Development of Microbial Inoculum to Enhance the Degradation of Organic Waste

Abstract

Organic waste has become a critical issue with rising population, urbanization and economic activities in Sri Lanka. There are number of methods that are used for organic waste management majoring organic composting. However, the main problem of this process is that it needs much time to degrade naturally. Therefore, this study is focused on the development of microbial consortium to enhance the degradation of organic waste. This study found out the effective method to reduce the time taken for degradation of 5kg of organic waste within 30 days by using Pseudomonas sp., Bacillus sp. and Aspergillus sp. which are isolated from the Kaduwela garbage site, Sri Lanka. These microorganisms were selected based on their extracellular enzyme activity by an enzyme assay and identified by using biochemical and morphological identification methods. There were two types of treatments that were used as individual and combination of the above-mentioned microorganisms in three different concentrations such as Mcfarland 1, 3 and 5 of bacterial isolates and spore suspension of Aspergillus sp. which equals to 3x10⁸spores /ml, 9x10⁸spores/ml and 1.2x10⁹spores/ml. Each of these concentrations was applied individually and 3 combined concentrations as low (T1), moderate (T2) and high (T3) of above mentioned microorganisms. The efficiency of degradation was analyzed by comparing C/N ratio, mean of degradation using One-way-Analysis of Variance (ANOVA) and degradation percentage.  According to the results, the highest concentration of combined consortium (T3), showed the lowest C/N ratio as 15:1 and the highest mean of degradation as 66.67%. With regard to the use of One-way ANOVA for combination, the mean value of control and T1 (P = 0.004), control and T2 (P = 0.001), control and T3 (P = 0.000) results obtained revealed that there were significantly different, confirming that highest concentration of combination of these three microorganisms was the best consortium to degrade organic waste efficiently.