Bio-Circular Economy: an Opportunity for Diversification for Sugar Industries in Compressed Biogas (CBG) and Organic Fertilizer Production

Press mud cake (PMC) is one of the world's most abundant sugarcane-based wastes, and in an Indian context, 8-10 million tonnes per annum is produced. The current use of PMC is restricted to use as filler material in bio-composting process or directly as fertilizer to improve soil fertility without any previous recovery of value-added products. However, considering its potential, only fertilizer use is not the best valorization route. Due to lack of transportation, press mud is unused and left in piles in most sugar mills, leading to blockage of drains and becoming a cause of water pollution. At the same time, increasing consumption of fossil fuels and environmental concern has led to increased use of compressed natural gas (CNG) in the transportation sector. Keeping in view limited resources of CNG, biogas is advised as potential fuel to provide continuous supply of CNG in the form of bio-CNG or Compressed Biogas (CBG). Therefore, to decrease the imports of crude oil and natural gas requirement and to increase the economic sustainability of sugar mills, utilization of wastes (spent wash and PMC)for biogas production through anaerobic digestion (AD) and further purification to produce CBG (a purified form of Biogas) will definitely generate additional revenue for sugar mills in India. This paper aims to produce a strong outlook on the importance of CBG production through anaerobic digestion and its purification. Further, an out sketch of five models has been designed showing the possibility to produce maximum CBG using existing biogas plant (sugar mill complex) with addition of a new biogas plant. Production of value-added CBG and recycle of digestate on organic fertilizer are perfect case of bio-circular economy.

Automated summary

This paper highlights the importance of producing compressed biogas (CBG) through anaerobic digestion and purification using press mud cake (PMC). The current use of PMC as filler material or fertilizer is not the best valorization route. Utilizing PMC for biogas production and further purification to produce CBG can generate additional revenue for sugar mills and have economic and environmental benefits.