Alissara Reungsang

Ubiquitous occurrence of sulfonamides in tropical Asian waters.

Seven sulfonamides, trimethoprim, five macrolides, lincomycin and three tetracyclines were measured in 150 water samples of sewage, livestock and aquaculture wastewater, and river and coastal waters, in five tropical Asian countries. The sum of the concentrations of the target antibiotics in sewage and heavily sewage-impacted waters were at sub- to low-ppb levels. The most abundant antibiotic was sulfamethoxazole (SMX), followed by lincomycin and sulfathiazole. The average concentration of SMX in sewage or heavily sewage-impacted waters was 1720 ng/L in Vietnam (Hanoi, Ho Chi Minh, Can Tho; n=15), 802ng/L in the Philippines (Manila; n=4), 538 ng/L in India (Kolkata; n=4), 282 ng/L in Indonesia (Jakarta; n=10), and 76 ng/L in Malaysia (Kuala Lumpur; n=6). These concentrations were higher than those in Japan, China, Europe, the US and Canada. A predominance of sulfonamides, especially SMX, is notable in these tropical countries. The higher average concentrations, and the predominance of SMX, can be ascribed to the lower cost of the antibiotics. Both the concentration and composition of antibiotics in livestock and aquaculture wastewater varied widely. In many cases, sulfamethazine (SMT), oxytetracycline (OTC), lincomycin, and SMX were predominant in livestock and aquaculture wastewater. Both human and animal antibiotics were widely distributed in the respective receiving waters (i.e., the Mekong River and Manila Bay). SMT/SMX ratios indicate a significant contribution from livestock wastewater to the Mekong River and nearby canals, with an estimated ~10% of river water SMX derived from such wastewater. Mass flow calculations estimate that 12 tons of SMX is discharged annually from the Mekong River into the South China Sea. Riverine inputs of antibiotics may significantly increase the concentration of such antibiotics in the coastal waters.

Delignification of disposable wooden chopsticks waste for fermentative hydrogen production by an enriched culture from a hot spring

Hydrogen (H2) production from lignocellulosic materials may be enhanced by removing lignin and increasing the porosity of the material prior to enzymatic hydrolysis. Alkaline pretreatment conditions, used to delignify disposable wooden chopsticks (DWC) waste, were investigated. The effects of NaOH concentration, temperature and retention time were examined and it was found that retention time had no effect on lignin removal or carbohydrate released in enzymatic hydrolysate. The highest percentage of lignin removal (41%) was obtained with 2% NaOH at 100°C, correlated with the highest carbohydrate released (67 mg/g pretreated DWC) in the hydrolysate. An enriched culture from a hot spring was used as inoculum for fermentative H2 production, and its optimum initial pH and temperature were determined to be 7.0 and 50°C, respectively. Furthermore, enzymatic hydrolysate from pretreated DWC was successfully demonstrated as a substrate for fermentative H2 production by the enriched culture. The maximum H2 yield and production rate were achieved at 195 mL H2/g total sugars consumed and 116 mL H2/(L·day), respectively.

Poly-β-hydroxyalkanoates production from cassava starch hydrolysate by Cupriavidus sp. KKU38

A bacterium capable of accumulating polyhydroxyalkanoates (PHAs), Cupriavidus sp. KKU38 (GenBank Accession no. AM260479), was isolated from cassava starch wastewater of cassava starch manufacturing process. KKU38 can utilize glucose, fructose, maltose and xylose for PHA production. Glucose was the most suitable sugar for PHA production giving the highest PHA content and yield of 73.88% and 0.16 g/g-total sugar consumed, respectively. Lactose and sucrose were not suitable carbon sources for both biomass and PHA productions. PHA production from cassava starch hydrolysate (CSH) by the strain KKU38 was maximized under N-limited conditions (COD:N:P of 100:1:2.43). The moderately high biomass concentrations of 5.97 g/L with PHA content and yield of 61.60% and 0.20 g/g-total sugar consumed, respectively, were obtained under the optimum conditions. The analysis of PHA produced under the optimum conditions by (1)H NMR, (13)C NMR and FT-IR indicated that the produced polymer is homopolymer polyhydroxybutyrate (PHB).

