Anaerobic Digestion of Wastewater for Renewable Energy Production

Dear Colleagues,

Progressive climate change and depletion of traditional fuels lead to the search for new solutions in the field of renewable energy production. The anaerobic digestion is recognized as one of the most promising technologies that indicate several environmental benefits, the most important ones include: reduction of greenhouse gas emissions, management of organic waste, thus reducing the need for landfill disposal, production of nutrient-rich digestate that might be used as a fertilizer. However, the most important is generation of high-quality renewable fuel, e.g., biogas. It is known as a versatile source of energy that finds several applications, such as production of electricity and heat, as vehicle fuel, and in several different types of industry.

However, despite numerous studies in the field of AD, there is still a need to improve the process performance, and hence increase biogas production. The main aim of this Special Issue of the journal Energies is to publish original papers, as well as extensive reviews related to recent and novel developments in the anaerobic digestion process, including application of pre-treatment methods, implementation of anaerobic co-digestion and bioaugmentation strategies, trace elements supplementation, and utilisation of various bioreactors configurations. Moreover, the studies in the field of purification and utilisation of biogas, and also regarding improving energy efficiency of AD are in demand.

Dr. Aleksandra Szaja
Guest Editor

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• pre-treatment methods
• industrial wastewater
• organic waste
• production, purification and utilisation of biogas
• anaerobic co-digestion
• bioaugmentation
• trace elements supplementation
• biochar application
• lignocellulosic biomass
• improving energy efficiency
• circular economy
• life cycle assessment
• nutrient recovery and digestate management
• modelling and process optimization
• digesters design

Title: Pre-treatment of coffee grounds using hydrodynamic cavitation
Authors: Aleksandra Szaja; Magdalena Lebiocka; Agnieszka Montusiewicz
Affiliation: Lublin University of Technology, Faculty of Environmental Engineering, Nadbystrzycka 40B, 20-618 Lublin, Poland

Title: Application of recycled filling to improve methane fermentation of confectionery wastewater in a vertical anaerobic labyrinth flow bioreactor.
Authors: Marcin Dębowski; Marcin Zieliński; Joanna Kazimierowicz
Affiliation: 1 Department of Environment Engineering, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, Str. Oczapowskiego 5, 10-719 Olsztyn, Poland 2 Department of Water Supply and Sewage Systems, Faculty of Civil Engineering and Environmental Sciences, Bialystok University of Technology, 15-351 Bialystok, Poland
Abstract: Confectionery wastewater is susceptible to biodegradation under anaerobic conditions. Previous studies by the authors have shown that the use of OLR at a level of 5 to 6 kg COD/m3·day allowed the production of biogas from 0.29±0.02 to 0.32±0.03 L/g COD removed. The FOS/TAC ratio was below 0.4 and the pH in the reactor chamber was 7.04±0.07–7.15±0.04, indicating the stability of the reactor. According to the authors, it is possible to further optimise the process by using an innovative filling that enables higher technological effects of the process. These relate to increasing the OLR, intensifying the biodegradation of organic compounds, increasing the quantity and improving the quality of the biogas produced, increasing the efficiency of phosphorus compound removal and reducing the amount of anaerobic sludge suspensions in the wastewater. The aim of the research is to determine the effects of recycled filling to improve methane fermentation and intensifying the treatment of confectionery wastewater in a vertical anaerobic labyrinth flow bioreactor.

Title: Comparison of the microbial fuel cell MFC and the photosynthetic microbial fuel cell pMFC in terms of the efficiency of anaerobic wastewater treatment and electricity production.
Authors: Paulina Rusanowska; Adam Starowicz; Magda Dudek; Marcin Dębowski; Łukasz Barczak; Marcin Zieliński
Affiliation: Department of Environmental Engineering, Faculty of Geoengineering, University of Warmia and Mazury in Olsztyn, 10-720 Olsztyn, Poland
Abstract: Microbial fuel cells are solutions that allow for simultaneous wastewater treatment and direct production of electricity. Using the potential differences of two chambers divided by a semi-permeable layer, in which anaerobic and aerobic conditions are maintained. A modification of the typical MFC, where aerobic conditions are obtained thanks to aeration, in pMFC systems the photosynthetic activity of algae is used. The publication compares the efficiency of wastewater treatment and production of electricity in two types of microbial fuel cells. Preliminary calculations of operating costs for solutions with aeration (MFC) and those using algae activity (pMFC) were presented.