Bio-ethanol production from waste biomass of Pogonatherum crinitum phytoremediator: an eco-friendly strategy for renewable energy

In this study, we have described three steps to produce ethanol from Pogonatherum crinitum, which was derived after the treatment of textile wastewater. (a) Production of biomass: biomass samples collected from a hydroponic P. crinitum phytoreactor treating dye textile effluents and augmented with Ca-alginate immobilized growth-promoting bacterium, Bacillus pumilus strain PgJ (consortium phytoreactor), and waste sorghum husks were collected and dried. Compositional analysis of biomass (consortium phytoreactor) showed that the concentration of cellulose, hemicelluloses and lignin was 42, 30 and 17%, respectively, whereas the biomass samples without the growth-promoting bacterium (normal phytoreactor) was slightly lower, 40, 29 and 16%, respectively. (b) Hydrolysate (sugar) production: a crude sample of the fungus, Phanerochaete chrysosporium containing hydrolytic enzymes such as endoglucanase (53.25 U/ml), exoglucanase (8.38 U/ml), glucoamylase (115.04 U/ml), xylanase (83.88 U/ml), LiP (0.972 U/ml) and MnP (0.459 U/ml) was obtained, and added to consortium, normal and control phytoreactor derived biomass supplemented with Tween-20 (0.2% v/v). The hydrolysate of biomass from consortium phytoreactor produced maximum reducing sugar (0.93 g/l) than hydrolysates of normal phytoreactor biomass (0.82 g/l) and control phytoreactor biomass (0.79 g/l). FTIR and XRD analysis confirmed structural changes in treated biomass. (c) Ethanol production: the bioethanol produced from enzymatic hydrolysates of waste biomass of consortium and normal phytoreactor using Saccharomyces cerevisiae (KCTC 7296) was 42.2 and 39.4 g/l, respectively, while control phytoreactor biomass hydrolysate showed only 25.5 g/l. Thus, the amalgamation of phytoremediation and bioethanol production can be the truly environment-friendly way to eliminate the problem of textile dye along with bioenergy generation.