Performance Evaluation and Optimization of an Industrial Wastewater Treatment Plant (Case Study: Bahir Dar Textile Factory, Ethiopia)

Abstract

Bahir Dar Textile Factory is one of the most important factories located at the edge of Blue Nile river. The factory generates a huge amount of wastewater after the manufacturing processes. The factory has an activated sludge wastewater treatment plant which treats a maximum of 1200m3 of wastewater in a single day. The main goal of this research was to evaluate the efficiency of the treatment plant, assess the possible impacts on the quality of Blue Nile river, that is followed by an optimization of the plant for a better effluent quality. Laboratory analysis and historical data were used as a main source to examine the behaviour of the existing treatment plant. Then water quality of the river is assessed to inspect the impact of the effluent after disposal. The wastewater treatment plant at the factory was found as efficient in terms of removing BOD5, Nitrogen and Ammonia concentration from the influent. While, TSS, TP, TKN and COD concentration were beyond recommended limits. This will directly affect the quality of the river and the aquatic life, so that, optimization and upgrading is expected to improve the treatment performance. In order to optimize and upgrade the treatment plant, a computer software program named GPS-X was used. Sample results were used for model calibration then different scenarios were conducted. The optimization of the treatment plant is addressed in two methods. The first one was to improve the effluent quality by adjusting some operational parameters within the existing plant, this shows a significant reduction of COD, TP, TKN and Ammonia. Secondly, three options are considered as an upgrading method so that, to improve the removal of TSS, a grit chamber and a sand filter were added to the treatment train as a result a substantial reduction of TSS is observed. The second option was addition of hybrid of anaerobic and anoxic tank before the activated sludge process, this shows a high decrease of COD and Phosphorus concentration. Lastly, Membrane Bioreactor replaced the activated sludge process and almost all of the physico-chemical parameters are reduced in substantial way. This was also beneficial in terms of operation, chemical cost and reduction of sludge.