Production Processes' Perforrmance Evaluation of Skyfat Tannery, Uganda

Abstract

The leather industry in Uganda contributes to the national economy in addition to environmental and waste management of the waste generated from the food processing industry by converting hides and skins into leather through a series of production processes using different chemical and mechanical methods. However, this industry sector uses old and inefficient technology that leads to the unsustainable use of resources and subsequent generation of wastes that are laden with pollutants detrimental to the environment. Therefore, the main objective of this study was to evaluate the production processes’ performance of Skyfat Tannery in Jinja district, Uganda. The study used both qualitative and quantitative research methods of data collection. The production processes used by Skyfat Tannery were identified and the quantities of material inputs and waste outputs i.e., solids, water, and chemicals were established using material flow analysis for all production process stages at Skyfat Tannery. The types, quantities, and management practices of the generated solid wastes were established. Wastewater management and treatment at Skyfat Tannery were established. Selected parameters namely; TSS, TDS, turbidity, BOD5, COD, electrical conductivity (EC), pH, sulphides, chromium VI, total chromium, total coliforms, zinc, lead, iron, oil and grease, magnesium, manganese, nitrates, phosphates, and sulphates were characterised in the wastewater and the wastewater treatment performance determined. Skyfat mostly uses conventional methods of production to process hides and/or skins and also employs some cleaner production processes which include green fleshing, industrial symbiosis, and mechanical desalting. Per tonne of wet salted hides, it was established that on average the total amount of chemicals and water used for all the production process stages at Skyfat Tannery was 2758.5 kg and 129.8 m3 respectively resulting in solids and wastewater laden with pollutants. The solid wastes generated by the tannery include fleshings, splits, hair, trimmings, and raw hides offcuts. Most solid wastes were generated from beam-house production processes. Eighty-two percent of the generated solid waste was used in industrial symbiosis where it is processed into gelatin and some exported. The tannery treated its wastewater using the pond system for secondary treatment and constructed a wetland for tertiary treatment. The concentration of some pollutants like BOD5, COD, TSS, TDS, Cr VI, total chromium, coliforms among others in the wastewater discharged in the natural wetland was higher than the standard limit set by NEMA (2020) for effluent discharge into water or land and causes loss in aquatic life due to eutrophication and toxicity. Overall, heavy metals had the highest removal efficiency of > 80% and sulphide had one of the lowest removal efficiency of -34.4%. Therefore, there is a need for the tannery to adopt cleaner production practices like industrial symbiosis for sludge management; enzymes for dehairing and wastewater treatment; and wastewater recycling and reuse to arrive at zero waste discharge. This will promote the sustainable use of resources and better environmental performance hence making it competitive at not only national but international levels.