Effects of hydrogen peroxide preoxidation on clarification and reduction of the microbial load of groundwater and surface water sources for household treatment

Household water treatment (HWT) technologies are a promising strategy for addressing the waterborne diseases burden. However, in order to be efficient, these are often limited to water quality and require it to not exceed a certain threshold of physicochemical and microbiological contamination. Additionally, some popular HWTs, as chlorination, are related to by-product formation. Preoxidation may improve source water quality, and hydrogen peroxide (H2O2) is an oxidant that has not been deeply explored in this specific application, so it could be an innovative approach to HWTs. We investigated effects of H2O2 preoxidation in two natural source waters (surface and groundwater), spiked with a high level of microorganisms. Clarification results suggested this pretreatment may improve life of HWTs. Reduction in microbial load of groundwater was considered ineffective, but 5-min H2O2 preoxidation at 15 mg L−1 led to >4.0 log10 inactivation of Phi X174 coliphage and >3.0 of Escherichia coli in surface water. We believe this performance was increased due to the presence of catalysts in the river water. This raised the point that water quality may be not only impairing, but potentially beneficial to the main HWT and characterization is crucial prior to the implementation of any technologies.

Stratification in a Reservoir Mixed by Bubble Plumes under Future Climate Scenarios

During summer, reservoir stratification can negatively impact source water quality. Mixing via bubble plumes (i.e., destratification) aims to minimise this. Within Blagdon Lake, a UK drinking water reservoir, a bubble plume system was found to be insufficient for maintaining homogeneity during a 2017 heatwave based on two in situ temperature chains. Air temperature will increase under future climate change which will affect stratification; this raises questions over the future applicability of these plumes. To evaluate bubble-plume performance now and in the future, AEM3D was used to simulate reservoir mixing. Calibration and validation were done on in situ measurements. The model performed well with a root mean squared error of 0.53 °C. Twelve future meteorological scenarios from the UK Climate Projection 2018 were taken and down-scaled to sub-daily values to simulate lake response to future summer periods. The down-scaling methods, based on diurnal patterns, showed mixed results. Future model runs covered five-year intervals from 2030 to 2080. Mixing events, mean water temperatures, and Schmidt stability were evaluated. Eight scenarios showed a significant increase in water temperature, with two of these scenarios showing significant decrease in mixing events. None showed a significant increase in energy requirements. Results suggest that future climate scenarios may not alter the stratification regime; however, the warmer water may favour growth conditions for certain species of cyanobacteria and accelerate sedimentary oxygen consumption. There is some evidence of the lake changing from polymictic to a more monomictic nature. The results demonstrate bubble plumes are unlikely to maintain water column homogeneity under future climates. Modelling artificial mixing systems under future climates is a powerful tool to inform system design and reservoir management including requirements to prevent future source water quality degradation.

Distribution, source, water quality and health risk assessment of dissolved heavy metals in major rivers in Wuhan, China

Heavy metals are released into the water system through various natural processes and anthropogenic activities, thus indirectly or directly endangering human health. The distribution, source, water quality and health risk assessment of dissolved heavy metals (V, Mn, Fe, Co, Ni, Zn, As, Mo, Sb) in major rivers in Wuhan were analyzed by correlation analysis (CA), principal component analysis (PCA), heavy metal pollution index (HPI), hazard index (HI) and carcinogenic risk (CR). The results showed that the spatial variability of heavy metal contents was pronounced. PCA and CA results indicated that natural sources controlled Mn, Fe, Co, Ni and Mo, and industrial emissions were the dominant factor for V, Zn and Sb, while As was mainly from the mixed input of urban and agricultural activities. According to the heavy metal pollution index (HPI, ranging from 23.74 to 184.0) analysis, it should be noted that As and Sb contribute most of the HPI values. The health risk assessment using HI and CR showed that V and Sb might have a potential non-carcinogenic risk and As might have a potential carcinogenic risk to adults and children in the study area (CR value exceeded target risk 10−4). At the same time, it was worth noting that As might have a potential non-carcinogenic risk for children around QLR (HI value exceeded the threshold value 1). The secular variation of As and Sb should be monitor in high-risk areas. The results of this study can provide important data for improving water resources management efficiency and heavy metal pollution prevention in Wuhan.

Source water quality requirements for artificial groundwater recharge

This study was an investigation of the need for pre-treatment of a new raw water source for artificial groundwater recharge. The study was done through a column test, well sampling and survey data relating to 11 artificial recharge plants in Sweden. The column test showed that only 30% of the natural organic matter (NOM) was removed from the new raw water source during infiltration. The survey revealed that the new water source's quality was within the range requiring pre-treatment prior to infiltration. The well sampling results showed a significant correlation between the NOM-content in the raw and treated waters for WTPs without pre-treatment (r = 0.78 and ρ = 0.04), indicating one of the short-term limitations of artificial recharge. The study results indicate that the new raw water source is unsuitable for direct use in artificial recharge and that treatment is required prior to infiltration.

Biosecurity in agriculture [electronic resource] : a suggested strategy for the protection of source water against pathogenic contamination

To reduce the threat of pathogenic responses in humans, the Government of Ontario has introduced the Clean Water Act. The Act is intended to identify, characterize, and mitigate risks to vulnerable sources of drinking water. Applying the appropriate level of protection in those areas where land use activities contribute to the contamination of source water can be achieved through the use of biosecurity strategies comprised of operational measures to treat manure prior to storage and handling. Recent outbreaks of waterborne disease linked to manure management practices has resulted in an increased awareness of the potential risks that livestock operations pose to source water quality. This investigation demonstrated that currently available treatment technologies can significantly reduce pathogen concentrations in livestock manure; however the extent that these measures can be integrated into the proposed Clean Water Act is limited by the lack of controlled, replicated studies conducted at the commercial-scale.

Biosecurity in agriculture [electronic resource] : a suggested strategy for the protection of source water against pathogenic contamination

To reduce the threat of pathogenic responses in humans, the Government of Ontario has introduced the Clean Water Act. The Act is intended to identify, characterize, and mitigate risks to vulnerable sources of drinking water. Applying the appropriate level of protection in those areas where land use activities contribute to the contamination of source water can be achieved through the use of biosecurity strategies comprised of operational measures to treat manure prior to storage and handling. Recent outbreaks of waterborne disease linked to manure management practices has resulted in an increased awareness of the potential risks that livestock operations pose to source water quality. This investigation demonstrated that currently available treatment technologies can significantly reduce pathogen concentrations in livestock manure; however the extent that these measures can be integrated into the proposed Clean Water Act is limited by the lack of controlled, replicated studies conducted at the commercial-scale.

The rules of temporal and spatial migration of Cd content

According to the survey dataset on the waters of Jiaozhou Bay from 1984 to 1988, this paper discusses the data of Cd content each year. From the perspectives of content size, horizontal distribution, vertical distribution, seasonal distribution, regional distribution, structural distribution and tendency distribution, it studies the source, water quality, distribution and migration conditions of Cd content in the waters of Jiaozhou Bay. On the scale of space, 21 migration rules have been gotten during the spatial and temporal variation process of Cd content in the waters of Jiaozhou Bay.