Inactivation of indicator organisms on different surfaces after urban floods

Influence of suspended particles and dissolved organic matters on virus enrichment in reclaimed water by two-step tangential flow ultrafiltration: Phenomena and mechanisms

Enteric virus concentration in large-volume water samples is crucial for detection and essential for assessing water safety. Certain dissolution and suspension components can affect the enrichment process. In this study, tangential flow ultrafiltration (TFUF) was used as an enrichment method for recovering enteric virus in water samples. Interestingly, the bacteriophage MS2 recovery in reclaimed water and the reclaimed water without particles were higher than that in ultrapure water. The simulated reclaimed water experiments showed that humic acid (HA) (92.16% ± 4.32%) and tryptophan (Try) (81.50 ± 7.71%) enhanced MS2 recovery, while the presence of kaolin (Kaolin) inhibited MS2 recovery with an efficiency of 63.13% ± 11.17%. Furthermore, Atomic force microscopy (AFM) revealed that the MS2-HA cluster and the MS2-Try cluster had larger roughness values on the membrane surface, making it difficult to be eluted, whereas MS2-Kaolin cluster had compact surfaces making it difficult to be eluted. Additionally, the MS2-HA cluster is bound to the membrane by single hydrogen bond with SO, whereas both the MS2-Try cluster and the MS2-Kaolin cluster are bound to the membrane by two hydrogen bonds, making eluting MS2 challenging. These findings have potential implications for validating standardized methods for virus enrichment in water samples.

Impact of filter material and holding time on spore sampling efficiency in water

Bacillus anthracis and other environmentally persistent pathogens pose a significant threat to human and environmental health. If contamination is spread over a wide area (e.g. resulting from a bioterrorism or biowarfare incident), readily deployable and scalable sample collection methods will be necessary for rapidly developing and implementing effective remediation strategies. A recent surge in environmental (eDNA) sampling technologies could prove useful for quantifying the extent and levels of contamination from biological agents in environmental and drinking water. In this study, three commonly used membrane filtration materials (cellulose acetate, cellulose nitrate, and nylon) were evaluated for spore filtration efficiency, yielding recoveries from 17%-68% to 25%-117% for high and low titer samples, respectively, where cellulose nitrate filters generated the highest recoveries. A holding time test revealed no statistically significant differences between spore recoveries when analyzed at the specified timepoints, suggesting that eDNA filter sampling techniques can yield and maintain a relatively high recovery of spores for an extended period of time between filtration and analysis without a detrimental impact on spore recoveries. The results shown here indicate that emerging eDNA technologies could be leveraged for sampling following a wide-area contamination incident and for other microbiological water sampling applications.

The threat of a new tetanus outbreak due to urban flooding disaster requires vigilance: a narrative review

Vaccines for tetanus prevention have rapidly progressed, and the number of outbreaks, especially the incidence of tetanus in developed countries, has decreased dramatically. However, the mortality rate associated with severe tetanus remains high. Tetanus eradication is difficult owing to the widespread presence of the spores of tetanus bacteria in the environment, but tetanus can be prevented by acquired immunity from vaccines. Older people, intravenous drug users, and migrants are at a high risk of tetanus in developed countries owing to the lack of booster vaccination programs. Natural disasters, especially floods, often cause an increase in the prevalence of tetanus because of the associated injuries. Precautions should be taken to combat the threat of a new tetanus outbreak due to floods in urban areas owing to global warming. In particular, Japan is facing a high risk of urban flooding-induced tetanus, despite its status as a developed country. This review aims to highlight the data on the epidemiology, causes, treatment, and prevention of tetanus and problems associated with tetanus countermeasures during future floods.

Metagenomics indicate that public health risk may be higher from flooding following dry versus rainy periods

Urban floodwater could lead to significant risk for public and environmental health from mobilization of microbial pathogens and overflow of wastewater treatment systems. Here, we attempted to assess this risk by obtaining metagenomic profiles of antibiotic resistance genes (ARGs), virulence factors (VFs) and pathogens present in floodwater samples collected in urban Atlanta, GA that were categorized in two distinct groups: floods that occurred after periods of drought and those after regular (seasonal) rain events. Even though no major (known) pathogens were present at the limit of detection of our sequencing effort (~3 Gbp/sample), we observed that floodwaters after drought showed a 2.5-fold higher abundance of both ARGs and VFs compared to floodwater after rainy days. These differences were mainly derived by several novel species of the Pseudomonas genus, which were more dominant in the former versus the latter samples and carried several genes to cope with osmotic stress in addition to ARGs and VFs. These results revealed that there are previously undescribed species that become mobilized after flooding events in the Southeast US urban settings and could represent an increased public health risk, especially after periods of drought, which warrants further attention.

