Ammonium carboxylate production from sugarcane trash using long-term air-lime pretreatment followed by mixed-culture fermentation

Sugarcane trash (ST) was converted to ammonium carboxylates using a novel bioprocessing strategy known as long-term air-lime pretreatment/mixed-culture fermentation. At mild conditions (50 °C, 5 weeks, 1-atm air, and excess lime loading of 0.4 g Ca(OH)₂/(g dry biomass)), air-lime pretreatment of ST had moderate delignification (64.4%) with little loss in polysaccharides. Without employing detoxification, sterility, expensive nutrients, or costly enzymes, the feedstock (80% treated ST/20% chicken manure) was fermented to primarily ammonium acetate (>75%) and butyrate by a mixed culture of marine microorganisms at 55 °C. In the best four-stage countercurrent fermentation, the product yield was 0.36 g total acids/(g VS fed) and the substrate conversion was 64%. Model predictions indicate both high acid concentrations (>47.5 g/L) and high substrate conversions (>70%) are possible at industrial scale.     

Effect of operating conditions of thermochemical liquefaction on biocrude production from Spirulina platensis

This study investigated the optimum thermochemical liquefaction (TCL) operating conditions for producing biocrude from Spirulina platensis. TCL experiments were performed at various temperatures (200-380 °C), holding times (0-120 min), and solids concentrations (10-50%). TCL conversion at 350 °C, 60 min holding time and 20% solids concentration produced the highest biocrude yield of 39.9% representing 98.3% carbon conversion efficiency. Light fraction biocrude (B₁) appeared at 300 °C or higher temperatures and represented 50-63% of the total biocrude. Biocrude obtained at 350-380 °C had similar fuel properties to that of petroleum crude with energy density of 34.7-39.9 MJ kg⁻¹ compared to 42.9 MJ kg⁻¹ for petroleum crude. Biocrude from conversion at 300 °C or above had 71-77% elemental carbon, and 0.6-11.6% elemental oxygen and viscosities in the range 40-68 cP. GC/MS of biocrude reported higher hydrocarbons (C₁₆-C₁₇), phenolics, carboxylic acids, esters, aldehydes, amines, and amides.