Potential Effects of Activated Carbon and Pectin-Coated Magnetite (Fe3O4) on Biogas and Methane Production From Sewage Sludge

Abstract

Recycling of sewage sludge as a renewable source is important in terms of controlling of waste sludge production efficiently and, ensuring environmental quality standards at the same time. Biogas is one of the methods of sludge recycling that occurs after anaerobic process.

In this study, the potential effects of Pectin-coated magnetite (Fe3O4) nanocomposite (PNC) and granular activated carbon (GAC), as the two typical conductive materials on biogas and methane production from sewage sludge were investigated. The effect of these two material on biogas and methane yields were determined by comparing the amount of gas produced from the control groups. Experimental work carried out under laboratory-scale fermentation reactors, and was continued for 21 days. The highest biogas production was determined as 554.3±0.59 mL/g-dw in the sample containing of 2.0 g PNC/gVSS, and the percentage of methane was measured as 43.5±0.3%. According to the obtained data, the fermentation with sewage sludge fed with the organic substrate at the same dosages of AC and PNC has created a positive impact on methane production. The highest methane production was determined as 254.2 ± 0.99 mL/g dw from the reactor containing these two materials at equal concentrations of 1.2 g PNC/gVSS 1.2 g AC/gVSS, the percentage of methane in the cumulative biogas volume was measured as 46.7±0.1%. The highest methane content was measured as 48.2 ± 0.1% from the reactor containing 2.0 gAC/g VSS.

FTIR and SEM analyzes were made to characterize AC and PNC before and after the anaerobic digestion process. Addition of AC, PNC and PNC/AC materials together have created a medium that have enhances microorganisms and potential to increase of the methane ratio by performing electron transfer between biogas-producing microorganism species. The results are important because of their positive effects on biogas and methane production efficiency.

Keywords: Activated Carbon (AC), Anaerobic Fermentation, Biogas, Fe3O4, Magnetite, Methane, Pectin-Nanocomposite (PNC)