Sustainable chemical synthesis platform-feasibility study of production and recovery of carboxylic acids from dark fermentation of organic fraction of municipal solid waste (OFMSW).

The objective of this work is to assess the sustainable resource recovery technique for valorizing organic fraction of municipal solid waste (OFMSW) into valuable chemicals, instead of landfilling. Landfilling of the OFMSW waste causes environmental degradation. The study aims to convert OFMSW to carboxylic acids a mixture of lactic, acetic, propionic, butyric and valeric acid via mixed culture fermentation, recover produced acids through adsorbent and finally evaluate the feasibility of the plan through Super Pro. The food waste is converted to carboxylic acids in the aqueous phase, by dark fermentation without pH control and without the addition of external inoculum at 37°C in a batch mode. Experiments were performed to improve acid yield by increasing total solid (TS) content and pretreating the food waste enzymatically. The produced carboxylic acids are then recovered using adsorbent-based techniques. The dark fermentation of the OFMSW produced mainly lactic acid in a non-controlled pH environment. The enzymatically pretreated waste in 35% TS system showed the highest yield of 0.26 g_acid/g_TS and acid concentration of 82 g/L. Non-pretreated waste in 28% TS system showed a yield of 0.16 g_acid/g_TS with 43.32 g/L of carboxylic acid. The acid recovery of 63% from Activated Carbon was obtained. The simulations based on experimental results generate a net profit of 8.6 million USD/year with a payback period of 6.7 years showing that dark fermentation of OFMSW is an economical platform. The recovered carboxylic acids can be used as platform chemicals, i.e. precursors to produce biofuels, bio-chemicals, and bio-materials.