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Thermoanaerobacterium-rich sludge was used for hydrogen production and phenol removal from palm oil mill effluent (POME) in the presence of phenol concentration of 100–1000 mg/L. Thermoanaerobacterium-rich sludge yielded the most hydrogen of 4.2 L H2/L-POME with 65% phenol removal efficiency at 400 mg/L phenol. Butyric acid and acetic acid were the main metabolites. The effects of oil palm ash, NH4NO3 and iron concentration (Fe2+) on hydrogen production and phenol removal efficiency from POME by Thermoanaerobacterium-rich sludge was investigated using response surface methodology (RSM). The RSM results indicated that the presence of 0.2 g Fe2+/L, 0.3 g/L NH4NO3 and 20 g/L oil palm ash in POME could improved phenol removal efficiency, with predicted hydrogen production and phenol removal efficiency of 3.45 L H2/L-POME and 93%, respectively. In a confirmation experiment under optimized conditions highly reproducible results were obtained, with hydrogen production and phenol removal efficiency of 3.43 ± 0.12 L H2/L-POME and 92 ± 1.5%, respectively. Simultaneous hydrogen production and phenol removal efficiency in continuous stirred tank reactor at hydraulic retention time (HRT) of 1 and 2 days were 4.0 L H2/L-POME with 85% and 4.2 L H2/L-POME with 92%, respectively. Phenol degrading Thermoanaerobacterium-rich sludge comprised of Thermoanaerobacterium thermosaccharolyticum, Thermoanaerobacterium aciditolerans, Desulfotomaculum sp., Bacillus coagulans and Clostridium uzonii. Phenol degrading Thermoanaerobacterium-rich sludge has great potential to harvest hydrogen from phenol-containing wastewater.

A biodiesel wastewater treatment technology was investigated for neutral alkalinity and COD removal by microbial fuel cell. An upflow bio-filter circuit (UBFC), a kind of biocatalyst MFC was renovated and reinvented. The developed system was combined with a pre-fermented (PF) and an influent adjusted (IA) procedure. The optimal conditions were operated with an organic loading rate (OLR) of 30.0 g COD/L-day, hydraulic retention time (HRT) of 1.04 day, maintained at pH level 6.5-7.5 and aerated at 2.0 L/min. An external resistance of circuit was set at 10 kΩ. The purposed process could improve the quality of the raw wastewater and obtained high efficiency of COD removal of 15.0 g COD/L-day. Moreover, the cost of UBFC system was only US$1775.7/m3 and the total power consumption was 0.152 kW/kg treated COD. The overall advantages of this invention are suitable for biodiesel wastewater treatment.

Sediment samples from hot spring were enriched for hydrogen-producing bacteria with xylose, glucose and mixed of both sugars at high temperature (60 °C). Enriched cultures encoded as PGR and YLT showed high cumulative hydrogen production in xylose–glucose mixed and xylose with hydrogen evolution of 1506 and 1487 mL H2/L-medium and hydrogen yields of 301.3 and 297.4 mL H2/g sugarconsumed, respectively. The enriched cultures coded PGR and YLT were produced acetate and butyrate as main soluble metabolites with high hydrogen production. PCR-DGGE profiling showed that the enriched cultures gave best hydrogen production from xylose–glucose mixed comprised of three groups of hydrogen-producing species, (A) relating to genus Bacillus sp. and Anoxybacillus sp., (B) relating to genus Caloramator sp. and Clostridium sp. and (C) relating to efficient hydrogen-producing species (Thermoanaerobacterium sp. and Caldicellulosiruptor sp.). These microbial consortia developed show promising to apply for biohydrogen production from lignocellulosic hydrolysate containing xylose–glucose mixed.

