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A model was developed for estimation of N-nitrosodimethylamine (NDMA) concentration in a case study of a chloraminated water distribution system in Australia using influencing parameters that had an impact on NDMA formation via a hybrid genetic algorithm method. The model was based on hydraulic retention time, temperature, and monochloramine residual. The genetic algorithm and quasi-Newton optimization with a Broyden–Fletcher–Goldfarb–Shanno Hessian updating method were combined into a hybrid parameter optimization scheme for robust calibration of NDMA model parameters. In order to test the applicability and the accuracy of the proposed model, NDMA concentration and water quality characteristics for 220 post-disinfection water samples collected between 2006 and 2016 were used. Good agreement between measured and estimated NDMA concentrations was observed by performing statistical analysis on an independent set of water sample data (R2= 0.93). This modeling approach has the potential to be used as a decision support tool in order to manage and improve the chloramine disinfection process.

Most alum sludge is disposed of in landfill sites in Australia, resulting in significant environmental pollution and management cost. Effective management of sludge in a more sustainable manner remains a critical social, environmental, and economic concern. To simultaneously solve the dilemma of sludge management, economic expenditure of disposal, greenhouse gas emissions, and social impacts, this study proposed a multi-objective model for supply chain design of alum sludge-derived supplementary cementitious material as a viable solution. This study identified and quantified the potential social benefit by considering different impacts of new working opportunities based on their type and location, optimized the greenhouse gas emission saving for the potential supply chain, and assessed the economic benefit of the optimal untapped supplementary cementitious material value chain. The viability and applicability of the model are demonstrated through a case study in Australia, where potential utilization paths for available alum sludge are valued. A set of Pareto-optimal solutions was generated using the ɛ-constraint method, and three compromise Pareto-optimal solutions showed a clear trade-off among three objectives. The result analysis of each single-objective optimization indicates that the maximum working opportunity brought by the proposed supply chain was over 3.6 million working hours. Besides, up to 5.5 billion tonnes of greenhouse gas emissions saving was reported when maximizing the environmental objective, and the maximum economic benefit in the form of net present value was over 200 million Australian dollars in simulated 20 years. The Pareto-optimal solutions report a trade-off among three objectives, and two compromised solutions are proposed based on the level of objective values.

Insufficient dissolved organic matter removal results in higher residual organics (measured as dissolved organic carbon, DOC) in the treated water which can act as precursors for disinfection by-products (DBPs) and consequently increases the potential for health risk. This study aims to use drinking water treatment sludge (DWTS) as a coagulant-aid to improve the DOC removal efficiency. The effect of various DWTS doses (between 0.5 and 3 g/L) on the coagulation performance (by alum) to treat natural surface water that has relatively low turbidity and high DOC at optimum pH (~6) was examined using standard jar tests procedure. Although addition of DWTS at doses lower than 1.5 g/L improved the DOC removal efficiency (by 4% and 12% at DWTS dose of 0.5 and 1.0 g/L, respectively), the turbidity levels increased. In comparison to optimum dose of alum without DWTS, the addition of DWTS at 3 g/L led to reduce the alum dose to ~50% to achieve similar removal efficiency of organics (70% DOC removal). Further, addition of DWTS improved the floc’s characteristics (achieve larger flocs and rapid growth rate; measured by photometric dispersion analyser, PDA) and settling rate significantly, and the produced sludge volume decreased by ~50% compared to the figure with no DWTS addition. Trihalomethane formation potential (THMFP) was also reduced (up to ∼ 30%) when DWTS used. The results indicate that DWTS reuse as a coagulant-aid has the potential to reduce DOC and control DBPs formation when the organic loads require high coagulant dose exceeding the WTP design limits.

