Recycling Discharged Treated Wastewater from Dairy Factories for Industrial and Irrigation Purposes

Abstract

The research aims to assess the input (raw water, RW) and output water (produced water, PW) specifications within the treatment unit of the Abu Ghraib dairy factory. The goal is to ensure that the output water aligns with Iraqi environmental standards outlined in Law 25 of 1967, addressing river water and discharged wastewater, and Law 3 of 2012, pertaining to the reuse of treated water for agricultural irrigation. Analysis of the provided PW samples indicates general adherence to approved specifications for chemical oxygen demand (COD), biological oxygen demand (BOD), acidity (pH), nitrate (NO₃), phosphates (PO₄), total dissolved solids (TDS), total suspended solids (S.S), chloride, and sodium adsorption rate. Effective removal of organic content is observed, with percentages ranging from 92% to 97% for COD and 92% to 97.8% for BOD across all samples. To enhance the treated water quality further, adsorption using activated carbon (AC) was implemented through a batch system involving 800 ml of PW and 2 gm of AC, with a variable time and an equilibrium period of 5 hours. Remarkably, this approach resulted in a 100% removal of both COD and BOD. Sodium absorption rate (SAR) values, before and after adsorption, were 4.7 and 4.86, respectively. In a continuous system using a fixed bed activated at different depths (10, 20, and 30 cm), maintaining a constant flow rate of 15 ml/min and an initial COD concentration of 75 ppm, breakthrough curve time and empty bed contact time increased proportionally with bed depth, showing the impact of this parameter on system performance.