Waste Generation and Physicochemical Qualities of Abattoir Wastewater in Hawassa City, Southern Ethiopia

Background: Improper disposal of abattoir waste without any treatment has severe impacts on the environment and human health. However, there lacks sufficient studies that quantify abattoir waste and physicochemical parameters of wastewater. Thus, this study aimed to estimate waste generation and physicochemical characteristics of wastewater discharged from Hawassa municipal abattoir. Methods: A cross-sectional study was conducted at Hawassa Municipality Abattoir. One year of cattle slaughtering data was collected from the Hawassa municipality registry from March, 2016 to February, 2017. Mathematical computational approach were used to evaluate magnitude and composition of waste generated from the actual number of cattle slaughtered. Samples were collected from two wastewater sites on sewer line into which the abattoir wastewater was discharged. Physicochemical characteristics of the wastewater were determined by different laboratory investigation methods. Statistical Package for the Social Sciences (SPSS) software version 21 was used to analyze the mean, standard deviation and one tail of t-test for two mean sample value was assumed for equal variance with 95% Confident Interval (CI) to determine significant difference of each physicochemical parameter between the two sites. Results: Hawassa Municipality Abattoir generated 2529.76 kg of waste per day and 923,994.84 kg of waste per year. The analyzed physicochemical parameters indicated high concentrations of Chemical Oxygen Demand (COD) (579 mg/L), Biochemical Oxygen Demand (BOD5) (641.30 mg/L), NH3 (56.32 mg/L), TDS (311.60 mg/L), Total Suspended Solid (TSS) (122.16 mg/L), and EC (838.40 μS/cm) at wastewater site 2 and elevated concentrations of PO43- (43.50 mg/L), NO3- (92.24 mg/L), NO2- (23.99 mg/L), and DO (7.67 mg/L) at wastewater site 1. The mean difference in the concentration of COD, BOD5, NO2-, NH3, TDS, TSS and EC obtained from two sites were statistically significant (P<0.05). Conclusion: In this study, large quantity of abattoir waste was generated, which was directly discharged into the environment without any treatment. The mean value of most physicochemical parameters were higher than the Ethiopian Environmental Protection Agency maximum permissible limit. Therefore, Hawassa municipality office should design and implement safe abattoir waste treatment technology to safeguard public and environment. Keywords: Abattoir; wastewater; Hawassa; physicochemical parameter