Search

Cryptosporidium oocysts pose a significant threat to public health due to its ability to contaminate environmental waters, leading to outbreaks of waterborne diseases and emphasizing the crucial need for effective water treatment and monitoring systems. This study aimed to investigate the decay of Cryptosporidium oocyst DNA in cow fecal matter under different environmental conditions prevalent in sub-tropical Southeast Queensland (SEQ) during summer and winter seasons. The effects of ambient sunlight and shaded conditions on the decay rates of C. parvum DNA in cow fecal samples were evaluated. The results showed that measurable levels of C. parvum DNA were observed for up to 60 days during the summer experiments, with a slower decay rate on the surface (k = -0.029) and sub-surface (k = -0.043) of the cowpat under shaded conditions than those on the surface (k = -0.064) and sub-surface (k = -0.079) under sunlight conditions. The decay rates of C. parvum DNA on the surface and sub-surface of the cowpat under shaded conditions were significantly slower (p = 0.004; p = 0.004) than those on the surface and sub-surface under sunlight conditions during summer experiments. During the winter treatments, measurable levels of C. parvum DNA were observed for up to 90 days, and the decay rates were slower on the surface (k = -0.036) and sub-surface (k = -0.034) of the cowpat under shaded conditions than those under sunlight conditions (k = -0.067 for surface and k = -0.057 for sub-surface). The decay rates of C. parvum DNA on the surface and sub-surface of the cowpat under shaded conditions were significantly slower than those on the surface (p = 0.009) and sub-surface (p = 0.041) under sunlight conditions during winter experiments. Moreover, the decay rate in the summer sunlight surface treatment (k = -0.064) was significantly faster from those in the winter shaded surface (k = -0.036; p = 0.018) and sub-surface (k = -0.034; p = 0.011) treatments. Similar results were also observed for summer sunlight sub-surface (k = -0.079), which was significantly faster than winter shaded surface (k = -0.036; p = 0.0008) and sub-surface (k = -0.034; p = 0.0005) treatments. Overall, these findings are important to enhance our understanding on the degradation of C. parvum DNA in cow fecal matter in SEQ, particularly in relation to seasonal variations and environmental conditions., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Large-scale wastewater schemes rely on multi-barrier approach for the production of safe and sustainable recycled water. In multi-barrier wastewater reclamation systems, conventional activated sludge process (ASP) often constitutes a major initial treatment step. The main aim of this research was to determine most appropriate sampling approach to establish pathogen removal efficacy of ASP. The results suggest that ASP is capable of reducing human adenovirus (HAdV) and polyomavirus (HPyV) by up to 3 log 10 . The virus removal data suggests that HAdV removal is comparable to somatic bacteriophage belonging to Microviridae family. Due to the high removal of Escherichia coli (>3 log 10 ) and very poor correlation with the enteric virus, it is not recommended that E. coli be used as a surrogate for enteric virus removal. The results also demonstrated no statistically significant differences (t test, P > 0.05) in calculated log removal values (LRVs) for HAdV, HPyV, and Microviridae from samples collected on hydraulic retention time (HRT) or simultaneous paired samples collected for influent and effluent. This indicates that a more practical approach of simultaneous sampling for influent and effluent could be used to determine pathogen removal efficiency of ASP. The results also suggest that a minimum of 10, preferably 20 samples, are required to fully capture variability in the removal of virus. In order to cover for the potential seasonal prevalence of viruses such as norovirus and rotavirus, sampling should be spread across all seasons.

