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Recently, microbial polyhydroxyalkanoates (PHA) were proposed as an alternative biofuel, termed 3-hydroxyalkanoate methyl ester (3HAME). PHA is a strong candidate to make biofuels and be used in the fuel additive market today. However, an optimization study of 3HAME from PHA has never been reported. In this paper, 3HBME was produced from polyhydroxybutyrate (PHB) via acid catalyst. The effects of acid types and concentration, alcohol, reaction temperature and time were determined. The optimal conditions for 3HBME production were methanol with 10% (v/v) H 2 SO 4 under a reaction temperature and a time of 67°C and 50 h, respectively. The highest yield of 3HBME (70.7%) was obtained under these optimal conditions. 3HBME was further characterized for chemical and fuel related properties following ASTM. The characteristics of 3HBME including acid value, free fatty acid, saponification and molecular mass were 2.16, 0.0098, 60.27 and 2792.434, respectively. The 3HBME properties were also compared with Thailand and ASTM standards. Almost all of the properties passed these standards. [ABSTRACT FROM AUTHOR]

Stillage, a liquid waste remaining after ethanol distillation, was collected and characterized. The liquid stillage contained reducing sugars (fructose and glucose) and volatile fatty acids including acetic acid, propionic acid and butyric acid. 1.48 g/L of reducing sugar was found in raw stillage. Therefore, the stillage was able to be utilized as a substrate for ethanol production. The production of ethanol from stillage was done using different glucose concentrations [10,20, 40 and control (raw material, no glucose addition)] and different microorganisms including Saccharomyces cerevisiae and Enterobacter aerogenes . In addition, the mix-culture of S. cerevisiae and E. aerogenes for ethanol production was also evaluated. The process was done under batch fermentation at 35 o C, 100 rpm for 96 h. The results showed that mix-culture between S. cerevisiae and E. aerogenes yield the highest ethanol (1.762 g ethanol/ g sugar) after 72 h of cultivation using the raw stillage (non-glucose addition) as a substrate. [ABSTRACT FROM AUTHOR]

The production of biofuels including ethanol and hydrogen from agricultural waste is being concern as a renewable energy. Pineapple peel, a by-product of the pineapple processing industry, account for 29-40% (w/w) of total pineapple weight. 36.25±2.87% of cellulose was achieved from pineapple peel after pretreatment with water and heat at 100oC for 4h. Afterwards, 0.5% (w/w) cellulase from Aspergillus niger (Sigma) was added for enzymatic hydrolysis. The maximum sugar production (34.03±1.30g/L) was obtained after 24h of incubation time. The enzyme hydrolysate was utilized as fermentation medium, with no nutritional addition to produce ethanol and hydrogen by Saccharomyces cerevisiae TISTR 5048 and Enterobacter aerogenes TISTR 1468. The maximum yield of ethanol (9.69g/L) with no hydrogen production by S. cerevisiae was achieved after 72h. However, the maximum ethanol and hydrogen from E. aerogenes were 1.38g/L and 1,416mL/L after 72h and 12h of cultivation, respectively. In addition, the 1.2-folds of biofuel production were increased when immobilized bacterial cell in matrix of loofah. [ABSTRACT FROM AUTHOR]