Animal and Technology Research Center

Segorbe, Spain

Animal and Technology Research Center

Segorbe, Spain

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Moset V.,Animal and Technology Research Center | Moset V.,Research Center y Tecnologia Animal | Cambra-Lopez M.,Polytechnic University of Valencia | Moller H.B.,University of Aarhus
Transactions of the ASABE | Year: 2012

Slurry acidification with sulfuric acid is a commonly used measure to reduce ammonia emissions from animal waste in Denmark. However, high sulfate content is an inhibiting factor in anaerobic digestion. The objective of this study was to investigate the sulfate concentration thresholds for inhibition of thermophilic anaerobic digestion of animal slurry. We conducted a batch assay for 114 days using two types of slurry (pig and cattle) and ten different sulfate concentrations per type of slurry (0 to 5000 mg SO4 2- L-1). Added sulfate concentrations higher than 2500 mg SO4 2- L-1 in pig slurry and higher than 2000 mg SO4 2- L-1 in cattle slurry caused reductions of more than 40% in methane production and accumulations of volatile fatty acids throughout the study. The biogas produced contained large amounts of hydrogen sulfide (3.2% in pig slurry and 1.9% in cattle slurry) with concentrations peaking in the first 20 days and subsequently decreasing. Waste properties can affect the inhibitory threshold of the sulfate in anaerobic digestion. Our results provide specific sulfate inhibition thresholds for pig and cattle slurries, which differ from other sulfate-rich wastewaters. © 2012 American Society of Agricultural and Biological Engineers.


Moset V.,Animal and Technology Research Center | Cerisuelo A.,Animal and Technology Research Center | Sutaryo S.,University of Aarhus | Moller H.B.,University of Aarhus
Water Research | Year: 2012

The effect of incorporating different ratios of acidified pig slurry on methane yield was evaluated in two scales of anaerobic digesters: Thermophilic (50 °C) pilot scale digester (120 l), operating with an average hydraulic retention time of 20 days and thermophilic (52 °C) full-scale digesters (10 and 30 m3), operating with an average hydraulic retention time of 30 days. In the lab-scale digester, different inclusion levels of acidified slurry (0-60%) were tested each 15 days, to determine the maximum ratio of acidified to non-acidified slurry causing inhibition and to find process state indicators helping to prevent process failure. In the full-scale digesters, the level of inclusion of the acidified slurry was chosen from the ratio causing methane inhibition in the pilot scale experiment and was carried on in a long-term process of 100 days. The optimal inclusion level of acidified pig slurry in anaerobic co-digestion with conventional slurry was 10%, which promoted anaerobic methane yield by nearly 20%. Higher inclusion levels caused methane inhibition and volatile fatty acids accumulations in both experiments. In order to prevent process failure, the most important traits to monitor in the anaerobic digestion of acidified pig slurry were found to be: sulfate content of the slurry, alkalinity parameters (especially partial alkalinity and the ratio of alkalinity) and total volatile fatty acids (especially acetic and butyric acids). © 2012 Elsevier Ltd.


Moset V.,Animal and Technology Research Center | Moset V.,Polytechnic University of Valencia | Cambra-Lopez M.,Polytechnic University of Valencia | Estelles F.,Polytechnic University of Valencia | And 2 more authors.
Biosystems Engineering | Year: 2012

Chemical composition and gas emissions from two types of pig slurry were evaluated: the liquid fraction of mechanical solid-liquid separated slurry (SS), and raw slurry (RS). The slurry was obtained at the end of a pig fattening period and was stored in 100 l vessels for 15 weeks simulating outdoor storage conditions. During this period, representative samples were taken and analysed for chemical composition. Methane, carbon dioxide, ammonia, water vapour and nitrous oxide emissions were recorded. The results showed a high biological degradation during the first five weeks of outdoor storage in SS and RS slurries, as a result of an increase in the dissolved chemical oxygen demand, volatile fatty acids and carbon dioxide emission observed in this period. However, methanogenic activity was not evident until week 6 of storage in both slurries, confirmed by the volatile fatty acids accumulation and the negligible methane emissions during the first five weeks of storage. The results showed that differences in the initial slurry organic matter content, influenced by solid separation process affects the evolution pattern of the organic matter degradation. Storage time can considerably affect the biodegradability of organic matter in pig slurry. © 2011 IAgrE.


PubMed | Animal and Technology Research Center
Type: Comparative Study | Journal: Water research | Year: 2012

The effect of incorporating different ratios of acidified pig slurry on methane yield was evaluated in two scales of anaerobic digesters: Thermophilic (50 C) pilot scale digester (120 l), operating with an average hydraulic retention time of 20 days and thermophilic (52 C) full-scale digesters (10 and 30 m(3)), operating with an average hydraulic retention time of 30 days. In the lab-scale digester, different inclusion levels of acidified slurry (0-60%) were tested each 15 days, to determine the maximum ratio of acidified to non-acidified slurry causing inhibition and to find process state indicators helping to prevent process failure. In the full-scale digesters, the level of inclusion of the acidified slurry was chosen from the ratio causing methane inhibition in the pilot scale experiment and was carried on in a long-term process of 100 days. The optimal inclusion level of acidified pig slurry in anaerobic co-digestion with conventional slurry was 10%, which promoted anaerobic methane yield by nearly 20%. Higher inclusion levels caused methane inhibition and volatile fatty acids accumulations in both experiments. In order to prevent process failure, the most important traits to monitor in the anaerobic digestion of acidified pig slurry were found to be: sulfate content of the slurry, alkalinity parameters (especially partial alkalinity and the ratio of alkalinity) and total volatile fatty acids (especially acetic and butyric acids).


Ferrer P.,Polytechnic University of Valencia | Cambra-Lopez M.,Polytechnic University of Valencia | Cerisuelo A.,Animal and Technology Research Center | Penaranda D.S.,Polytechnic University of Valencia | And 2 more authors.
Waste Management | Year: 2014

Anaerobic co-digestion of pig slurry with four agricultural substrates (tomato, pepper, persimmon and peach) was investigated. Each agricultural substrate was tested in co-digestion with pig slurry at four inclusion levels: 0%, 15%, 30% and 50%. Inclusion levels consisted in the replacement of the volatile solids (VS) from the pig slurry with the VS from the agricultural substrate. The effect of substrate type and inclusion level on the biochemical methane potential (BMP) was evaluated in a batch assay performed at 35. °C for 100. days. Agricultural substrate's chemical composition was also analyzed and related with BMP. Additionally, Bacteria and Archaea domains together with the four main methanogenic archaeal orders were quantified using quantitative real-time TaqMan polymerase chain reaction (qPCR) at the end of the experiment to determine the influence of agricultural substrate on sludge's microbial composition. Results showed that vegetable substrates (pepper and tomato) had higher lipid and protein content and lower carbohydrates than fruit substrates (persimmon and peach). Among substrates, vegetable substrates showed higher BMP than fruit substrates. Higher BMP values were obtained with increasing addition of agricultural substrate. The replacement of 50% of VS from pig slurry by tomato and pepper increased BMP in 41% and 44%, respectively compared with pig slurry only. Lower increments in BMP were achieved with lower inclusion levels. Results from qPCR showed that total bacteria and total archaea gene concentrations were similar in all combinations tested. Methanomicrobiales gene concentrations dominated over the rest of individual archaeal orders. © 2013 Elsevier Ltd.

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