Surface analysis of pilot distribution system pipe autopsies: The relationship of organic and inorganic deposits to input water quality.

Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) surface analysis was conducted to characterise deposits in polyethylene pipes used in a novel pilot water distribution system (PDS). The system consisted of four (4) parallel distribution systems receiving water from different treatment processes, ranging from conventional coagulation through to an advanced membrane filtration system. After two years of operation, the distribution system was shut down and samples of pipe were collected for autopsy analysis.

Fate of geosmin and 2-methylisoborneol in full-scale water treatment plants.

The increasing frequency and intensity of taste and odour (T&O) producing cyanobacteria in water sources is a growing global issue. Geosmin and 2-methylisoborneol (MIB) are the main cyanobacterial T&O compounds and can cause complaints from consumers at levels as low as 10 ng/L. However, literature concerning the performance of full-scale treatment processes for geosmin and MIB removal is rare.

Assessing the impact of water treatment on bacterial biofilms in drinking water distribution systems using high-throughput DNA sequencing.

Biofilm control in drinking water distribution systems (DWDSs) is crucial, as biofilms are known to reduce flow efficiency, impair taste and quality of drinking water and have been implicated in the transmission of harmful pathogens. Microorganisms within biofilm communities are more resistant to disinfection compared to planktonic microorganisms, making them difficult to manage in DWDSs. This study evaluates the impact of four unique drinking water treatments on biofilm community structure using metagenomic DNA sequencing.

Drought to flood: a comparative assessment of four parallel surface water treatments during the 2010-2012 inflows to the Murray-Darling Basin, South Australia.

Four treatment processes; conventional coagulation, magnetic ion exchange (MIEX)/coagulation, with and without granular activated carbon (GAC), and membrane treatment combining microfiltration (MF) and nanofiltration (NF), were operated in parallel using the same source water from the Murray-Darling basin in South Australia. During the two year study, high levels of natural organic matter and turbidity arising from floods affecting the Murray-Darling basin in 2010-2012 challenged the four processes. The comparative study indicated that all four processes could effectively meet basic water quality guidelines of turbidity and colour despite challenging source water quality but that the more advanced treatments improved overall organic and bacterial removal.

The effects of various control and water treatment processes on the membrane integrity and toxin fate of cyanobacteria.

Cyanobacterial blooms are one of the main contaminants that can degrade drinking water quality with the associated taste, odour and toxic compounds. Although a wide range of techniques have shown promise for cyanobacterial bloom control and cyanobacterial cell/metabolite removal in reservoirs and water treatment plants (WTPs), these treatments may have negative consequences through release of intracellular metabolites into the surrounding water. This study assessed the impact of copper sulphate (CuSO4), chlorine, potassium permanganate (KMnO4), hydrogen peroxide (H2O2) and ozone on Microcystis aeruginosa culture and the toxins it produced.

Evaluating the effectiveness of copper sulphate, chlorine, potassium permanganate, hydrogen peroxide and ozone on cyanobacterial cell integrity.

Cyanobacterial blooms are continuously critical challenges in drinking water systems which can have various negative impacts such as production of taste, odour and toxic compounds. Furthermore, the intracellular metabolites could be released into surrounding waters when the cyanobacterial membranes are destroyed. Although a variety of techniques have been developed to control cyanobacterial blooms and remove cyanobacterial cells or metabolites in water treatment processes, the effect of these treatments on the membrane integrity of cyanobacterial cells have not been systematically studied and compared.

Impact of potassium permanganate on cyanobacterial cell integrity and toxin release and degradation.

Potassium permanganate (KMnO4) is commonly used as a pre-treatment oxidant to remove soluble manganese (Mn) and iron (Fe) which can contribute to dirty water in drinking water supplies. Because Mn and Fe problems are commonly associated with thermal stratification in summer and autumn, they frequently coincide with the presence of cyanobacteria. The use of KMnO4 as an oxidant for Mn and Fe control therefore needs to consider the potential impacts on cyanobacterial cell integrity and toxin release.

