Analytical (hydro)pyrolysis of pinewood and wheat straw in chloride molten salts : a route for 2-methyl furan production

2-methyl furan (MF) is a fuel additive with improved fuel characteristics compared to bio-ethanol. Unfortunately, the production of MF (from furfural (FF) hydrogenation) is not economically feasible. Interestingly, molten salts in biomass pyrolysis have shown to promote the formation of furans (mainly FF). Because molten salts hydropyrolysis could be an alternative route to both produce FF and convert it into MF, an assessment is indispensable. Molten salts pyrolysis and hydropyrolysis of pinewood and wheat straw and related model compounds were studied in a micro-reactor. The effect of hydropyrolysis process variables was assessed on the total detectable condensable vapors and MF formation. At low pressures (0.4 MPa), the chloride salts favored the production of FF and acetic regardless of the reaction atmosphere. Under a high pressure of hydrogen though (1.6 and 3.0 MPa), the conversion of FF to MF was enhanced through hydrogenation, hydrodeoxygenation and demethylation reactions. Molten salts hydropyrolysis at 350 °C and pressures of either 1.6 MPa (biomass mass fraction of 0.09) or 3.0 MPa (biomass mass fraction of 0.24) were optimal and yielded ca. 8 wt% to 9 wt% MF. Reaction temperatures >350 °C were unfavorable for the MF yield and instead promoted furfural decarbonylation to furan

Integrating photobioreactor with conventional activated sludge treatment for nitrogen removal from sidestream digestate : current challenges and opportunities

Sidestream digestate is a liquid effluent stream generated from the anaerobic sludge digestion process in a wastewater treatment plant (WWTP). It is rich in inorganic nutrients, mainly nitrogen and phosphorus, and it requires further treatment in order to meet the stringent discharge/regulatory standards. It is usually treated through conventional activated sludge process (ASP) in the WWTPs. However, its direct recirculation to the WWTP imparts burden of excess nutrient removal on the biological treatment, i.e. in terms of the increased energy costs for aeration and it can pose a higher risk of eutrophication in the receiving water body. One alternative is the integration of photobioreactor (PBR) with ASP treatment for enhanced nitrogen removal from sidestream digestate. This paper critically reviewed the techno-economic feasibility of integrating a PBR with the ASP of a WWTP for sidestream digestate treatment. It is estimated that the integrated PBR-ASP process requires small land area and can achieve high nitrogen removal. Microalgae, owing to its high ability in nutrient cycling and biomass production, can effectively be used as biocatalysts for the treatment of sidestream digestate. Microalgae can assimilate nitrogen resulting in oxygen production by photosynthesis. The heterotrophic bacteria mineralise the pollutants present in wastewater, i.e. in the presence of oxygen, releasing carbon dioxide through bacterial respiration. The carbon dioxide is utilised by the microalgae to complete the photosynthetic cycle for wastewater treatment, thus decreasing the greenhouse emissions. The microalgae-bacterial treatment as compared to ASP can reduce more than 50% of the energy costs