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Article Type

Article

Abstract

The treated wastewater by the industrial Wastewater Treatment Plant (WWTP) commonly named (INGECO) in Al-Doura refinery suffers from highly sulfate concentrations that exceed the EPA specified limits of 250 mg/L. Therefore, laboratory water quality historical data have been reviewed and analyzed to determine the annual rate, maximum, and peak sulfate concentrations that were found to be 360 mg/L, 425 mg/L, and 550 mg/L, respectively. Through field inspection aimed at specifying the reasons for the high sulfate concentrations in the wastewater of most refinery process units, it was found that the maximum required sulfate remaining concentration should not exceed 10 mg/L for use in energy units. In this study, using a Reverse Osmosis (RO) system with four stages, the results obtained indicated that the sulfate (SO4), Total Dissolved Solids (TDS), and chloride removal efficiencies when directly used with treated wastewater ranged between 95.97% to 98.35%, 95.06% to 97.60%, and 98.38% to 98.93%, respectively. With five stages, the removal efficiencies were 99.18%, 99.30%, and 99.38%, respectively. The major advantage of the direct use of the RO system was the production of high-quality water, while a major disadvantage is the expensive treatment cost of about 0.4 $US/m3, and the production of brine that requires disposal with additional costs. In pretreatment by chemical precipitation with the RO system of one and two membranes for reuse purposes to reduce maximum and peak concentrations to 250 mg/L, it was found that in one membrane (sulfate, chloride, and TDS) achieved removal efficiencies of 98.80%, 91.10%, 96.10%, and 97.90%, 92.00%, 96.00%, respectively. With two membranes, the removal efficiencies were 98.80%, 93.0%, 96.40%, and 98.80%, 95.00%, 96.40%, respectively. One of the most important additional benefits of this method is maintaining the osmosis membranes from rapid damage, but one of the most significant disadvantages is the high cost of about 0.59 $US/m3.

Keywords

Sulfate, Wastewater Treatment, Al-Doura Refinery, Reverse Osmosis.

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