Assessment of Pollution Loads in River Nyando and the Contribution from Muhoroni Sugar Factory

Abstract

River water pollution is a problem that affects both industrialised industrial and growth, population are developing countries. Agricultural responsible development for river environmental. pollutioIl'.River Nyando, polluted by siltationand chemicals activities in the catchment In Kenya, and an urban' general for instance, from is agricultural zone and by effluents from Muhoroni sugar factory and Agro-Chemical and Food Company. This study assessed pollution loads in the river and the contributions from Muhoroni Sugar Company (MUSCO) and the Agro Chemical and Food Company (ACFC). The pollution load in River Nyando at Ahero before the river enters Lake Victoria and the variation of the pollutants downstream after the discharge points were determined. Composite samples sampling sites overwere taken a per Lod of from eight selected four months. Physico- chemical water quality parameters, organic pollutants and coliform counts described were in American determined Public by standard methods Health Association (APHA, 1992) . Heavy metals were determined by an Atomic Absorption Spectrophotometer (AAS). The results indicated that River Nyando had high pollution loads from both diffuse and point sources. The fluxes for biochemical alkalinity, oxygen hardness, demand total (BOD), solids nitrates, (TS), total phosphorus, heavy metals and total coliform were highest in November when the river discharge was also highest. The flux for solids was 853.2 tonnes/day. BOD load was 84.80 tonnes/day and the total coliforms were 502 /100ml in November. Cadmium and chromium metals were not detected inv the river water. Lead was the most abundant with the highest average flux of 84.26x10· 2 t/day in November. The lagoons reduced significantly the BOD levels in the ex-factory effluent to 74.95mg/L (p<0.005). The, reduction efficiency of the lagoons was 94.58% and 60.82% for total suspended solrns (TSS) and chemical oxygen demand (COD) respectively. The lagoons were not very efficient in reducing other pollutants like total nitrogen, conductivity, sulphates and heavy metals in the effluent. Hence an alternative treatment method is recommended. ACFC and MUSCO deposited an average of 663.37 and 28.47 tonnes TS and 15.88 and 4.4 t.onne a BOD per month respectively. To reduce pollution from point and diffuse sources, it is suggested that agricultural inputs be used rationally and soil erosion be controlled in the catchment zone. The collection and treatment effluents to permissible industrial cleaner frameworks The are domestic and industrial standards and the adoption production frequent assessment recommended of technology of pollution involvement requdrements levels of for legal as in and adopting well rivers of as are political pollution reduction measures. A study on the purification capacity and efficiency of the swamp through which River Nyando enters Lake Victoria is recommended.