Management strategies for anaerobic digestate of organic fraction of municipal solid waste: Current status and future prospects

Anaerobic digestion has emerged as the preferred treatment for organic fraction of municipal solid waste. Digestate management strategies are devised not only for safe disposal but also to increase the value and marketability. Regulations and standards for digestate management are framed to address the pollution concerns, conserve vulnerable zones, prevent communicable diseases, and to educate on digestate storage and applications. Regulations and the desired end uses are the main drivers for the enhancement of digestate through pretreatment, in vessel cleaning, and post-digestion treatment technologies for solid and liquid fractions of digestate. The current management practice involves utilization of digestate for land application either as fertilizer or soil improver. Prospects are bright for alternative usage such as microalgal cultivation, biofuel and bioethanol production. Presently, the focus of optimization of the anaerobic digestion process is directed only towards enhancing biogas yield, ignoring the quality of digestate produced. A paradigm shift is needed in the approach from 'biogas optimization' to 'integrated biogas-digestate optimization'.