Substantiation of the efficiency of installing emergency storage tanks at wastewater pumping stations

Summary

Improving the reliability of wastewater disposal systems is provided by measures that prevent the intrusion of raw wastewater into the ground and spills onto the land surface. Such measures include backing up pressure and gravity pipeline sections of the network, using their accumulating capacity and installing emergency storage tanks. Based on the life cycle cost assessment, studies of the effectiveness of using emergency storage tanks at wastewater pumping stations were carried out. It is shown that with a certain length of pressure pipelines of two or more strings, the option of installing emergency storage tanks may be most economically viable. As a result, dependences of the efficiency of installing emergency storage tanks on the pressure pipeline length and pumping station capacity were obtained. For wastewater disposal systems in Irkutsk, all wastewater pumping stations are divided into two groups with emergency storage tanks and two pressure pipelines. The results of the study will be useful in updating the scheme for the development of the water supply and wastewater disposal systems of the city.

Key words

sewerage pumping station , pressure pipeline , life cycle cost , emergency storage tank , improving the reliability of wastewater disposal systems

Improving the environmental safety of wastewater disposal system on the basis of emergency storage tanks

Summary

A new structure is proposed – an emergency storage tank for wastewater pumping stations that provides for improving the environmental safety and controllability of the wastewater disposal system by regulating wastewater in underground storage facilities. Owing to the specific features the tank usable volume is filled with wastewater from gravity sewers; the wastewater is retained in it for a certain time and removed together with the sludge eliminating any additional pumping equipment. The range of application of the emergency storage tank extends to the systems for the disposal of domestic, storm and industrial wastewater. This innovative device should become an essential component of the municipal engineering infrastructure and meet environmental requirements for wastewater disposal. Structural solutions adopted in the development of a horizontal storage tank as the main multifunctional accumulating element are focused on the possibility of installing this structure in the built-up areas of the city, as well as in adverse hydrological conditions. To determine the usable volume of horizontal storage tanks the standard mathematical modeling approaches were used with the help of the approximation method. A method is proposed for calculating the storage capacity of the tank, as well as calculating the volume of the ballast chamber of a horizontal storage tank. The aspects of the resistance to floating up of underground elements are considered. The modular principle of the tanks design provides for installing it both by trenchless and cut-and-cover methods; whereas the available additional ballast opens the door for operating in difficult hydrological conditions. It is recommended to equip the existing and projected wastewater pumping stations with the developed emergency storage tank.

Key words

wastewater , sludge , reliability , sewerage pumping station , emergency storage tank , controllability of the wastewater disposal system , wastewater flow control