Exploration of appropriate media to influence sustainable on-site sanitation choices in Sri Lanka- visualization with still images or a video.

Pit latrines are the most common form of improved sanitation in many rapidly developing countries. However, they cause the highest amount of groundwater pollution among on-site sanitation (OSS) facilities. Many households in developing countries use groundwater as their main or sub-source, and pit latrines are not a sustainable solution. Thus, the conversion from pit latrines to septic tanks is required. We created two types of media, still images and a video, to illustrate the differences in functions and hygiene risks between pit latrines and septic tanks. Moreover, a survey was conducted in Sri Lanka to determine the media choice that would increase the people's preference for septic tanks as their next OSS, even weeks after the information is presented. The choice of the next OSS participants selected before they were presented with the images was the same as that currently in use, reflecting the belief that the problem of pit latrines was not currently apparent and need not be changed. However, a video presentation of the information made it possible for a larger group of people to choose the usage of septic tanks in the future, especially in suburban areas where the problems were likely to occur.

Pharmaceutical Contaminants in Shallow Groundwater and Their Implication for Poor Sanitation Facilities in Low-Income Countries.

Rudimentary on-site sanitation systems (OSSs) are extensively used in low-income countries despite the risk of groundwater contamination. The present study investigated the potential impact of community soak pits on sandy shallow aquifers in a rural area in Sri Lanka. Thirty-two groundwater samples were collected and measured for the traditional indicators fecal bacteria Escherichia coli, total coliforms, nitrate, and chloride; 7 pharmaceuticals were added as wastewater indicators. Analysis showed that the local groundwater is infected by fecal bacteria, but it was unable to determine whether the source of fecal bacteria is the OSSs. Similarly, nitrate and chloride provided unclear evidence. Conversely, detection of 3 pharmaceuticals at trace levels in groundwater evidenced wastewater impact from OSSs. Caffeine was detected in 89% of the sample at a maximum concentration 7.9 ng/L, indicating fecal pollution. Carbamazepine was detected in 42% of the samples with a concentration of up to 6.9 ng/L, whereas sulfamethoxazole was detected in only 2 samples. The presence of carbamazepine and sulfamethoxazole was also consistent with recorded drug use of the residents. Escherichia coli showed a moderate positive correlation with caffeine concentration (Kendall's τ = 0.38, p = 0.017), indicating concurring short-lifetime fecal bacteria and labile wastewater organic compounds. Nitrate showed a significant correlation with carbamazepine concentration (τ = 0.39, p = 0.016). Fecal bacteria and nitrate can be used in screening for micropollutants in domestic wells impacted by OSSs. The present case study emphasizes the potential impact of poor sanitation on groundwater resources and the necessity of sanitation improvement in achieving Sustainable Development Goals in developing countries. Environ Toxicol Chem 2022;41:266-274. © 2021 SETAC.

Hygiene risk of waterborne pathogenic viruses in rural communities using onsite sanitation systems and shallow dug wells.

We evaluated the hygienic influence of onsite sanitation systems (OSSs) on drinking water wells in rural Sri Lanka by determining the safe setback distance between wells and the management of OSSs. Although previous studies have used bacterial indicators such as E. coli to evaluate the OSS impact, these parameters cannot assess the hygiene risk for waterborne pathogenic viruses (e.g. rotaviruses). Therefore, pepper mild mottle virus was selected as an indicator of human-specific faecal virus contamination. From a viral perspective, not only can the horizontal distance between a well and the nearest OSS reasonably represent hygiene safety, but the OSS sludge management can mitigate the contamination of wells even at short distances from the OSSs. Quantitative microbial risk assessment suggests that the infection risk of rotavirus was extremely high compared to the international standard. As proper management of OSSs would be key to reducing viral risk, it is necessary to reach out to the residents who are unaware of the importance and necessity of such management.

Bactericidal and virucidal mechanisms in the alkaline disinfection of compost using calcium lime and ash.

In the present study, the bactericidal and virucidal mechanisms in the alkaline disinfection of compost with calcium lime and ash were investigated. Two indicator microorganisms, Escherichia coli and MS2 coliphage, were used as surrogates for enteric pathogens. The alkaline-treated compost with calcium oxide (CaO) or ash resulted primarily in damage to the outer membrane and enzyme activities of E. coli. The alkaline treatment of compost also led to the infectivity loss of the coliphage because of the partial capsid damage and RNA exteriorization due to a raised pH, which is proportional to the amount of alkaline agents added. These results indicate that the alkaline treatment of compost using calcium oxide and ash is effective and can contribute to the safe usage of compost from a mixing type dry toilet.

