Biodegradation Potentials of Cassava Mill Effluent (CME) by Indigenous Microorganisms

Abstract

The indiscriminate discharge of Cassava mill effluent pose serious environmental and public health implications. This work was aimed at assessing the biodegradation potentials of indigenous microbial isolates from cassava mill effluent using screening and shake flask degradation tests. The mean heterotrophic bacterial and fungal counts were 3.4±0.26 x 10⁶cfu/ml and 1.1±0.20 x 10⁶cfu/ml respectively. The microorganisms isolated, characterized and identified include the genus Pseudomonas (15.48%), Bacillus (12.41%), Acetobacter and Rhizopus (10.88%), Corynebacterium (9.33%), Lactobacillus, Micrococcus and Aspergillus (7.79%), Staphylococcus and Penicillium (6.25%) and Saccharomyces species (4.62%). The pH (5.39 ± 0.14), electrical conductivity (2506.90 ± 45.35), sulphate (210.87 ± 5.31), nitrate (365.28 ± 3.61), phosphate (107.70 ± 2.10), cyanide (19.93 ± 0.25), chemical oxygen demand (1728.33 ± 19.66), biological oxygen demand (1141.51 ± 12.69), iron (206.43±2.05), zinc (54.56 ± 0.62), manganese (19.96 ± 0.35), copper (10.67 ± 0.10) and nickel (3.28 ± 0.46) in mg/l were above the Federal Environmental Protection Agency standard for effluent discharge. Bacillus, Pseudomonas, Aspergillus and Penicillium species which had the highest turbidity were used for bioremediation studies. The consortium of microorganisms demonstrated the highest efficacy. Bioremediation of cassava mill effluent by these microorganisms was manifested in the reduction of biological oxygen demand (consortium of Pseudomonas and Bacillus species 97.42%), (Aspergillus and Penicillium species 75.32%) and chemical oxygen demand (Pseudomonas and Bacillus species 37.63%), (Aspergillus and Penicillium species 44.97%). The study has shown that microbial isolates have the potentials of reducing pollution effect thereby enhancing management of cassava mill effluent before eventual discharge into the environment.

Keywords: Biodegradation, Environmental management, Microorganisms, Turbidity, Cassava mill effluent, Ebelle.