Evaluation of some physical, chemical and biological properties of treated wastewater in Karbala wastewater treatment plant

Abstract

In order to evaluate the efficiency of wastewater treatment plant in Karbala and the possibility of using treated water for irrigation purposes and groundwater recharge, wastewater samples were taken before entering plant, other samples of treated wastewater were also taken to conduct various physical, chemical and bacteriological analyses and to estimate heavy metals in them, including: Nickel, Chromium, Cobalt, Lead, Iron, Cadmium, Manganese, Vanadium, Zinc and Copper. The results showed the following:

pH value of treated water increased from 7.48 to 7.59 , electrical conductivity decreased from 8.50 to 1.20 dS-1 , total dissolved solids (TDS) decreased from 5150 to 775 mg L-1, total suspended solids (TSS) from 99.00 – 9.00 mg L-1, biochemical oxygen demand (COD) from 236 – 10 mg L-1, total hardness (TH) from 66.50 – 3.47 mg L-1, SAR value ranged from 6.80 to 0.800 (mmol charge L-1) ½, turbidity value ranged from 200 to 0.90 NTU, water grade changed from C4S1 to C3S1. Concentrations of cataions, Calcium, Magnesium, Sodium, Potassium, and Ammonium, decreased from97.00 - 2.81 mmol L-1, 10.29-1.90 mmol L-1, 8.23-0.29 mmol L-1 and 2.50-0.81 mmol L-1 ions of the above elements respectively. Concentrations of anaions in treated wastewater for sulfate, nitrate, phosphate, and chloride and ions decreased from 13.97 -1.73 mmol L-1 , 8.29 -0.05 mmol L-1 , 8.10 - 0.03 mmol L-1, 24.23 - 5.09 mmol L-1, for the above anaions, respectively. The concentrations of heavy metals in treated wastewater decreased, including Iron from 90.80 - 0.21 mg L-1 , Zinc 0.51 - 0.00 mg L-1, Copper 0.99-0.00 mg L-1, Vanadium 0.09-0.00 mg L-1, Cadmium 0.40-0.00 mg L-1, Nickel 0.85-0.00 mg L-1, Manganese 85.40-0.19 mg L-1, Cobalt from 0.94-0.00 mg L-1 and Chromium from 95.00-0.26 mg L-1. Total bacteria and coliform bacteria also disappeared in treated wastewater with a removal rate of 100%.