Evaluation of biohydrogen production from rice straw hydrolysate via Clostridium sp. YM1: In-lab fermentation and techno-economic study

This study investigates the potential of rice straw (RS) to be used as a feedstock for the production of biohydrogen (BioH2). To simplify the structure of the RS, thermochemical treatment is applied using HNO3 and NaOH at different concentrations. At a concentration of 1% (v/v) nitric acid (HNO3), the highest sugar concentration achieved was 27.73 g/L. This condition was utilized in dark fermentation with Clostridium sp. YM1 at 30 degrees C in an anaerobic environment, resulting in a biohydrogen production that surpasses the yield of the control sample by 27%. Furthermore, supplementation of 20 mg of ferrous and magnesium ions enhanced the biohydrogen yield (HY), which achieved 1.12 molH2/molsugar and 1.19 molH2/molsugar, respectively. This study demonstrated that butyric acid fermentation was the main pathway for Clostridium sp. YM1 to produce BioH2 from HNO3-treated RS. The findings were further evaluated for their economic profitability using SuperPro designer in batch production mode to treat 100 kgRS/batch that demonstrated the feasibility of the project with payback period (PBP), and net present value (NPV) of 3.78 years and USD 4,722,929, respectively. The study herein provides valuable insights and recommendations aimed at enhancing the feasibility of the conversion of RS into BioH2, thereby advancing the potential for sustainable bioenergy production.