Immobilization of anaerobic bacteria on rubberized-coir for psychrophilic digestion of night soil

Low-ambient temperatures, <30 °C, are known to cause drastic reduction in the efficiency of anaerobic biodigesters due to low-growth rate of the constituent bacterial consortium. Immobilization of anaerobic bacteria has been attempted in the biodigester operating at 10 °C. Various matrices were screened and evaluated for the immobilization of bacteria in digesters. Anaerobic digestion of night soil was carried out with hydraulic retention time in the range of 9-18 days. Among the tested matrices, rubberized-coir was found to be the most useful at 10 °C with optimum hydraulic retention time of 15 days. Optimum amount of coir was found as 25 g/L of the working volume of biodigesters. Immobilization of bacteria on the coir was observed by scanning electron microscopy and fluorescent microscopy. The study indicates that rubberized coir can be utilized to increase biodegradation of night soil at higher organic loading. Another advantage of using this matrix is that it is renewable and easily available in comparison to other synthetic polymeric matrices.