V. Sudharsan Varma

Optimization of waste combinations during in-vessel composting of agricultural waste

In-vessel composting of agricultural waste is a well-described approach for stabilization of compost within a short time period. Although composting studies have shown the different combinations of waste materials for producing good quality compost, studies of the particular ratio of the waste materials in the mix are still limited. In the present study, composting was conducted with a combination of vegetable waste, cow dung, sawdust and dry leaves using a 550 L rotary drum composter. Application of a radial basis functional neural network was used to simulate the composting process. The model utilizes physico-chemical parameters with different waste materials as input variables and three output variables: volatile solids, soluble biochemical oxygen demand and carbon dioxide evolution. For the selected model, the coefficient of determination reached the high value of 0.997. The complicated interaction of agricultural waste components during composting makes it a nonlinear problem so it is difficult to find the optimal waste combinations for producing quality compost. Optimization of a trained radial basis functional model has yielded the optimal proportion as 62 kg, 17 kg and 9 kg for vegetable waste, cow dung and sawdust, respectively. The results showed that the predictive radial basis functional model described for drum composting of agricultural waste was well suited for organic matter degradation and can be successfully applied.

Bio-conversion of organic waste using composting technologies - a review

Composting is nowadays evolving as a highly technical process for processing organic waste separately replacing landfilling along with municipal solid waste. Vegetable waste with high organic content can be composted to produce nutrient rich material that can work as soil conditioner instead of dumping in open landfills. Various studies reveal that due to high organic content of vegetable waste it increases leachability, thereby contaminating the groundwater and increasing greenhouse gas emissions on open dumping. Since the nitrogen and carbon rich materials are layered in an optimal balanced composition in composting, microbes decompose the material faster to produce high quality compost with nutrient value. Vegetable waste rich in organic nitrogen can be easily mineralised by compost microorganisms to form NH4 and NO3, thereby successfully incorporating them in the compost. Depending on the source of organic waste, composting methodology can be selected for the efficient degradation and better compost quality. In the present study, it has been reviewed about the composting methodologies practiced for organic waste providing the optimised parameters for improving the processes.