Hydrothermal pretreatment of Platanus orientalis Linn fallen leaves: effects of process conditions on anaerobic digestion

ABSTRACTPlatanus orientalis Linn is widely distributed as a famous street tree, and its fallen leaves are a rich biomass resource. The fallen leaves of Platanus orientalis Linn (FLPOL) can be resourcefully treated by generating biogas through anaerobic digestion. This study aimed to assess the anaerobic digestion (AD) performance of FLPOL under different hydrothermal pretreatment (HTP) conditions (solid–liquid ratio 2–10%, residence times 0.5–2.5 h, and temperatures 120–200°C). The solid–liquid ratio, residence time, and temperature determined by energy balance calculation were 6%, 2.0 h, and 180°C, respectively, and the energy balance was 1.823 kJ/g biomass. Under these conditions, the methane yield of the process water was 56.85 mL/g·VS. The methanogenic potential, hydrolysis rate, maximum methanogenic rate, and the lag period obtained by the Fitzhugh first-order kinetic model and the modified Gompertz model were 101.803 mL/g·VS, 0.130 d−1, 14.207 mL/(g·VS·d) and 1.332 d, respectively. The research results suggest that HTP has an important role in promoting the large-scale AD application of FLPOL.KEYWORDS: Anaerobic digestionPlatanus orientalis Linn fallen leavesenergy balancehydrothermal pretreatmentkinetic simulation AcknowledgmentsThe authors acknowledge Xiaocong Liu and Tong Zuo for their support in the laboratory.Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationNotes on contributorsLei GongLei Gong (male), Associate Professor, Master Supervisor, Cleaner Production Auditor, Member of Shandong Environmental Impact Assessment Expert Database, Director of Environment and Safety Teaching Experiment Center. Mainly engaged in the research work of biological treatment technology of odor and organic waste gas, anaerobic digestion of organic waste, microbial fuel cell and so on. Presided over and participated in more than 20 scientific research projects and 1 technology transformation project since work; participated in the formulation of 1 national standard and 1 industry group standard as the main editor, published more than 20 academic papers, edited 1 monograph, and participated in the editing 1 textbook; 17 authorised patents, including 4 invention patents and 1 invention patent assignment.Xiaofan MaXiaofan Ma (Female), graduate student, studying in Qingdao University of Science and Technology, College of Environment and Safety Engineering, the main research direction is the use of microbial fuel cell treatment of methane, has been published in the journal of the Sci paper (First authors).Hongbin XueHongbin Xue (male), Worked in the Safety and Environment Department of Shandong Diantu Ecological Environment Engineering Co.Chunqian GuoChunqian Guo (male), graduate student, studying in Qingdao University of Science and Technology, College of Environment and Safety Engineering, at present, the research direction is anaerobic product recycling, and two research papers have been published.Shijun ZhangShijun Zhang (male), born in 1997, is a postgraduate student majoring in safety engineering, currently studying in the School of Environment and Safety Engineering, Qingdao University of Science and Technology, with the main research areas of photocatalytic CO2 reduction and photocatalytic antimicrobial marine antifouling.Jun ZhouJun Zhou (male), Associate Professor, Master Supervisor, Groundwater pollution control, soil pollution remediation technology, solid waste treatment and disposal. He has presided over more than 20 scientific research projects, among which he has undertaken 2 Natural Science Funds of Shandong Province, 1 Key Research and Development Project of Shandong Province, and 1 Key Laboratory Open Fund of Shandong Province as the first person in charge of the projects; and more than 10 technology research and development projects entrusted by enterprises and institutions. He has published more than 30 papers in academic journals at home and abroad, including more than 10 SCI and EI papers.Haonan ZhangHaonan Zhang (male), the main research direction is the study of biomass anaerobic digestion process and effect based on hydrothermal pretreatment and accelerator, with 4 sci papers published.