Study of the changes in the thermal conditions of sewer networks in winter

Summary

Sewer pipelines are one of the main components of a sanitation system that determines its integrity and effectiveness. The sanitation system of Kyzyl has been constructed in the areas with a rigorous climate that is characterized by deep seasonal soil freezing exceeding 3.2 m. Reducing the depth of laying sewer pipelines against this background is a critical task. The study was aiming at the substantiation of reducing the pipe laying depth while maintaining the integrity of their operation in the normal way and ensuring non-freezing in possible emergency situations. The results of full-scale studies of the thermal conditions of operating the sanitation system of Kyzyl in winter are presented. The results of wastewater temperature measurements in different sewer network sections at different times of the day are given. Based on the obtained data a thermotechnical calculation of the network was carried out that provided for assigning 1.8 m pipe laying depth of the building drains with possible reduction in future.

Key words

sewerage network , wastewater , frost soil , pipe laying depth , thermal conditions , thermotechnical calculation

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Comparative evaluation of the methods of phosphorus removal from wastewater

Summary

The evaluation of the methods of eliminating phosphorus, a most important nutrient that is a limiting element in water body eutrophication, from wastewater is presented. Biological, physical, chemical and combined methods are considered that differ from each other in the method of implementation, construction and operating expenditures. The biological method is based on phosphorus removal through its utilization in biomass synthesis in the biological system. Physical and chemical methods suppose mandatory application of chemicals used for free phosphate-ion binding to low soluble ortho-phosphate. Combined methods suppose dephosphorization at the biological treatment stage with subsequent inclusion of phosphate-ions into crystals at the physical and chemical treatment stage. The examples of practical implementation of the methods are presented; process flow schemes are considered; the process parameters of the treatment facilities are pointed out where the process of phosphorus removal is taking place; the data on the process efficiency is provided; the advantages and drawbacks of the applied methods are reported. The experience of adjustment works is described together with the results of experimental selection of chemicals for phosphorus binding and determination of the optimal point of their addition carried out by the authors in the laboratory, during pilot and full-scale studies.

Key words

filter , nitrification , bioreactor , reagent , aeration tank , denitrification , nutrient , wastewater , crystal , dephosphorization , effluent polishing , sludge growth