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The feasibility of pretreatment involving soaking in aqueous ammonia (SAA) for the anaerobic digestion (AD) of eight different types of agricultural biomass of Ugandan origin was investigated. Moderate pretreatment temperatures of 60 and 90 °C were employed, and the NH3 concentration, solid-to-liquid ratio, and pretreatment time were fixed at 15.0% (w/w), 1:6, and 6 h, respectively. The delignification efficiencies of the SAA pretreatment ranged from 51.1 to 76.6%, and the maximum value was observed for maize bran pretreated at 90 °C. Biochemical methane potential experiments proved that the breaking of the complex bonds of lignin made fermentable sugars easily accessible to microorganisms. In all cases, the SAA pretreatment enhanced the methane potential of the eight types of Ugandan biomass compared with its untreated counterparts. The pretreated maize bran exhibited the highest methane yield of 291.5 mL CH4/g COD, which is 83.1% of the theoretical conversion. SAA followed by AD is useful for employing Ugandan agricultural biomass as a renewable energy source. [ABSTRACT FROM AUTHOR]

Abstract Pretreatment of the empty fruit brunch (EFB) from oil palm was investigated for H 2 fermentation. The EFB was hydrolyzed at various temperatures, H 2 SO 4 concentrations, and reaction times. Subsequently, the acid-hydrolysate underwent enzymatic saccharification under various temperature, pH, and enzymatic loading conditions. Response surface methodology derived the optimum sugar concentration (SC), hydrogen production rate (HPR), and hydrogen yield (HY) as 28.30 g L−1, 2601.24 mL H 2 L−1d−1, and 275.75 mL H 2 g−1 total sugar (TS), respectively, at 120 °C, 60 min of reaction, and 6 vol% H 2 SO 4 , with the combined severity factor of 1.75. Enzymatic hydrolysis enhanced the SC, HY, and HPR to 34.52 g L−1, 283.91 mL H 2 g−1 TS, and 3266.86 mL H 2 L−1d−1, respectively, at 45 °C, pH 5.0, and 1.17 mg enzyme mL−1. Dilute acid hydrolysis would be a viable pretreatment for biohydrogen production from EFB. Subsequent enzymatic hydrolysis can be performed if enhanced HPR is required. Highlights • Dilute acid and enzymatic hydrolysis were optimized for oil palm empty fruit bunch. • Response surface methodology was used for optimization of pretreatment. • Dilute acid hydrolysis effectively pretreated the biomass for H 2 fermentation. • Subsequent enzymatic saccharification enhanced H 2 production rate. [ABSTRACT FROM AUTHOR]

The native form of lignocellulosic biomass is resistant to enzymatic breakdown. A well-designed pretreatment that can promote enzymatic hydrolysis of biomass with reasonable processing cost is therefore necessary. To this end, a number of different types of pretreatment technologies have been developed with a common goal of making biomass more susceptible to enzymatic saccharification. Among those, a pretreatment method using alkaline reagent has emerged as one of the most viable process options due primarily to its strong pretreatment effect and relatively simple process scheme. The main features of alkaline pretreatment are that it selectively removes lignin without degrading carbohydrates, and increases porosity and surface area, thereby enhancing enzymatic hydrolysis. In this review, the leading alkaline pretreatment technologies are described and their features and comparative performances are discussed from a process viewpoint. Attempts were also made to give insights into the chemical and physical changes of biomass brought about by pretreatment. [ABSTRACT FROM AUTHOR]

Abstract: This study compares the efficacy of soaking and percolation pretreatments with alkaline solutions for lignocellulosic biomass. The pretreated biomasses underwent enzymatic hydrolysis. Various biomasses such as rice straw and barley were pretreated by soaking processes in various alkaline solutions including sodium hydroxide, potassium hydroxide, aqueous ammonia and sodium carbonate. The enzymatic digestibility of rice straw and barley that had been pretreated by soaking in aqueous ammonia was 85% and 95%, respectively. Eucalyptus residue, Larix leptolepis and Pinus rigida exhibited relatively low enzymatic digestibility in the range of 3.2%–8.3%. Nevertheless, the enzymatic digestibility of pretreated eucalyptus residue was increased by five times compared to that of the initial biomass. In the pretreatment of eucalyptus residue, delignification was more than doubled with percolation pretreatment compared to soaking pretreatment. The enzymatic digestibility of the percolation pretreated eucalyptus residue was increased 12 times. [Copyright &y& Elsevier]

Abstract: The current status and challenges associated with the production and utilization of cellulosic ethanol in Korea are reviewed in this paper. Cellulosic ethanol has emerged as a promising option for mitigating Korea’s CO2 emissions and enhancing its energy security. Korea’s limited biomass resources is the most critical barrier to achieving its implementation targets for cellulosic ethanol. Efforts to identify new suitable biomass resources for cellulosic ethanol production are ongoing and intensive. Aquatic biomasses including macroalgae and plantation wastes collected in the Southeast Asia region have been found to have great potential as feedstocks for the production of cellulosic ethanol. R&D explorations into the development of technologies that can convert biomass materials to ethanol more efficiently also are underway. It is expected that cellulosic ethanol will be in supply from 2020 and that, by 2030, its use will have effectively reduced Korea’s total gasoline consumption by 10%. [Copyright &y& Elsevier]

Abstract: Liberation of fermentable sugars from recalcitrant lignocellulosic biomass is one of the key challenges in production of cellulosic ethanol. Here we developed a two-stage pretreatment process using aqueous ammonia and dilute sulfuric acid in a percolation mode to improve production of fermentable sugars from rice straw. Aqueous NH3 was used in the first stage which removed lignin selectively but left most of cellulose (97%) and hemicellulose (77%). Dilute acid was applied in the second stage which removed most of hemicellulose, partially disrupted the crystalline structure of cellulose, and thus enhanced enzymatic digestibility of cellulose in the solids remaining. Under the optimal pretreatment conditions, the enzymatic hydrolysis yields of the two-stage treated samples were 96.9% and 90.8% with enzyme loadings of 60 and 15FPU/g of glucan, respectively. The overall sugar conversions of cellulose and hemicellulose into glucose and xylose by enzymatic and acid hydrolysis reached 89.0% and 71.7%, respectively. [Copyright &y& Elsevier]