The Value of In Vivo Monitoring and Chlorination for the Control of Toxic Cyanobacteria in Drinking Water Production.

RÉSUMÉ: La prolifération croissante des cyanobactéries (CBs) toxiques dans les sources d'eau potable et dans les usines de traitement d'eau potable est une préoccupation mondiale. L‟utilisation de sondes in vivo, permettant la détection de fluorescence de la phycocyanine (PC) des CBs, est une technologie émergente et largement employée pour détecter les CBs dans les eaux de source. Dans les traitements varies de l‟eau de source qui contient des CBs toxiques la chloration directe de cette eau peut engendrer l‟endommagement de cellules, causer le relargage de toxines ainsi que la formation des sous-produits de désinfection. La chloration, bien que prouvée être efficace pour l'oxydation de certaines espèces des CBs et des cyanotoxines, aucune information n‟est disponible sur sa cinétique de saxitoxines (STXS: saxitoxine, C-toxines et gonyautoxines) produites par Anabaena circinalis. De plus, il y a peu d'informations sur la chloration des différentes cellules toxiques de CBs, sur la demande en chlore des cellules de CBs, la chloration de toxines, et sur l‟éventualité de la formation de sous-produits de désinfection en présence de matériaux cellulaires. Par ailleurs, le sort des CBs, et les toxines qui leur sont associés à l'intérieur des usines de traitement d'eau potable (après différents procédés de traitement conventionnels et avancés) exigent une investigation plus approfondie. Les experts australiens sont les pionniers dans la gestion des problèmes reliés aux CBs toxiques. Dans le but d‟aider à la préparation d‟un plan de gestion des problèmes de CBs et leurs toxines pour la province du Québec (Canada), une visite industrielle a été financée pour documenter les expériences australiennes dans ce domaine. ABSTRACT: The increasing occurrence of toxic cyanobacterial blooms in drinking water (DW) sources and inside drinking water treatment plants (DWTPs) is a global concern. The applications of in vivo probes, which can detect the fluorescence of the cyanobacterial phycocyanin, are an emerging and widely used technology for cyanobacterial detection in source waters. Direct chlorination of source water containing toxic cyanobacterial cells for different treatment purposes might cause cell damage, toxin release and disinfection by-product (DBP) formation. While chlorination has been proven to be efficient for oxidation of certain cyanobacteria (CB) species and cyanotoxins, there is no information available on chlorination kinetics of saxitoxins (STXs: saxitoxin, C-toxins and, gonyautoxins) produced by Anabaena circinalis. Furthermore, there is limited information available on chlorination of different toxic CB cells, chlorine demand of CB cells, toxins chlorination, and DBP formation potentials in the presence of cellular materials. Moreover, the fate of CB and their associated toxins inside DWTPs (after different conventional and advanced treatment processes) requires further investigation. Australian DW experts are the pioneers in dealing with toxic CB related issues. In order to prepare a management plan for the province of Quebec (Canada), an industrial visit was funded to document Australian experiences dealing with CB related problems

Comparative Assessment of Physical and Chemical Cyanobacteria Cell Lysis Methods for Total Microcystin-LR Analysis

ABSTRACT: Standardization and validation of alternative cell lysis methods used for quantifying total cyanotoxins is needed to improve laboratory response time goals for total cyanotoxin analysis. In this study, five cell lysis methods (i.e., probe sonication, microwave, freeze-thaw, chemical lysis with Abraxis QuikLyseTM, and chemical lysis with copper sulfate) were assessed using laboratory-cultured Microcystis aeruginosa (M. aeruginosa) cells. Methods were evaluated for destruction of cells (as determined by optical density of the sample) and recovery of total microcystin-LR (MC-LR) using three M. aeruginosa cell densities (i.e., 1 × 105 cells/mL (low-density), 1 × 106 cells/mL (medium-density), and 1 × 107 cells/mL (high-density)). Of the physical lysis methods, both freeze-thaw (1 to 5 cycles) and pulsed probe sonication (2 to 10 min) resulted in >80% destruction of cells and consistent (>80%) release and recovery of intracellular MC-LR. Microwave (3 to 5 min) did not demonstrate the same decrease in optical density (80% intracellular MC-LR. Abraxis QuikLyseTM was similarly effective for intracellular MC-LR recovery across the different M. aeruginosa cell densities. Copper sulfate (up to 500 mg/L Cu2+) did not lyse cells nor release intracellular MC-LR within 20 min. None of the methods appeared to cause degradation of MC-LR. Probe sonication, microwave, and Abraxis QuikLyseTM served as rapid lysis methods (within minutes) with varying associated costs, while freeze-thaw provided a viable, low-cost alternative if time permits

