The paucity of proper sanitation facilities has contributed to the spread of waterborne diseases in many developing countries. The primary goal of this study was to demonstrate the feasibility of using a wastewater electrolysis cell (WEC) for toilet wastewater disinfection. The treated wastewater was designed to reuse for toilet flushing and agricultural irrigation. Laboratory-scale electrochemical (EC) disinfection experiments were performed to investigate the disinfection efficiency of the WEC with four seeded microorganisms (Escherichia coli, Enterococcus, recombinant adenovirus serotype 5, and bacteriophage MS2). In addition, the formation of organic disinfection byproducts (DBPs) trihalomethanes (THMs) and haloacetic acids (HAA5) at the end of the EC treatment was also investigated. The results showed that at an applied cell voltage of +4 V, the WEC achieved 5-log10 reductions of all four seeded microorganisms in real toilet wastewater within 60 min. In contrast, chemical chlorination (CC) disinfection using hypochlorite [NaClO] was only effective for the inactivation of bacteria. Due to the rapid formation of chloramines, less than 0.5-log10 reduction of MS2 was observed in toilet wastewater even at the highest [NaClO] dosage (36 mg/L, as Cl2) over a 1 h reaction. Experiments using laboratory model waters showed that free reactive chlorine generated in situ during EC disinfection process was the main disinfectant responsible for the inactivation of microorganisms. However, the production of hydroxyl radicals [•OH], and other reactive oxygen species by the active bismuth-doped TiO2 anode were negligible under the same electrolytic conditions. The formation of THMs and HAA5 were found to increase with higher applied cell voltage. Based on the energy consumption estimates, the WEC system can be operated using solar energy stored in a DC battery as the sole power source.

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This study investigated the occurrence of three types of vibrios in Southern California recreational beach waters during the peak marine bathing season in 2007. Over 160 water samples were concentrated and enriched for the detection of vibrios. Four sets of PCR primers, specific for Vibrio cholerae, V. parahaemolyticus, and V. vulnificus species and the V. parahaemolyticus toxin gene, respectively, were used for the amplification of bacterial genomic DNA. Of 66 samples from Doheny State Beach, CA, 40.1% were positive for V. cholerae and 27.3% were positive for V. parahaemolyticus, and 1 sample (1.5%) was positive for the V. parahaemolyticus toxin gene. Of the 96 samples from Avalon Harbor, CA, 18.7% were positive for V. cholerae, 69.8% were positive for V. parahaemolyticus, and 5.2% were positive for the V. parahaemolyticus toxin gene. The detection of the V. cholerae genetic marker was significantly more frequent at Doheny State Beach, while the detection of the V. parahaemolyticus genetic marker was significantly more frequent at Avalon Harbor. A probability-of-illness model for V. parahaemolyticus was applied to the data. The risk for bathers exposed to recreational waters at two beaches was evaluated through Monte Carlo simulation techniques. The results suggest that the microbial risk from vibrios during beach recreation was below the illness benchmark set by the U.S. EPA. However, the risk varied with location and the type of water recreation activities. Surfers and children were exposed to a higher risk of vibrio diseases. Microbial risk assessment can serve as a useful tool for the management of risk related to opportunistic marine pathogens.

De facto reuse refers to the use of surface water that contains a considerable portion of wastewater effluent from upstream communities as a source water for drinking water supplies. In contrast to the highly regulated domestic wastewater reuse practices in the U.S., not much is known regarding the human health risk associated with de facto reuse. Trinity River, Texas, a wastewater dominated river that is used as the main source of drinking water for Houston, is used as an exemplar to quantify the health risk associated with exposure to Cryptosporidium and norovirus through drinking water contaminated with wastewater effluents. The results show that the annual infection risks exceed the U.S. EPA recommended annual safe drinking water health risk of 10-4 per person per year (pppy) for all scenarios considered. However, a comparison of the corresponding disease burdens with the World Health Organization's annual disease burden for safe drinking water of 10-6 DALYs pppy indicates the disease burdens are mostly within the acceptable range of the guideline. This difference in risk interpretations reflects the difference in the fundamental definition of the two risk benchmarks as well as the gaps in data and risk models (including the conversion from infection to illness risk and expected DALY per infection). The results also imply that the current safe drinking water regulatory framework should be reexamined to best achieve the goal of human health protection. The outcomes of this study provide an overall picture of the potential risk associated with de facto reuse, which contributes to a better understanding of the practice and decisions in wastewater reuse in the U.S. and the rest of the world.

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For stormwater harvesting to achieve its full potential in mitigating water scarcity problems and restoring stream health, it is necessary to evaluate the human and environmental health risks and benefits associated with it. Stormwater harbors large amounts of pollutants and has traditionally been viewed as a leading cause of water‐quality degradation of receiving waters. Harvesting stormwater for household use raises questions of human exposure to pollutants, especially human pathogens, which have the potential to cause large‐scale disease outbreaks. These issues are compounded by uncertainties relating to the performance of stormwater treatment technologies in pathogen removal. Quantitative microbial risk assessment provides an objective risk estimate based on scientific data and the best assumptions, which can be used to educate and instil confidence in stakeholders of the practice. Although limited, human health risk studies have positively supported the use of minimally treated rainwater and stormwater for some non‐potable applications. In addition to the well‐known benefit of preserving the stream hydrology and ecology, wetlands used for harvesting stormwater can also provide new habitats for wildlife that benefit environmental health. A fundamental change from viewing stormwater as waste to resource requires the coordinated efforts in research, education, and effective communication. WIREs Water 2015, 2:683–699. doi: 10.1002/wat2.1107 This article is categorized under: Engineering Water > Water, Health, and Sanitation

Marine beaches are important recreational and economic resources in Brazil, but the beaches' water quality is negatively impacted by the discharge of domestic sewage effluent. The occurrence of diarrheagenic Escherichiacoli among the E. coli isolated from three Brazilian marine beaches was investigated. Multiplex and single step PCR were used to screen 99 E. coli isolates for ten target toxin genes. Six toxin genes, stx1, eae, estp, esth, astA, and bfpA, were identified in 1% to 35% of the isolates. A quantitative microbial risk assessment (QMRA) of human exposure to diarrheagenic E. coli during marine recreation was carried out. The results indicated that the diarrheagenic E. coli risk is well below the U.S. EPA's recommended daily recreational risk benchmark. However, the overall recreational health risk due to all pathogens in the water could be much higher and exceeded the U.S. EPA's benchmark.