Anaerobic Digestion Technology for Methane Production Using Deer Manure Under Different Experimental Conditions

Abstract

Anaerobic digestion (AD) is an important technology for the treatment of livestock and poultry manure. The optimal experimental conditions were studied, with deer manure as a fermentation material and mushroom residue as an inoculum. At the same time, methane production was increased by adding zeolite and changing the magnetic field conditions. The results showed that a 6% solid content was the best condition for producing methane. The optimal conditions for methane production were obtained by adding 35 g of mushroom residue to 80 g of deer manure at 35 °C. The addition of organic wastewater (OW) improved methane production. The result of improving the methane production factor showed that adding zeolite during the reaction process could increase the methane production rate. When the amount of zeolite was over 8% total solids (TSes), methane production could improve, but the rate decreased. Setting a different magnetic field strength in the AD environment showed that when the distance between the magnetic field and the reactor was 50 mm and the magnetic field strength was 10–50 mT, the methane production increment and the content of methane in the mixed gases increased.

Study of the performance of biogas production by mixed fermentation of cow dung, deer manure, and mushroom fungus

“…B, 50°C F I G U R E 7 Cumulative biogas production at different temperatures F I G U R E 8 Cumulative biogas production of each proportion at different temperatures 47.0%-53.8%. 21 As shown in Figures 2 and 3, the biogas yield by AD of mixing deer manure and mushroom fungus was significantly lower than that of mixing deer manure, cow dung, and mushroom fungus, because the mixing of various materials can overcome the deficiency of unbalanced nutrient content in single material AD and provide a better environment for the growth of anaerobic microorganisms, thereby significantly improving biogas production. 42 The maximum potential of biogas production by AD of cow dung alone is significantly lower than that of mixing deer manure, cow dung, and mushroom fungus.…”

“…43 The results of AD of deer manure showed that the cumulative biogas production was less than 0.02 m 3 ·kg −1 and the CH 4 content was less than 50%. 21 As shown in Figures 2 and 3, the biogas yield by AD of mixing deer manure and mushroom fungus was significantly lower than that of mixing deer manure, cow dung, and mushroom fungus, because the mixing of various materials can overcome the deficiency of unbalanced nutrient content in single material AD and provide a better environment for the growth of anaerobic microorganisms, thereby significantly improving biogas production. 44 By comparing the U2, U3, and U4 experimental groups, it can be seen that the cumulative biogas production of U3 experimental group is the highest, and the CH 4 content is 60%-70% at 50°C.…”

“…23,24 The C/N ratio of deer manure ranged from 25.72 to 30.06, and the gas production effect is the best at about 25. 20,21 Therefore, the C/N ratio index will not have a significant impact on AD gas production.…”

“…Therefore, using livestock manure and mushroom fungus as a substrate for AD to produce biogas can not only adjust the C/N ratio of the substrate to the optimal state but also make up for the AD undernutrition of a single raw material, 16 promote the conversion of refractory components, such as the lignocellulose that is rich in straw, improve the stability of AD process, and enhance the synergistic effect of microorganisms, thereby making the fermentation substrate more balanced and improving the buffering capacity and stability of the fermentation system. 21 Therefore, the AD of livestock and poultry manure mixed with mushroom residue to produce biogas is relatively complex. 18 At the same time, mushroom fungus plays the role of adding biological bacteria in the AD process.…”

“…20 In addition, the addition of organic wastewater or limestone can increase AD CH 4 production of deer manure. 21 Therefore, the AD of livestock and poultry manure mixed with mushroom residue to produce biogas is relatively complex. In this experiment, cow dung, deer manure, and mushroom fungus were studied.…”