Water supply and wastewater disposal in the Arctic Region:
advanced technical soltions (a review)

Summary

In Canada wastewater treatment technology has been developed for small isolated arctic communities based on the effective biodegradation of organic carbon using a combination of anaerobic methanogenic and microbial bioelectrochemical processes that provide for biomethane generation. Microbial electrochemical degradation is executed in a membrane-free flow-type reactor with a bioanode and a biocathode operating at a voltage below the threshold of water electrolysis. In laboratory-based experiments in a wide range of mesophilic and psychrophilic temperatures (5–23 °C) a high efficiency of reducing BOD₅ (90–97%) was achieved with a residual content of less than 7 mg/l. Energy consumption is 0.6 kWh/kg COD. Low energy consumption along with the production of biomethane ensures the operation of the reactor in the mode of power generation. For the conditions of Greenland a scheme of wastewater disinfection involving chemical coagulation and addition of peracetic acid, and/or ultraviolet irradiation was developed. Complete inactivation of Escherichia coli is achieved with the combined use of ultraviolet radiation (2.1 kWh/m³) and peracetic acid. Preliminary coagulation is an essential prerequisite for the effective inactivation of microorganisms. In the United States a closed water treatment scheme based on the peroxone process with reuse of water for drinking purposes has been proposed for the city of Fairbanks (Alaska). The big advantage of the closed-loop scheme is 85% conservation of the water in the system while preserving the thermal energy obtained from different water heaters. As a result the purified warm water is returned to the consumer; while less energy is required for its additional heating. In addition, the mineralization of organic substances in the oxidation process ensures the achievement of 0.7 mg/l residual COD.

Key words

wastewater , water disinfection , water treatment , ultraviolet irradiation , water reuse , the Arctic Region , preliminary coagulation , peracetic acid , peroxone process , heat energy of water , anaerobic methanogenic process , microbial electrochemical process

Experience of retrofitting the technology of wash water utilization at the Omsk water treatment facilities

Summary

The main phases of addressing holistically the problem water source pollution with wastewater generated at the Omsk water treatment plant are considered. The results of technologic pre-engineering that provided for determining the optimal flow scheme of the treatment process and filter wash water reuse as well for defining the process parameters of combined treatment of river and wash water are presented. It is shown that the chemicals mainly used for drinking water purification can be used for filter wash water treatment. The studies were carried out by test coagulation method, i. e. by adding various amounts of polluted wash water and chemicals used at the water treatment plant into raw river water. The efficiency of combined treatment of river water is improving with increasing the amount of added polluted wash water. The design concepts and process flow scheme of water treatment that provided for constructing and commissioning filter wash water reuse unit with minimum capital expenditures are presented. The operating experience affirmed the correctness of the adopted process and design solutions. As a result the abstraction of raw river water was reduced by 9–13% and wash water discharge into the Irtysh River- the water source was completely abandoned. Wash water treatment is carried out together with raw river water at the water treatment facilities. Herewith the drinking water quality fully meets the requirements of Sanitary Regulations and Norms 2.1.4.1074-01.

Key words

water treatment , reagent treatment , wash water , water reuse , resource conservation

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