Improving the efficiency of water resources management: decentralized grey water treatment

Summary

The established over the course of decades strategy of municipal wastewater treatment needs to be revised since it is not oriented toward water reuse (instead of effluent discharge into the receiving waters); it is not designed for nutrients removal and demands significant expenditures for the removal of xenobiotics. The centralized wastewater treatment does not provide for the qualitative solution of the given problem. Overseas the concept of separate collection and decentralized treatment of concentrated black water containing urea and faeces and grey water containing bath, shower and sink water, water from washing machines and dishwashers, kitchen water has been rapidly developed. Grey water contains much less (compared to black water and municipal wastewater) xenobiotics and pathogens and can be a source of water of different purity levels. This approach predetermines more sustainable municipal water supply, in particular, by avoiding meeting all the demands from a single drinking water source, all the more in cases when there is no need in high-quality water. In USA, Japan, Australia, Israel, some EU countries studies of different scales are carried out; in practice different schemes of nonpotable use of grey water after the required treatment have been implemented.

Key words

grey water , decentralized treatment , treatment process flow schemes , xenobiotics , water reuse

Process engineering solutions for the purification
of low-mineralized cold groundwater with chemicals

Summary

The paper completes a series of studies on the purification of low-mineralized cold groundwater, often used for drinking water supply in the Russian regions in permafrost zones. The update of the earlier developed process solutions and expansion of their scope of application are reported. A full description of the chemical processes occurring during water treatment with chemicals including hydrogen peroxide, potassium permanganate, and caustic soda is provided. The proposed process solutions provide for drinking water meeting the regulatory quality standards for organoleptic indicators, iron, manganese, hydrogen sulfide, phenols, and oil products. At the same time the consistency of the water after purification is guaranteed which allows to prevent from the secondary pollution in water mains and distribution networks. Two basic process flow schemes of the water conditioning process are presented that differ in their scope of application depending on the quantitative composition of groundwater. Water quality indicators after purification are presented based on the results obtained during the pilot tests at various sites. It is noted that the developed process solutions provide for upgrading outdated groundwater de-ironing facilities at minimal cost, whereby the standard quality of the water is provided.

Key words

potassium permanganate , cold low-mineralized ground water , stabilization treatment , caustic soda , treatment process flow schemes , hydrogen peroxide , iron, manganese, hydrogen sulfide removal