The acetate uptake by polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were compared under different pH conditions. These two microorganisms are known to play key roles in the enhanced biological phosphorus removal (EBPR) processes. In this study, micro-autoradiography (MAR) with acetate as the radio-labeled substrate and fluorescence in situ hybridization (FISH) with PAOmix probe and GB probe were applied. Activated sludge samples taken at a wastewater treatment plant were subjected to anaerobic batch incubation with radio-labeled acetate at different initial pH conditions. The relative amount of carbon uptake by each cell was estimated based on the silver granule area around the cell. The results showed that anaerobic acetate uptake by PAOmix-positive and GB-positive cells were affected by the initial pH. Both PAOs and GAOs were found to have a weak tendency to take up less acetate under higher initial pH conditions.
To resolve problems of water reservoirs such as deterioration of scenic beauty, reduction in aquatic organisms, and odors resulting from advanced nutrient enrichment, and to promote activation of multiple functions of water reservoirs, we carried out field investigations of water quality and bottom mud at Koya Pond, where dredging work was performed as a water quality improvement measure. We attempted to calculate the elusion rate of nutrient salts from bottom mud using a simulated in situ method. Results showed that water pollution is considerable during summer, and that pollution occurs even after dredging, the COD is high at water temperatures greater than 30°C, and T-N and T-P are high at water temperature around 25°C under anaerobic conditions because the elusion of bottom mud is considered to be great. The elusion rate of T-N under aerobic conditions is 1.12-1.33 times higher than that under anaerobic condition, and elusion rate of T-P under anaerobic conditions is 3.01-7.73 times higher than that under aerobic conditions.
The effects of supercritical CO2 bubbling (SC-CO2) treatment on the inactivation of microorganisms in water prior to treatment at a municipal water filtering plant (untreated water) were investigated as a way to produce safe drinking water. The coliform bacterial count decreased concomitantly with increasing CO2/sample flow rate in the SC-CO2 treatment. In particular, coliform bacteria could not be detected at a CO2/sample flow rate greater than 55%. Also, the total bacterial count dropped rapidly at first stage and slowly at second stage in the SC-CO2 treatment. Upon observation of Escherichia coli before and after the SC-CO2 treatment with scanning electron microscopy and transmission electron microscopy, it was observed that the cells treated with SC-CO2 were shorter than untreated cells and that cytoplasm with low electronic density in the treated cells disappeared. In addition, four types of metabolic enzyme in E. coli cells were effectively inactivated by the SC-CO2 treatment. These results suggested that SC-CO2 treatment could effectively inactivate microorganisms in untreated water, and induce morphological changes and inactivate metabolic enzymes of E. coli cells.
Forage rice has high potential to produce biomass, and the vertical flow (VF) constructed wetland in which forage rice is cultivated is one of the effective ways to achieve the purification of eutrophicated water and biomass production simultaneously. To design and manage the VF constructed wetlands cultivated with forage rice adequately, nutrient dynamics and the growth of the rice should be understood quantitatively. In this study, we performed a series of experiments replicating VF constructed wetlands involving the cultivation of a variety of forage rice ("Kusahonami") using river water (supply rate : 0.1, 0.2, and 0.6 m3/(m2·day)) for 169 days. The results showed that the rice biomass increased with the river water supply rate. A mathematical model was developed based on these experimental observations in order to quantitatively explain the nitrogen dynamics in VF constructed wetlands cultivated with forage rice. The changes in both the rate of nitrogen assimilation by rice and the denitrification rate with the change in the rate of water supply were simulated with the proposed model.
We estimated four methods of calculating loads of nutrients from a citrus orchard in Japan. River water discharge and nutrient loads were examined every week for 2 years and more intensively at the time of one rainfall event. River water level was recorded automatically at 5-minute intervals. Nutrient concentrations and water discharge data obtained for the load varied with the evaluation methods, because the estimations made during rain events differed. Nutrient loads calculated by the four methods ranged from 2004 kg/year to 4194 kg/year for total nitrogen and from 30.3 kg/year to 44.6 kg/year for total phosphorus from the watershed area of 78.3 ha with citrus orchard and forest. Particulate form nutrients from farmland were loaded by runoff during rainfall events, and nutrient load increased quickly more so with phosphorus than with nitrogen during rainfall events. There is thus a need to quantify the degree of nutrient load from farmland in rainfall events. Continuous observation data will be needed to obtain appropriate values for load from diffuse pollution sources.
