Performance Assessment of Zero Liquid Discharge Wastewater Treatment Plant in the case of Adama Industrial Park

Abstract

In the industrial parks, advanced domestic and industrial wastewater treatment facilities such as Zero liquid discharge (ZLD) were constructed with the aim of recovering the majority of water for reuse and to address human health and environmental concerns related to effluent discharges from the textile industries. However, the performance assessment of the zero liquid discharge plant constructed in different parks of the country were not done yet and the present study were conducted to assess the performance of zero liquid discharge plant implemented in Adama industrial park. The wastewater samples were collected from Receiving, Equalization Tank, Dissolved air floater (DAF), Aeration Tank, Membrane bioreactor (MBR), Multi effect evaporator (MEE), Reverse Osmosis, and Effluent Treatment Plant Blended Tank using grab and composite sampling methods. The samples taken from the different process units were well prepared and analyzed for the major wastewater physico-chemical parameters; pH, EC, TDS, color, TSS, Turbidity, TN, TP, COD, TH, TA, SiO2 and BOD5 as well as heavy metals. The performance assessment was conducted over 8 weeks in the months of February and March. The results showed that the overall efficiency of the ZLD with respect to the major parameters were 90.85% (EC), 90.86% (TDS), 100% (color), 100% (TSS), 100% (Turbidity), 100% (TN), 100% (TP), 99.56% (COD), 98.86% (TH), 99.22% (TA), 99.99% (SiO2) and 99.86% (BOD5). The result with respect to heavy metals were mostly below the discharge limit. This confirmed, the overall performance of ZLD plant was found to meet the design and discharge criteria as prescribed by the authorities. Moreover, the result revealed that operation of the DAF, MBR, and RO units generally has a significant impact on the plant’s overall performance.