Cyanide Biodegradation Potentials of Microbial Isolates from Cassava Processing Wastewater

Abstract

Nigeria, the world’s largest producer of cassava, Manihot esculenta (Crantz) very unfortunately, has consistently generated so much waste from cassava mills which are usually discharged on land or water indiscriminately and this in turn, affects the biota, especially in the southern part of the country where most of the mills are located. The cassava tuber contain significant amounts of hydrocyanic acid which is highly toxic to humans and animals. Biological methods harness the metabolic capabilities of some microorganisms that naturally use pollutants, as a source of nitrogen. The availability and accessibility of pollutants as substrates for microbial degradation are critical for bioremediation success. This study was aimed at isolating and characterizing of microorganisms that is able to use cyanide as nitrogen source from cassava wastewater, using mineral salt agar. Cassava wastewater and soil samples were collected from local Cassava Mill garri processing Plant located at Amansea, Awka-North and Amaenyi, Awka-South Local Government of Anambra State. Microbial isolation and identification were done using standard methods. Data were analyzed using one way ANOVA and Turkey test at P < 0.05. Among the microbial strains isolated from the liquid effluent of cassava processing factories, Pseudomonas aeruginosa, Bacillus thuringiensis, Stenotrophomonas maltophilia and Paeniclostridium sordelli were able to degrade 87.50%, 83.33%, 84.38%, 79.16% in media containing 1ml of cassava waste water and 84.41%, 83.87%, 81.72%, 74.19% in media containing 0.5ml of cassava waste water. The study clearly demonstrates the potential of aerobic treatment with cyanide degrading microorganism for cyanide removal in cassava factory wastewaters. This will create a safe and friendly environment in communities where cassava tubers are processed into products.