AbstractA specifically designed pilot plant facility located at the Mount Pleasant Water Treatment Plant in South Australia was used to investigate the efficiencies of several drinking water treatment processes, including (1) magnetic ion exchange (MIEX) as a pretreatment followed by conventional coagulation treatment, (2) conventional coagulation at pilot the plant alone, (3) MIEX followed by microfiltration (MF), and (4) MF alone. Dissolved organic matter (DOM) removal efficiency of the treatment processes and more importantly the treated water quality was assessed using dissolved organic carbon (DOC) measurement and together with the changes in the chromophoric organics character based on their molecular weight profiles determined by high-performance size exclusion chromatography (HPSEC) were also reported. Cluster analyses (CAs) were performed using the HPSEC peak area (after separated by peak fitting), and supported by DOC, UV absorbance at 254 nm, and SUVA in order to compare treatment efficiencies of these technologies. It was a novel way of applying CA as a data mining tool to interpret and assess DOM removal results. From the results of these CA, it was found that the MIEX process provided consistent treatment performance and highest removal of DOM, as well as removal of a broad range of molecular weight organics. In comparison coagulation with alum tended to remove the high molecular weight (>1000 Da) compounds. This statistical approach provided improved understanding of the performances of the treatment processes, investigated at a molecular level, for the removal of DOM.

A specifically designed pilot plant facility located at the Mount Pleasant Water Treatment Plant in South Australia was used to investigate the efficiencies of several drinking water treatment processes, including (1) magnetic ion exchange (MIEX) as a pretreatment followed by conventional coagulation treatment, (2) conventional coagulation at pilot the plant alone, (3) MIEX followed by microfiltration (MF), and (4) MF alone. Dissolved organic matter (DOM) removal efficiency of the treatment processes and more importantly the treated water quality was assessed using dissolved organic carbon (DOC) measurement and together with the changes in the chromophoric organics character based on their molecular weight profiles determined by high-performance size exclusion chromatography (HPSEC) were also reported. Cluster analyses (CAs) were performed using the HPSEC peak area (after separated by peak fitting), and supported by DOC, UV absorbance at 254 nm, and SUVA in order to compare treatment efficiencies of these technologies. It was a novel way of applying CA as a data mining tool to interpret and assess DOM removal results. From the results of these CA, it was found that the MIEX process provided consistent treatment performance and highest removal of DOM, as well as removal of a broad range of molecular weight organics. In comparison coagulation with alum tended to remove the high molecular weight (>1000 Da) compounds. This statistical approach provided improved understanding of the performances of the treatment processes, investigated at a molecular level, for the removal of DOM.

AbstractThis work aimed to demonstrate the effect of optimised coagulation on minimise fouling for coagulation–ultrafiltration process. Coagulation as pretreatment has the potential to mitigate fouling and enhance flux. Operating parameters were tested by a matrix of experiments for various mixing conditions and coagulant doses. In coagulation experiments, varied shear forces were applied to generate different floc characteristics in order to assess the effect on membrane fouling. Floc properties were investigated with an optical monitoring technique to identify structure, size and growth of flocs. It was shown that stronger flocs are of advantage for fouling mitigation and that the coagulant dosage is crucial for the performance of filtration. The impact of water quality was assessed using general water quality parameters and organic characterisation techniques to investigate the performance of each treatment step. The treatment efficiency was further assessed based on comparing the molecular size fractions of the organic matter before and after coagulation using a size exclusion chromatography technique. The result confirmed the significance of organic character on treatment performance.

This work aimed to demonstrate the effect of optimised coagulation on minimise fouling for coagulation–ultrafiltration process. Coagulation as pretreatment has the potential to mitigate fouling and enhance flux. Operating parameters were tested by a matrix of experiments for various mixing conditions and coagulant doses. In coagulation experiments, varied shear forces were applied to generate different floc characteristics in order to assess the effect on membrane fouling. Floc properties were investigated with an optical monitoring technique to identify structure, size and growth of flocs. It was shown that stronger flocs are of advantage for fouling mitigation and that the coagulant dosage is crucial for the performance of filtration. The impact of water quality was assessed using general water quality parameters and organic characterisation techniques to investigate the performance of each treatment step. The treatment efficiency was further assessed based on comparing the molecular size fractions of the organic matter before and after coagulation using a size exclusion chromatography technique. The result confirmed the significance of organic character on treatment performance.