Xylose and glucose are the major sugar components of lignocellulosic hydrolysate. This study aims to develop thermophilic hydrogen-producing consortia from eight sediments-rich samples of geothermal springs in Southern Thailand by repeated batch cultivation at 60 °C with glucose, xylose and xylose–glucose mixed substrates. Significant hydrogen production potentials were obtained from thermophilic enriched cultures encoded as PGR and YLT with the maximum hydrogen yields of 241.4 and 231.6 mL H2/g sugarconsumed, respectively. After repeated batch cultivation the hydrogen yield from xylose–glucose mixed substrate of PGR increased to 375 mL H2/g sugarconsumed which was 30% higher than that of YLT (287 mL H2/g sugarconsumed). Soluble metabolites from xylose–glucose mixed substrates were composed mostly of butyric acid (20.6–21.8 mM), acetic acid (7.2–13.5 mM), lactic acid (8.2–11.7 mM) and butanol (4.4–13.0 mM). Denaturing gradient gel electrophoresis (DGGE) profiles illustrated small difference in microbial patterns of PGR enriched with glucose, xylose–glucose mixed substrate and xylose. The dominant populations were affiliated with low G + C content Gram-positive bacteria, Thermoanaerobacterium sp., Thermoanaerobacter sp., Caloramater sp. and Anoxybacillus sp. based on the 16S rRNA gene. Cultivation of the enriched culture PGR in oil palm trunk hydrolysate, the maximum hydrogen yield of 301 mL H2/g sugarconsumed was achieved at hydrolysate concentration of 40% (v/v). At higher concentration to 80% (v/v), the hydrogen fermentation process was inhibited. Therefore, the efficient thermophilic hydrogen-producing consortia PGR has successfully developed and has great potential for production of biohydrogen from mixed sugars hydrolysate.

Natural microbial consortia from hot spring samples were used to developed thermophilic mixed cultures for biohydrogen production from cassava starch processing wastewater (CSPW). Significant hydrogen production potentials were obtained from three thermophilic mixed cultures namely PK, SW and PR with maximum hydrogen production yields of 249.3, 180 and 124.9 mL H2/g starch, respectively from raw cassava starch and 252.4, 224.4 and 165.4 mL H2/g starch, respectively from gelatinized cassava starch. Acetic acid-ethanol and acetic-lactic acid type fermentation were observed in cassava starch fermentation, based on three thermophilic mixed cultures performance. The thermophilic mixed cultures PK, SW and PR exhibited the maximum hydrogen yield of 287, 264 and 232 mL H2/g starch in CSPW, respectively corresponding to 53%, 48.7% and 42.8% of the theoretical values. Phylogenetic analysis of thermophilic mixed cultures revealed that members involved cassava starch degrading bacteria and hydrogen producers in both raw cassava starch and CSPW were phylogenetically related to the Thermoanaerobacterium saccharolyticum, Thermoanaerobacterium thermosaccharolyticum, Anoxybacillus sp., Geobacillus sp. and Clostridium sp.

In southernmost Thailand, big scale production of catfish demands a development of new lines of catfish-based products to fully utilize the raw material. Pla-duk-ra (dried fermented catfish) is one such innovation. Traditional method of sunlight drying is commonly used to dry Pla-duk-ra. However, products are highly prone to contamination since they are dried in exposed area. Direct exposure to sunlight could also affect heat labile and light-sensitive nutrients. In this study, other methods of drying were investigated to dry Pla-duk-ra with improved hygiene practice, physical properties and sensory profile. Two scenarios were studied in this work. The objective of the first scenario was to determine the best range of temperature to dry a good and acceptable Pla-duk-ra by comparing open sun drying (range 40˚C to 50˚C) and shade drying (under the roof; 30˚C to 40˚C) . The best range of temperature obtained was then used for the second scenario where open sun, infrared and tray drying were further studied. Moisture content, water activity, colour, texture profile analysis were performed on the Pla-duk-ra samples. Fried Pla-duk-ra was used in sensory evaluation to investigate consumer’s acceptance and preference. Open sun drying was found to be more superior to dry Pla-duk-ra resulting in darker shade of product as compared to shade drying. The moisture content for open sun drying and shade drying of Pla-duk-ra were reported 23.65% and 28.06%, respectively. Infrared heater gave the highest water activity (0.77) with the highest score for redness. Meanwhile, Pla-duk-ra dried under the hot-air tray resulted in the highest score for brightness (L*). Overall acceptance by the consumer showed that the Pla-duk-ra dried under the hot-air tray was the most preferred followed by open sun drying and infrared heater drying. To this end, hot-air tray drying could be applied in drying Pla-duk-ra in large scale production.