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.