AbstractThe application of a new combined fractionation technique (CFT) using high performance size exclusion chromatography (HPSEC) and rapid resin fractionation (RRF) for characterization of natural organic matter (NOM) in raw and post-coagulated water samples was assessed. Two natural water samples from Myponga and Hope Valley reservoirs, South Australia, respectively, were selected for this NOM removal by coagulation study. With the use of HPSEC and RRF individually, removal in the low molecular weight (LMW) organic region was observed by comparison of the HPSEC profiles of raw and treated waters and the removal of the hydrophobic organics was observed by comparing the RRF results. A new organic fractionation and characterization technique involving the sequential application of the two techniques, called RRF–HPSEC, was developed to provide additional analytical information particularly to determine the key control factor for the removal of LMW organics. The RRF–HPSEC results showed that good removal of LMW organics could be linked to the presence of high ratio of hydrophobic LMW organics compared with hydrophilic LMW organics. It was revealed, therefore, that the removal of LMW organics was achieved mainly through the reduction of hydrophobic fractions compared with hydrophilic fractions with the corresponding molecular weight.

The application of a new combined fractionation technique (CFT) using high performance size exclusion chromatography (HPSEC) and rapid resin fractionation (RRF) for characterization of natural organic matter (NOM) in raw and post-coagulated water samples was assessed. Two natural water samples from Myponga and Hope Valley reservoirs, South Australia, respectively, were selected for this NOM removal by coagulation study. With the use of HPSEC and RRF individually, removal in the low molecular weight (LMW) organic region was observed by comparison of the HPSEC profiles of raw and treated waters and the removal of the hydrophobic organics was observed by comparing the RRF results. A new organic fractionation and characterization technique involving the sequential application of the two techniques, called RRF–HPSEC, was developed to provide additional analytical information particularly to determine the key control factor for the removal of LMW organics. The RRF–HPSEC results showed that good removal of LMW organics could be linked to the presence of high ratio of hydrophobic LMW organics compared with hydrophilic LMW organics. It was revealed, therefore, that the removal of LMW organics was achieved mainly through the reduction of hydrophobic fractions compared with hydrophilic fractions with the corresponding molecular weight.

The use of nanotechnologies in water treatment for the removal of natural organic matter (NOM) is a relatively new concept. Using simple self-assembled monolayer (SAM) techniques, a silica substrate was modified as an adsorbent and tested for its potential for reduction of water quality parameters such as UV absorbance, colour and dissolved organic carbon (DOC). Silica particles that were coated with an amino-siloxane SAM (NH2-SAM) were evaluated in both a high surface area powder form and also a more realistic granular sand form. Initial results using direct stirred contact with powdered NH2-SAM showed promising results with 60% reduction of UV254after 1 h and up to 70% removal of DOC with higher doses and contact times. NH2-SAM powder removed NOM in a broader and less selective molecular weight (MW) range than coagulation treatment and this removal was enhanced by pH control at 6, especially for medium MW components. When NH2-SAM sand was applied, the significantly reduced effective surface area resulted in lower DOC removal but colour removal was still considerable for realistic treatment plant contact times. Attempted regeneration with acidic solutions showed greater effectiveness at lower applied pH, however recovery of adsorption capacity reduced with successive adsorption/regeneration cycles highlighting the need for further refinement of operating conditions for more effective application of this relatively simple water treatment technology.

The use of nanotechnologies in water treatment for the removal of natural organic matter (NOM) is a relatively new concept. Using simple self-assembled monolayer (SAM) techniques, a silica substrate was modified as an adsorbent and tested for its potential for reduction of water quality parameters such as UV absorbance, colour and dissolved organic carbon (DOC). Silica particles that were coated with an amino-siloxane SAM (NH2-SAM) were evaluated in both a high surface area powder form and also a more realistic granular sand form. Initial results using direct stirred contact with powdered NH2-SAM showed promising results with 60% reduction of UV254after 1 h and up to 70% removal of DOC with higher doses and contact times. NH2-SAM powder removed NOM in a broader and less selective molecular weight (MW) range than coagulation treatment and this removal was enhanced by pH control at 6, especially for medium MW components. When NH2-SAM sand was applied, the significantly reduced effective surface area resulted in lower DOC removal but colour removal was still considerable for realistic treatment plant contact times. Attempted regeneration with acidic solutions showed greater effectiveness at lower applied pH, however recovery of adsorption capacity reduced with successive adsorption/regeneration cycles highlighting the need for further refinement of operating conditions for more effective application of this relatively simple water treatment technology.

