TREATABILITY STUDIES OF FLOUR MILLS EFFLUENT – A CASE STUDY OF ALKAUSAR FLOUR MILLS ISLAMABAD

Abstract

Pakistan is increasingly confronted with shortage of fresh water resources as annual per capita water availability has reduced to less than 1000 m3. Wastewater reclamation and reuse practices must be adopted to deal with the situations. For this purpose, small and medium scale industries may play a vital role. With this mind set, treatment of process wastewater from Al-Kausar Flour Mills (AFM) Islamabad, Pakistan was investigated using Physico – chemical treatment options. Total water consumption of AFM is 74.1 m3/day. Experimental setup comprised of primary sedimentation, horizontal flow roughing filter (HFRF), and coagulation/flocculation/settling setup followed by dual media filtration. Ferric chloride (FeCl3.6H2O) and alum (Al2(SO4)3.18H2O ) were used as coagulants. Results revealed that flour mill’s process wastewater had high concentration of total suspended solid (TSS) i.e. 2388±114.68 mg/L whereas other parameters such as BOD5, COD, sulphates, chlorides and phosphates etc. were all within the national effluent quality standards of Pakistan. Four treatment options (A – C) were employed. Ferric chloride provided appreciable suspended solids removal in terms of turbidity even at low dose. However, each option resulted in more than 98% of turbidity removal. Option B, comprised of primary sedimentation, HFRF and coagulation, flocculation, secondary sedimentation and dual media filtration with 25 mg/L ferric chloride dose was observed to be the most suitable option to make AFM effluent recommended for different water reuse categories. It was also evaluated that AFM may save up to Rs. 83,300 per year in term of electricity bills and water abstraction charges while chemical cost of plant is being met through these savings.