Upgrading the wastewater treatment facilities of the Istra city and Istra Area

Summary

The necessity for the reconstruction of the wastewater treatment facilities of the Istra city and minor wastewater treatment facilities operated by MUE «Istrinskii Vodokanal» of the Istra Area was stipulated by stringent requirements to the effluent quality that were not possible to meet at the existing facilities, and also by the actual wastewater flow increase and equipment wear. The reconstruction provides for the introduction of modern equipment and advanced technologies of wastewater treatment and sludge handling while making maximal use of the existing buildings and facilities. The maximum amount of work was carried out during reconstructing biological treatment line of the Istra wastewater treatment facilities. The project includes allocating nitrification-denitrification zones in the aeration tank and replacing the outdated aeration system with a system with disk fine-bubble membrane aerators. To improve the operation efficiency of the biological treatment facilities and reduce power consumption advanced air blowers were installed. Tertiary treatment facilities were upgraded; drum screens were replaced with microscreen filters. To solve the problem of sludge utilization the composting technology is being developed. Booster pumping stations were upgraded with installing power-operated grinding screens. The project of upgrading wastewater treatment facilities of Dedovsk town (20,000 m3/day) and Obushkovo village was designed. In 2008 the reconstruction of the wastewater treatment facilities of Snegiri holiday home was completed. The design of the biological treatment facilities making use of the biolfilter building and two sections of percolating biofilters proved to be an interesting engineering solution. At present the step-by-step reconstruction with capacity increase of the wastewater treatment facilities in Pavlovskoe and Onufrievo settlements, and Rozhdestveno village is underway. The entire project is implemented by the specialists of the Istra Vodokanal in cooperation with BIFAR Scientific-Production Firm that has developed the basic process solutions and design documentation.

Key words

treatment facilities , reconstruction , wastewater , biological treatment , nitri-denitrification , aftertreatment , membrane aerator , adjustable air blower , microscreen filter , grinding screen

Control valves in controlled pneumatic aeration processes

Summary

Through the 2013–2019 program of the Ministry of Energy and Public Utilities of the Samara Area «Samarskie Kommunal’nye Sistemy» Company has developed and has been successfully implementing the project of upgrading the municipal wastewater treatment facilities. In order to improve the energy efficiency retrofitting the systems of aeration and air distribution, equipping with compressors with controlled air supply to the aeration tanks within 45–100% range is envisaged. The general concept of control has been substantiated that includes complex level of process control and a two-loop automation scheme «aeration tank gate valve control – air blower group». The method of selecting control valves for the air supply control system for pneumatic wastewater aeration has been developed and substantiated. The method is based on the dependence of compressed media flow through the control valve stated in IEC 60534-2-1 International Standard. Under full-scale conditions with the use of precision equipment the flow characteristics of IRIS (DN300) control valve manufactured by Egger were studied. The average percentage error of the method was 6.79%. The method error does not matter much for the automated control since PID-control provides for supplying the required air amount according to the condition of compliance to О₂, NH₄ set values and current measurements of the supplied air amount. The classification of control valves is presented based on the type of the dependence of K_v/K_vs valve capacity coefficients from the rate of valve opening. Technological modes were identified: comparison of the theoretical and experimental flow characteristics of the control valve, pressure difference at the control valve, pressure difference in the «control valve – aerators» system, aerial environment temperature before the valve. The suggested method of the control valve calculation is a part of the «Energy efficiency of the controlled air supply to the aeration tanks» comprehensive mathematical model.

Key words

energy efficiency , automated control system , membrane aerator , wastewater treatment facilities , pneumatic aeration system , control valves , flow coefficient , diaphragm gate valve