The Paris Agreement, with its target of net-zero emissions by 2050, has forced the concrete industry to reduce its energy consumption and carbon emissions. Therefore, the development of green concrete with a lower environmental impact is urgently required. In this case study, alum sludge was used as both sand and cement replacement in concrete blocks, and the compressive behaviour of concrete blocks and constructed masonry walls was first investigated. For cement replacement, the strength of blocks decreased with increasing alum sludge ash (ASA) content when the cement replacement ratio was higher than 10% by weight. These results were attributed to the fact that the filler effect and pozzolanic reaction of ASA compensated for the cement dilution effect at a moderate replacement ratio. However, the cement dilution effect dominated the mechanism with further ASA addition. For sand replacement, 10% oven-dried alum sludge addition degraded the mechanical performance of blocks significantly due to high organic content, which might hinder cement hydration. The compression behaviour of masonry walls was also influenced by alum sludge, and the testing results showed that the sludge addition increased ductility of the masonry wall but decreased the strength insignificantly. Therefore, the sludge-derived blocks were suitable for masonry application. Furthermore, a life cycle assessment model was developed based on the designed sludge-derived cement supply chain in South Australia. The obtained results indicate that the annual reduced greenhouse gas emissions were around 1,3339,549 tons, which equaled to the amount of greenhouse gas released from 28,898 passenger vehicles driven for a year.

Cyanobacteria (blue‐green algae) produce toxins and tastes and odors that can significantly impair water quality. The removal of cyanobacterial cells without cell damage could significantly reduce the concentration of tastes, odors, and toxic cell metabolites present in treated water. Cultured cyanobacterium, hepatotoxic Microcystis aeruginosa, was mixed with reservoir water to simulate water entering a treatment plant during an algal bloom. A bench‐top jar‐test apparatus (flocculation) and a full‐scale pilot plant (flocculation–sedimentation–filtration) rated at 600 mL/min were used to evaluate the effectiveness of conventional water treatment processes in removing cyanobacterial cells. Removal of cells by flocculation using a jar‐test apparatus with aluminum sulfate dosed at concentrations used in water treatment practice varied between 70 and 83%. Results obtained from the pilot experiment indicated 99.9% of the cells were removed. More important, no additional release of microcystin (toxin) was found in the finished water.

An intelligent automated ammonia monitoring system was developed based on a commercial ammonia selective electrode used in flow injection analysis (FIA) mode. A prototype automatic monitoring system was produced and interfaced to an IBM personal computer. The interfacing involved the design and fabrication of a sensor interface, an inter-integrated circuit (I2C) card and a flow injection analysis controller. This ammonia monitoring system will be used in conjunction with the dissolved oxygen and temperature sensors for the determination of ammonia toxicity. Use of a sodium hydroxide reagent line allowed determination of total ammonia (un-ionized (NH3) + ionized (NH4+)). With the output of the pH and temperature probes, un-ionized ammonia can be determined based on an equilibrium calculation. This experimental system was controlled under an expert system, Crystal. It provides the knowledge of equipment setup, control and results interpretation based on the rules stored in its knowledge base.

Protein, the main component of extracellular polymeric substances, plays a vital role in sediment dewatering. Tannic acid (TA) can bind with protein, so was used as a new conditioner for sediment dewatering. The benefit of using TA as a conditioner for sediment dewatering and its mechanism were explored in this study. A series of laboratory-based experiments were conducted and the water content (Wc) of sediment cakes, specific resistance to filtration (SRF) and the filterable dehydration rate were used to evaluate the sediment dewaterability. The results showed that at the optimal dosage of 0.20 mmol/gTS (total solid), TA reduced Wc of sediment cakes by 12.3% and SRF by 70.6%, and increased the filterable dehydration rate by 9%. These results indicated TA effectively improved the dewatering performance of sediment. The conditioning mechanism study of TA supported that the protein content was reduced by combining with TA, and the bound water was gradually converted into free water. When TA was added in sufficient amount, the particle size gradually increased, large and dense aggregates were formed which enhanced the dewatering performance of the sediment. These results confirm the feasibility of using TA as an effective option for rapid dewatering of sediment and provide a reference for selecting the appropriate conditioner for sediment dewatering.