Prognostic Assessment of the Viability of Hydrothermal Liquefaction as a Post-Resource Recovery Step after Enhanced Biomethane Generation Using Co-Digestion Technologies

Abstract

In line with global efforts at encouraging paradigm transitions from waste disposal to resource recovery, the anaerobic co-digestion of substrates of wet hydrolyzed meat processing dissolved air flotation sludge and meat processing stock yard waste was investigated in the present study. It was demonstrated that the co-digestion of these substrates leads to the introduction of co-digestion synergizing effects. This study assessed biomethane potentials of the co-digestion of different substrate mixtures, with the preferred substrate mixture composed of stockyard waste and wet hydrolyzed meat processing dissolved air flotation sludge, present in a 4:1 ratio on a volatile solid mass basis. This co-digestion substrate mix ratio presented an experimentally determined cumulative biomethane potential of 264.13 mL/gVSadded (volatile solid). The experimentally determined cumulative biomethane potential was greater than the predicted maximum cumulative biomethane potential of 148.4 mL/gVSadded, anticipated from a similar substrate mixture if synergizing effects were non-existent. The viability of integrating a downstream hydrothermal liquefaction processing of the digestate residue from the co-digestion process, for enhanced resource recovery, was also initially assessed. Assessments were undertaken via the theoretical based estimation of the yields of useful products of biocrude and biochar obtainable from the hydrothermal liquefaction processing of the digestate residue. The environmental sustainability of the proposed integrated system of anaerobic digestion and hydrothermal liquefaction technologies was also initially assessed. The opportunity for secondary resource recovery from the digestate, via the employment of the hydrothermal liquefaction process and the dependence of the environmental sustainability of the integrated system on the moisture content of the digestate, were established. It is anticipated that the results of this study will constitute an invaluable basis for the future large-scale implementation of the proposed integrated system for enhanced value extraction from organic waste streams.

Scaled-Up Biodiesel Production from Meat Processing Dissolved Air Flotation Sludge: A Simulation Study

“…However, in line with the resource recovery principle, this stream is not considered as waste, but rather a by-product that can effectively serve as a feedstock for secondary biomethane generation via an anaerobic digestion process. The utilisation of this residue as a co-digestion substrate is therefore investigated in another study [72].…”

Desulphurisation of Biogas: A Systematic Qualitative and Economic-Based Quantitative Review of Alternative Strategies

“…A review of literatures, however, highlights an upsurge in the application of anaerobic digestion (AD) technologies in recent times [3,4]. This observation may be reflective of the strategic preference of this conversion pathway due to its capability to facilitate a simultaneous management of high moisture organic waste streams while also generating bioenergy in the form of biogas at a reduced cost [2,5]. The biogas product is typically composed of carbon dioxide (CO 2 ) and biomethane (CH 4 ) which are present in volumetric percentages of 30-40% and 60-70%, respectively [6].…”

“…Equations (1)- (5) illustrate the formation of soluble sulphides (HS − ) via reactions involving intermediate products of the anaerobic digestion (AD) of acetates (Equation (1)), propionates (Equations (2) and (3)), and butyrates (Equations (4) and (5)). This shows that sulphate reducers will outcompete with methanogens because they have better affinities for acetate and H 2 [16].…”

“…Equations (1)- (5) highlights the formation of soluble sulphides (HS − ) within the digester, which may be converted to dissolved H 2 S as follows; H 2 S ↔ H + + HS − (6) where the concentrations of the species of HS − and H 2 S in the aqueous phase are determined using the Henderson-Hasselbach, relationship as follows [19];…”

A PESTLE Analysis of Biofuels Energy Industry in Europe

“…">Problem ContextThe problem context indicates a research interest in the sustainability of the biofuel production processes. Understanding the interrelation between the two is essential for the future of biofuels since it is its sustainability, both economically and environmentally, which has created greater attention for biofuels among the many other alternative energy sources [80][81][82][83][84][85][86][87][88][89][90]. Since the possibilities in production processes depend on the type of feedstock used in the processes, several feedstocks are taken into account [91][92][93][94].…”