Computer Aided Process Designing of Sewage Treatment Plant Using Activated Sludge Process

Abstract

Sewage is generated by residential, institutional, commercial and industrial establishments. It includes household waste from toilet, baths, showers, sinks, kitchen and so forth that is disposed off sewers. Sewage treatment is the process of removing contaminants from commercial and household sewage, both runoff (effluents) and domestic. It includes physical, chemical, and biological processes to remove physical, chemical and biological contaminants. There are two fundamental reasons for treatment of sewage viz., prevention of pollution for the protecting of the environment, preventing the spread of water borne diseases for protection of public health. Proper design, construction together with good operation and maintenance are essential for sewage treatment plants (STP), in order to produce effluents which are satisfying the safe disposal standards prescribed by the regulatory authorities. In the present study a computer program in ASP.NET has been developed for comprehensive design of sewage treatment plant which incorporates activated sludge process as biological treatment method. All the units of STP were included in the design by referring various standard procedures and manuals. The validity of the software has been tested by comparing designed values with an existing STP. This program not only helps in sizing the treatment units but also helps in understanding the plant’s capacity as well as in deciding the future expansion works needed for increased hydraulic and organic loadings. The program also incorporated sludge management where the sludge is stabilized in anaerobic digester and the biogas produced is used for power generation. In this way, the power requirement of the plant from outside sources can be reduced. The software is unique in itself as it is not needed to be installed in the computer but is available online with URL (www.oberoiinfra.co.in) and is password protected. This software can also work on mobiles through opera mini. The program is user friendly and interactive as it provides ranges to the user in the various stages of the design and it also gives message to the user for any value which is out of range. Some of the units in the program are optional and the user can skip them if he does not wish to design that units. The program along with the treatment units also calculates the capacity on different pumps required, oxygen required for aeration and power required for mixing in the digester. The program in the end provides result sheet showing the sizes of all the units calculated are given alongwith a flow diagram , thus provides complete process design with a facility of printout on A1 and A2 sheets. Hence, this computer aided design provides accurate, precise and time saving means for designing of STP.