Current and prognostic overview on the strategic exploitation of anaerobic digestion and digestate: A review

The depletion of fossil fuels and increasing demand for energy are encountered by generating renewable biogas.
Anaerobic digestion (AD) produces not only biogas, also other value-added products from the digestate using
various organic, municipal and industrial wastes which have several benefits like remediating waste, reduces
greenhouse gas emissions, renewable energy generation and securing socio-economic status of bio-based industries.
This review work critically analyzes the biorefinery approaches on AD process for the production of
biogas and digestate, and their direct and indirect utilization. The left-out residue obtained from AD is called
‘digestate’ which enriched with organic matter, nitrogen, heavy metals and other valuable micronutrients.
However, the direct disposal of digestate to the land as fertilizer/landfills creates various environmental issues.
Keeping this view, the digestate should be upgraded or transformed into high valued products such as biofertilizer,
pyrochar, biodiesel, syngas and soil conditioner that can aid to enrich the soil nutrients and ensures the
safe environment as well. In this context, the present review focused to illustrate the current techniques and
different strategic exploitations on AD proper management of digestate products for storage and further applications.
Such a technology transfer provides a proven strategic mechanism towards the enhancement of the
sustainability of bio-based industries, attaining the energy demand, safest waste management, protection of
environment and reduces the socio-economic issues of the industrial sector.