Assessment of the production of biodiesel from urban wastewater-derived lipids

Abstract

Production of biodiesel is one of the most important European targets within renewables for the future. To consider biodiesel a feasible alternative to fossil fuel, unconventional resources need to be exploited. This review aims to provide up-to-date knowledge on the existing reuse of lipids from urban wastewater to produce biodiesel. Lipids are readily removed by mixed microbial populations during wastewater treatments in sewage plants. Assessment results on potential annual European market supply indicate 3-414 10 4 tons (min for activated and max for grease trap sludge) of potentially extractable biodiesel from wastewater and an expected biodiesel demand of 14.8 10 6 tons. Considering the prospect of transforming sewage plants into biorefineries, we may cover on average 1.5, 6.2, 6.7 and 24.4% of activated, primary, scum and grease trap sludge respectively, of the European biodiesel market from wastewater-derived lipids. In addition, by implementing an optimized biotechnology selector, the overall biodiesel yield could be higher due to increased lipid incorporation into microbial biomass. This is not an insignificant amount and, if efficiently implemented, could represent an exploitable resource for biofuel production, an important and desired step towards a circular economy. The technology readiness level is still very low. There are several challenges and possible drawbacks, e.g., biogas yield loss, substrate depletion, or formation of floating sludge. Finally, no definitive legislative barriers towards wastewater-derived lipids have been identified; however, quality criteria as well as waste status have to be defined. Recently, many reports and regulations have been introducing circular economy principles in areas where sustainability of renewables is strongly considered. Generally, renewable sources having a high environmental impact such as indirect land use change due to crop-to-fuel cultivation, which needs to be better regulated. Accordingly, the limit

Challenges and opportunities for more efficient water use and circular wastewater management. The case of Campania Region, Italy

“…Robles et al (2020) described the state of the art of nutrient recovery by examining the benefits and limitations of different recovery technologies; they conclude too that more research is needed to optimize these recovery technologies and broaden their applicability. Frkova et al (2020) evaluated the technical feasibility of removing lipids from urban wastewater for biodiesel production and demonstrated that a non-negligible amount is extractable for the production of biofuels. However, the study also found that lipid recovery methods are still limited and none of them are currently used on a large scale.…”

Heterogeneous Solid Acid Catalysts for Sustainable Biodiesel Production from Wastewater-Derived Sludge: A Systematic and Critical Review

“…Cost-benefit analyses (CBAs), sensitivity analysis (SA), and scenario modeling are applied in the identification of key cost drivers, assessment of risk values, as well as optimization of process parameters that ensure big returns. Moreover, the results of techno-economic analysis do not only offer valuable insights into the competitiveness of biodiesel production using solid acid catalysts compared to the other methods of production of biodiesel but also contribute towards educated choices and strategic planning for the creation of sustainable and economically profitable businesses meant to produce biodiesel [97].…”

Wastewater Refinery: Producing Multiple Valuable Outputs from Wastewater

“…The cultivation of aquatic weeds on wastewater, such as duckweed, with the subsequent processing in biorefinery schemes to obtain multiple outputs, including ethanol, methane, and volatile fatty acids, has also been studied [35,36]. Other researchers have focused on individual elements that could be included when conceptualizing a biorefinery, such as the recovery of lipids from wastewater for the production of biodiesel [37] or the cultivation of cellulase on domestic wastewater [38]. Wastewater-based biorefinery schemes have been referred to as "wastewater biorefinery" [39,40].…”