Synergistic Effect of Magnetite and Bioelectrochemical Systems on Anaerobic Digestion

Conventionally, the anaerobic digestion of industrial effluent to biogas constitutes less than 65% methane, which warrants its potential methanation to mitigate carbon dioxide and other anthropogenic gas emissions. The performance of the anaerobic digestion process can be enhanced by improving biochemical activities. The aim of this study was to examine the synergistic effect of the magnetite and bioelectrochemical systems (BES) on anaerobic digestion by comparing four digesters, namely a microbial fuel cell (MFC), microbial electrolysis cell (MEC), MEC with 1 g of magnetite nanoparticles (MECM), and a control digester with only sewage sludge (500 mL) and inoculum (300 mL). The MFC digester was equipped with zinc and copper electrodes including a 100 Ω resistor, whereas the MEC was supplied with 0.4 V on the electrodes. The MECM digester performed better as it improved microbial activity, increased the content of methane (by 43% compared to 41% of the control), and reduced contaminants (carbon oxygen demand, phosphates, colour, turbidity, total suspended solids, and total organic carbon) by more than 81.9%. Current density (jmax = 25.0 mA/m2) and electrical conductivity (275 µS/cm) were also high. The prospects of combining magnetite and bioelectrochemical systems seem very promising as they showed a great possibility for use in bioelectrochemical methane generation and wastewater treatment.

Feasibility Study of Methane Generation from Swine Manure and Eichhornia Crassipes [Mart.] Solms

This research was made to study the feasibility of methane generation from swine manure and water hyacinth (Eichhornia Crassipes [Mart.] Solms) under mesophilic conditions. The component of Eichhornia Crassipes [Mart.] Solms was analyzed before pretreatment that was 21.47% cellulose, 14.98% hemicellulose and 9.88% lignin respectively. Eichhornia Crassipes [Mart.] Solms was pre-treated by using the physical pre-treatment and physicalchemical pre-treatment method. The experiment was batch-test operated within forty days of fermentation when incubated at 37 °C. The highest methane production was obtained from water hyacinth physical pre-treatment with a swine manure ratio of 50:50, Hmax 490 ml, Rmax 0.90 ml h-1 and a yield of 135 ml CH4/ g TVS removal respectively. In terms of physicalchemical pre-treatment for water hyacinth, the highest methane production was obtained with water hyacinth to swine manure 50:50 ratio with Hmax 290 ml, Rmax 0.59 ml h-1 and a yield of 130 ml CH4/ g TVS removal respectively. These results showed that the physical pre-treatment method was suitable as a water hyacinth pretreatment for methane production. In terms of economic feasibility, it was evaluated that the cost, net present value (NPV), a benefit to cost ratio (B/C ratio) and payback period (PBP) were 64.27 USD, 12,116.60, 10.52 and thirteen months respectively. Finally, this research will be useful for aquatic invasive species management and biogas production.

Scenarios of Bioenergy Recovery from Organic Fraction of Residual Municipal Waste in the Marche Region (Italy)

In the Marche Region (Central Italy), the residual municipal waste (RMW) is commonly processed in mechanical biological treatment (MBT) systems. In these systems, following a first mechanical selection, the undersize organic fraction from RMW (us-OFRMW) undergoes a partial aerobic biological treatment before being landfilled as a biostabilised fraction (bios-OFRMW) without dedicated energy or material recovery. Alternative us-OFRMW management scenarios have been elaborated for this region, at both present (reference year 2019) and future (reference year 2035) time bases. In the first scenario, the potential bioenergy recovery through anaerobic digestion (AD) from the us-OFRMW was evaluated. The second scenario aimed at evaluating the residual methane generation expected from the bios-OFRMW once landfilled, thus contributing also to the potential environmental impact connected with landfill gas (LFG) diffuse emissions from the regional landfills. The diversion to AD, at the present time, would allow a potential bioenergy recovery from the us-OFRMW equal to 4.35 MWel, while the alternative scenario involves greenhouse gas (GHG) emissions equal to 195 kg CO2 eq. per ton of deposited bios-OFRMW. In the future, the decreased amount of the us-OFRMW addressed to AD would still contribute with a potential bioenergy recovery of 3.47 MWel.