Determination of rate constants and half-lives for the simultaneous biodegradation of several cyanobacterial metabolites in Australian source waters.

The fate of five cyanobacterial metabolites was assessed in water sourced from Lake Burragorang (Warragamba Dam) in New South Wales, Australia. All of the studied metabolites were shown to be biodegradable in this water source. For some metabolites, biodegradation was influenced by factors, including temperature, location (within the water body) and seasonal variations.

Comparison of drinking water treatment process streams for optimal bacteriological water quality.

Four pilot-scale treatment process streams (Stream 1 - Conventional treatment (coagulation/flocculation/dual media filtration); Stream 2 - Magnetic ion exchange (MIEX)/Conventional treatment; Stream 3 - MIEX/Conventional treatment/granular activated carbon (GAC) filtration; Stream 4 - Microfiltration/nanofiltration) were commissioned to compare their effectiveness in producing high quality potable water prior to disinfection. Despite receiving highly variable source water quality throughout the investigation, each stream consistently reduced colour and turbidity to below Australian Drinking Water Guideline levels, with the exception of Stream 1 which was difficult to manage due to the reactive nature of coagulation control. Of particular interest was the bacteriological quality of the treated waters where flow cytometry was shown to be the superior monitoring tool in comparison to the traditional heterotrophic plate count method.

Fate of cyanobacteria and their metabolites during water treatment sludge management processes.

Cyanobacteria and their metabolites are an issue for water authorities; however, little is known as to the fate of coagulated cyanobacterial-laden sludge during waste management processes in water treatment plants (WTPs). This paper provides information on the cell integrity of Anabaena circinalis and Cylindrospermopsis raciborskii during: laboratory-scale coagulation/sedimentation processes; direct filtration and backwashing procedures; and cyanobacterial-laden sludge management practices. In addition, the metabolites produced by A.

Removal of cyanobacterial metabolites through wastewater treatment plant filters.

Wastewaters have the potential to proliferate excessive numbers of cyanobacteria due to high nutrient levels. This could translate to the production of metabolites, such as the saxitoxins, geosmin and 2-methylisoborneol (MIB), which can impair the quality of wastewater destined for re-use. Biological sand filtration was assessed for its ability to remove these metabolites from a wastewater.

Biodegradation of multiple cyanobacterial metabolites in drinking water supplies.

The fate of multiple cyanobacterial metabolites was assessed in two Australian source waters. The saxitoxins were the only metabolites shown to be non-biodegradable in Myponga Reservoir water, while microcystin-LR (MCLR) and geosmin were biodegradable in this water source. Likewise, cylindrospermopsin (CYN) was shown to be biodegradable in River Murray water.

Biological treatment options for cyanobacteria metabolite removal--a review.

The treatment of cyanobacterial metabolites can consume many resources for water authorities which can be problematic especially with the recent shift away from chemical- and energy-intensive processes towards carbon and climate neutrality. In recent times, there has been a renaissance in biological treatment, in particular, biological filtration processes, for cyanobacteria metabolite removal. This in part, is due to the advances in molecular microbiology which has assisted in further understanding the biodegradation processes of specific cyanobacteria metabolites.

Fate of toxic cyanobacterial cells and disinfection by-products formation after chlorination.

Drinking water sources in many regions are subject to proliferation of toxic cyanobacteria (CB). Chlorination of source water containing toxic cyanobacterial cells for diverse treatment purposes might cause cell damage, toxin release and disinfection by-products (DBP) formation. There is limited information available on chlorination of different toxic CB cells and DBP formation potentials.

Assessing granular media filtration for the removal of chemical contaminants from wastewater.

Granular media filtration was evaluated for the removal of a suite of chemical contaminants that can be found in wastewater. Laboratory- and pilot-scale sand and granular activated carbon (GAC) filters were trialled for their ability to remove atrazine, estrone (E1), 17α-ethynylestradiol (EE2), N-nitrosodimethylamine (NDMA), N-nitrosomorpholine (NMOR) and N-nitrosodiethylamine (NDEA). In general, sand filtration was ineffective in removing the contaminants from a tertiary treated wastewater, with the exception of E1 and EE2, where efficient removals were observed after approximately 150 d.

