Evaluating the Effectiveness of Waste Management Systems for Tea Factory in Kenya: a Case Study of Maramba Tea Factory in Kiambu County

Abstract

The Government of Kenya and the world has put emphasis on the need to invest in waste management systems. Much of the emphasis has been on Municipal and residential wastes management. However, agro industries (which includes tea factories) wastes management challenges is on the rise. Performance of the already existing management systems is therefore critical in sustaining our environment. A waste management system should be based on a clear characterisation of wastes, the quantities and qualities of the wastes and identification of waste sources. The study evaluated the effectiveness of existing wastes management systems in Maramba Tea Factory in Kiambu County, Kenya for solid, liquid and thermal wastes management systems using Benchmarking Method. Primary data and secondary data were collected. Purposively and convenience sampling techniques were utilised when choosing the wastewater sample points in the lagoons, upstream and downstream of the river. Existing liquid wastes (wastewater) were treated through naturally aerated lagoons. There were no clear systems to manage solid wastes, though most of the organic wastes are disposed in the banana garden, metal solid wastes were disposed of by selling and for thermal wastes, there was chimney for the boiler but no pipe lagging that would reduce heat loss. Characterisation of waste generated was done through observation. The types of wastes identified were organic solid wastes, inorganic solid wastes, Liquid wastes and Thermal wastes. The quantities of wastes were determined by weighing. The Organic solid wastes from tea processing stages were 486.47 kilograms per month and inorganic solid wastes (sacks and polythene bags) were 15.38 kilograms per month. The amounts of liquid wastes generated for the study period were estimated at 80% of the amount of water used. The highest with major cleaning estimated at an average of 111.52m3 per month and the least with minor cleaning averaged at 42.24m3 per month. The quantity of thermal wastes generated at the factory was due to heat loss from the wood fuel used as a source of energy. The total amount of heat loss was found to be 1145.51kcal/kg representing 37.45%. of the Gross Calorific Value (GCV) of wood fuel. The highest heat loss being due to dry flue gas with 675.85kcal/kg representing a 22.09% of total GCV of wood fuel and the least being due to moisture present in the combustion air at 24.78kcal/kg representing 0.810 % of the total GCV of wood fuel. The qualities of wastewater were achieved through analysing the BOD5, COD, PH and Electrical conductivity (EC) and comparing the values to the standards recommended by NEMA. The BOD 5days at 20 oC at 83.7mg/L, COD at 106.63mg/L, EC at 31.87 S/CM and pH of 7.1 were established. The thermal waste systems were evaluated by determining the boiler efficiency. Boiler efficiency at Maramba Tea Factory was 62.55%. The analysis with ANOVA showed significant differences in the water quality parameter values from source through to the lagoon to the river. Investigating the efficiency of these systems contributed to the theory of waste management and provided the literature needed to document the state of waste management systems in tea factories in Kenya. It was concluded that both solid, liquid and thermal waste management systems at Maramba Tea Factory are only partially effective. More studies need to be carried out in tea industries to enable development of guidelines for waste management in such industries.