Laboratory Investigation of Cow Manure and Digested synergistic with Municipal Organic Solid Waste in Anaerobic Digestion Process for efficiency increasing

Abstract

Background and Objectives: Increasing production rate, biogas volume and pressure, methane composition as an alternative for fossil fuels and reducing digestion time and the digestion process efficiency. The effect of adding a mixture of cow manure (CM) and digested to municipal organic solid waste (MOSW) in order to increase productivity of anaerobic digestion (AD) process is considered.Methods: Through three steps single MOSW, CM and digested mixing under mesophilic temperature were treated by laboratory scale Semi-Batch anaerobic digestion setup. Digested and CM mixing effect with MOSW were studied and evaluated by investigating of physical-chemistry properties, feed and digested elemental analysis, and also biogas pressure and volume measuring, AD time and biogas analysis. Findings: Adding mixture of digested and CM with MOSW increases feed dry part (organic and ash) and its carbon and nitrogen content. Transformation rate in MOSW co-digestion with digested and CM mixture (3rd step) compare to co-digestion of MOSW with digested (2rd step) and also conversion percent of mentioned quantities derived from 2rd step compare to single digestion of MOSW (1rd step) are increased. Biogas volume and pressure in base on feed mass unit and also biogas relative component during of shorter digestion time, in 3rd step compare to 2rd and also in 2rd step compare to 1rd are increased.Discussion and Conclusion: Digested and CM mixing with MOSW not only contributes in increasing the organic part of the feed, but also collaborates in inoculation in AD process and increases the methane generation. Existence of AD active microorganisms, especially methanogenic as well as enrichment of their growth and reproduction environment by tracer components and elements, accelerates the process, increases the biogas volume and pressure and also methane production efficiency as an energy producing part of the process.