Study on Natural Organic Materials as Biofilm Carriers for the Optimization of Anaerobic Digestion

Abstract

Increased Methane productivity and organic matter removal efficiency in anaerobic digestion can be achieved by retaining microbial consortia inside the reactors using biofilm carriers. In this study, the performance of anaerobic reactors was assessed using natural organic materials i.e. luffa sponge, coconut husk fiber and wood chips as biofilm carriers. Anaerobic batch mode bioreactors comprising of carrier materials for biofilms and control bioreactor were run in parallel at mesophilic temperature (35 °C). Methane content, biogas yield, pH, volatile solids, chemical oxygen demand, VFA/alkalinity ratio and total organic carbon was measured before and after the experiment. Scanning electron microscopy was used to identify the morphology of the methanogenic bacteria present in the biofilms. Maximum methane concentration and volatile solids removal efficiency was obtained from luffa sponge reactor i.e. 77.7% and 82.6% respectively. Furthermore, determination of biokinetic parameters lag phase (ʎ) and production rate (Rm) was also performed using three kinetic models i.e. Modified Gompertz Model, Logistics growth model and Transference function model. Among the kinetic models, logistics growth model and modified Gompertz model provided the best fit with the experimental data providing the R2 of 0.989 and 0.975 respectively.