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Mass and Energy Balances of Dry Thermophilic Anaerobic Digestion Treating Swine Manure Mixed with Rice Straw.

Zhou S, Zhang J, Zou G, Riya S, Hosomi M - Biotechnol Res Int (2015)

Bottom Line: The results suggest that methane yield using the proposed DT-AD system increased with a higher C/N ratio and shorter SRT.However, the biogas yield increased when the SRT was shortened to 40 days, and the generated energy was greater than consumed energy when C/N ratio was 20 : 1 and 30 : 1.The results suggest that with the correct optimization of C/N ratio and SRT, the proposed DT-AD system, followed by using digestate for forage rice production, can attain energy self-sufficiency.

View Article: PubMed Central - PubMed

Affiliation: Eco-Environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China.

ABSTRACT
To evaluate the feasibility of swine manure treatment by a proposed Dry Thermophilic Anaerobic Digestion (DT-AD) system, we evaluated the methane yield of swine manure treated using a DT-AD method with rice straw under different C/N ratios and solid retention time (SRT) and calculated the mass and energy balances when the DT-AD system is used for swine manure treatment from a model farm with 1000 pigs and the digested residue is used for forage rice production. A traditional swine manure treatment Oxidation Ditch system was used as the study control. The results suggest that methane yield using the proposed DT-AD system increased with a higher C/N ratio and shorter SRT. Correspondently, for the DT-AD system running with SRT of 80 days, the net energy yields for all treatments were negative, due to low biogas production and high heat loss of digestion tank. However, the biogas yield increased when the SRT was shortened to 40 days, and the generated energy was greater than consumed energy when C/N ratio was 20 : 1 and 30 : 1. The results suggest that with the correct optimization of C/N ratio and SRT, the proposed DT-AD system, followed by using digestate for forage rice production, can attain energy self-sufficiency.

No MeSH data available.


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Comparison of energy balances between traditional and proposed systems under 80 and 40 days of SRTs.
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fig5: Comparison of energy balances between traditional and proposed systems under 80 and 40 days of SRTs.

Mentions: Because the same scale of pig farms was used for the energy balances calculations comparing the traditional and proposed systems, the fuel and power consumed in these farms are both the same with the SRTs of 80 and 40 days (Figure 5). However, in the proposed system, 10% of the feed is replaced by grain that was fertilized using digestate, so the energy was deduced from the total consumption energy. Among the items contributing to energy consumption, heat loss from digestion tank in the DT-AD process was the largest element. The heat loss increased significantly with C/N ratio of feedstock increased at the same SRT because higher C/N ratio of feedstock made the tank bigger. Similarly, electrical requirement of DT-AD plant also increased with bigger tank. In addition, to achieve the higher C/N ratio, larger area of paddy field was needed for rice production, which resulted in the higher electrical demand for rice production for higher C/N ratio process. Furthermore, compared with the SRT of 80 days, energy consumption for the heat loss decreased significantly due to the smaller tank when the SRT was shortened from 80 days to 40 days.


Mass and Energy Balances of Dry Thermophilic Anaerobic Digestion Treating Swine Manure Mixed with Rice Straw.

Zhou S, Zhang J, Zou G, Riya S, Hosomi M - Biotechnol Res Int (2015)

Comparison of energy balances between traditional and proposed systems under 80 and 40 days of SRTs.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4644824&req=5

fig5: Comparison of energy balances between traditional and proposed systems under 80 and 40 days of SRTs.
Mentions: Because the same scale of pig farms was used for the energy balances calculations comparing the traditional and proposed systems, the fuel and power consumed in these farms are both the same with the SRTs of 80 and 40 days (Figure 5). However, in the proposed system, 10% of the feed is replaced by grain that was fertilized using digestate, so the energy was deduced from the total consumption energy. Among the items contributing to energy consumption, heat loss from digestion tank in the DT-AD process was the largest element. The heat loss increased significantly with C/N ratio of feedstock increased at the same SRT because higher C/N ratio of feedstock made the tank bigger. Similarly, electrical requirement of DT-AD plant also increased with bigger tank. In addition, to achieve the higher C/N ratio, larger area of paddy field was needed for rice production, which resulted in the higher electrical demand for rice production for higher C/N ratio process. Furthermore, compared with the SRT of 80 days, energy consumption for the heat loss decreased significantly due to the smaller tank when the SRT was shortened from 80 days to 40 days.

Bottom Line: The results suggest that methane yield using the proposed DT-AD system increased with a higher C/N ratio and shorter SRT.However, the biogas yield increased when the SRT was shortened to 40 days, and the generated energy was greater than consumed energy when C/N ratio was 20 : 1 and 30 : 1.The results suggest that with the correct optimization of C/N ratio and SRT, the proposed DT-AD system, followed by using digestate for forage rice production, can attain energy self-sufficiency.

View Article: PubMed Central - PubMed

Affiliation: Eco-Environmental Protection Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai 201403, China.

ABSTRACT
To evaluate the feasibility of swine manure treatment by a proposed Dry Thermophilic Anaerobic Digestion (DT-AD) system, we evaluated the methane yield of swine manure treated using a DT-AD method with rice straw under different C/N ratios and solid retention time (SRT) and calculated the mass and energy balances when the DT-AD system is used for swine manure treatment from a model farm with 1000 pigs and the digested residue is used for forage rice production. A traditional swine manure treatment Oxidation Ditch system was used as the study control. The results suggest that methane yield using the proposed DT-AD system increased with a higher C/N ratio and shorter SRT. Correspondently, for the DT-AD system running with SRT of 80 days, the net energy yields for all treatments were negative, due to low biogas production and high heat loss of digestion tank. However, the biogas yield increased when the SRT was shortened to 40 days, and the generated energy was greater than consumed energy when C/N ratio was 20 : 1 and 30 : 1. The results suggest that with the correct optimization of C/N ratio and SRT, the proposed DT-AD system, followed by using digestate for forage rice production, can attain energy self-sufficiency.

No MeSH data available.


Related in: MedlinePlus