• Journal of Environmental Science International
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• v.31 no.7
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• pp.609-616
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• 2022

In this study, the effect of different reaction times for thermal-alkaline pretreatment on the solubilization and biogasification of polyhydroxybutyrate (PHB) were evaluated. Thermal-alkaline pretreatment tests were performed at 73 ℃ and pH 13 at 0-120 h reaction times. The mesophilic anaerobic batch tests were performed with untreated and pretreated PHB samples. The increase in the pretreatment reaction time results in a 52.8-98.8% increase of the abiotic solubilization efficiency of the PHB samples. The reaction time required to achieve solubilization efficiencies of 50%, 90%, and 95% were 10.5, 52.0, and 89.6 h, respectively. The biogasification of the untreated PHB samples achieved a specific methane production rate of 3.6 mL CH₄/g VSS/d and require 101.3 d for complete biogasification. The thermal-alkaline pretreatment significantly improved specific methane production rate (10.2-16.0 time increase), lag time (shortened by 76-81%), and time for complete biogasification (shortened by 21-83%) for the biogasification of the PHB samples when compared to those of the untreated PHB samples. The improvement was higher as the reaction time of the thermal-alkaline pretreatment increased. The findings of this study could be used as a valuable reference for the optimization of the biogasification process in the treatment of PHB wastes.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.183-192
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• 2015

Response surface methodology (RSM) based on a Box-Behnken Design (BBD) was applied to optimize the thermal-alkaline pre-treatment operating conditions for anaerobic digestion of flotation scum in food waste leachate. Three independent variables such as thermal temperature, NaOH concentration and reaction time were evaluated. The maximum methane production of 369.2 mL $CH_4/g$ VS was estimated under the optimum conditions at $62.0^{\circ}C$, 10.1% NaOH and 35.4 min reaction time. A confirmation test of the predicted optimum conditions verified the validity of the BBD with RSM. The analysis of variance indicated that methane production was more sensitive to both NaOH concentration and thermal temperature than reaction time. Thermal-alkaline pretreatment enhanced the improvement of 40% in methane production compared to the control experiment due to the effective hydrolysis and/or solubilization of organic matters. The fractions with molecular weight cut-off of scum in food waste leachate were conducted before and after pre-treatment to estimate the behaviors of organic matters. The experiment results found that thermal-alkaline pre-treatment could reduce the organic matters more than 10kD with increase the organic matters less than 1kD.

• Journal of the Korean Wood Science and Technology
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• v.22 no.3
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• pp.32-38
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• 1994

The methods in wood processing are so limited at present that a scope of its utilization is restricted. This often makes wood itself less valuable as a material comparing with other materials, that is, plastics, metals, and glass. Such differences are due to a lack of plasticity in wood, i.e. it cannot be melted, dissolved, or softened sufficiently for molding. However, once plastic properties are added to wood, it becomes more useful material. This further broadens the method in wood processing to a variety of fields. In this way, wooden material which is limited in use can be modified into a high quality product with additional value. Furthermore, utilization of wastes from wood, for example, would be made viable. In this study, thermoplasticization was carried out by benzylation of wood(sawdust). Various factors those affect the reaction were tested to produce benzylated wood with different degrees of substitution. Reaction temperature and time were the quite important factors. Optimum reaction temperature was 110$^{\circ}C$, and weight percent gains(WPG) of final products increased gradually with the increase of reaction time. The pretreatment (or preswelling) of wood with alkaline solution had a critical effect on benzylation. and the concentration of alkaline solution should be above 30% to obtain high weight percent gain. The thermal flow temperature of the benzylated wood decreased with the increase in weight percent gain, that of 80% weight percent gain is about 200$^{\circ}C$.

• Transactions of the Korean hydrogen and new energy society
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• v.26 no.1
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• pp.71-78
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• 2015

This study was performed to optimize the integrated thermal-alkali pre-treatment of flotation scum for the enhanced biodegradability. The optimum conditions of the integrated thermal-alkali pre-treatment were obtained using response surface methodology. The disintegration degree of carbohydrate (69.2%) and protein (57.3) were estimated under the optimum conditions. Although the optimum conditions were different, the disintegration degrees were similarly. A fermentative hydrogen batch test was conducted to evaluate the hydrogen production from scum with and/or without. The maximum hydrogen production from scum with pre-treatment was of 0.64 mol H2/mol hexoseadded, which about 1.4 times higher than without pre-treatment.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.1
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• pp.90-98
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• 2001

The slow degradation rate of sewage sludge in anaerobic digesters is due to the rate limiting step of sludge hydrolysis. Therefore, the pre-treatment process had been carried out using acidic(pH 1.5, 3, 4, 5) and alkaline(pH9, 10, 13), thermal(50, 100, 150, $200^{\circ}C$) and ultrasonic treatment(400W, 20kHz, 15, 20, 25, 30, 35, 40, 50, 60min). In the best conditions of each treatment, the SCOD ratio(%) of treated/untreared samples were increased 102% in acid(pH5), 986% in alkali(pH13), 959% in thermal($200^{\circ}C$) and 1123% in ultrasonic(35min) treatment. As the result, the ultrasonic treatment was most effective, followed by alkali, thermal, acidic treatment. In the effects of total gas productivity, the thermal($200^{\circ}C$) pretreatment was the highest, followed by thermal($150^{\circ}C$), ultrasonic(90min), alkaline(pH9) and ultrasonic(50min).