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This paper proposes a two-part process for producing biocrude with reduced impurities. The biocrude was produced from hydrothermal liquefaction (HTL) of Spirulina sp. and Tetraselmis sp. in a batch reactor at both 300 and 350°C, 5min, and 16%w/w solid feed composition. The resultant biocrudes were vacuum distilled at a maximum temperature of 360°C. It was shown that biocrude quality could be enhanced without using catalyst by vacuum distillation (VD). The biocrude yield for Spirulina sp. was 36wt% at 300°C, 42wt% at 350°C, and for Tetraselmis sp. was 34wt% at 300°C, and 58wt% at 350°C. VD of Spirulina sp. biocrude obtained at 300 and 350°C led to 62 and 67wt% distilled biocrudes yield, respectively. VD of Tetraselmis sp. biocrude obtained at 300°C was 70wt%, and 73wt% at 350°C. The higher heating values (HHV) increased from 32MJ/kg to 40MJ/kg. There were substantial reductions in oxygen, metallic content, and boiling point ranges in distilled biocrudes.

Effect of biochar addition on hydrogen and methane production in two-phase anaerobic digestion of aqueous carbohydrates was studied using bench-scale bioreactors. The cultures with biochar additions were placed in 100ml reactors and incubated at 35°C and pH 5 for hydrogen production. The residual cultures were then used for methane production, incubated at 35°C and pH 7. Daily yields of hydrogen and methane and weekly yield of volatile fatty acids (VFA) were measured. The hydrogen and methane production potentials, rate and lag phases of the two phases were analysed using the Gompertz model. The results showed that biochar addition increased the maximum production rates of hydrogen by 32.5% and methane 41.6%, improved hydrogen yield by 31.0% and methane 10.0%, and shortened the lag phases in the two phases by 36.0% and 41.0%, respectively. Biochar addition also enhanced VFA generation during hydrogen production and VFA degradation in methane production.

Air-cathode microbial fuel cells (MFCs), obtained by inoculating with an aerobic activated sludge, were activated over a one month period, at pH 10.0, to obtain alkaline MFCs. The alkaline MFCs produced stable power of 118mWm(-2) and a maximum power density of 213mWm(-2) at pH 10.0, using glucose as substrate. The performance of the MFCs was enhanced to produce a stable power of 140mWm(-2) and a maximum power density of 235mWm(-2) by increasing pH to 11.0. This is the highest pH for stably operating MFCs reported in the literature. Power production was found to be suppressed at higher pH (12.0) and lower pH (9.0). Microbial analysis indicated that Firmicutes phylum was largely enriched in the anodic biofilms (88%), within which Eremococcus genus was the dominant group (47%). It is the first time that Eremococcus genus was described in bio-electrochemical systems.

The anaerobic digestion process in anaerobic membrane bioreactors is an effective way for waste management, energy sustainability and pollution control in the environment. This digestion process basically involves the production of volatile fatty acids and biohydrogen as intermediate products and methane as a final product. This paper compares the value of bioproducts from different stages of anaerobic membrane bioreactors through a thorough assessment. The value was assessed in terms of technical feasibility, economic assessment, environmental impact and impact on society. Even though the current research objective is more inclined to optimize the production of methane, the intermediate products could also be considered as economically attractive and environment friendly options. Hence, this is the first review study to correlate the idea into an anaerobic membrane bioreactor which is expected to guide future research pathways regarding anaerobic process and its bioproducts.

Effect of hydrothermal carbonization (HTC) on the hydrochar pelletization and the aldehydes/ketones emission from pellets during storage was investigated. Pellets made from the hydrochar were stored in sealed apparatuses for sampling. The energy consumption during pelletization and the pellets' properties before/after storage, including dimension, density, moisture content, hardness, aldehyde/ketones emission amount/rate and unsaturated fatty acid amount, were analyzed. Compared with untreated-sawdust-pellets, the hydrochar-pellets required more energy consumption for pelletization, and achieved the improved qualities, resulting in the higher stability degree during storage. The species and amount of unsaturated fatty acids in the hydrochar-pellets were higher than those in the untreated-sawdust-pellets. The unsaturated fatty acids content in the hydrochar-pellets was decreased with increasing HTC temperature. Higher aldehydes/ketones emission amount and rates with a longer emission period were found for the hydrochar-pellets, associated with variations of structure and unsaturated fatty acid composition in pellets.

The effect of dissolved oxygen concentration on lipid accumulation in Trichosporon oleaginosus has been investigated. The experiment was performed in 15 L fermenters. The dissolved oxygen concentration varied by adjusting the agitation and aeration. High dissolved oxygen level at 50%-60% enhanced cell growth. Maintaining low dissolved oxygen concentration at 20%-30% during lipogenesis phase led to high final lipid content (51%) in Trichosporon oleaginosus. The consumptions of energy and cost of the process were evaluated. The energy consumption in the dissolved oxygen level optimized process was 41% less than that with dissolved oxygen level at 50%-60%. In addition, the cost was also reduced around one time in the dissolved oxygen level optimized process compared to the one with dissolved oxygen level at 50%-60%. The study provided a feasible way of enhancing lipid accumulation in Trichosporon oleaginosus and reducing the consumption of energy and cost of lipid production from Trichosporon oleaginosus.

This study aimed to assess the impacts of organic loading rate (OLR) (435-870 mgCOD/L·d) on nutrients recovery via a double-chamber microbial fuel cell (MFC) for treating domestic wastewater. Electricity generation was also explored at different OLRs, including power density and coulombic efficiency. Experimental results suggested the MFC could successfully treat municipal wastewater with over 90% of organics being removed at a wider range of OLR from 435 to 725 mgCOD/L·d. Besides, the maximum power density achieved in the MFC was 253.84 mW/m2 at the OLR of 435 mgCOD/L·d. Higher OLR may disrupt the recovery of PO43--P and NH4+-N via the MFC. The same pattern was observed for the coulombic efficiency of the MFC and its highest value was 25.01% at the OLR of 435 mgCOD/L·d. It can be concluded that nutrients and electrical power can be simultaneously recovered from municipal wastewater via the dual-chamber MFC.

A hybrid system integrating a microbial fuel cell (MFC)-based biosensor with upflow anaerobic sludge blanket (UASB) was investigated for real-time online monitoring of the internal operation of the UASB reactor. The features concerned were its rapidity and steadiness with a constant operation condition. In addition, the signal feedback mechanism was examined by the relationship between voltage and time point of changed COD concentration. The sensitivity of different concentrations was explored by comparing the signal feedback time point between the voltage and pH. Results showed that the electrical signal feedback was more sensitive than pH and the thresholds of sensitivity were S=3×10(-5)V/(mg/L) and S=8×10(-5)V/(mg/L) in different concentration ranges, respectively. Although only 0.94% of the influent COD was translated into electricity and applied for biosensing, this integrated system indicated great potential without additional COD consumption for real-time monitoring.