Mass balance in the treatment of organic wastes from restaurants in bioreactor

ABSTRACT

The treatment of organic solid waste by anaerobic digestion is carried out by a consortium of microorganisms, in which the methanogenic archaea bacteria are the limiting of the process because they are more sensitive to changes in environmental conditions and have slow growth. To monitor the treatment, some variables of anaerobic digester process are monitored, among them, the chemical oxygen demand (COD), usually used to estimate the degradable material and that can be converted into biogas. In order to evaluate the efficiency of biomass conversion process into methane, this article is based on adapted mass balance of the literature using COD values ​​and volume of biogas generated in anaerobic reactor, here called the bioreactor. Biogas production was monitored daily using the water displacement method, with the aid of an electronic counter.The treatment was satisfactory, based on mass balance, which showed that 50% of the amount of COD entered into the system was completely converted into methane gas. Comparing to the values described in the literature that are in the range of 50 to 70%, the treatment efficiency can be elevated with adjustments to control parameters which influence the process of anaerobic digestion, such as keep the temperature constant at 37°C and balanced pH and alkalinity, which can improve the environmental conditions at all stages of degradation of organic matter and increase conversion into methane gas.

Keywords:
organic waste; anaerobic digestion; mass conversion; biogas; efficiency