Cyanotoxins and cyanobacteria cell accumulations in drinking water treatment plants with a low risk of bloom formation at the source

Toxic cyanobacteria have been shown to accumulate in drinking water treatment plants that are susceptible to algal blooms. However, the risk for plants that do not experience algal blooms, but that receive a low influx of cells, is not well known. This study determined the extent of cell accumulation and presence of cyanotoxins across the treatment trains of four plants in the Great Lakes region. Samples were collected for microscopic enumeration and enzyme-linked immunosorbent assay (ELISA) measurements for microcystins, anatoxin-a, saxitoxin, cylindrospermopsin, and beta-methylamino-L-alanine (BMAA). Low cell influxes (under 1000 cells/mL) resulted in significant cell accumulations (over 1 x 10(5) cells/mL) in clarifier sludge and filter backwash samples. Microcystins peaked at 7.2 microg/L in one clarifier sludge sample, exceeding the raw water concentration by a factor of 12. Anatoxin-a was detected in the finished drinking water of one plant at 0.6 microg/L. BMAA may have been detected in three finished water samples, though inconsistencies among the BMAA ELISAs call these results into question. In summary, the results show that plants receiving a low influx of cells can be at risk of toxic cyanobacterial accumulation, and therefore, the absence of a bloom at the source does not indicate the absence of risk

Impact of UV-H₂O₂ advanced oxidation and aging processes on GAC capacity for the removal of cyanobacterial taste and odor compounds

ABSTRACT: Cyanobacteria and their taste and odor (T&O) compounds are a growing concern in water sources globally. Geosmin and 2-methylisoborneol (MIB) are the most commonly detected T&O compounds associated with cyanobacterial presence in drinking water sources. The use of ultraviolet and hydrogen peroxide (H₂O₂) as an advanced oxidation treatment for T&O control is an emerging technology. However, residual H₂O₂ (>80% of the initial dose) has to be removed from water prior final disinfection. Recently, granular activated carbon (GAC) is used to remove H₂O₂ residual. The objective of this study is to assess the impact of H₂O₂ quenching and aging processes on GAC capacity for the removal of geosmin and MIB. Pilot columns with different types of GAC and presence/absence of H₂O₂ have been used for this study. H₂O₂ removal for the operational period of 6 months has no significant impact on GAC capacity to remove the geosmin and MIB from water

Degradation of progestagens by oxidation with potassium permanganate in wastewater effluents

Background: This study investigated the oxidation of selected progestagenic steroid hormones by potassium permanganate at pH 6.0 and 8.0 in ultrapure water and wastewater effluents, using bench-scale assays. Second order rate constants for the reaction of potassium permanganate with progestagens (levonorgestrel, medroxyprogesterone, norethindrone and progesterone) was determined as a function of pH, presence of natural organic matter and temperature. This work also illustrates the advantages of using a novel analytical method, the laser diode thermal desorption (LDTD-APCI) interface coupled to tandem mass spectrometry apparatus, allowing for the quick determination of oxidation rate constants and increasing sample throughput. Results: The second-order rate constants for progestagens with permanganate determined in bench-scale experiments ranged from 23 to 368 M-1 sec(-1) in both wastewater and ultrapure waters with pH values of 6.0 and 8.0. Two pairs of progestagens exhibited similar reaction rate constants, i.e. progesterone and medroxyprogesterone (23 to 80 M-1 sec(-1) in ultrapure water and 26 to 149 M-1 sec(-1) in wastewaters, at pH 6.0 and 8.0) and levonorgestrel and norethindrone (179 to 224 M-1 sec(-1) in ultrapure water and 180 to 368 M-1 sec(-1) in wastewaters, at pH 6.0 and 8.0). The presence of dissolved natural organic matter and the pH conditions improved the oxidation rate constants for progestagens with potassium permanganate only at alkaline pH. Reaction rates measured in Milli-Q water could therefore be used to provide conservative estimates for the oxidation rates of the four selected progestagens in wastewaters when exposed to potassium permanganate. The progestagen removal efficiencies was lower for progesterone and medroxyprogesterone (48 to 87%) than for levonorgestrel and norethindrone (78 to 97%) in Milli-Q and wastewaters at pH 6.0-8.2 using potassium permanganate dosages of 1 to 5 mg L-1 after contact times of 10 to 60 min. Conclusion: This work presents the first results on the permanganate-promoted oxidation of progestagens, as a function of pH, temperature as well as NOM. Progestagen concentrations used to determine rate constants were analyzed using an ultrafast laser diode thermal desorption interface coupled to tandemmass spectrometry for the analysis of water sample for progestagens