[A Case of Pancreatic Metastasis of Renal Cell Carcinoma].

A 69-year-old woman underwent right nephrectomy for the treatment of renal cell carcinoma. Nine years later, a 2 cm, solitary tumor was detected in the pancreas tail using computed tomography, and the patient underwent distal pancreatectomy and splenectomy. The pathological diagnosis was metastasis of renal cell carcinoma. A year later, a new tumor was confirmed in the pancreas head on a follow-upCT scan. Nine years after the resection of the pancreatic metastasis, the pancreas head tumor had increased in size. It was determined to be renal cell carcinoma metastasis, but the patient remains alive and well 20 years after the initial resection.

A fate model of pathogenic viruses in a composting toilet based on coliphage inactivation.

A composting toilet using sawdust as a matrix has the potential to trap pathogens that might occasionally be contained in human feces. Therefore, care should be taken when handling the sawdust. It should also be noted that pathogenic viruses tend to have stronger tolerance than pathogenic bacteria. The fates of several species of coliphages, T4, lambda, Qbeta and MS2, in sawdust were investigated as a viral model. The fates of coliphages were significantly different among them, and they changed in response to temperature and the water content of the sawdust. As the results, T4 coliphage had the strongest tolerance and Qbeta had the weakest one in sawdust. It was estimated the days required to decrease virus to a safe level based on a risk assessment. According to the rates of Qbeta and T4, 15 days and 167 days were required respectively for a safe level of infection risk based on actually operated composting toilet condition. Thus, it was significantly different depending on the species and sawdust conditions.

Environmental and economic life cycle assessment for sewage sludge treatment processes in Japan.

Life cycle assessment for sewage sludge treatment was carried out by estimating the environmental and economic impacts of the six alternative scenarios most often used in Japan: dewatering, composting, drying, incineration, incinerated ash melting and dewatered sludge melting, each with or without digestion. Three end-of-life treatments were also studied: landfilling, agricultural application and building material application. The results demonstrate that sewage sludge digestion can reduce the environmental load and cost through reduced dry matter volume. The global warming potential (GWP) generated from incineration and melting processes can be significantly reduced through the reuse of waste heat for electricity and/or heat generation. Equipment production in scenarios except dewatering has an important effect on GWP, whereas the contribution of construction is negligible. In addition, the results show that the dewatering scenario has the highest impact on land use and cost, the drying scenario has the highest impact on GWP and acidification, and the incinerated ash melting scenario has the highest impact on human toxicity due to re-emissions of heavy metals from incinerated ash in the melting unit process. On the contrary, the dewatering, composting and incineration scenarios generate the lowest impact on human toxicity, land use and acidification, respectively, and the incinerated ash melting scenario has the lowest impact on GWP and cost. Heavy metals released from atmospheric effluents generated the highest human toxicity impact, with the effect of dioxin emissions being significantly lower. This study proved that the dewatered sludge melting scenario is an environmentally optimal and economically affordable method.

Water systems and urban sanitation: a historical comparison of Tokyo and Singapore.

The importance of a water supply and sewage treatment for urban sanitation is recognized in the modern world. Their contributions to public health have not, however, been well demonstrated by historical data, especially in Asian cities. In this research, we focused on the Asian cities of Tokyo and Singapore, which both developed significantly in the 20th century. We analysed their development processes statistically to determine what the key elements for the protection of urban sanitation have been. Although both cities constructed modern water supply systems at almost same time (Tokyo in 1898 and Singapore in 1878), and similarly modern wastewater treatment systems (Tokyo in 1922 and Singapore in 1913), the prevalence of water-borne diseases in Tokyo was more serious than it was in Singapore, in spite of Singapore's high infant mortality rate. The main reason for this was the differences in the systems of night-soil transport. We found that the water supply system in itself was not enough to resolve all urban sanitation problems, and appropriate night-soil removal was also crucial. In addition, historical trends and water consumption vary by city, so the appropriate technology and system are also different according to the unique characteristics and needs of each.

Effects of wastewater disinfection on waterborne bacteria and viruses.

