A Two‐Phase Anaerobic Digestion Process for Biogas Production for Combined Heat and Power Generation for Remote Communities

Abstract

In a conventional anaerobic digestion ( AD ) process, a feedstock rich in organic matters is converted to a combustible gas, known as biogas , containing mainly methane ( CH 4 ) and carbon dioxide, under the action of microorganisms such as methanogenic microbes in the absence of oxygen. However, the conventional AD process is slow and difficult to control for optimal biogas production. A two‐phase anaerobic digestion (T‐ PAD ) process is a sequential anaerobic process, in which hydrogen and CO 2 are produced in the first phase and methane and CO 2 are produced in the second phase. The two streams are then combined to form a hydrogen‐enriched biogas, which has a much improved ignition quality if used in gas engines for combined heat and power ( CHP ) generation, an emerging technology especially for off‐the‐grid remote energy services. This article describes the principles of the T‐ PAD process, provides a sound technical procedure and engineering protocol for designing and integrating the T‐ PAD into a CHP system, and completes with an illustration of the working of a case study of a pilot‐scale process demonstration unit.

Energy recovery from one- and two-stage anaerobic digestion of food waste

“…Nevertheless, 1S-AD is a well-established system for the treatment of organic waste, characterized by a simple set-up and relatively limited investment and operating costs, and as a matter of fact most of the full-scale digestion plants in Europe (90 % of the installed AD capacity) are designed and operated as one-stage systems (Rapport et al, 2012). A major drawback in such cases is that the produced biogas is frequently reported to display a poor quality in terms of its calorific value (Zhang et al, 2015;Sunyoto et al, 2016).…”