Applying mass balance dilution technique for wastewater disposal to Greater-Zab river in Erbil, Kurdistan region-Iraq

Treatment is essential for wastewaters prior to its disposal to the environment or water sources. Numerous wastewater treatment techniques are applied for the treatment of wastewater types. To date, dilution via mass balance approach has not been reported for treatment of various types of wastewaters in Erbil City, Kurdistan Region-Iraq. Consequently, the aim of this work was to examine the treatment of various types of wastewaters using dilution method by river water through applying mass balance approach. Characteristics of different types of wastewaters and Greater-Zab River water in Erbil City were studied. Slaughterhouse, tannery, municipal, landfill-leachate, dairy, and refinery wastewaters in Erbil City were used in the present work. Mass balance approach was applied to verify that dilution of various types of wastewaters using Greater-Zab river water. Dilution factor and required amount of river water were calculated. Temperature, biochemical oxygen demand (BOD), and Dissolved oxygen (DO) were studied using mass balance approach. Results revealed that dilution factor for Erbil wastewaters varied from 10.36 to 513.91. Mixing of wastewaters with Greater-Zab river water led to decreasing of DO in the river water by 3.525 % and increasing of BOD in the Greater-Zab River water. Dilution using various quantities of raw river water via applying mass balance approach resulted in decreasing the pollutants in the wastewaters to an acceptable level and it was regarded as a treatment process. Each type of wastewater needs a definite quantity of raw water for the treatment. Commonly, sedimentation is suggested prior dilution of wastewater with the Greater-Zab River water. Maximum discharge of 1,182 m3/s is sufficient for treatment of all mentioned types of wastewaters in Erbil City.