Simulation and optimization of chemically enhanced primary/activated sludge treatment for small communities

Over the last two decades, the use of coagulation and flocculation has been emphasized for the enhancement of primary sedimentation in municipal wastewater treatment plants. This work is concerned with the development of an approach for the simulation and optimization of a chemically enhanced primary treatment (CEPT)/activated sludge scheme for municipal wastewater treatment using ferric chloride as a coagulant. A mathematical model has been developed which comprises empirical relations for the CEPT stage based on reported experimental data. The activated sludge model has been based on reported rules of thumb.

Optimization has been undertaken using the BOX Complex Routine to minimize a cost objective function with controlling parameters. The effect of varying operating cost components on the cost function has been also assessed via sensitivity analysis.

Results indicate that, for small communities, the addition of a CEPT stage is recommended based on technical and economic consideration for current and prospective costs and prices.