Air stripping of ammonia from pig slurry: characterisation and feasibility as a pre- or post-treatment to mesophilic anaerobic digestion

Abstract Background Increasing the efficiency of the biogas production process is possible by modifying the technological installations of the biogas plant. In this study, specific solutions based on a mathematical model that lead to favorable results were proposed. Three configurations were considered: classical anaerobic digestion (AD) and its two modifications, two-phase AD (TPAD) and autogenerative high-pressure digestion (AHPD). The model has been validated based on measurements from a biogas plant located in Poland. Afterward, the TPAD and AHPD concepts were numerically tested for the same volume and feeding conditions. Results The TPAD system increased the overall biogas production from 9.06 to 9.59%, depending on the feedstock composition, while the content of methane was slightly lower in the whole production chain. On the other hand, the AHPD provided the best purity of the produced fuel, in which a methane content value of 82.13% was reached. At the same time, the overpressure leads to a decrease of around 7.5% in the volumetric production efficiency. The study indicated that the dilution of maize silage with pig manure, instead of water, can have significant benefits in the selected configurations. The content of pig slurry strengthens the impact of the selected process modifications—in the first case, by increasing the production efficiency, and in the second, by improving the methane content in the biogas. Conclusions The proposed mathematical model of the AD process proved to be a valuable tool for the description and design of biogas plant. The analysis shows that the overall impact of the presented process modifications is mutually opposite. The feedstock composition has a moderate and unsteady impact on the production profile, in the tested modifications. The dilution with pig manure, instead of water, leads to a slightly better efficiency in the classical configuration. For the TPAD process, the trend is very similar, but the AHPD biogas plant indicates a reverse tendency. Overall, the recommendation from this article is to use the AHPD concept if the composition of the biogas is the most important. In the case in which the performance is the most important factor, it is favorable to use the TPAD configuration.

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Anaerobic digestion and post-treatment of swine wastewater using IC–SBR process with bypass of raw wastewater

Process Biochemistry ◽

10.1016/j.procbio.2005.10.022 ◽

2006 ◽

Vol 41 (4) ◽

pp. 965-969 ◽

Cited By ~ 73

Author(s):

Liang-Wei Deng ◽

Ping Zheng ◽

Zi-Ai Chen

Keyword(s):

Anaerobic Digestion ◽

Post Treatment ◽

Swine Wastewater ◽

Raw Wastewater

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Study of thermal hydrolysis as a pretreatment to mesophilic anaerobic digestion of pig slurry

Water Science & Technology ◽

10.2166/wst.2001.0193 ◽

2001 ◽

Vol 44 (4) ◽

pp. 109-116 ◽

Cited By ~ 62

Author(s):

A. Bonmatí ◽

X. Flotats ◽

L. Mateu ◽

E. Campos

Keyword(s):

Anaerobic Digestion ◽

Biogas Production ◽

Limiting Factor ◽

Pig Slurry ◽

Thermal Hydrolysis ◽

Organic Matter Degradation ◽

Thermal Pretreatment ◽

Digestion Process ◽

Degradation Tests ◽

Thermal Phenomena

Feasibility of anaerobic digestion of pig slurry is dependent, among other factors, on the biogas production rate, which is low compared with other organic wastes, and on the profitable uses of surplus thermal energy produced, a limiting factor in warm geographical areas. The objectives of this work are determining whether low temperature thermal pretreatment (<90°C) improves pig slurry anaerobic digestion, and determining whether organic matter degradation during the thermal pretreatment is due to thermal phenomena (80°C) or to enzymatic ones (60°C). The thermal degradation tests showed that hydrolysis occurring during the thermal pretreatment is due to thermal phenomena. The increase in soluble substances were significantly larger at 80°C than at 60°C (both during 3 h). Two types of slurry were used in the batch anaerobic digestion tests. The effect of thermal pretreatment differed with the type of slurry: it was positive with almost non-degraded slurries containing low NH4+-N concentration, and negative (inhibition of the anaerobic digestion process) when using degraded slurries with high NH4+-N content.

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EMISSIONS OF NH3, CH4 AND N2O DURING STORAGE AND AFTER APPLICATION OF UNTREATED AND ANAEROBICALLY DIGESTED SLURRY

Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca Agriculture ◽

10.15835/buasvmcn-agr:1425 ◽

1970 ◽

Vol 63 ◽

Author(s):

G. Moitzi ◽

B. Amon ◽

T. Amon ◽

V. Kryvoruchko ◽

C. Wagner-Alt ◽

...

Keyword(s):

Renewable Energy ◽

Anaerobic Digestion ◽

Pig Slurry ◽

Gaseous Emissions ◽

Ch4 Emissions ◽

Dynamic Chamber ◽

Fermentation Tank ◽

Application Techniques ◽

Ch4 And N2o ◽

Anaerobically Digested Slurry

The paper presents the investigations results of the effect of anaerobic digestion on emissions of NH3, N2O and CH4 during storage and after application of slurry. Dairy cattle and pig slurry was stored in concrete tanks (12 m3) over a period of 100 days. Gaseous emissions were collected continuously by a large open dynamic chamber. Gas concentrations (NH3, N2O and CH4) were analysed by high resolution FTIR-spectrometry. After storage, the slurries were surface applied on permanent grassland. NH3 emissions were followed for two days by a large open-dynamic-chamber. N2O and CH4 emissions were quantified with closed chambers until day 20 after application. 65 – 95 % of net total NH3 emissions were lost after slurry application. NH3 abatement will therefore be effective, if low emission application techniques are used. This is especially important when anaerobically digested slurry is applied. More than 90 % of net total CH4 emissions from untreated slurry were lost during slurry storage. Anaerobically digested slurry still emitted methane during storage. These emissions can be totally avoided if the secondary fermentation tank and the slurry store are connected with the gas bearing system of the biogas plant. Then, CH4 produced in these tanks is collected and used as renewable energy source. In conclusion it can be assumed that biogas plants will play a major role in the reduction of greenhouse gas emissions as they generate renewable energy and reduce CH4 emissions during manure storage. Furthermore, anaerobic digestion improves the fertiliser value of animal manures.

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