Variation of Erbil Municipal Wastewater Characteristics Throughout 26 Years (1994-2020) with Possible Treatments and Reusing: A Review

Abstract

This research aimed to study characteristics variation of Erbil municipal wastewater (EMWW) during 26 years (1994-2020), appropriate treatment using different methods, and suitability of the treated wastewater (WW) for disposal to the natural environment or using for irrigation purpose. Forty-seven WW quality parameters were studied. A number of EMWW characteristics such as five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total suspended solids (TSS) were exceeded the WW discharge standards. Consequently, EMWW needs treatment process prior to disposal to the environment. Primary treatment units with lagoons or oxidation ditch or wetland were applied as first scenario for treatment of EMWW; While, using only lagoons or oxidation ditch or wetland directly was the second situation. EMWW normally regarded as weak/low to medium WW type and it is classified as good to injurious irrigation water kind. Commonly, time had not great effect on EMWW characteristics. Life style, climate, sewerage system (combined or separate systems), climate, and areas/zones had effect on the quality of the municipal WWs. Primary units plus wetland led to removal efficiency of 94.75 %, 93.07 %, 89.47 %, 96.72 %, and 57.68 % for BOD5, COD, NH3-N, TSS and PO4, respectively. Treatment of EMWW using both primary units and wetland resulted in achieving effluents agreed with the standards for disposal of WW. Generally, treated EMWW can be used for cooked vegetables and irrigating green areas.