Effect of Kalerwe Abattoir wastewater on the water quality of Nsooba Channel

Abstract

The unregulated discharge of industrial wastewater from point sources into inland fresh water aquatic systems coupled with the resultant deterioration of water quality, are largely un-documented in many developing countries, Uganda inclusive. The aim of this study was to assess the impact of Kalerwe abattoir wastewater on the water quality of Nsooba channel. Five sampling points were identified. Sampling point S1 was located 100m upstream of Kalerwe abattoir effluent discharge point into Nsooba Channel; sampling point S2 was located at the discharge point of Kalerwe abattoir effluent into Nsoba Channel; Sampling point S3 was located 100 m downstream of sampling point S2; Sampling point S4 was located further downstream after the entry of Kiyanja and Katanga streams into the Nsooba channel, and Sampling point S5 was located at the entry point of Nsooba channel into Lubigi wetland. Water samples were collected and analyzed for physico-chemical and microbiological parameters namely; temperature, pH, electrical conductivity (EC), total suspended solids (TSS), total dissolved solids, phosphate(PO43-), nitrate (NO3-), nitrite (NO2-), ammonia nitrogen and chemical oxygen demand (COD) total bacterial count (heterotrophic, total and feacal coliform counts). Abattoir wastewater exhibited significantly higher levels (where is P-value) of total dissolved solids [1385.5+23.40 mg/L], phosphate (PO43-) [241.03+6.18 mg/L], nitrate (NO3-) [4.16 ± 0.46 mg/L], nitrite (NO2-) [1.63 ± 0.49 mg/L ], ammonia nitrogen [63.58 +1.51mg/L] and chemical oxygen demand (COD) [12559 ± 2019 mg/L] compared to both upstream as well as downstream regions along Nsooba Channel. The mean heterotrophic bacterial counts and fecal coliform counts of abattoir effluent were 5.67 x 1013 and 4.13 x 105 cfu/100ml, respectively. However, there was a general decrease in both total heterotrophic bacterial counts [4.2 x 1013cfu/100 mL] as well as fecal coliforms [6.13 x 104 cfu/ 100 mL] at upstream and downstream of the abattoir discharge points along Nsooba channel. It was thus concluded that the release of Kalerwe abattoir effluents x significantly impacts the water quality of Nsooba channel and eventually, Lubiji wetland. It is therefore imperative that Kalerwe abattoir undertakes the task of pre-treating its wastewater before releasing it into the channel.