Assessment of the water treatment process's empirical model predictions for the management of aesthetic and health risks associated with cyanobacteria

ABSTRACT: Potentially toxic cyanobacteria have been increasingly detected worldwide in water supply systems in recent years. The management of cyanobacteria in source water and through drinking water treatment processes has been a focus of global research for over thirty years. However, despite the volume of research outcomes and the publication of guidance documents, gaps still exist in the knowledge base that inhibits the confident application of individual treatment strategies for the mitigation of aesthetic and health risks associated with cyanobacteria and their metabolites at the full-scale. The main objective of this project is to deliver a suite of tools and other resources to the water industry to support the implementation of a regulatory framework for the management of water quality for the assessment and management of aesthetic and toxicity risks associated with cyanobacteria. This study includes (1) the development of a guide (based on real-world examples) for treatment plant operators to perform plant audits and investigative sampling to assess the risk associated with cyanobacteria in their plants, and validate the performance of existing unit processes, and (2) the validation of a treatment model that can be applied at any plant and used to as a guide to the removals of cyanobacteria and metabolites and the expected quality of treated water under a range of challenges from cyanobacteria. Full-scale sampling was undertaken at three Australian regions in 14 water treatment plants to validate the model. The results presented in this paper represent a comprehensive database of full-scale removal efficiencies of 2-methylisoborneol (MIB) and geosmin for a range of water quality and treatment processes. The major findings and conclusions from this project include: (1) the investigative sampling procedures developed are effective and have been successfully applied by utilities; and (2) while routine monitoring data is important, investigative sampling within the water treatment plant provides more detailed and insightful information about the effectiveness of unit processes within the plant. This paper also identifies the knowledge gaps and needs for further studies

Can cyanobacterial diversity in the source predict the diversity in sludge and the risk of toxin release in a drinking water treatment plant?

ABSTRACT: Conventional processes (coagulation, flocculation, sedimentation, and filtration) are widely used in drinking water treatment plants and are considered a good treatment strategy to eliminate cyanobacterial cells and cell-bound cyanotoxins. The diversity of cyanobacteria was investigated using taxonomic cell counts and shotgun metagenomics over two seasons in a drinking water treat- ment plant before, during, and after the bloom. Changes in the community structure over time at the phylum, genus, and species levels were monitored in samples retrieved from raw water (RW), sludge in the holding tank (ST), and sludge supernatant (SST). Aphanothece clathrata brevis, Microcystis aeruginosa, Dolichospermum spiroides, and Chroococcus minimus were predominant species detected in RW by taxonomic cell counts. Shotgun metagenomics revealed that Proteobacteria was the pre- dominant phylum in RW before and after the cyanobacterial bloom. Taxonomic cell counts and shotgun metagenomic showed that the Dolichospermum bloom occurred inside the plant. Cyanobac- teria and Bacteroidetes were the major bacterial phyla during the bloom. Shotgun metagenomics also showed that Synechococcus, Microcystis, and Dolichospermum were the predominant detected cyanobacterial genera in the samples. Conventional treatment removed more than 92% of cyanobac- terial cells but led to cell accumulation in the sludge up to 31 times more than in the RW influx. Coagulation/sedimentation selectively removed more than 96% of Microcystis and Dolichospermum. Cyanobacterial community in the sludge varied from raw water to sludge during sludge storage (1–13 days). This variation was due to the selective removal of coagulation/sedimentation as well as the accumulation of captured cells over the period of storage time. However, the prediction of the cyanobacterial community composition in the SST remained a challenge. Among nutrient parameters, orthophosphate availability was related to community profile in RW samples, whereas communities in ST were influenced by total nitrogen, Kjeldahl nitrogen (N- Kjeldahl), total and particulate phos- phorous, and total organic carbon (TOC). No trend was observed on the impact of nutrients on SST communities. This study profiled new health-related, environmental, and technical challenges for the production of drinking water due to the complex fate of cyanobacteria in cyanobacteria-laden sludge and supernatant