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In this paper, the anaerobic treatment of a high organic-strength wastewater-type feedstock, referred as the liquid fraction of pressed municipal solid waste (LPW) was studied for energy recovery and organic matter removal. The processes investigated were (i) dark fermentation to produce biohydrogen, (ii) anaerobic digestion for biogas formation and (iii) microbial fuel cells for electrical energy generation. To find a feasible alternative for LPW treatment (meeting the two-fold aims given above), various one- as well as multi-stage processes were tested. The applications were evaluated based on their (i) COD removal efficiencies and (ii) specific energy gain. As a result, considering the former aspect, the single-stage processes could be ranked as: microbial fuel cell (92.4%)> anaerobic digestion (50.2%)> hydrogen fermentation (8.8%). From the latter standpoint, an order of hydrogen fermentation (2277 J g COD d)> anaerobic digestion (205 J g COD d)> microbial fuel cell (0.43 J g COD d) was attained. The assessment showed that combined, multi-step treatment was necessary to simultaneously achieve efficient organic matter removal and energy recovery from LPW. Therefore, a three-stage system (hydrogen fermentation-biomethanation-bioelectrochemical cell in sequence) was suggested. The different approaches were characterized via the estimation of COD balance, as well.

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Consumption and related waste production is an integral part of our daily lives. The waste generation worldwide depends on the economic strength of the given region/country, and it increases from year to year. More and more attention is drawn to the re-use, recycling, reutilization of the waste which are driven mainly by environmental concerns and economic interests. Regional waste management systems have been established in Hungary with the support of EU funds, which process the waste according to European standards. In addition to this in January 2013 new Waste Management Act was introduced in Hungary, with the main objectives to increase the rate of recycling and to significantly decrease the proportion and amount of waste taken for final disposal at landfill sites. By the development of waste handling techniques and the harmonisation of the legal environment and instruments to the European standards the Hungarian waste management has achieved a restructuring phase, where the core issues of the sustainable waste management are considered and implemented.

Facing the new challenge in Hungary to meet the EU legislation diverting waste stream from the landfill is inevitable. Low-waste design products and reuse are preferred, although recycling and recovery are also necessary to reach the ambitious goal of waste management. Besides finding new methods for recycling materials from Mixed Municipal Solid Waste (MSW), it is beneficial to make use of an appropriate fraction as an energy source for industry and for power generation. To reach the end-of-waste status of MSW, special standard requirements must be met by special processes. Standardisation processes also assist customers to develop their technology to be prepared for the new type of fuel transformed from waste, by setting up limits and giving specifications. In this way, Refuse Derived Fuel (RDF) or Solid Recovered Fuel (SRF) can be introduced to various technologies as a replacement for non-renewable fuel, especially for the cement industry and power plants.