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The palm oil agroindustry not only produces the most consumed vegetable oil in the world, but also a significant quantity of residual biomass. This waste represents real opportunity to create a variety of products. In the context of sustainable oil production, the use of biomass to generate value-added products can be addressed through the evolution of existing palm oil mills (POMs) into biorefineries. In this manuscript, the authors present a literature review of potential uses for biomass generated in palm plantations and at the POM, including the main properties, quantities, and current practices. After this, a review of novel, less traditional is made. Finally, strategies for the synthesis and analysis of POM biorefinery concepts are discussed. This review highlights the need for development of high-value products from POM waste and the urgency to incubate these emerging technologies for gradual transition into biorefineries. Based on short term economic performance, biomass pelletization and anaerobic digestion of POME are the most promising technologies. Furthermore, the production of biochar has great potential when the environmental performance is taken into account. More work is needed to evaluate the long term economic, social, and environmental impact of other new technologies both now and in the future. [ABSTRACT FROM AUTHOR]

Background: Oleaginous microalgae contain a high level of lipids, which can be extracted and converted to biofuel. The lipid-extracted residue can then be further utilized through anaerobic digestion to produce biogas. However, long-chain fatty acids (LCFAs) have been identified as the main inhibitory factor on microbial activity of anaerobic consortium. In this study, the mechanism of LCFA inhibition on anaerobic digestion of whole and lipid-extracted algal biomass was investigated with a range of calcium concentrations against various inoculum to substrate ratios as a means to alleviate the LCFA inhibition. Results: Whole algal biomass of Nannochloropsis salina represents high lipid content algal biomass while lipidextracted residue represents its low lipid counterpart. The anaerobic digestion experiments were conducted in a series of serum bottles at 35 °C for 20 days. A kinetic model, considering LCFA inhibition on hydrolysis, acidogenesis as well as methanogenesis steps, was developed from the observed phenomenon of inhibition factors as a function of the LCFA concentration and specific biomass content or calcium concentration. The results showed that inoculum to substrate ratio had a stronger effect on biogas production than calcium, and calcium had no effect on biogas production when inoculum concentration was extremely low. The microbial community analysis by high-throughput Illumina Miseq sequencing indicated that diversity of both bacterial and methanogenic communities decreased with elevation of lipid concentration. Hydrolytic bacteria and aceticlastic methanogens dominated bacterial and archaea communities, respectively, in both high and low LCFA concentration digesters. Conclusions: This study demonstrated that inoculum concentration has a more significant effect on alleviating LCFA inhibition than calcium concentration, while calcium only played a role when inoculum concentration met a threshold level. The model revealed that each functional microbial group was subject to different levels of LCFA inhibition. Although methanogens were the most susceptible microbes to LCFA inhibition, the inhibition factor for hydrolytic bacteria was more highly affected by inoculum concentration. The microbial community analysis indicated that the bacterial community was affected more than the methanogenic community by high LCFAs concentration. Syntrophic acetogens were sensitive to high LCFA concentrations and thus showed a decreased abundance in such an environment. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a new strategy, improving biomass retention with fiber material present within the dairy manure as biofilm carriers, was evaluated for treating flushed dairy manure in a psychrophilic anaerobic sequencing batch reactor (ASBR). A kinetic study was carried out for process control and design by comparing four microbial growth kinetic models, i.e. first order, Grau, Monod and Chen and Hashimoto models. A volumetric methane production rate of 0.24L/L/d of and a specific methane productivity of 0.19L/gVSloaded were achieved at 6days HRT. It was proved that an ASBR using manure fiber as support media not only improved methane production but also reduced the necessary HRT and temperature to achieve a similar treating efficiency compared with current technologies. The kinetic model can be used for design and optimization of the process. [Copyright &y& Elsevier]

Highlights: [•] SMP for whole microalgae were better than lipid-extracted microalgae residues. [•] The control of I/S ratio during BMP could overcome pH drop and LCFA inhibition. [•] No signs of VFA or ammonia inhibition occurred when digested at I/S⩾1.0 ratio. [•] Higher methane production was not related to species but to lipid content of biomass. [Copyright &y& Elsevier]