and SDI10 values remained low as did the turbidity until the end of the filtration run. The MWD analysis showed the removal efficiencies of organic materials like biopolymers, fulvic acids, low MW acids for even experiments with the highest filtration velocity (60 m/h) and lowest packing density (105 kg/m3). This pre-treatment has a small foot print as it has the capacity of operating at a very high filtration velocity
Chinu, KJ, Johir, MH, Vigneswaran, S, Shon, H & Kandasamy, JK 2009, 'Biofilter as pretreatment to membrane based desalination: Evaluation in terms of fouling index', Desalination, vol. 247, no. 1-3, pp. 77-84.View/Download from: Publisher's site
The removal of particulate matter and dissolved organic matter from seawater by the use of biofiltration was investigated. Granular activated carbon (GAC) and anthracite were used as biofilter media at two different filtration velocities. Filtrate quality was measured in terms of silt density index (SDI), modified fouling index (MFI) and turbidity removal. Reverse osmosis (RO) was used as a post-treatment. Both biofilters demonstrated similar fouling reduction behavior in terms of SDI and MFI. Fouling potential in terms of MFI values decreased to 10 s/L2 within the first 10â15 days of operation and kept constant up to the remaining experimental period of 55 days of operation for both GAC and anthracite biofilter. The filtrate turbidity was steady after 10 days and remained low at a value of 0.2â0.3 NTU and 0.28â0.31 NTU for anthracite and GAC biofilter, respectively. Furthermore, the headloss development was low and within 20 cm for biofilter operated at a low velocity of 5 m/h. A post-treatment of reverse osmosis after a pretreatment of GAC and anthracite biofilters showed a reduction in normalized flux decline (J/J0) from 0.22 to 0.12 and 0.35 to 0.21 during the first 20 h, respectively. The RO flux for seawater declined at a faster rate and continued even after 3 days when no pretreatment was provided.
Johir, MH, Chinu, KJ, Vigneswaran, S & Shon, H 2009, 'In-line flocculation - filtration as pre-treatment to reverse osmosis desalination', Desalination, vol. 247, no. 1-3, pp. 85-93.View/Download from: Publisher's site
In this paper the performance of single and dual media filters with in-line flocculation have been examined as pretreatment to seawater reverse osmosis (SWRO). A comparison of filter performance was made between single medium filter (80 cm) consisting of sand or anthracite, and dual media filter consisting of sand (40 cm at the bottom) and anthracite (40 cm on top). Short term (6 hours) experiments were conducted with in-line coagulation followed by direct filtration. Filtration velocities of 5 m/h and 10 m/h were used. The performances of these filters were assessed in terms of turbidity removal, head loss build-up, and organic compound removal in terms of molecular weight distribution (MWD). The efficiency of the filter as pretreatment was evaluated in terms of silt density index (SDI) and modified fouling index (MFI). It was found that the turbidity removal was high and all the filters produced more or less same quality water. There was a slower buildup of head loss for coarser filter medium. A post treatment of reverse osmosis after an inline-flocculation-dual media filtration showed lower normalized flux decline (J/J0) (0.35 to 0.22 during the first 20 hours operation) while, seawater without any pretreatment showed steeper flux decline (0.18 to 0.11 at first 20 hours operation) in RO.
