The Influence of CO2 Injection into Manure as a Pretreatment Method for Increased Biogas Production

Abstract

Manure is considered a by-product or organic waste in cattle, pig, chicken or other animal breeding farms, which can be a valuable product as compost or feedstock for biogas production. The production of biomethane from biogas always copes with the formation of carbon dioxide (CO2) as a by-product. This CO2 may be recycled through the feedstock as a pretreatment to maximize homogeneity, and improve biogas yield and biogas quality. The CO2-pretreatment process of cow manure (CoM), chicken manure (ChM) and pig manure (PM) was performed in the continuously fed agitated reactor at 25 °C temperature and ambient barometric pressure. Biogas yield and composition exploration were performed in an anaerobic continuous feeding digester with controlled mesophilic (37 °C) environmental conditions. The CO2 pretreated PM, CoM and ChM yielded 234.62 ± 10.93 L/kgVS, 82.01 ± 3.19 L/kgVS and 374.53 ± 9.27 L/kgVS biomethane from feedstock volatile solids, respectively. The biomethane yield from CO2 pretreated CoM, ChM and PM achieved was higher over untreated manure by +33.78%, +28.76% and +21.78%, respectively. The anaerobic digestion process of tested feedstocks was stable, and the pH of the substrate was kept steady at a pH of CoM 7.77 ± 0.02, PM 8.07 ± 0.02 and ChM 8.09 ± 0.02 during all the experiment. The oxidation-reduction potential after pretreatment was within the optimal range (−255 ± 39.0 to −391 ± 16.8 mV) for anaerobic digestion. This process also had a positive effect on the energy generated from the feedstock, with ChM showing the greatest increase, from 2.38 MJ/kg to 3.06 MJ/kg.

Chicken Manure Pretreatment for Enhancing Biogas and Methane Production

“…The environmental characterization data of inoculum, CM and SF are provided in Table 2. The TS of raw chicken manure in our study is comparable with data from the literature [11,59]. The lower content of dry matter (approx.…”

Aspen Plus(r) Process Simulation Model of the Biomass Ash-Based Treatment of Anaerobic Digestate for Production of Fertilizer and Upgradation of Biogas

“…storage, nutrient recovery and solid-liquid separation) should be recognized for the overall monitoring of the valorization technology [12,13,47]. Particularly, the CO2 injection is employed as manure pretreatment to increase the production of CH4 by promoting the bioconversion of the inorganic source of carbon directly through hydrogenotrophic methanogenesis, indirectly through homoacetogenic acetate formation followed by acetolactic methanogenesis or via electron transfer [47]. Therefore, the stabilization reactor was fed with the streams of biogas and anaerobic digestate as described in the Figure 1 and Figure 7.…”

Processing of Agricultural Residues with a High Concentration of Structural Carbohydrates into Biogas Using Selective Biological Products

“…Periodic loading studies were carried out in stands with vertical laboratory biogas digesters and their control and parameter measurement system. The methodology is presented by Žalys et al [38]. The laboratory bench consists of a 20 L vertical reactor, where extracted biogas accumulates in the upper part of the reactor and enters the volumetric biogas meter.…”