Potential of Wheat Straw for Biogas Production by Anaerobic Digestion in South Africa: A Review

Abstract

Wheat straw (WS) is a promising substrate for biogas production by anaerobic digestion (AD) due to its high carbohydrate content. An estimated 0.603 million t yr−1 of WS are generated from wheat production systems in South Africa. This is equivalent to an energy potential of 11 PJ. Despite this, WS is still undervalued as a bioenergy resource in South Africa due to its structural complexity and low nitrogen content. WS disposal methods, such as use in livestock bedding, burning and burying into the soil, inter alia, are not sustainable and may contribute to global warming and climate change. The commercialization of the AD of WS needs to be further developed and promoted. Pre-treatment (i.e., physical, chemical, biological and hybrid methods) and anaerobic co-digestion (AcoD) are novel strategies that can support the conversion of WS into biogas and other value-added products. Current and future research should focus on optimizing pre-treatment and AcoD conditions towards industrialization of WS into valuable products. This paper focuses on the potential use of WS for biogas production in South Africa. The aim is to create information that will promote research and development, and encourage policy makers and stakeholders to participate and invest in WS biogas technology. Were WS biogas technology fully adopted, we believe that it would alleviate energy insecurity and environmental degradation, and sustain the livelihoods of citizens in South Africa.