Yi di Chen

Bio: Yi di Chen is an academic researcher from Harbin Institute of Technology. The author has contributed to research in topics: Biomass & Anaerobic digestion. The author has an hindex of 5, co-authored 5 publications receiving 369 citations.

Feasibility of CO2 mitigation and carbohydrate production by microalga Scenedesmus obliquus CNW-N used for bioethanol fermentation under outdoor conditions: effects of seasonal changes.

Abstract: Although outdoor cultivation systems have been widely used for mass production of microalgae at a relatively low cost, there are still limited efforts on outdoor cultivation of carbohydrate-rich microalgae that were further used as feedstock for fermentative bioethanol production. In particular, the effects of seasonal changes on cell growth, CO2 fixation, and carbohydrate production of the microalgae have not been well investigated. This work demonstrates the feasibility of using outdoor tubular photobioreactors (PBR) for whole-year-round cultivation of a carbohydrate-rich microalga Scenedesmus obliquus CNW-N in southern Taiwan. Time-course profile of the carbohydrate content under nitrogen-deficient conditions was monitored to assess the seasonal changes. The optimal CO2 fixation rate and carbohydrate productivity were 430.2 mg L−1 d−1and 111.8 mg L−1d−1, respectively, which were obtained during the summer time. Under nitrogen starvation, the microalgal biomass can accumulate nearly 45–50% of carbohydrates, mainly composed of glucose that accounted for 70–80% of the total carbohydrates in the microalgal cells. This glucose-rich microalgal biomass is apparently a very suitable carbon source for bioethanol fermentation. This work shows the feasibility of combining CO2 fixation and bioethanol production using microalgae grown in outdoor photobioreactors as feedstock. The understanding of the seasonal changes in the carbohydrate productivity makes this approach more practically viable. The novel strategy proposed in this study could be a promising alternative to the existing technology dealing with CO2 mitigation and biofuels production.

Integration of sludge digestion and microalgae cultivation for enhancing bioenergy and biorefinery

Abstract: Sludge generated from wastewater treatment plants causes severe environmental problems, which can be significantly reduced using anaerobic digestion. However, CO2, anaerobic digestate, and the residues from anaerobic digestion process still need to be treated. Accordingly, some energy-rich microalgae can grow well in sludge digestate contained wastewater, which enhances its economic feasibility for biofuel production. Therefore, in this review, the integration of sludge digestion and microalgal cultivation is proposed for enhancing the performance of bioenergy and biorefinery industries. Microalgae can simultaneously utilize sludge digestate and CO2 as the carbon sources for biofuel production and biogas upgradation. This comprehensive review mainly analyzes different compositions of anaerobic digestate, sludge pretreatment methods, favorable environmental factors, and different CO2 concentrations, which influence the growth of microalgae and the accumulation of bioenergy. Finally, the waste residues from sludge digestion and microalgae cultivation are converted to bio-gas, bio-oil, and biochar, which can be used as biofuels, supercapacitors, adsorbents, and catalysts through thermal conversion. This review indicates that the pyrolysis process has a positive net energy production and hydrothermal treatment can be chosen as the wet biomass conversion method. The aim of this review is to provide useful information for combining the sludge digestion and microalgal cultivation to simultaneously reduce the pollutants and produce bioenergy.

Hierarchical porous biochar from shrimp shell for persulfate activation: A two-electron transfer path and key impact factors

Abstract: Herein, hierarchical porous biochar from shrimp shell (PSS-bio) was prepared and applied for persulfate activation for 2,4-dichlorophenol removal. The pyrolysis temperature was found to play an important role in carbon structure and property modulation, where PSS-bio obtained at 800 °C (PSS-800) exhibited the fastest adsorption capacity and the best catalytic activity with the degradation rates 29 times higher than that of PSS-bio obtained at 400 °C (PSS-400). Further analysis demonstrated that hierarchical pores and carbon configuration were two key impact factors of biochar in AOP. Interestingly, the original free-radical dominated pathway in PSS-400 also changed into a non-radical one (direct two-electron transfer path) in PSS-800, whose efficiency could be somewhat disturbed by pH values, humic acid and anions regardless of their concentrations as low as 5 mM or as high as 500 mM, demonstrating its application potential for the treatment of both highly saline water and organic-rich water.