In this study, we investigated the use of Illumina high-throughput sequencing of 16S ribosomal RNA (rRNA) amplicons to explore microbial diversity and community structure in raw and secondary treated wastewater (WW) samples from four municipal wastewater treatment plants (WWTPs A-D) across Australia. Sequence reads were analyzed to determine the abundance and diversity of bacterial communities in raw and secondary treated WW samples across the four WWTPs. In addition, sequence reads were also characterized to phenotypic features and to estimate the abundance of potential pathogenic bacterial genera and antibiotic-resistant genes in total bacterial communities. The mean coverage, Shannon diversity index, observed richness (S obs ), and abundance-based coverage estimate (ACE) of richness for raw and secondary treated WW samples did not differ significantly (P > 0.05) among the four WWTPs examined. Generally, raw and secondary treated WW samples were dominated by members of the genera Pseudomonas, Arcobacter, and Bacteroides. Evaluation of source contributions to secondary treated WW, done using SourceTracker, revealed that 8.80-61.4% of the bacterial communities in secondary treated WW samples were attributed to raw WW. Twenty-five bacterial genera were classified as containing potential bacterial pathogens. The abundance of potentially pathogenic genera in raw WW samples was higher than that found in secondary treated WW samples. Among the pathogenic genera identified, Pseudomonas and Arcobacter had the greatest percentage of the sequence reads. The abundances of antibiotic resistance genes were generally low (<0.5%), except for genes encoding ABC transporters, which accounted for approximately 3% of inferred genes. These findings provided a comprehensive profile of bacterial communities, including potential bacterial pathogens and antibiotic-resistant genes, in raw and secondary treated WW samples from four WWTPs across Australia and demonstrated that Illumina high-throughput sequencing can be an alternative approach for monitoring WW quality in order to protect environmental and human health.

Secondary treated wastewater was infiltrated through a 9 m-thick calcareous vadose zone during a 39 month managed aquifer recharge (MAR) field trial to determine potential improvements in the recycled water quality. The water quality improvements of the recycled water were based on changes in the chemistry and microbiology of (i) the recycled water prior to infiltration relative to (ii) groundwater immediately down-gradient from the infiltration gallery. Changes in the average concentrations of several constituents in the recycled water were identified with reductions of 30% for phosphorous, 66% for fluoride, 62% for iron and 51% for total organic carbon when the secondary treated wastewater was infiltrated at an applied rate of 17.5 L per minute with a residence time of approximately four days in the vadose zone and less than two days in the aquifer. Reductions were also noted for oxazepam and temazepam among the pharmaceuticals tested and for a range of microbial pathogens, but reductions were harder to quantify as their magnitudes varied over time. Total nitrogen and carbamazepine persisted in groundwater down-gradient from the infiltration galleries. Infiltration does potentially offer a range of water quality improvements over direct injection to the water table without passage through the unsaturated zone; however, additional treatment options for the non-potable water may still need to be considered, depending on the receiving environment or the end use of the recovered water., (Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.)

