Low-temperature thermal pre-treatment of municipal wastewater sludge: process optimization and effects on solubilization and anaerobic degradation

The present study examines the relationship between the degree of solubilization and biodegradability of wastewater sludge in anaerobic digestion as a result of low-temperature thermal pre-treatment. The main effect of thermal pre-treatment is the disintegration of cell membranes and thus solubilization of organic compounds. There is an established correlation between chemical oxygen demand (COD) solubilization and temperature of thermal pre-treatment, but results of thermal pre-treatment in terms of biodegradability are not well understood. Aiming to determine the impact of low temperature treatments on biogas production, the thermal pre-treatment process was first optimized based on an experimental design study on waste activated sludge in batch mode. The optimum temperature, reaction time and pH of the process were determined to be 80\ua0°C, 5\ua0h and pH 10, respectively. All three factors had a strong individual effect (p\ua

Near-critical and Supercritical Water and Their Applications for Biorefineries

XVI, 474 p. 134 illus., 53 illus. in color.onlin

LIQUEFACTION OF CORN DISTILLERS DRIED GRAINS WITH SOLUBLES (DDGS) IN HOT-COMPRESSED PHENOL

The present work aims to liquefy corn Distillers Dried Grains with Solubles (DDGS), a by-product in corn ethanol production, to produce liquid products as a potential substitute for petroleum-derived phenol or an additive in the manufacturing of phenolic resins. Efficient liquefaction of DDGS has been realized with hot-compressed phenol at 200-450oC. Effects of liquefaction temperature, initial phenol/DDGS ratio, residence time and catalysts on yields of liquefaction products, as well as characterizations of typical liquid and solid products, have been investigated. The yield of liquid products increased with temperature, while it peaked at around 300oC, due to condensation/cracking reactions of the liquid intermediates/products to form solid products (i.e., coke/char) at temperatures higher than 300oC. The liquid yield increased monotonically with the initial phenol/DDGS ratio for a specified treatment time and temperature. An increased residence time generally produced a lower yield of liquid products, and a higher yield of solid residue, which was likely due to the increased coke/char formation from liquid products for a prolonged residence time. The yield of liquid products reached a maximum of 97% at 300oC for 5 min-operation with Phenol/DDGS of 2/1. K2CO3, Rb2CO3 and NaOH were found very effective catalysts for enhancing the liquid yields. The use of these catalysts resulted in 25% increase in the liquid yields for 5 min-operation with Phenol/DDGS of 1/1 at 300oC

Exotic glycerol dehydrogenase expressing Escherichia coli increases yield of 2,3-butanediol

Abstract Background The thriving of biodiesel industry has led to produce 10% (v/v) crude glycerol, thus creating an overflow problem. Biofuel production is restricted by Escherichia coli due to its toxicity to bacterial cells. Therefore, a platform chemical and fuel additive 2,3-butanediol (2,3-BD) with low toxicity to microbes could be a promising alternative for biofuel production by recombinant E. coli using glycerol as the sole substrate. Results A novel expression system of E. coli was developed to express the dhaD gene encoding glycerol dehydrogenase (GDH) to produce value-added metabolic products through aerobic biotransformation of glycerol. The dhaD gene obtained from Klebsiella pneumoniae SRP2 was expressed in E. coli BL21(DE3)pLysS using an E. coli–K. pneumoniae shuttle vector pJET1.2/blunt consisting of chloramphenicol-resistance gene under the control of the T7lac promotor. RT-PCR analysis and dhaD overexpression confirmed that the 2,3-BD synthesis pathway gene was expressed on RNA and protein levels. Therefore, the recombinant E. coli exhibited a 38.9-fold higher enzyme activity (312.57 units/mg protein), yielding 8.97 g/L 2,3-BD, a 2.4-fold increase with respect to the non-recombinant strain. Conclusions The engineered strain E. coli BL21(DE3)pLysS/pJET1.2/blunt-dhaD, carrying the 2,3-BD pathway gene dhaD from our newly isolated Klebsiella pneumoniae SRP2 strain, displayed the best ability to synthesize 2,3-BD from low-cost biomass glycerol. The value of expression of an important glycerol metabolism gene dhaD is the highest ever achieved with an engineered E. coli strain. From these results, the first reported dhaD expression system has paved the way for improvement of 2,3-BD production and is efficient for another heterologous gene expression in E. coli

Ash Deposition in Biomass Combustion or Co-Firing for Power/Heat Generation

This paper presents a concise overview of ash deposition in combustion or co-firing of biomass (woody biomass, agricultural residues, peat, etc.) with other fuels for power/heat generation. In this article, the following five research aspects on biomass combustion ash deposition are reviewed and discussed: influence of biomass fuel characteristics, deposit-related challenges, ash deposition monitoring and analysis of ash deposits, mechanisms and chemistry of fly ash deposition, and key technologies for reducing ash deposition and corrosion in biomass-involved combustion

Forest biomass supply chain optimization for a biorefinery aiming to produce high-value bio-based materials and chemicals from lignin and forestry residues: A review of literature

Technological development has enabled the production of new value-added products from lignocellulosic residues, such as lignin. This has allowed the forest industry to diversify its product portfolio and maximize the economic returns from feedstock, while simultaneously working towards sustainable alternatives to petroleum-based products. Although previous research has explored industrial-scale production opportunities, many challenges persist including the cost of woody biomass and its supply chain reliability. While numerous studies have addressed these issues, their emphasis has traditionally been on bioenergy, with little focus on biochemicals and biomaterials/bio-products. This review seeks to address this gap through a systematic study of the work recently reported by researchers. A lot of work has been published from United States and Canada with an emphasis on bioenergy production (84.8%), 4.6% of the work is focused on biomass-to-materials or chemicals, and 10.6% addressed both. Between 2012 and 2015, the majority of research is focusing on “biomass-to-materials and chemicals” and both “biomass-to-energy and biomass-to-materials and chemicals” were published. This fact highlights recent interests in diversified biorefinery portfolios. However, further work concerning the forest biomass supply chain optimization and new high-value bio-based materials and chemicals is necessary.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Progress of Catalytic Valorization of Bio-Glycerol with Urea into Glycerol Carbonate as a Monomer for Polymeric Materials

Versatile polymers with highly adjustable characteristics and a broad range of applications are possibly developed owing to the contemporary industrial polymerization techniques. However, industrial production of large amounts of chemicals and polymers heavily depends on petroleum resources which are dwindling and unsustainable. Of particular interest is to utilize sustainable and green resources for the manufacture of polymeric materials. The efficient transformation of bio-glycerol to the relevant functional derivatives are being widely investigated owing to the increasing demand for enhancing the value of glycerol manufactured by biodiesel and oleochemical industries. With respect to glycerol-based polymer chemistry and technology, considering the economy and environmental benefits, using effective catalysts for the selective transformation of bio-glycerol and urea into glycerol carbonate (GC) as a polymer monomer is of great significance. In this review, recent studies on GC synthesis involving the catalysts such as zinc, magnesium, tungsten, ionic liquid-based catalysts, reaction conditions, and possible pathways are primarily described. Some critical issues and challenges with respect to the rational development of heterogeneous catalytic materials like well-balanced acid-base sites are also illustrated