Biosolubilization of Indonesia’s Subbituminous Coal Using Neurospora intermedia

Abstract

Recognizing its high volatile matter content, liquefaction to convert subbituminous coal with relatively low calorific value into liquid fuel by thermal or biological process has been subjected to extensive research. The former has been implemented commercially whereas the latter challenges for further studies. This paper looks into low-rank coal upgrading through subbituminous biosolubilization using Neurospora intermedia as the bioconverting agent. N. intermedia was initially cultured on agar medium containing a carbon source (glucose, sucrose, or cellulose) in a petri dish. After four days cultivation, sterilized coal particles with diameter of 1.5-2.5 mm were spread on N. intermedia culture. It was observed that N. intermedia could grow on the solid culture containing glucose, sucrose, and cellulose. However, the biosolubilization product was only observed from the solid culture with glucose and sucrose as carbon source. The highest biosolubilization rate was 1.07 × 10−3 abs/min and about 83% of coal could be solubilized when the media contained 15 g/L of glucose. The FTIR analysis showed that the spectrum of biosolubilization product was similar to the initial coal spectrum, but it contained small amount of aliphatic C-H group compounds and high amount of carbonyl, hydroxyl, and amine groups.