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

Abstract

For the first time, a steady state computational simulation for the production of biodiesel from meat processing dissolved air flotation sludge via an integrated process of in-situ hydrolysis and esterification technologies has been investigated. Important thermophysical properties of the intrinsic lipids of dissolved air flotation sludge were estimated using chemical constituent fragment methods. The environmental performance and the economic performance of the biodiesel production process were assessed via the estimation of the net energy ratio (NER) and the unit production cost, respectively. Since electrical energy requirements may be satisfied via either non-renewable (case A) or renewable sources (case B), the NER was determined for both scenarios. To enhance the robustness of the study results, uncertainties in the NER and the unit cost of the biodiesel production process due to the variability of the underlying study assumptions were also assessed. Uncertainty analysis indicated that the likely range of the NER for the biodiesel production process for cases A and B are 1.76 to 3.32 and 1.82 to 3.36, respectively, at 95% probability. Uncertainty analysis also showed that the likely range of the unit production cost for biodiesel is $US0.41/kg-biodiesel to $US0.71/kg-biodiesel at 95% probability. The results that were obtained in this study therefore provide evidence of both the environmental sustainability and the economic viability of biodiesel production from dissolved air flotation sludge via the proposed integrated process of in-situ hydrolysis and esterification.

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

“…To reflect possible effects of inflation, the annualised capital cost in the present year of 2019 (C 2019 ) was estimated from the calculated annualised capital cost for the reference year of i (C i ), using the chemical engineering plant cost (CEPCI) index as follows [28];…”

“…The annualised capital cost in US $ for year i, for biogas desulphurisation system, with reference capacity, vref in m 3 , and denoted by C i , vref was subsequently estimated as follows [28];…”

“…The uncertainties in the unit desulphurisation cost U c were estimated for the different desulphurisation technologies for 50% to 150% variations in the annual operating cost and the annualised capital costs. Investigations into uncertainties in the U c estimates for the different desulphurisation technologies were achieved via Monte Carlo simulations that employ randomised sequences of estimates to numerically determine its probability density according to the probability density function, defined as follows [28];…”

“…where x represents the values of the U c for different values of annual operating cost, annualised capital cost, interest rate, and the project lifetime, µ represents the mean value of U c , and σ represents the standard deviation of U c . This approach has been employed in a previous study [28], where the area under the curve of f (x) for the interval (a,b) specifies the probability, β, of U c existing within that interval (a,b) and is calculated using the probability density function as follows [28];…”

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

“…Recent studies have demonstrated that meat processing dissolved air flotation (DAF) sludge can serve as a cheap and sustainable biodiesel feedstock via an integrated two-step in-situ hydrolysis and esterification pathway [2]. Crucially however, the utilization of meat processing DAF sludge as a biodiesel feedstock will result in the generation of significant masses of wet hydrolyzed DAF sludge (WHDS) after the biodiesel production process [3,4]. This WHDS residue was identified as constituting a secondary waste stream that must be efficiently utilized to prevent possible secondary pollution issues.…”