Application of powdered activated carbon for the adsorption of cylindrospermopsin and microcystin toxins from drinking water supplies.

Cylindrospermopsin (CYN) and microcystin are two potent toxins that can be produced by cyanobacteria in drinking water supplies. This study investigated the application of powdered activated carbon (PAC) for the removal of these toxins under conditions that could be experienced in a water treatment plant. Two different PACs were evaluated for their ability to remove CYN and four microcystin variants from various drinking water supplies.

Removal of cyanobacterial metabolites by nanofiltration from two treated waters.

Cyanobacterial metabolites, both toxic and non-toxic, are a major problem for the water industry. Nanofiltration (NF) may be an effective treatment option for removing organic micropollutants, such as cyanobacterial metabolites, from drinking water due to its size exclusion properties. A rapid bench scale membrane test (RBSMT) unit was utilised to trial four NF membranes to remove the cyanobacterial metabolites, microcystin, cylindrospermopsin (CYN), 2-methylisoborneol (MIB) and geosmin (GSM) in two treated waters sourced from the Palmer and Myponga water treatment plants.

A coagulation-powdered activated carbon-ultrafiltration--multiple barrier approach for removing toxins from two Australian cyanobacterial blooms.

Cyanobacteria are a major problem for the world wide water industry as they can produce metabolites toxic to humans in addition to taste and odour compounds that make drinking water aesthetically displeasing. Removal of cyanobacterial toxins from drinking water is important to avoid serious illness in consumers. This objective can be confidently achieved through the application of the multiple barrier approach to drinking water quality and safety.

Release and oxidation of cell-bound saxitoxins during chlorination of Anabaena circinalis cells.

Surface water sources are increasingly subject to proliferation of toxic cyanobacteria. Direct chlorination of source water containing toxic cyanobacterial cells for different treatment purposes might cause cell damage and toxin release. There is limited information available on chlorination of saxitoxins (STXs: saxitoxin, C-toxins, and gonyautoxins) produced by Anabaena circinalis.

Determining the fate of Microcystis aeruginosa cells and microcystin toxins following chloramination.

The cyanobacterium Microcystis aeruginosa can produce potent toxins known as microcystins. While many studies have focussed on the chlorination of microcystin toxins, little work has been conducted with respect to the chloramination of the microcystins. In addition, no studies have been reported on the effect of chloramination on intact Microcystis cells.

Investigations into the biodegradation of microcystin-LR in wastewaters.

Microcystins are potent hepatotoxins that can be produced by cyanobacteria. These organisms can proliferate in wastewaters due to a number of factors including high concentrations of nutrients for growth. As treated wastewaters are now being considered as supplementary drinking water sources, in addition to their frequent use for irrigated agriculture, it is imperative that these wastewaters are free of toxins such as microcystins.

Optimising water treatment practices for the removal of Anabaena circinalis and its associated metabolites, geosmin and saxitoxins.

The cyanobacterium Anabaena circinalis has the ability to co-produce geosmin and saxitoxins, compounds which can compromise the quality of drinking water. This study provides pertinent information in optimising water treatment practices for the removal of geosmin and saxitoxins. In particular, it demonstrates that pre-oxidation using potassium permanganate could be applied at the head of water treatment plants without releasing intracellular geosmin and saxitoxins from A.

Development of an mlrA gene-directed TaqMan PCR assay for quantitative assessment of microcystin-degrading bacteria within water treatment plant sand filter biofilms.

We report for the first time a quantitative mlrA gene-directed TaqMan PCR assay for the rapid detection of microcystin-degrading bacteria. This was applied, in combination with 16S ribosomal DNA-directed quantitative PCR and denaturing gradient gel electrophoresis, to study virgin sand filter column biofilm development and to correlate mlrA gene abundance with microcystin removal efficiency.