Performance assessment of wastewater treatment plant of Hawassa St. George Brewery, Hawassa, Ethiopia

Abstract

The aim of this study was to evaluate the performance efficiency of the wastewater treatment plant of Hawassa St. George brewery by collecting wastewater samples from the influent and outlet of each treatment unit and analyzed using standard methods for major physicochemical parameters. Results of the present study revealed that except for temperature (36-38 ⁰C), all of the other analyzed parameters of raw wastewater exceeded the national discharge limit indicating the necessity of treating the raw wastewater generated by the brewery. In most cases, the values decreased as the wastewater passed over the treatment units of the plant indicating an involvement of the units in the removal of pollutants. The brewery’s treated final effluent had a mean value of 8.6±0.08 (pH), 24.9±0.6^oC (temperature), 203.0 mg/L (COD), 17.7 mg/L (NH_4-N), 3.62 mg/L (SO₂⁴), 220.6μS/cm (EC), 49.8 mg/L (BOD₅), and 529.6 NTU (turbidity), which were within national industrial wastewater discharge limits. However, the values of some parameters namely, TN (41.0 mg/L), TP (24.3 mg/L), H₂S (3.1 mg/L) and TDS (110.6 mg/L), were higher than the limits. The overall pollutant removal efficiency of the treatment plant was 96.0% (BOD), 92.3% (TSS), 92.0% (COD), 88.5% (EC), 80.6% (TDS), 49.6% (turbidity), 43.0% (SO₄^2-), 42.7% (NH_4-N), 33.6% (temperature), 32.8% (TN), 31.8% (pH), and 30.4% (TP). This result shows that the overall removal efficiency was higher only for BOD₅, TSS, COD, TDS, and EC, all others (especially nutrients) had less than 50.0% efficiencies. Higher nutrient concentration exceeding the discharge limits in final effluent and poor removal efficiency of the treatment plant indicates that the Hawassa St. Gorge brewery waste treatment plant is not effective enough to lower concentrations of these parameters below the discharge limit. Therefore, in order to make the plant more efficient and to reduce the effect of effluent, the factory should take some technological, technical and recycling measures.

Keywords: Brewery, Hawassa, Performance, St. George, Treatment, Wastewater