Development of cell-imprinted polymer surfaces for Cryptosporidium capture and detection

Cryptosporidium parvum is waterborne parasite that can cause potentially life-threatening gastrointestinal disease and is resistant to conventional water treatment processes, including chlorine disinfection. The current Environmental Protection Agency-approved method for oocyst detection and quantification is expensive, limiting the ability of water utilities to monitor complex watersheds thoroughly to understand the fate and transport of C. parvum oocysts. In this work, whole cell imprinting was used to create selective and sensitive surfaces for the capture of C. parvum oocysts in water. Cell-imprinted Polydimethylsiloxane (PDMS) was manufactured using a modified stamping approach, and sensitivity and selectivity were analyzed using different water chemistries and different surrogate biological and non-biological particles. The overall binding affinity was determined to be less than that of highly specific antibodies, but on par with standard antibodies and immune-enabled technologies. These initial results demonstrate the potential for developing devices using cell-imprinting for use in waterborne pathogen analysis.

CFD Modelling of the Transport of Soluble Pollutants from Sewer Networks to Surface Flows during Urban Flood Events

Surcharging urban drainage systems are a potential source of pathogenic contamination of floodwater. While a number of previous studies have investigated net sewer to surface hydraulic flow rates through manholes and gullies during flood events, an understanding of how pollutants move from sewer networks to surface flood water is currently lacking. This paper presents a 3D CFD model to quantify flow and solute mass exchange through hydraulic structures featuring complex interacting pipe and surface flows commonly associated with urban flood events. The model is compared against experimental datasets from a large-scale physical model designed to study pipe/surface interactions during flood simulations. Results show that the CFD model accurately describes pipe to surface flow partition and solute transport processes through the manhole in the experimental setup. After validation, the model is used to elucidate key timescales which describe mass flow rates entering surface flows from pipe networks. Numerical experiments show that following arrival of a well-mixed solute at the exchange structure, solute mass exchange to the surface grows asymptotically to a value equivalent to the ratio of flow partition, with associated timescales a function of the flow conditions and diffusive transport inside the manhole.

The role of wet wipes and sanitary towels as a source of white microplastic fibres in the marine environment

Understanding source elements of the ocean plastic crisis is key to effective pollution reduction management and policy. The ubiquity of microplastic (MP) fibres in the oceans is considered to derive primarily from clothing fibres released in grey water. Microplastic fibres degraded from widely flushed personal care textile products (wet wipes and sanitary towels) have not been clearly identified in aquatic systems to date. Unregulated personal hygiene and sanitary product labelling fails to identify textile materials. This study demonstrated that white MP fibres in sediments adjacent to a wastewater treatment plant (WWTP) are comparable with white fibres from sewage-related waste and commercially available consumer sanitary products. Commercially available non-flushable wipes are manufactured from either polyethylene terephthalate (PET), polypropylene (PP), or a combination of PET and cellulose. Fifty percent of brands labelled flushable that were tested were comprised of a mixture of PET and cellulose and the remainder of cellulose alone. Sanitary towels are made from PP, PE, or a combination of high-density polyethylene (HDPE) and PP. The accumulation of large quantities of washed-up sewage-related macro-debris (including wet wipes and sanitary towels) intermingled with seaweed biomass adjacent to the WWTP was associated with a combined sewer overflow. Microplastic fibres extracted from this waste were similar to those extracted from intertidal sediments in close proximity to the WWTP over a ten-month period. In comparison, fibres extracted from locations spatially removed from the WWTP were primarily comprised of ABS, PP and polystyrene. The results confirm that wet wipes and sanitary towels flushed down toilets are an underestimated source of white MP fibres in the environment. Given the global distribution and projected growth of the non-woven textile industry, there is a need for increased public awareness of MP pollution in the marine environment from the inappropriate disposal of sanitary products down the toilet, instead of diversion to alternative land-based waste management.