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Plochl M.,BioenergieBeratungBornim GmbH | Heiermann M.,Leibniz Institute for Agricultural Engineering | Rodemann B.,Julius Kuhn Institute | Bandte M.,Humboldt University of Berlin | Buttner C.,Humboldt University of Berlin
Journal of Environmental Management | Year: 2014

Knowledge of fate and behavior of plant pathogens in the biogas production chain is limited and hampers the estimation and evaluation of the potential phytosanitary risk if digestate is spread on arable land as a fertilizer. Therefore, simulation is an appropriate tool to demonstrate the effects which influence the steady state of pathogen infected plant material in both digesters and digestate. Simple approaches of kinetics of inactivation and mass balances of infected material were carried out considering single-step as well as two-step digestion. The simulation revealed a very fast to fast reduction of infected material after a singular feeding, reaching a cutback to less than 1% of input within 4 days even for D90-values of 68h. Steady state mass balances below input rate could be calculated with D90-values of less than 2h at a continuous hourly feeding. At higher D90-values steady state mass balances exceed the input rate but are still clearly below the sum of input mass. Dilution further decreases mass balances to values 10-5 to 10-6Mgm-3 for first-step digestion and 10-8 to 10-9 for second-step. © 2013 Elsevier Ltd.

Bandte M.,Humboldt University of Berlin | Schleusner Y.,Humboldt University of Berlin | Heiermann M.,Leibniz Institute for Agricultural Engineering | Plochl M.,BioenergieBeratungBornim GmbH | Buttner C.,Humboldt University of Berlin
Bioenergy Research | Year: 2013

Feedstock of anaerobic digestion infected with phytopathogens could enhance the risk of spreading those pathogens to uninfested field through digestate. The viability of Fusarium proliferatum, Fusarium verticillioides, Sclerotinia sclerotiorum, and Rhizoctonia solani was investigated in anaerobic digestion experiments using infected plant material of sorghum (Sorghum bicolor), sugar beet (Beta vulgaris subsp. vulgaris var. altissima), and potato (Solanum tuberosum L.). Results from lab-scale reactors were confirmed in full-scale biogas plants. Anaerobic digestion under mesophilic conditions (35-42 °C) reduced most of the phytopathogens of feedstocks investigated. Thus, S. sclerotiorum and R. solani lost their viability within 6 h. In the case of sorghum, however, Fusarium spp. infected feedstock required a maximum of 138 h for sanitation. Thus, the risk of spreading plant pathogens with the digestate can only be decreased when the feedstock would undergo an additional treatment before anaerobic digestion or of the resulting digestate. © 2013 Springer Science+Business Media New York.

Schattauer A.,Leibniz Institute for Agricultural Engineering | Abdoun E.,Johann Heinrich Von Thunen Institute | Weiland P.,Johann Heinrich Von Thunen Institute | Plochl M.,BioenergieBeratungBornim GmbH | Heiermann M.,Leibniz Institute for Agricultural Engineering
Biosystems Engineering | Year: 2011

Ten biogas plants across Europe were investigated for the concentrations of trace elements in their digestates. Many of these trace elements are important micro nutrients and act as microbial agents responsible for the anaerobic digestion of organic material. Great variations in concentrations from biogas plant to biogas plant were found covering a range of 1-2 orders of magnitude. No deficit of nutrients was detected in any of the biogas plants tested, but those plants with high inputs of energy crops and manure had lower values. Also biogas plants feeding high amounts of glycerol in addition to their agricultural feedstock generally showed low concentrations of micro nutrients. The highest concentrations of nutrients were detected at biogas plants fed by bleaching earth. Biogas plants fed with wastes like blood, kitchen and food waste also revealed higher concentrations of micro nutrients. © 2010 IAgrE.

Quinones T.S.,Leibniz Institute for Agricultural Engineering | Plochl M.,BioenergieBeratungBornim GmbH | Budde J.,Leibniz Institute for Agricultural Engineering | Heiermann M.,Leibniz Institute for Agricultural Engineering
Energy and Fuels | Year: 2011

Continuous bio-methanization of different feedstocks (rye grain silage, maize silage, feed residue (mix of silages), solid cattle manure, and grass silage) was investigated in a long-term laboratory-scale experiment with and without enzyme application. Ten-liter reactors were operated simultaneously in a two-step digestion mode for the continuous production of biogas from different feedstocks over 354 days. One set of reactors was operated as main digester, while the second set was used for the second step. The daily input of feedstock was increased from an organic loading rate of 1 to 3 kg ODM·m -3·d-1. All digesters were run under stable conditions, indicated by the ratio of volatile fatty acids to the total inorganic carbon, ranging around 0.2 in the first step and 0.15 in the second step. The hydraulic retention time was maintained between 80 and 90 days during the experiment. The application of enzymes was able to enhance biogas production by 10-15% and increase the methane content of biogas by an increment of 5-10% for the investigated materials except for feed residue. The increase in biogas yields was also reflected in the change in the ratios of heating values of the methane produced to the dry materials. These ratios ranged between 0.43 and 0.71 for the untreated feedstock, increasing to 0.44-0.88 after enzyme application. © 2011 American Chemical Society.

Froschle B.,Bavarian State Research Center for Agriculture | Heiermann M.,Leibniz Institute for Agricultural Engineering | Lebuhn M.,Bavarian State Research Center for Agriculture | Messelhausse U.,Bavarian Health and Food Safety Authority | Plochl M.,BioenergieBeratungBornim GmbH
Advances in Biochemical Engineering/Biotechnology | Year: 2015

The increasing number of agricultural biogas plants and higher amounts of digestate spread on agricultural land arouse a considerable interest in the hygiene situation of digested products. This chapter reviews the current knowledge on sanitation during anaerobic digestion and the hygienic status of digestate concerning a multitude of pathogens potentially compromising the health of humans, animals and plants. Physical, chemical and biological parameters influencing the efficiency of sanitation in anaerobic digestion are considered. The degree of germ reduction depends particularly on the resistance of the pathogen of concern, the processing conditions, the feedstock composition and the diligence of the operation management. Most scientific studies facing sanitation in biogas plants have provided data ascertaining reduction of pathogens by the biogas process. Some pathogens, however, are able to persist virtually unaffected due to the ability to build resistant permanent forms. As compared to the feedstock, the sanitary status of the digestate is thus improved or in the worst case, the sanitary quality remains almost unchanged. According to this, the spreading of digestate on agricultural area in accordance to current rules and best practice recommendations is considered to impose no additional risk for the health of humans, animals and plants. © Springer International Publishing Switzerland 2015.

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