4 research outputs found
Wastewater reuse in central Asia: implications for the design of pond systems
No full textThe paper examines the potential of waste stabilisation ponds to provide water for reuse in extreme continental climates such as those of central Asia, where precipitation is low and summer evaporation rates are high. A simple model is used to predict water availability, BOD and faecal coliform removal for different configurations and operating regimes. The results show a significant proportion of flows could be saved for irrigation or river and aquifer replenishment: if current standard designs can be modified for these climates, the outcome is likely to be both more robust and more flexible in terms of types of reuse. The paper concludes with three case studies of evaporation pond systems in Kazakhstan, assessing their potential for conversion to full biological treatment systems for water conservation and reuse
Waste stabilisation ponds in extreme continental climates: a comparison of design methods from the USA, Canada, northern Europe and the former Soviet Union
No full textThe paper presents a brief review of the application of WSPs in extreme climates where ice formation occurs during winter. Design standards and methods are compared and different systems are described. Design equations developed by the US EPA and normative standards from the former Soviet Union are compared in a simple example using typical wastewater and performance characteristics. The results are similar except at low temperatures, where the Soviet method can give pond depths outside the prescribed limits. The paper examines construction and operational aspects of extreme climate WSPs, comparing North American, Northern European and Russian standards. It considers why WSP systems have not been widely adopted in Russia and the NIS, and looks at the advantages these systems may have in countries in economic transition
Seasonal responses of continental climate waste stabilisation ponds: potential implications for design and operation
No full textInfluence of annual climate variability on the design of waste stabilisation ponds for continental climates
No full textWSPs are widely used in North America, and offer huge potential for other continental climate regions. The standard design and operating protocol is robust even at high latitudes, but may be conservative elsewhere. A simple model based on first-order kinetics for biochemical oxygen demand (BOD) is used to consider some alternative design and operating protocols, using long-term daily climate records for cities across continental central Asia. Options include changing the discharge period; retaining treated water in the pond over the winter; and changing the facultative pond loading. Annual variability in climate parameters has a major effect, in particular on the date at which treated wastewater meets appropriate standards for discharge or re-use: the earlier the discharge, the greater the variability in effluent quality. Skilful management of these systems may therefore be required to maximise their performance. While current models require development, it is clear modelling could provide tools and guidelines that would allow the design of continental climate WSP to be tailored to specific regional and local climate condition