Wastewater disinfection is practiced with the goal of reducing risks of human exposure to pathogenic microorganisms. In most circumstances, the efficacy of a wastewater disinfection process is regulated and monitored based on measurements of the responses of indicator bacteria. However, inactivation of indicator bacteria does not guarantee an acceptable degree of inactivation among other waterborne microorganisms (e.g., microbial pathogens). Undisinfected effluent samples from several municipal wastewater treatment facilities were collected for analysis. Facilities were selected to provide a broad spectrum of effluent quality, particularly as related to nitrogenous compounds. Samples were subjected to bench-scale chlorination and dechlorination and UV irradiation under conditions that allowed compliance with relevant discharge regulations and such that disinfectant exposures could be accurately quantified. Disinfected samples were subjected to a battery of assays to assess the immediate and long-term effects of wastewater disinfection on waterborne bacteria and viruses. In general, (viable) bacterial populations showed an immediate decline as a result of disinfectant exposure; however, incubation of disinfected samples under conditions that were designed to mimic the conditions in a receiving stream resulted in substantial recovery of the total bacterial community. The bacterial groups that are commonly used as indicators do not provide an accurate representation of the response of the bacterial community to disinfectant exposure and subsequent recovery in the environment. UV irradiation and chlorination/dechlorination both accomplished measurable inactivation of indigenous phage; however, the extent of inactivation was fairly modest under the conditions of disinfection used in this study. UV irradiation was consistently more effective as a virucide than chlorination/dechlorination under the conditions of application, based on measurements of virus (phage) diversity and concentration. Taken together, and when considered in conjunction with previously published research, the results of these experiments illustrate several important limitations of common disinfection processes as applied in the treatment of municipal wastewaters. In general, it is not clear that conventional disinfection processes, as commonly implemented, are effective for control of the risks of disease transmission, particularly those associated with viral pathogens. Microbial quality in receiving streams may not be substantially improved by the application of these disinfection processes; under some circumstances, an argument can be made that disinfection may actually yield a decrease in effluent and receiving water quality. Decisions regarding the need for effluent disinfection must account for site-specific characteristics, but it is not clear that disinfection of municipal wastewater effluents is necessary or beneficial for all facilities. When direct human contact or ingestion of municipal wastewater effluents is likely, disinfection may be necessary. Under these circumstances, UV irradiation appears to be superior to chlorination in terms of microbial quality and chemistry and toxicology. This advantage is particularly evident in effluents that contain appreciable quantities of ammonia-nitrogen or organic nitrogen.

Application of microbial risk assessment on a residentially-operated bio-toilet.

The Sustainable Sanitation System is a new wastewater treatment system that incorporates a non-flushing toilet (Bio-toilet) that converts excreta into a reusable resource (as fertilizer or humus for organic agriculture) and reduces the pollution load to environments of the rivers, the lakes, and the sea. However, the risk of exposure to pathogens should be considered, because excrement is stored in the Bio-toilet. The aim of the present work is to analyze the health risk of dealing with the matrix (excreta and urine mixed with sawdust) of the Bio-toilet. Therefore, the fate of pathogenic viruses was investigated using coliphages as a virus index, and the modeling of the die-off rate in matrix was introduced. Then the microbial risk assessment was applied to a Bio-toilet that was actually used in a residential house; the infection risks of rotavirus and enterovirus as reference pathogens were calculated. According to the lab-scale experiment using coliphages for investing the die-off rate of viruses in the Bio-toilet, Qbeta had a higher die-off, which was greatly influenced by the water content and temperature. On the other hand, T4 showed a lower rate and was independent of water content. Therefore, these two phages' data were used as critical examples, such as viruses having high or low possibilities of remaining in the Bio-toilet during the risk assessment analysis. As the result of the risk assessment, the storage time required for an acceptable infectious risk level has wide variations in both rotavirus and enterovirus cases depending on the phage that was used. These were 0-260 days' and 0-160 days' difference, respectively.

Association of photosynthesis and photocatalytic inhibition of algal growth by TiO2.

