Claudia Maurer
University of Stuttgart, Germany
Title: Demand-oriented co-digestion of separated biowaste press filtrate to optimize energy management at wastewater treatment plants
Biography
Biography: Claudia Maurer
Abstract
The high-quality energetic utilization of biomass, in particular of biogenic residues for the efficient production of bioenergy, plays an important role in achieving the European and national energy and climate policy objectives. The integration of fluctuating power generation from wind energy and photovoltaics plays an important role in a targeted energy supply with a high share of renewable energies. In addition to a sustainable expansion of the use of renewable energies and increased resource efficiency, targeted demand-oriented energy recovery from biogenic residues can make an important contribution to the system integration of renewable energies and to balance fluctuating energy generation. Due to the flexible and adaptable operation of biogas-fueled Combined Heat and Power (CHP) units, electricity can be generated when other renewable energy sources are not available. Power generation is decentralized to existing plants, supporting the power supply and making grid operations more secure. High investment costs, lengthy permitting processes, and resistance from the public, among other factors, pose significant challenges to the rapid expansion of biowaste anaerobic digestion plants. Furthermore, existing composting plants cannot always be expanded with digestion stages in the context of cascade utilization, as factors such as plant size and biowaste quality play a decisive role. Against this background, the alternative recycling paths for biowaste to generate energy is increasing. Liquid emissions from composting plant have been identified as a known problem in composting plant. Hereby, process water, condensation water, wastewater from plant cleaning were not accurately distinguished from each other in practice due to mostly common discharge and collection systems (Amlinger, et al., 2005). The amount of leachate (process water and other wastewater) is between 10-60 L/t waste and the amount of condensed water is between 5-300 L/t waste, depending on the process. (Hupe, et al., 1998)At the same time, there are more than 1,200 wastewater treatment plants (WWTP) in Germany that currently produce digester gas (Blesl, et al., 2010), but only cover about 50% of their own energy demand. Due to the specific energy density and limited dewaterability of sludge from wastewater treatment, it is not possible to realize the maximum technical space load in sludge digestion plants (ABWASSERTECHNISCHE VEREINIGUNG, 1996). Thus, co-digestion of sewage sludge with biowaste is a reasonable, efficient and cost-effective alternative.