Mehran Sugar Mills Limited (MSM) started a campaign for reducing the quantity of its liquid effluents & their pollutant concentration. The objective was to reduce effluent flow to a minimum value of COD, and also to reduce canal water requirements for the Mill. MSM’s total effluent generation is 2000 m3/day, COD 2500 mg/l, pH 6-9. MSM decided to set up an ETP plant to meet the National Environmental Quality Standards (NEQS).

WOG proposed Sequential Batch Reactor based ETP for Mehran sugar with feed flow of 2000 cubic meter per day.

Plant operation is 24 hours & SBR operation cycle is 6 hours per batch. Each batch process involves 5 phases i.e. Static Fill phase, Aerate Fill phase, React phase, Settle phase and Decant phase. MLSS considered for SBR tank designing is 3500-4500 mg/l. Static Mixer continuously mixes the effluent. Acid dosing neutralizes the waste water pH. Fine bubble diffused aeration is provided in Sequential batch reactor tank. Centrifuge machine operation is for dewatering into sludge cakes.

The plant is operating successfully, meeting the NEQS limits, and having COD <150 ppm & BOD <50 ppm.