The relationship of photosynthesis and photocatalytic inhibition of algal growth (Chroococcus sp.) by TiO2 was investigated by an ATP assay under ultraviolet (UV) and fluorescent light (FL) irradiations. The adverse effects of what on Chroococcus sp. growth in the TiO2+FL+UV run are larger than those in the TiO2+UV run. The difference is considered to be caused by oxygen generated by Chroococcus sp. under FL irradiation. A rate equation for the relationship of light irradiation intensity to rate of decrease in the Chroococcus sp. population on the basis of the Langmuir-Hinshelwood model has been proposed. The experimental data are in good agreement with the proposed model. In this study, the optimum FL intensity is 0.51 mW/cm2.

Field survey of a sustainable sanitation system in a residential house.

Sustainable sanitation is an approach for more ecological and sustainable water resources management. In this paper, we proposed one of the new integrated waste treatment systems: an "sustainable sanitation system" that includes separation of the black water from water system by a non-flushing toilet (bio-toilet), and a gray water treatment based on a biological and ecological concept. Sustainable sanitation system also converts the domestic waste to soil conditioners and fertilizers, for farmland use. As one of the case studies, Environmentally Symbiotic Housing in which people actually live using the bio-toilet for the black water treatment and the household wastewater treatment facility for the gray water was introduced. The availability of this system was investigated by analyzing the sawdust used in the bio-toilet and the quality of the effluent in the household wastewater treatment facility. As the result, the water content of the sawdust did not exceed 60% in any of the sampling points and the BOD and COD of the effluent of the household wastewater treatment facility were below 10 and 20 mg/L respectively, due to the low loading. Compared to the pollution load on the water environment created by the conventional system, it was found that the effluent of the house has a lower load than the tertiary treatment and the volume of the water consumption is 75% of the conventional system.

Photodecolorization of azo dyes by extracellular metabolites under fluorescent light and influence of operational parameters.

The contribution of extracellular metabolites (EM) to the decolorant activity of newly isolated photosynthetic bacteria was observed. The decolorization process was considered to occur by two paths: photochemical decolorization by EM and photobiological decolorization by photosynthetic bacteria. In addition, the decolorization of several azo dyes by EM under black light and fluorescent light irradiation was investigated. It was found that EM were capable of decolorizing the azo dyes directly under visible light irradiation, and the overall dye decolorization followed first-order decay kinetics. Moreover, the decolorization reaction is a nonenzymatic reaction and the unknown metabolite with the decolorizing ability had an apparent molecular weight lower than 3 kDa as determined by ultrafiltration. In addition, its decolorization activity was stable even after heating sterilization at 121 degrees C for 10 min. Furthermore, the decolorization rate increased with increasing optical intensity, temperature and EM concentration, and decreased with increasing initial dye concentration. Decolorization of dye was best at pH 8.

Controlling algal growth in photo-dependent decolorant sludge by photocatalysis.

In the treatment of synthetic dye wastewater by photosynthetic bacteria under optical irradiation, excessive algal growth and adhesion on the walls of the reactor are serious problems. The adverse effects of excessive algal growth on photosynthetic bacterial activity are significantly greater than those of the decreased optical irradiation of the solution. In this report, we investigated the effects of photocatalysis on the growth of algae (Chroococcus sp.) and photosynthetic bacteria. The different sensitivities of Chroococcus sp. and photosynthetic bacteria to photocatalysis were observed by an ATP assay. Moreover, from microscopy findings, some algae were damaged by TiO2 with UV. We suggested that some algae suffered from membrane damage and consequently cell substances were released, resulting in the increase of dissolved material following treatment using TiO2 with UV.

Effects of photocatalysis on biological decolorization reactor and biological activity of isolated photosynthetic bacteria.

In the treatment of synthetic dye wastewater by photosynthetic bacteria under optical irradiation, excessive algal growth and adhesion on the wall of the reactor has been a severe problem. A laboratory scale flow-through model reactor with thin film photocatalysis for improving the efficiency of optical irradiation and controlling algal adhesion is presented. The system showed the efficiency of continuous biodegradation of dye was improved significantly by thin film photocatalysis. Moreover, the effects of photocatalysis on the color removal activity and the growth of isolated photosynthetic bacteria were investigated in batch experiment. Although photocatalytic reactions of TiO2 could inhibit the growth of isolated photosynthetic bacteria, the negative effects of photocatalysis on photosynthetic bacterial growth and decolorant activity were negligible under UV+FL irradiation. These results implicate the possibility of using thin film photocatalysis for controlling algal adhesion and enhancing the decolorant efficiency of photosynthetic bacteria.