Evaluation of Biomethane Yields From High-Energy Organic Waste and Sewage Sludge: A Pilot Study for a Wastewater Treatment Plant

Abstract

The article describes a pilot study on a wastewater treatment plant operating a biogas plant (2.793 MW). The authors of the experiment used organic waste material, including: chicken fat with feathers (FF), molasses (M), glycerol (GL), raw sewage sludge (SS) and digested sewage sludge as an inoculum. The parameters of raw and digested sludge were compared, e.g. changes in the concentrations of ammonium nitrogen (N-NH4+), alkalinities, chemical oxygen demand (COD) and light metal ions. Potential biodegradation pathways for the organic waste used in the experiments were also proposed. The proposed sequences of chemical reactions are a useful tool for further biochemical analyses and for the mathematical modeling of anaerobic digestion. The results showed that fat with feathers was the most valuable high-energy substrate as it gave a cumulative methane yield of 822 m 3 /mg VS (VS-volatile solids). There were comparable values of cumulative methane yield from molasses (350 m 3 /mg VS) and glycerol (342 m 3 /mg VS), whereas sewage sludge gave the lowest yield (246 m 3 /mg VS).

The Efficiency of Industrial and Laboratory Anaerobic Digesters of Organic Substrates: The Use of the Biochemical Methane Potential Correction Coefficient

“…To sum up, the biochemical methanogenic potential of the substrates used in the laboratory investigations was comparable to the data provided in reference publications [51][52][53][54]. The values of biogas and methane obtained in the industrial-scale production were lower than in the laboratory tests due to the disturbances that occurred in real installations.…”

The Use of Lignin as a Microbial Carrier in the Co-Digestion of Cheese and Wafer Waste

“…Apart from the VFA concentration, the volatile fatty acids/total alkalinity (VFA/TA) ratio is commonly used to assess the process stability. The curves corresponding to variation in the VFA/TA ratio during the decomposition of substances in individual samples show that the process proceeded without inhibition, according to the assumed ranges of values specifying stable digester and some instability [15,43] (Figure 4). The highest VFA/TA ratio of 4.9 was noted for the combination of the co-substrates with lignin (WF+CE/lignin).…”

“…On the contrary, it favors the development and activity of methanogenic consortia [14,26]. The main advantage of stabilized sewage sludge is its high buffer capacity due to its considerable alkalinity developed in the raw sewage sludge digestion process, where nitrates were reduced to carbonates and hydrogencarbonates (total denitrification) [43].…”

Energy Efficiency of Comminution and Extrusion of Maize Substrates Subjected to Methane Fermentation

“…In order to evaluate the usefulness of comminution, it is necessary to compare the energy consumed by pretreatment with the energy obtained from the increased yield of methane. Equations (1), (2), and (3) were used to calculate the energy yield of comminution and the yield of biomethane per dry organic matter. The energy efficiency of comminution was always calculated per megagram of DOM.…”

“…The global economy needs to use waste and by-products to generate renewable energy in order to achieve sustainable development and to protect the climate and natural resources [1]. Anaerobic digestion (AD) is a proven technology of handling organic waste, which yields high-energy products such as methane and digestate [2]. Apart from that, the use of biodegradable waste significantly reduces the emissions of greenhouse gases and odors resulting from uncontrolled fermentation [3].…”