Evaluation of Natural-Based Coagulants Efficacy in Removal of Cyanobacteria from Huruma Wastewater Samples, Eldoret, Kenya

Abstract

There is water deficit and quality crisis in the world due to water pollution mainly by eutrophic nutrients and heavy metals. Eutrophication is the enrichment of aquatic ecosystems by nutrients resulting in an increase in growth of macrophytes such as duckweed and phytoplanktons such as cyanobacteria that lead to degradation of the water quality. Cyanobacteria bloom changes the odor and taste of water with some producing potent toxins which lower water quality. The objective of this study was to evaluate the efficacy of locally available natural- based coagulants namely, Moringa oleifera seeds, Aloe barbadensis miller leaf and Cactus Opuntia stricta leaf in removal of cyanobacteria from wastewater samples collected from Huruma wastewater stabilization ponds, Eldoret. Wastewater samples were collected from the outlet of the last maturation pond at Huruma wastewater treatment plant, where the final effluents are released to river Sosiani. Physical chemical parameters were determined using multitester pH meter, phosphate were analysed using ammonium molybdate method while nitrate were analysed using brucine method. Cyanobacteria biomass was determined using chlorophyll a analysis method. Means of the mentioned parameters were calculated and analyzed using ANOVA and significant means separated using Tukey’s test at 5% level. There were significant differences in reduction of physical chemical parameters and nutrients by the locally based coagulants (P = 0.00). The range of cyanobacteria removal efficiency by the coagulants was as follows; Moringa oleifera 62%, Aloe barbadensis miller leaf 47.3% and Cactus Opuntia stricta leaf 52.2%. These coagulants can be used to treat wastewater contaminated by cyanobacteria