Johir, MH, Lee, J, Vigneswaran, S, Kandasamy, JK & Shaw, K 2009, 'Treatment of Stormwater using Fibre Filter Media', Water, Air, & Soil Pollution: Focus, vol. 9, no. 5-6, pp. 439-447.View/Download from: Publisher's site
In this study, a high-rate fibre filter was used as a pre-treatment to stormwater in conjunction with in-line flocculation. The effect of operating the fibre filter with different packing densities (105, 115 and 125 kg/m3) and filtration velocities (20, 40, 60 m/h) with and without in-line flocculation was investigated. In-line flocculation was provided using 5, 10 and 15 mg/L of ferric chloride (FeCl3Â·6H2O). The filter performance was studied in terms of pressure drop (ÎP), solids removal efficiency, heavy metals (total) removal efficiency and total organic carbon (TOC) removal efficiency. It is found that the use of in-line flocculation at a dose of 15 mg/L improved the performance of fibre filter as measured by turbidity removal (95%), total suspended solids reduction (98%), colour removal efficiency (99%), TOC removal (reduced by 30â40 %) and total coliform removal (93%). The modified fouling index reduced from 750â950 to 12 s/L2 proving that fibre filter can be an excellent pre-treatment to membrane filtration that may be consider as post-treatment. The removal efficiency of heavy metal was variable as their concentration in raw water was small. Even though the concentration of some of these metals such as iron, aluminium, copper and zinc were reduced, others like nickel, chromium and cadmium showed lower removal rates
This paper presents the results of experiments on the application of dual media and single media deep bed filters as pre-treatments to stormwater. In-line flocculation-filtration experiments were conducted with dual and single media filter. The single filter media (80 cm) consisted of either anthracite or sand, and the dual media filter consisted of sand (40 cm at the bottom) and anthracite (40 cm on top). Filtration velocities of 5 m/h, 10 m/h and 15 m/h were examined. The removal efficiency for turbidity, suspended solids and TOC was found to be 95%, 99% and 30â45% respectively at a flocculant dose of FeCl3 of 15 mg/L. The anthracite filter media showed a lower headloss development (26 cm, operated at 5 m/h filtration velocity with FeCl3 dose of 5 mg/L). The removal efficiency for nitrogen was lower than phosphorus which was relatively good (up to 50%). The removal efficiency for heavy metals such as Cd, Pb, Cr and Ni was found to be very low for all tested filtration systems because concentrations of these metals in the influent were also low. This filter can be used as a pretreatment to a membrane filter as the modified fouling index was reduced from 750 s/L2 (for stormwater) to 15 s/L2 (for filtered effluent). Detailed submerged membrane filter experiments conducted with pre-treated water showed that the membrane filter can be successfully be used as post-treatment to in-line flocculant-filter at a sustainable flux of 10 L/m2.h to remove the remaining solids and pathogens. An increase of air scouring in the membrane unit decreased the pressure development although it did not have any effect on increasing the critical flux beyond 10 L/m2.h.
Lee, J, Johir, J, Chinu, KJ, Shon, H, Vigneswaran, S, Kandasamy, JK, Kim, CW & Shaw, K 2009, 'Hybrid filtration method for pre-treatment of seawater reverse osmosis (SWRO)', Desalination, vol. 247, no. 1-3, pp. 15-24.View/Download from: Publisher's site
Hybrid processes combining fi bre fi lter with deep bed fi ltration process such as (i) fi bre fi lter and sand fi lter, (ii) fi bre fi lter and anthracite and (iii) fi bre fi lter and dual media fi lter were investigated as pre- treatments to SWRO. Seawater was drawn from Chowder Bay, Sydney. The eff ect of diff erent pretreatment hybrid systems was investigated in terms of silt density index (SDI10), modifi ed fouling index (MFI), headloss across the fi lters and reduction in turbidity and dissolved organic carbon (DOC). The in-line fl occulation in fi bre fi lter improved the performance of the pretreatment hybrid system as measured by the MFI, SDI10, headloss, turbidity and DOC removal. The lowest SDI10 and MFI were found with a fi bre fi lter operated at a fi ltration velocity of 40 m/h followed by dual media fi lter operated at a fi ltration velocity of 5 m/h. The lowest headloss and turbidity was found with a fi bre fi lter operated at a fi ltration velocity of 40 m/hr followed by anthracite operated at a fi ltration velocity of 5 m/h. This system also gave an effl uent with the lowest DOC of 0.64 mg/L corresponding to a removal effi ciency of about 70%.
Johir, MA 2012, 'Stormwater management, harvesting and reuse, Encyclopedia of Sustainability Science and Technology, Springer. pp 10095-10117'.
