Browsing by Author "Huang, Zhigang"
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Item Open Access Cultivation of microalgae in adjusted wastewater to enhance biofuel production and reduce environmental impact: pyrolysis performances and life cycle assessment(Elsevier, 2022-04-21) Li, Gang; Hu, Ruichen; Wang, Nan; Yang, Tenglun; Xu, Fuzhuo; Li, Jiale; Wu, Jiahui; Huang, Zhigang; Pan, Minmin; Lyu, TaoThe interest in microalgae as a renewable and sustainable feedstock for biofuels production has inspired a new focus in biorefinery. Current innovations in microalgae technology include the use of wastewater as the cultivation medium towards nutrients recovery, renewable energy generation, as well as wastewater treatment. Though recent studies have favoured the competitiveness of such an approach, how to maintain a high-quality microalgae-derived biofuel production in real wastewater with fluctuations in nutrient contents is still a challenge. This study investigated a strategy of adjusting the nutrient composition of the feeding wastewater (i.e. anaerobic digestion effluent) for microalgae cultivation (Desmodesmus sp.) and biofuel production. The addition of an appropriate amount of nutrients, including magnesium, iron and phosphorus, significantly enhanced the microalgal biomass production (0.78 g L−1) compared with the original wastewater (0.35 g L−1) and the standard BG11 microalgae cultivation medium (0.54 g L−1). In terms of the potential biofuel quality, the use of adjusted wastewater led to a higher content of valuable products (aliphatic hydrocarbon and fatty acids were accounted for 23.98% and 42.33% of the whole biomass, respectively) along with a reduction in potentially toxic substances (nitrogen-containing compounds and polycyclic aromatic hydrocarbons were accounted for 7.96% and 7.09% of the whole biomass, respectively) compared with the other cultivation groups. Moreover, the lower optimal temperature of pyrolysis engendered by the adjusted wastewater was significant for reduction of process energy consumption, which in turn led to overall lowered environmental impacts (838.52 mPET2000, applying life cycle assessment) than did the original wastewater (1165.67 mPET2000) and standard cultivation medium (1347.63 mPET2000). This study demonstrated that the adjustment of wastewater can act as a potential approach for the improvement in the quality of microalgal biofuel production, with consequent reduced environmental impacts.Item Open Access Microbial behavior and influencing factors in the anaerobic digestion of distiller: a comprehensive review(MDPI, 2023-02-21) Li, Gang; Xu, Fuzhuo; Yang, Tenglun; Wang, Xiqing; Lyu, Tao; Huang, ZhigangAnaerobic digestion technology is regarded as the most ideal technology for the treatment of a distiller in terms of environmental protection, resource utilization, and cost. However, there are some limitations to this process, the most prominent of which is microbial activity. The purpose of this paper is to provide a critical review of the microorganisms involved in the anaerobic digestion process of a distiller, with emphasis on the archaea community. The effects of operating parameters on microbial activity and process, such as pH, temperature, TAN, etc., are discussed. By understanding the activity of microorganisms, the anaerobic treatment technology of a distiller can be more mature. Aiming at the problem that anaerobic treatment of a distiller alone is not effective, the synergistic effect of different substrates is briefly discussed. In addition, the recent literature on the use of microorganisms to purify a distiller was collected in order to better purify the distiller and reduce harm. In the future, more studies are needed to elucidate the interactions between microorganisms and establish the mechanisms of microbial interactions in different environments.Item Open Access Valorisation of microalgae residues after lipid extraction: Pyrolysis characteristics for biofuel production(Elsevier, 2021-12-31) Huang, Zhigang; Zhang, Jiang; Pan, Minmin; Hao, Yuhang; Hu, Ruichen; Xiao, Wenbo; Li, Gang; Lyu, TaoAs a promising source of renewable energy, biofuel from microalgae pyrolysis is seen as a competitive alternative to fossil fuels. However, currently, the widely applied pre-treatment process of lipid extraction results in large amounts of microalgae residues, which though with energy potential, being considered as process wastes and ignored of its re-utilization potential. In this study, a new workflow of biofuel generation from microalgae biomass through lipid extraction and pyrolysis of defatted microalgae residues was proposed and assessed. The effects of lipid extraction and pyrolysis temperature (350–750 ℃) on pyrolysis products were investigated, and pyrolysis pathways were postulated. To address the twin goals of lowering emission of pollutants and elevating energy products, an optimal pyrolysis temperature of 650 ℃ was suggested. After extraction of lipids, the relative contents of valuable products (aromatic, aliphatic hydrocarbons and fatty acids) and some harmful by-products, e.g., PAHs, significantly reduced, while other harmful substrates, e.g., nitrogen-compounds increased. Mechanistic investigations indicated that pyrolysis of proteins without the presence of lipids could promote higher production of nitrogen-containing organics and aromatics. These results reveal the effects of lipid extraction and variation of temperature on microalgal pyrolysis, and also provide a basis for full utilization of microalgae as an aid to alleviate many fossil energy problems.