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On the basis of a detailed case study this paper questions the equity of centralised piped drinking water supply systems installed by the government of Nepal in rural areas. The study shows how processes of socio-technical interaction and change alter the physical water supply infrastructure of the installed public water supply system, simultaneously altering patterns of access to taps and water. The analysis suggests that this happens through a process of “informal privatisation”, with community taps becoming appropriated by individuals over time, cutting off some families from their access to community tap water while reinforcing the water security of others. This process is deeply shaped by prevailing relations of power and cultural difference along axes of gender, caste and wealth.  相似文献   
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Biological treatment of high-strength nitrogenous wastewater is challenging due to low growth rate of autotrophic nitrifiers. This study reports bioaugmentation of Thiosphaera pantotropha capable of simultaneously performing heterotrophic nitrification and aerobic denitrification (SND) in sequencing batch reactors (SBRs). SBRs fed with 1:1 organic-nitrogen (N) and NH4 +-N were started up with activated sludge and T. pantotropha by gradual increase in N concentration. Sludge bulking problems initially observed could be overcome through improved aeration and mixing and change in carbon source. N removal decreased with increase in initial nitrogen concentration, and only 50–60 % removal could be achieved at the highest N concentration of 1000 mg L?1 at 12-h cycle time. SND accounted for 28 % nitrogen loss. Reducing the settling time to 5–10 min and addition of divalent metal ions gradually improved the settling characteristics of sludge. Sludge aggregates of 0.05–0.2 mm diameter, much smaller than typical aerobic granules, were formed and progressive increase in settling velocity, specific gravity, Ca2+, Mg2+, protein, and polysaccharides was observed over time. Granulation facilitated total nitrogen (TN) removal at a constant rate over the entire 12-h cycle and thus increased TN removal up to 70 %. Concentrations of NO2 ?-N and NO3 ?-N were consistently low indicating effective denitrification. Nitrogen removal was possibly limited by urea hydrolysis/nitrification. Presence of T. pantotropha in the SBRs was confirmed through biochemical tests and 16S rDNA analysis.  相似文献   
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Environmental Science and Pollution Research - Exposure to lead among children, as well as adults, is a major global health issue. With diverse routes of exposure (e.g., food, air, and water)...  相似文献   
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