Johir, MA, Singh, G, Kandasamy, J, Vigneswaran, S, Kus, B & Naidu, R 2012, 'Stormwater Harvesting and Reuse' in Meyers, RA (ed), Encyclopedia of Sustainability Science and Technology, Springer, Germany, pp. 111095-10117.View/Download from: Publisher's site
Rapid urbanization has contributed to considerable increases in urban stromwater runoff and pollution, a deterioration of the water quality of urban waterways , and significant threats to its ecosystem. Stormwater runoff is the most neglected resource and, given that it contributes significantly to diffuse pollution of our waterways, it needs to be managed in more sustainable way to capture its benefits and at the same time to reduce the adverse impacts on waterways and receiving waters. A cultural change is occurring in urban stormwater management practice. Environmental aspects are becoming a major focus, with potentially profound effects on the traditional approach to stormwater management. An integrated approach to stormwater treatment and management and stormwater harvesting regards stormwater as a resource rather than a waste and considers all aspects of runoff within a development, including implementation of water quality/quantity controls, maximizing water reuse/conservation whilst preserving the amenity and environmental values within the catchment. Stormwater harvesting and reuse offers a potential alternative water supply for at least non-potable uses. The benefits of a successful stormwater harvesting systems include reductions in stormwater pollution loads to downstream waterways and estuaries, and in stormwater volumes and discharges. Methods of assessment to check the extent to which stormwater treatment systems are meeting their design objectives and compliance to water quality standards is important.
Johir, MA 2011, 'Evaluation and comparison of seawater and brackish water pre-treatment, Membrane-Based Desalination: An Integrated Approach (MEDINA), IWA Publishing, UK, pp. 33-70.'.
Johir, MA, Orem, Y, Messalem, R, Ben-David, E, Herzberg, M, Kushmaro, A, Ji, X, Di Profio, G, Curcio, E, Drioli, E, Laroche, JF, Remize, P, Leparc, J, Vigneswaran, S, Chinu, KJ, Lee, J, Shon, H, Kandasamy, JK, Ye, Y, Sim, LN, Herulah, B, Chen, V, Fane, AC, Tansakul, C, Laborie, S & Cabassud, C 2011, 'Evaluation and comparison of seawater and brackish water pre-treatment' in Drioli, E, Criscuoli, A & Macedonio, F (eds), Membrane-Based Desalination: An Integrated Approach (MEDINA), IWA Publishing, UK, pp. 33-70.
Shanmuganathan, S, Johir, MAH, Listowski, A, Vigneswaran, S & Kandasamy, J 2015, 'Sustainable Processes for Treatment of Waste Water Reverse Osmosis Concentrate to achieve Zero Waste Discharge: A Detailed Study in Water Reclamation Plant', Waste Management for Resource Utilisation (Procedia Environmental Sciences), International Conference on Solid Waste Management, Elsevier, Bengaluru, India, pp. 930-937.View/Download from: Publisher's site
Water reclamation systems based on dense membrane treatment such as reverse osmosis (RO) are being progressively applied to meet water quantity and quality requirements for a range of urban and environmental applications. The RO concentrate usually represents 25% of the feed water flow and contains the organic and inorganic contaminants at higher concentrations. The amount of RO concentrate waste water requiring disposal must be as minimal as possible (near zero-discharge); the recovery of high quality water should be as high as possible. Management issues related to proper treatment and disposal of RO concentrate are an important aspect of sustainable water reclamation practice. The RO concentrate is a significant component of water treatment process and poorly managed treatment and disposal of RO concentrate causes significant consequences. Even in a small to medium size water reclamation plant in Sydney, 2000 kL of water is treated by RO and around 300 kL of RO concentrate is produced daily. This RO concentrate consists of a high level of organics (25-30mg/L of DOC which is mainly refractory organics) and inorganic salts (Cl− = 400-650mg/L, Na+ = 400-500mg/L, Ca2+ = 93-200mg/L, K+ = 63-100mg/L). The RO concentrate waste disposal cost can be minimized and made valuable by reclaiming the RO concentrate with the aim of producing salts from the solutes and recycling the water to the treatment system. Technologies for recovery of high salt concentration from the RO concentrate such as forward osmosis (FO) and membrane distillation (MD) are either energy intensive or not developed in large scale. In this study, we highlight a sustainable membrane adsorption hybrid system in treating this RO concentrate.
Johir, MA 2012, Testing integrated nutrient recovery, SCOPE Newsletter – no 86.