Investigating the feasibility of reusing the effluent from the urban sewage treatment plant (Case study: South Tehran treatment plant)

Abstract

The current study was carried out with the aim of measuring the feasibility of reusing the effluent from the wastewater treatment plant in south Tehran. For this purpose, pH, BOD5, COD, NO₃-, PO₄^3-, SO₄^2-, TDS, TSS, Turbidity, EC, fecal coliform and total coliform were investigated during 6 stages of sampling from the incoming wastewater and the outgoing wastewater from the treatment plant. The average pH, BOD5, COD, NO₃-, PO₄^3-, SO₄^2-, TDS and TSS entering the treatment plant are 7.19, 211.4, 392, 68.8, 12.4, 464, 793.4, 217.8 mg/liter respectively, Turbidity 126.25 NTU, EC 1006.6 Micro mouse/cm, fecal coliform was 1200 MPN and total coliform was 1254 MPN, the highest organic load entering the treatment plant was in May and August 2020. The average total removal efficiency for pH, BOD5, COD, NO₃-, PO₄^3-, SO₄^2-, TDS, TSS, which is equal to 6.9, 15, 31.16, 6.06, 2.99, 83, 465.13, 7.5 mg/L, respectively. Turbidity was 6.21 NTU, EC was 762.83 micro mouse/cm, fecal coliform was 8.75 MPN and total coliform was 63.5 MPN. By comparing the results of the quality parameters with the standards of the Environmental Protection Organization, it was found that the effluent of the treatment plant is in a favorable condition for discharge to surface water, absorbent wells and irrigation and agricultural uses, which indicates the correct operation of the treatment plant and compliance with the established rules and standards. Also, the efficiency of the sewage treatment system using the activated sludge method in this treatment plant is favorable.