Biological Treatment Articles

Recovery of Ammonia from Liquid Digestate for NOx Removal
© Montanuniversität Leoben (11/2012)
Liquid digestate from biogas plants contains significant amounts of ammonia, which has to be removed in order to close in-plant water circulation without the risk of inhibiting the anaerobic digestion processes. Technologies like air-stripping turn out to be very cost-intensive and therefore not economically feasible for digestate processing.

Experience with Continuous Dry Digestion Using the Example of the Digestion Plant in Hoppstädten (from the view of the supplier and the operator)
© Arbeitsgemeinschaft Stoffspezifische Abfallbehandlung ASA e.V. (9/2012)
STRABAG Umweltanlagen GmbH improved the concept of the digester environment practice-oriented by planning, construction, commissioning and operational support of many digestion plants with different input materials. The continuous dry digestion is explained in detail with the help of the plant in Hoppstädten. The experiences made are summarized from the view of the supplier and the operator.

Integrated Development Concerning a Resource-Efficient Operation of MBT-Processes with RTO-Technology
© Arbeitsgemeinschaft Stoffspezifische Abfallbehandlung ASA e.V. (9/2012)
Due to the installation of regenerative thermal oxidizers (RTO) for exhaust air purification in the field of mechanical-biological waste treatment plants three general issues emerged:
• corrosion, preferential in the crude gas feeding systems and in the discharge systems of clean gas,
• deposits at the ceramic heat storage units,
• unanticipated high consumption of additional fuel.
The paper refers to the objectives of a recently started research project dealing with these issues in an integrated approach, which particularly includes the interaction between the MBT-process itself and the exhaust air purification system.

Material stream specific conversion of disposal plants Example of a further development of the MBT Association of the ZAK
© Arbeitsgemeinschaft Stoffspezifische Abfallbehandlung ASA e.V. (9/2012)
The changing frame conditions in waste management caused the ZAK as operator of one of the first plants with mechanical biological residual waste treatment - grown from single units - to look for solutions dealing with increasing specific costs at a simultaneous preservation of values and the fulfilment of social and ecological standards. An alternative to a possible shutdown or an unchanged continuance of the status quo appeared to be a good chance for an alternative use of the network of plants into biological biowaste treatment plant in the frame of an inter-communal cooperation project with cluster formation in waste management. During the realisation existing plants were for the second time subject to a conversion of use type and hereby the waste management centre sharpens its profile of a competence centre for biomass.

Liquid Fuel from MSW
© NMC Ltd. (10/2011)
Europe has become more dependent on external energy sources in the last decades. This dependence is more problematic since most of the fossil energy sources are in non-allied countries; moreover there have been conflicts in those countries for a long time now.

MBT technologies in "starting" and "advanced" countries: What’s different?
© NMC Ltd. (10/2011)
The presentation will commence with a critical discussion of the term „stage of development“ of a country in respect to solid waste management. Based on a survey at the relevant national authorities of all (at time of the survey 47) member states of the Council of Europe criteria other than the reduction of biodegradable wastes going to landfill – which the EU “Landfill Directive” 1999/31 has turned into a standard criterion in Europe – are presented that help define the stage of development of country from a waste perspective, such as presence of a National Waste Management Plan, or the regular collection and reporting of waste quantities to a national authority for planning purposes.

Development of natural gas qualities in Europe
© Oldenbourg Industrieverlag (10/2011)
Natural gas qualities in Europe will become increasingly diverse and combustion characteristics (Wobbe index, methane number) will vary over wider ranges. The article presents the gas qualities to be expected over the medium term and analyses and discusses their effects on future gas utilisation. Aside from rich (high-calorifi c) LNG qualities, future natural gas and biomethane qualities are not expected to cause problems in gas utilisation in most European countries. With certain restrictions this also applies where up to 10 % of hydrogen produced from renewable surplus electricity is admixed except for three important applications: tanks for compressed natural gas used as a motor fuel, gas turbines with premixed burners and underground porous rock storage facilities; here further R&D input is still required. Biomethane produced from contaminated feedstock may carry undesirable trace substances. Particularly careful treatment and quality control are then necessary. Hydrogen or methane produced from renewable surplus electricity will have a high purity level and, like biomethane, will contribute to further reducing CO2 emissions. This will make natural gas an even more climate-protecting fuel compared with other fossil fuels.

Energy Efficient Aeration in a Single Low Pressure Hollow Sheet Membrane Filtration Module
© Oldenbourg Industrieverlag (9/2011)
The main drawback of membrane bioreactors (MBR) systems is the fouling of the membrane, which is decreased and/or prevented through gas sparging. However, this practice is based on rules of thumb or trialand- error approaches which are tedious, very time-consuming, do not necessarily provide optimal fouling control and they are not energy effi cient. Therefore, dedicated experiments are needed to fully understand the hydrodynamics of it. A hollow sheet (HS) MBR was studied. Experimental velocity measurements were made using micro-propellers and compared to CFD results. A good agreement between experimental measurements and CFD results was found (error less than 11 % on average). Due to the fact that the shear stress measurements were not performed, they were extracted from the CFD simulations, as the CFD simulation was validated against velocity data. The results of shear stress shows that the shear is homogeneously distributes over the predominant part of the membrane surface.

Biopolymere - Materialtypen, Marktsituation, Anwendungen und Zukunftsperspektiven
© TU Dresden, Institut für Abfallwirtschaft und Altlasten (9/2011)
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The impact of increased differientiate collection on existing MBT plant and possible upgrading scenarios: the experiences of a central Italy plant
© Wasteconsult international (5/2011)
The management and the production of MSW has been interested by many changes, during the last twenty years, mainly related to the new policy strategies in recycling and recovering. A large part of the Italian existing MBT facilities operates since the 1990, designed when the waste quality and quantity were quite different from the current one.