Towards Circular Economy: Evaluation of Sewage Sludge Biogas Solutions

Abstract

Today it is obvious that the existing linear model of the economy does not correlate with the principles of sustainable development. The circular economy model can replace the current linear economy whilst addressing the issues of environmental deterioration, social equity and long-term economic growth. In the context of effectively implementing circular economy objectives, particular importance should be attributed to wastewater treatment sludge management, due to the possibility of recovering valuable raw materials and using its energy potential. Anaerobic digestion is one of the methods of recovering energy from sewage sludge. The main goal of this study is to make a preliminary evaluation of possible sewage sludge biogas and biomethane solutions using a computation model called MCBioCH4 and compare its results with laboratory tests of sewage sludge fermentation from the northern wastewater treatment plant (WWTP) of Ekaterinburg (Russian Federation). Laboratory experiments were conducted to determine the volume and qualitative composition of biogas produced throughout anaerobic fermentation of raw materials coming from the WWTP. The specific productivity of samples ranged between 308.46 Nm3/tvs and 583.08 Nm3/tvs depending if mesophilic or thermophilic conditions were analyzed, or if the experiment was conducted with or without sludge pre-treatment. Output values from the laboratory were used as input for MCBioCH4 to calculate the flow of biogas or biomethane produced. For the case study of Ekaterinburg two possible energy conversion options were selected: B-H (biogas combustion with cogeneration of electrical and thermal energy) and M-T (biomethane to be used in transports). The results of the energy module showed a net energy content of the biogas between 6575 MWh/year and 7200 MWh/year. Both options yielded a favorable greenhouse gas (GHG) balance, meaning that avoided emissions are higher than produced emissions. The results discussion also showed that, in this case, the B-H option is preferable to the M-T option. The implementation of the biogas/biomethane energy conversion system in Ekaterinburg WWTP necessitates further investigations to clarify the remaining technical and economic aspects

Halocarbon Emissions from Hazardous Waste Landfills: Analysis of Sources and Risks

“…A consistent emission of 1,2-dichloroethane was also measured during the composting process of WWTP sludge [30]. Given the high volume produced and the high costs of disposal, the valorization of WWTP sludge constitutes an important topic of research [46,47].…”

Adsorptive Findings on Selected Biomasses for Removal of Phenol from Aqueous Solutions

“…Thus, selected biomasses, Acacia nilotica branches, Lantana camera, and rice husk, yielded value-added products in the forms of activated adsorbents with the appreciable capacity of phenol removal from aqueous solutions. Biomasses, ANB, LC, and RH, causing threats to the environment, can be used effectively for the removal and recycling of phenol from aqueous solutions under the concept of a circular economy [38].…”

Evaluation of Green Coffee-Roasting Biogas with Modeling Valorization of Possible Solutions

“…For more details, refer to Ravina et al [ 27 ]. The MCBioCH4 model was recently applied to the evaluation of the anaerobic digestion of mixed agriculture–zootechnic waste matter [ 28 ] and wastewater sludge treatment [ 29 , 30 ].…”