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ABSTRACT
The most commonly used biological treatment of municipal and industrial wastewater is the Activated Sludge Process. The design of activated process is usually done manually; this is often difficult and susceptible to errors due to the large number of equations involved (which call for approximations and round off errors). Also, the determination of the effects of changes in design parameters are very difficult and time-consuming for manual computations. This paper therefore employs the Visual Basic 6.0 programming for design and simulation of completely mixed activated sludge (CMAS) process. Algorithm and flow chart based on kinetic model were used for developing the Visual Basic code, ASPSIM. The code was tested using a design problem from standard text book. Results obtained proves that the Visual BASIC 6.0 program ASP-SIM is a useful tool for predicting the effect of temperature on design and operation of completely mixed activated plant design and operation.
KEY WORDS: Simulation, BOD, temperature, activated sludge process, and Visual Basic.
I. INTRODUCTION
The design of biological wastewater treatment plant is usually done by using equations based on mathematical models; in order to specify the plant dimensions, configurations, and process conditions. The design of activated sludge process for wastewater treatment using kinetic models involves solving complicated equations for a given condition (variable temperature). When the conditions change, the calculations have to be repeated. Activated sludge process plants are often installed and operated in locations with widely varying climatic conditions (Benefield & Randall, 1980; Tchobanoglous & Others, 2003; Agunwamba, 2007).
The effects of temperature change must therefore be considered in the design and operations of such plants. In most parts of the world with desert condition like North Africa and Northern part of Nigeria in particular, temperatures may range from as low as 12 0C during the months of December and January to as high as 40 0C during the months of March and April. This wide range in temperature may have serious consequence on the activated sludge process plant operation. Metabolic activities of microorganism, oxygen transfer rate and the settling characteristics of biological solids are affected by temperature. To predict the effect of temperature on the activated sludge process plant design and operation requires the use of computer aided software. This paper focuses on...