Improved biogas production and biodegradation of oilseed rape straw by using kitchen waste and duck droppings as co-substrates in two-phase anaerobic digestion

Abstract

Oilseed rape straw (ORS) is a kind of biorefractory waste widely existing in the rural area of China, which is highly suitable to mix with kitchen waste (KW) and duck droppings (DD) in two-phase anaerobic digestion (AD). This research introduced the importance of KW and DD addition to improve the biogas production and biodegradation of ORS. A set of comparative experiments were conducted on two-phase mono- and co-digestion with organic load of 60 g VS/L. The total methane yield (TMY) and the biodegradation of ORS of co-digestions were obviously improving, and the synergistic effect found in the two-phase co-digestions. The optimum mixing ratio of ORS, KW and DD was 50:40:10, and the corresponding TMY and VS degradation rate of ORS were 374.5 mL/g VS and 49.7%, respectively. Addition of KW and DD maintained the pH within the optimal range for the hydrolyzing-acidification, improved the phase separation and buffering capacity of AD system.

Thermophilic Biogas Upgrading via ex Situ Addition of H2 and CO2 Using Codigested Feedstocks of Cow Manure and the Organic Fraction of Solid Municipal Waste

“…The VS/TS ratio is an indicator of organic matter in these feedstocks. 37 In this study, high VS/TS ratios for CM and OFSMW of 0.87 and 0.73, respectively, imply that these substrates are easily biodegradable. This was confirmed by the high carbohydrate content (58.16 and 75.14 wt %) and low contents of protein (10.38 and 10.13 wt %) and fats (1.14 and 3.91 wt %).…”

“… 11 , 36 The resulting metabolites (H 2 and VFAs) are then used by the methanogenic species in the final stage of anaerobic digestion. 37 Hence, the formation of these intermediates is important because they affect the overall production of CH 4 . Furthermore, the C/N ratio for CM and OFSMW was 22.27 and 26.33, respectively.…”

“… 36 As opposed to monodigestion, the codigestion of organic feedstocks offers several benefits, such as balance of nutrients, optimum carbon-to-nitrogen ratio, and increased buffering capacity, which subsequently leads to enhanced biogas production. 37 Among the feedstocks, the organic fraction of solid municipal waste (OFSMW) is deemed a suitable feedstock for biogas upgrading processes because it is an abundant waste material, comprising of various food components (bread, apple, orange, carrot, cabbage, potato, etc. ), some of which are high in carbohydrates such as starch (bread, potato), whereas others are high in fructose (apple, orange, etc.).…”

Operational Parameters of Biogas Plants: A Review and Evaluation Study

“…The increase of the VFAs leads to a drop in the pH value. On the other hand, an increase in the alkalinity sources causes an increase in pH [33,62,[138][139][140][141][142][143].…”

Biogas Potential for Improved Sustainability in Guangzhou, China—A Study Focusing on Food Waste on Xiaoguwei Island

“…The methane content in the raw biogas produced accounted for 42.2 ± 1.8% (Table 5). The results of bio-methane yield for Guangzhou University FW represented around 50% of the theoretical values of 649 to 661 mL CH4/g VS of FW from China [49,74], and those values can be an indication that some pretreatment is necessary to improve the methane production. However, the results are comparable with other studies, in different conditions, especially without pretreatment, as shown in Table 6.…”