This population-based epidemiologic study investigated the associations of individuals' socio-demographic statuses, sanitary systems and habits, water supply and drainage conditions with diarrhoea incidences among 707 children younger than 5 years who were living in slum communities with various water logging patterns in Dhaka, Bangladesh. We conducted a home-visiting survey during the pre-monsoon period from December 2006 to April 2007. Nine slum communities were selected that had been experiencing five different water logging conditions. One non-water logging community was selected as a control. The Disability Adjusted Life Years (DALYs) were calculated using data on diarrhoea morbidity and mortality. Although DALYs lost because of diarrhoea were very small in a non-inundation type community, but were the highest in persistent drainage inundation type communities. Among the factors correlated with DALYs, control variables for mother's illiteracy and household income strongly attenuated most of these correlations to statistical null, except for mother's age (less than 15 years-old), using hanging latrine and not washing hands before eating, and after defecation. In conclusion, water logging conditions and socio-economic statuses may strongly contribute to diarrhoea incidence in the city's slum communities. In such communities, interventions to address both water logging and socio-economic conditions may be critical for reducing diarrhoea incidences.
An investigation of the water quality in an under-populated watershed was conducted over a 15-year period in which data was collected at weekly intervals. The purposes of this study were to analyze the long-term trends in water quality and to evaluate the relationship between the water quality and precipitation. Concentrations of total phosphorus (T-P), chemical oxygen demand (COD), and suspended solids (SS) reached remarkably high values under heavy precipitation conditions, and these concentrations increased exponentially with the amount of precipitation. Over the course of this study, the population, number of factories, animals (cow and pig), and area of agricultural land exhibited clearly decreasing trends, while steady progress in domestic wastewater treatment was realized. However, no clear decrease in the parameters of water quality was observed, and some nitrogen, phosphorus, and COD concentrations increased even though no significant change in precipitation occurred. A possible hypothesis explaining this lack of a clear decrease in water quality is that specific pollutant outflows from forests and agricultural lands may have increased in recent years. This is because poorly managed forests and agricultural lands in the under-populated watershed have adversely affected the water quality of the rivers.
River and estuarine sediment is suggested to play an important role in transmission of microbes in the water environment. However, although effective methods to recover bacteria from sediment are available, preparation methods for viruses, especially using molecular detection methods, are still under development. In this study, preparation methods for viruses in sediment were evaluated by qPCR methods. Thirty-six sediment samples were collected from the Takagi River and the Matsushima Bay receiving the Takagi River from December 2007 to May 2008 and tested for fecal coliforms, Bacteroides spp., human adenoviruses and Cryptosporidium spp. As the results, recovery rate of a preparation method for RNA viruses was low (Geometric mean: 3.3%, n=11), while that for DNA viruses was relatively high and stable (Geometric mean: 37%, n=6). The detection rate was the highest for fecal coliforms (92%, 33/36), followed by Bacteroides spp. (61%, 22/36). Human adenoviruses and Cryptosporidium spp. were not detected partly due to the limited sediment volume (0.5 g) applicable to the DNA extraction kit. Although the high positive rates of fecal coliforms and Bacteroides showed that the preparation methods for fecal indicator bacteria were applicable for environmental application, it was recommended that more effective methods for enteric viruses and protozoa be developed for direct monitoring of pathogens in sediment.
Spatial patterns of water quality at 29 sites, in a mixed land use watershed located in southeastern Brazil, were examined for eight metals, sampled over nine years -Arsenic, Cadmium, Copper, Lead, Mercury, Nickel, Selenium, and Zinc. Data analysis included delineation of the area of influence of each monitoring station, based on GIS analysis of Shuttle Radar Topography Mission (SRTM) images, estimation of the upper prediction limit 95% (UPL95) with censored data by the Kaplan-Meier technique, hierarchical cluster analysis (CA), Kruskal-Wallis and Friedman test. The locations of the groups generated by CA agreed with land and soil use and impact of anthropogenic activities. Use of UPL95 as entry data in CA allowed better use and interpretation of monitoring data. Areas with natural background metal-concentration levels in the drainage basin and areas of concern were identified.
A great amount of fertilizer is applied to tea plantation area to improve the quality of the product in Japan. Field surveys on water quality of a small river whose watershed includes tea plantation fields and questionnaire survey to the owners in the area were carried out to make clear the runoff characteristics of nutrients, both nitrogen and phosphorus, from a small watershed including the tea plantation area, and to estimate the annual budget of the nutrients. The concentrations of nitrate and phosphate in the stream water in dry period through the tea field were up to 8.09mgN/L and 0.065mgP/L respectively, which were more than 10 times higher than those in the upstream water which run through the forest. Seasonal variations of the N concentrations and P concentrations in dry periods were observed which were independent from the timing of fertilizer application. During a storm event, the concentrations of phosphate, particulate phosphorus and particulate nitrogen increased while those of nitrate decreased. Large amount of nitrogen fertilizer, 620kgN/ha/year, was applied to the tea plantation area in a year and it was estimated that only 12% of the nitrogen input was recovered as harvest product and 86 % of the input was discharged downstream through the river. 55kgP/ha/year of phosphorus fertilizer was applied to the area in a year, and it was estimated that 10 % of the phosphorus input was recovered and 38 % discharged.