A bioanalytical test battery was used for monitoring organic micropollutants across an indirect potable reuse scheme testing sites across the complete water cycle from sewage to drinking water to assess the efficacy of different treatment barriers. The indirect potable reuse scheme consists of seven treatment barriers: (1) source control, (2) wastewater treatment plant, (3) microfiltration, (4) reverse osmosis, (5) advanced oxidation, (6) natural environment in a reservoir and (7) drinking water treatment plant. Bioanalytical results provide complementary information to chemical analysis on the sum of micropollutants acting together in mixtures. Six endpoints targeting the groups of chemicals with modes of toxic action of particular relevance for human and environmental health were included in the evaluation: genotoxicity, estrogenicity (endocrine disruption), neurotoxicity, phytotoxicity, dioxin-like activity and non-specific cell toxicity. The toxicity of water samples was expressed as toxic equivalent concentrations (TEQ), a measure that translates the effect of the mixtures of unknown and potentially unidentified chemicals in a water sample to the effect that a known reference compound would cause. For each bioassay a different representative reference compound was selected. In this study, the TEQ concept was applied for the first time to the umuC test indicative of genotoxicity using 4-nitroquinoline as the reference compound for direct genotoxicity and benzo[a]pyrene for genotoxicity after metabolic activation. The TEQ were observed to decrease across the seven treatment barriers in all six selected bioassays. Each bioassay showed a differentiated picture representative for a different group of chemicals and their mixture effect. The TEQ of the samples across the seven barriers were in the same order of magnitude as seen during previous individual studies in wastewater and advanced water treatment plants and reservoirs. For the first time a benchmarking was performed that allows direct comparison of different treatment technologies and covers several orders of magnitude of TEQ from highly contaminated sewage to drinking water with TEQ close or below the limit of detection. Detection limits of the bioassays were decreased in comparison to earlier studies by optimizing sample preparation and test protocols, and were comparable to or lower than the quantification limits of the routine chemical analysis, which allowed monitoring of the presence and removal of micropollutants post Barrier 2 and in drinking water. The results obtained by bioanalytical tools were reproducible, robust and consistent with previous studies assessing the effectiveness of the wastewater and advanced water treatment plants. The results of this study indicate that bioanalytical results expressed as TEQ are useful to assess removal efficiency of micropollutants throughout all treatment steps of water recycling., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A quantitative microbial risk assessment (QMRA) was performed at four managed aquifer recharge (MAR) sites (Australia, South Africa, Belgium, Mexico) where reclaimed wastewater and stormwater is recycled via aquifers for drinking water supplies, using the same risk-based approach that is used for public water supplies. For each of the sites, the aquifer treatment barrier was assessed for its log(10) removal capacity much like for other water treatment technologies. This information was then integrated into a broader risk assessment to determine the human health burden from the four MAR sites. For the Australian and South African cases, managing the aquifer treatment barrier was found to be critical for the schemes to have low risk. For the Belgian case study, the large treatment trains both in terms of pre- and post-aquifer recharge ensures that the risk is always low. In the Mexico case study, the risk was high due to the lack of pre-treatment and the low residence times of the recharge water in the aquifer. A further sensitivity analysis demonstrated that human health risk can be managed if aquifers are integrated into a treatment train to attenuate pathogens. However, reduction in human health disease burden (as measured in disability adjusted life years, DALYs) varied depending upon the number of pathogens in the recharge source water. The beta-Poisson dose response curve used for translating rotavirus and Cryptosporidium numbers into DALYs coupled with their slow environmental decay rates means poor quality injectant leads to aquifers having reduced value to reduce DALYs. For these systems, like the Mexican case study, longer residence times are required to meet their DALYs guideline for drinking water. Nevertheless the results showed that the risks from pathogens can still be reduced and recharging via an aquifer is safer than discharging directly into surface water bodies., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Managed Aquifer Recharge (MAR) is becoming a mechanism used for recycling treated wastewater and captured urban stormwater and is being used as a treatment barrier to remove contaminants such as pathogens from the recharged water. There is still a need, however, to demonstrate the effectiveness of MAR to reduce any residual risk of pathogens in the recovered water. A MAR research site recharging secondary treated wastewater in an unconfined carbonate aquifer was used in conjunction with a static Quantitative Microbial Risk Assessment (QMRA) to assess the microbial pathogen risk in the recovered water following infiltration and aquifer passage. The research involved undertaking a detailed hydrogeological assessment of the aquifer at the MAR site and determining the decay rates of reference pathogens from an in-situ decay study. These variables along with literature data were then used in the static QMRA which demonstrated that the recovered water at this site did not meet the Australian Guidelines for recycled water when used for differing private green space irrigation scenarios. The results also confirmed the importance of obtaining local hydrogeological data as local heterogeneity can influence of residence time in the aquifer which, in turn, influences the outcomes. The research demonstrated that a static QMRA can be used to determine the residual risk from pathogens in recovered water and showed that it can be a valuable tool in the preliminary design and operation of MAR systems and the incorporation of complementary engineered treatment processes to ensure that there is acceptable health risk from the recovered water., (Crown Copyright 2009. Published by Elsevier Ltd. All rights reserved.)

Treated effluent is increasingly being used to irrigate municipal green spaces such as sporting ovals, but the potential risks to human health from faecal-oral pathogens present in the effluent have remained largely unreported. This is the first reported study where a quantitative microbial risk assessment (QMRA) was performed to evaluate the effect of varying withholding periods in terms of pathogen inactivation credits to risks to human health from sporting ovals irrigated with secondary treated effluent. The calculations on pathogen removal rates in this study suggest that a mean 0.7 log removal for bacteria and 0.4 log for viral pathogens could be achieved over a 4 hour period. [ABSTRACT FROM AUTHOR]