Effluent discharge from a leather processing plant: A case study of East African Tanners (K) Ltd in Njiru, Nairobi

Abstract

This study assessed the effluent discharge from leather processing at East African Tanners (K) Ltd at Njiru location in Nairobi. The objective was to characterize and quantify the effluent discharged from leather processing. The study categorized the inputs and raw materials used in the tanneries, their state and assessed their contribution to the quality of the effluent discharged. An attempt to quantify the waste generated, waste management and the tannery's compliance to EMCA (1999) was conducted. Effluent samples were collected at three levels; raw, treated and final (entry to sewer), with sampling replicated twice a week for three weeks. Samples were taken to the laboratory for analysis of the levels of chromium, pH, BOD, COD, sodium, sulphide, TDS, TSS, oil and grease. A comparative analysis carried out against established standards by NEMA, NWSC and Water Quality Regulations 2006 indicated high levels of all indentified parameters beyond Maximum Allowable Levels (MALs) Findings from this study indicate that; presence of dung, blood, soil and salts among other impurities and inputs used in the processing of leather contribute to the composition of the effluent discharged. All the parameters analyzed displayed similar trends across the ETP (R, T and F) with significant difference P<;0.05 in characteristic of effluent observed among treatments where raw effluent was significantly higher than treated and final effluent. Levels for the pollutants were above the maximum allowable levels despite the above average rating against EMCA (1999). The conclusion drawn is that Environmental Management Systems of the tannery are not efficient enough to ensure that the effluent is adequately treated. Results showed that there is interconnectedness of state of raw materials and inputs with the quality and quantity of effluent discharged. Observations also indicated that compliance to environmental standards does not translate to sound waste water management. This study therefore recommends that environment inspections; monitoring and evaluation are scaled up through supportive policy and legal frameworks that are adequately strengthened. A deliberate effort is made to support the tanning sector with incentives \and subsidies to encourage investment in environmentally sound technologies, machinery and practices. An evaluation on the efficiency of effluent treatment plants in Kenyan tanneries is conducted to ascertain their levels of efficiency. An investigation of chromium levels at Ruai sewage treatment plant; Soil and ground water analysis in areas adjacent to tanneries and treatment plants is conducted.