음식물쓰레기의 생물전기화학 혐기성 소화에 대한 유기물부하율의 영향

Abstract

The study on the coal tar pitch binder for the fabrication of bioelectrochemical electrode was performed and then enhanced bioelectrochemical anaerobic digestion for food waste was studied using the electrode prepared with the binder. For the binder study, the coal tar pitch binders containing different amounts of nickel were tried for the fabrication of the bioelectrode consisting of multiwall carbon nanotube and exfoilated graphite, and the bioelectrochemical properties were examined in microbial fuel cells(MFCs). During the enrichment of electrochemically active bacteria on the electrode in MFCs, the voltage was quickly increased after a short lag time, indicating that the coal tar pitch binder is a biocompatible material. The biomass attached on the electrode surface was more at higher Ni content in the binder. The internal resistance of the MFC was lower for the electrode with more biomass. The ideal content of Ni to coal tar pitch in the binder for bioelectrode was 10% in weight. The maximum power density was 731.8 mW/m2, which was higher 23.7% than the electrode with Nafion binder as control. In the study for enhanced bioelectrochemical anaerobic digestion of food waste, the coal tar pitch binder containing Ni was used for the fabrication of the anode and the cathode. The anode and the cathode were equipped inside a lab scale conventional anaerobic digester, and their potentials were maintained at –250 mV vs. Ag/AgCl and –550 mV vs. Ag/AgCl, respectively. The performance of bioelectrochemical anaerobic digestion for food waste was examined at different organic loading rates ranged from 0.70 to 4.25 g VS/L.d. The bioelectrochemical anaerobic digester was rapidly stabilized within 25days after the start-up, and at less than 1.97 g VS/L.d of organic loading rate, the state variables such as pH (7.0-7.8) and alkalinity (10-12 g/L as CaCO3) were very stable. The VFAs was maintained at 400-500 mg HAc/L, and the main component of the VFAs was acetic acid (80%). At 1.97 g VS/L.d of organic loading rate, the performance was significantly high in terms of the specific methane production rate (1.37 L CH4/L.d), and the methane content in the biogas (around 74%). The removal efficiencies of VS and COD were also as high as 80.1% and 85.1%, respectively, and the overall energy efficiency was 91.2%. However, the process stability was deteriorated at 4.25 g VS/L.d of organic loading rate. From above results, it is concluded that the coal tar pitch containing Ni is a good binder for the fabrication of the bioelectrochemical electrode, and the bioelectrochemical anaerobic digester for food waste equipped with the bioelectrodes is quite stable and well performed at less than 1.97 g VS/L.d of organic loading rate.