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Bio-based and bio-degradable plastics such as polybutylene succinate (PBS) have the potential to become sustainable alternatives to petrochemical-based plastics. Polybutylene succinate can be produced from bio-based succinic acid and 1,4-butanediol using first-generation (1G) or secondgeneration (2G) sugars. A cradle-to-grave environmental assessment was performed for PBS products in Europe to investigate the non-renewable energy use (NREU) and greenhouse gas (GHG) impacts. The products investigated are single-use trays and agricultural film, with incineration, industrial composting and degradation on agricultural land as end-of-life scenarios. Both end products manufactured from fully bio-based PBS and from partly bio-based PBS (made from bio-based succinic acid and fossil fuel-based 1,4 butanediol) were analysed. We examine corn (1G) as well as corn stover, wheat straw, miscanthus and hardwood as 2G feedstocks. For the cradle-to-grave system, 1G fully bio-based PBS plastic products were found to have environmental impacts comparable with their petrochemical incumbents, while 2G fully bio-based PBS plastic products allow to reduce NREU and GHG by around one third under the condition of avoidance of concentration of sugars and energy integration of the pretreatment process with monomer production. Without energy integration and with concentration of Modeling and Analysis: NREU and GHG balance of succinic acid-based PBS products made from lignocellulosic biomass MK Patel et al.sugars (i.e., separate production), the impacts of 2G fully bio-based PBS products are approximately 15-20% lower than those of 1G fully bio-based PBS products. The environmental analysis of PBS products supports the value proposition related to PBS products while also pointing out areas requiring further research and development.

A process based on partial nitrification and recirculation into the anaerobic digester was studied to remove nitrogen from digested manure and thus reduce enhanced gaseous ammonia emissions due to on-farm biogas production. An anaerobic reactor representing an anaerobic manure digester was fed with a nitrite solution and digested manure liquor. Nitrite was efficiently removed from the influent and ammonium formation was observed first. Ammonium was subsequently eliminated up to a maximum of 90% of the influent concentration, indicating anaerobic ammonium oxidation activity. This activity, however, decreased again and was lost at the end of the 4-month operation period. In a 1.5 L aerobic CSTR that was fed with digested manure liquor, ammonium was efficiently removed from the influent. Nitrite and nitrate formation was observed but mass balances indicated significant N-removal. Accumulation of suspended solids was observed at the end of the experiment suggesting presence of oxygen-free environments. In a second test in a 15 L CSTR where suspended solids sedimentation could be avoided, low N-removal rates were observed in the absence of biofilm carrier elements whereas high N-removal rates were achieved in their presence. A simple one-stage process based on immobilized biomass could therefore be installed downstream of agricultural anaerobic digesters in order to mitigate undesirable gaseous ammonia emissions.

The main aim of this study was to analyze dilute acid pretreatment for the Douglas fir wood in order to improve the efficiency of hydrolysis with an ultimate aim to produce bioethanol. Compositional analysis of the untreated Douglas fir biomass revealed the presence of 63.3 % carbohydrate of which 57.2 % was C6 sugars. The total lignin content was approximately 30 %. A partial fractional factorial design was opted for performing the pretreatment experiments employing sulfuric acid (H2SO4). Acid concentration, solids loading, residence time, reaction temperature, and particle size of feedstock were evaluated simultaneously for improving the enzymatic digestibility of Douglas fir biomass. Enzymatic saccharification of the pretreated biomass was done using a commercial cellulase preparation and the total reducing sugars liberated was monitored. Saccharification efficiency was correlated with the parameters and the best combination of parameters for obtaining feedstock suited for enzymatic saccharification was determined.