Thermophilic Solid-State Anaerobic Digestion of Corn Straw, Cattle Manure, and Vegetable Waste: Effect of Temperature, Total Solid Content, and C/N Ratio

Abstract

Thermophilic solid-state anaerobic digestion (SS-AD) of agricultural wastes, i.e., corn straw, cattle manure, and vegetable waste, was carried out in this study. The effects of temperature (40-60°C), initial solid content (ISC, 17.5-32.5%), and C/N ratio (15-32 : 1) on biogas production were evaluated using a Box-Behnken experimental design (BBD) combined with response surface methodology (RSM). The results showed that optimization of process parameters is important to promote the SS-AD performance. All the factors, including interactive terms (except the ISC), were significant in the quadratic model for biogas production with SS-AD. Among the three operation parameters, the C/N ratio had the largest effect on biogas production, followed by temperature, and a maximum biogas yield of 241.4 mL gVS-1 could be achieved at 47.3°C, ISC = 24.81 % , and C / N = 22.35 . After 20 d of SS-AD, the microbial community structure under different conditions was characterized by high-throughput sequencing, showing that Firmicutes, Bacteroidetes, Chloroflexi, Synergistetes, and Proteobacteria dominated the bacterial community, and that Firmicutes had a competitive advantage over Bacteroidetes at elevated temperatures. The biogas production values and relative abundance of OPB54 and Bacteroidia after 20 d of SS-AD can be fitted well using a quadratic model, implying that OPB54 and Bacteroidia play important roles in the methanogenic metabolism for agricultural waste thermophilic SS-AD.

Influence upon Biogas Production of the C/N Ratio and the Heavy Metal Incidence in the Manure Composition

“…Likewise, the quality of the compost is influenced by the C/N ratio [38] (p. 37). The recommended C/N ratio for anaerobic degradation is considered 20-30 [27,29], but some researchers think that lower C/N ratios (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) can produce good results [39] (p. 121-181). Since a ratio lower than 20 can inhibit the process, and a ratio greater than 30 leads to a decrease in the amount of biogas [3,40].…”

“…It is to be noted that the amount and number of heavy metals found in organic matter should not be ignored during the anaerobic digestion process either. The uncontrolled use of animal manure with a high content of heavy metals as raw material in the production of biogas can lead to the inhibition of the anaerobic digestion process [59] (p. [1][2][3][4][5][6][7][8][9][10][11][12][13][14], affecting the production of biogas and methane [60] (p. 266-272). While a high concentration of heavy metals inhibits the process of anaerobic digestion, a lower concentration can generate the growth of microorganisms [61] (p. 100099).…”

“…2 Another advantage of using the waste lies in the fact that it is widely distributed and ensures a low purchase price [10] (p. [1][2][3][4][5][6][7][8][9][10]. Following some studies, it was concluded that reactors fueled with pig manure can generate up to 6.597.520 MWh/year [11] (p. 4933).…”

Effect of Rice Straw on Methane Production Potential of Cow Manure

“…혐기성 소화를 위한 최적의 C/N비는 20~30이다 [28]. 우분을 단독으로 소화할 때보다 우분을 볏짚이나 옥수수짚과 같은 농업부산물과 병합소화 할 때 C/N 비가 향상되었고 [27], 이는 메탄 수율도 향상시켰다 [30] 3). 마찬가지로 최대 메탄 잠재량도 우분과 볏짚의 비가 1:2일 때 158.59 mL/g-VS로 가장 높았고, 이는 우분 단일소화보다 약 9% 증가한 양이다(Table 3).…”

Biological Processes for Pollution Control: Current Research and Emerging Technologies 2020

“…A. Sasi et al developed a Bacillus licheniformis mutant strain that could produce hyperchitinase, which has the excellent potential of recycling and processing chitin waste from crustaceans and shrimp, adding value to the crustacean industry [21]. L. Su et al applied thermophilic solid-state anaerobic digestion of agricultural wastes, i.e., corn straw, cattle manure, and vegetable waste, and investigated the effects of temperature, total solid content, and C/N ratio [22].…”