Yebo Li

Bio: Yebo Li is an academic researcher from Ohio Agricultural Research and Development Center. The author has contributed to research in topics: Anaerobic digestion & Biogas. The author has an hindex of 52, co-authored 129 publications receiving 10960 citations. Previous affiliations of Yebo Li include Ohio State University & Rutgers University.

Nutrient recovery from wastewater streams by microalgae: Status and prospects

Abstract: Disposal of wastewater often results in high nutrient loading into aquatic environments, which may lead to favorable conditions for undesirable phytoplankton blooms. Microalgae are efficient in removing nitrogen, phosphorus, and toxic metals from wastewater under controlled environments. If key nutrients in the wastewater stream can be used to grow microalgae for biofuel production, the nutrients can be removed, thus significantly reducing the risk of harmful phytoplankton overgrowth. This review paper summarizes the major nutrient components of different wastewater streams, the mechanisms of algal nutrient uptake, nutrient removal performance of various species of microalgae when cultured in wastewater, and current microalgae production systems. Finally, new algae cultivation technologies applicable for biofuel production and nutrient recovery in polluted water bodies are discussed.

Solid-state anaerobic digestion for methane production from organic waste

Abstract: Solid-state anaerobic digestion (SS-AD) generally occurs at solid concentrations higher than 15%. In contrast, liquid anaerobic digestion (AD) handles feedstocks with solid concentrations between 0.5% and 15%. Animal manure, sewage sludge, and food waste are generally treated by liquid AD, while organic fractions of municipal solid waste (OFMSW) and lignocellulosic biomass such as crop residues and energy crops can be processed through SS-AD. Some advantages of SS-AD include smaller reactor capacity requirements, less energy used for heating, and no processing energy needed for stirring. Due to its lower water content, the digestate of SS-AD is much easier to handle than the effluent of liquid AD. However, SS-AD systems also have disadvantages such as larger amounts of required inocula and much longer retention time. The principles and applications of the SS-AD process are reviewed in this paper. The variation in biogas production yields of different feedstocks is discussed as well as the need for pretreatment of lignocellulosic biomass to enhance biogas production. The effects of major operational parameters, including C/N ratio, solids content, temperature, and inoculation on the performance of SS-AD are summarized. While an increase in operating temperature can improve both the biogas yield and the production efficiency, other practices such as using AD digestate or leachate as an inoculant or decreasing the solid content, may increase the biogas yield but have negative impact on production efficiency. Different reactor configurations used in current commercial scale SS-AD systems and the impact of economics on system selection are also discussed.

Lignocellulosic biomass pyrolysis: A review of product properties and effects of pyrolysis parameters

Abstract: Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.

Review on research achievements of biogas from anaerobic digestion

Abstract: With the rising demand for renewable energy and environmental protection, anaerobic digestion of biogas technology has attracted considerable attention within the scientific community. This paper presents a comprehensive review of research achievements on anaerobic digestion developments for biogas production. The review includes a discussion of factors affecting efficiency (temperature, pH, C/N ratio, OLR and retention time), accelerants (greenery biomass, biological pure culture and inorganic additives), reactors (conventional anaerobic reactors, sludge retention reactors and anaerobic membrane reactors) and biogas AD processes (lignocellulose waste, municipal solid waste, food waste, livestock manure and waste activated sludge) based on substrate characteristics and discusses the application of each forementioned aspect. The factors affecting efficiency are crucial to anaerobic digestion, because they play a major role in biogas production and determine the metabolic conditions for microorganism growth. As an additive, an accelerant is not only regarded as a nutrient resource, but can also improve biodegradability. The focus of reactor design is the sufficient utilization of a substrate by changing the feeding method and enhancing the attachment to biomass. The optimal digestion process balances the optimal digest conditions with the cost-optimal input/output ratio. Additionally, establishment of theoretical and technological studies should emphasize practicality based on laboratory-scale experiments because further development of biogas plants would allow for a transition from household to medium- and large-scale projects; therefore, improving stability and efficiency are recommended for advancing AD research.