Polyhydroxyalkanoates production from effluent of hydrogen fermentation process by Cupriavidus sp. KKU38

This study investigated the use of the residual sugar and volatile fatty acids (VFAs) in the effluent of the hydrogen production process to produce polyhydroxyalkanoates (PHAs) by Cupriavidus sp. KKU38 in batch fermentation. VFAs in the effluent were lactic, butyric, acetic and propionic acids with a total VFA concentration of 1725 mg/L. The C/N ratio of effluent was 100:2.5, which is defined as the excess carbon and limited nitrogen condition suitable for PHA production. The experiments were conducted in 250-mL Erlenmeyer flasks with a 100 mL working volume. The inoculum size was 30% (v/v) with the initial number of cells 106 cells/mL. Residual sugars and acetic acid in the effluent were the major substrates used to produce PHAs while lactic and butyric acids in the effluent were used for biomass synthesis. The maximum PHA concentration and PHA content obtained were 0.85 g/L and 71.42% (w/w) of dry biomass weight, respectively. After fermentation, carbon oxygen demand (COD) in the effluent was reduced by up to 82.73%.

Enhancement of biohydrogen production from sweet sorghum syrup by anaerobic seed sludge in an anaerobic sequencing batch reactor by nutrient and vitamin supplementations.

This study attempted to enhance biohydrogen production from sweet sorghum syrup by anaerobic seed sludge in a 1.3 L (1 L working volume) anaerobic sequencing batch reactor (ASBR) by supplementation with nutrients and vitamins. Four treatments, i.e. nutrient and vitamin supplementation, only nutrient supplementation, no supplements and only vitamin supplementation, were conducted using 30 g/L sweet sorghum syrup as the substrate with 1.45 g/L FeSO 4 in ASBR. The ASBR was operated at 24 hour hydraulic retention time at a controlled pH of 5.0. Results indicated that nutrient and vitamin supplementations could increase hydrogen production rate (HPR; 3.2 L H 2/L− d ) and hydrogen yield (HY; 1.6 mol H 2/mol hexose) up to 5 fold in comparison to the control (0.6 L H 2/L− d and 0.34 mol H 2/mol hexose, respectively). The polymerase chain reaction-denatured gradient gel electrophoresis analysis indicated that the predominant hydrogen producers were Clostridia species. The higher hydrogen production obtained from the treatments with nutrient supplementation might be due to the presence of Clostridia species together with Klebsiella sp. and Desulfovibrio sp. Lack of nutrients in treatments without the supplementation and in treatment where only vitamin solution was added could lead to the reduction of hydrogen production efficiency of Clostridia species. The presence of lactic acid bacteria, i.e. Enterococcus sp. and Lactobacillus sp., caused an adverse effect on hydrogen-producing bacteria, resulting in a low HPR and HY in these two treatments.

Effect of biogas sparging on the performance of bio-hydrogen reactor over a long-term operation.

This study aimed to enhance hydrogen production from sugarcane syrup by biogas sparging. Two-stage continuous stirred tank reactor (CSTR) and upflow anaerobic sludge blanket (UASB) reactor were used to produce hydrogen and methane, respectively. Biogas produced from the UASB was used to sparge into the CSTR. Results indicated that sparging with biogas increased the hydrogen production rate (HPR) by 35% (from 17.1 to 23.1 L/L.d) resulted from a reduction in the hydrogen partial pressure. A fluctuation of HPR was observed during a long term monitoring because CO2 in the sparging gas and carbon source in the feedstock were consumed by Enterobacter sp. to produce succinic acid without hydrogen production. Mixed gas released from the CSTR after the sparging can be considered as bio-hythane (H2+CH4). In addition, a continuous sparging biogas into CSTR release a partial pressure in the headspace of the methane reactor. In consequent, the methane production rate is increased.

Selection of support materials for immobilization of Burkholderia cepacia PCL3 in treatment of carbofuran-contaminated water

This study investigated the utilization of agricultural matrices as the support materials for cell immobilization to improve the technique of bioremediation. Coir, bulrush, banana stem and water hyacinth stem in both delignified and undelignified forms were used to immobilize Burkholderia cepacia PCL3 in bioremediation of carbofuran at 5 mg l−1 in synthetic wastewater. Undelignified coir was found to be the most suitable support material for cell immobilization, giving the short half-life of carbofuran of 3.40 d (2.8 times shorter than the treatments with free cells). In addition, it could be reused three times without a loss in ability to degrade carbofuran. The growth and degradation ability of free cells were completely inhibited at the initial carbofuran concentrations of 250 mg l−1, while there was no inhibitory effect of carbofuran on the immobilized cells. The results indicated a great potential for using the agricultural matrices as support material for cell immobilization to improve the overall efficiency of carbofuran bioremediation in contaminated water by B. cepacia PCL3.

Water environment conservation in a closed water body by high concentrated oxygen water.

In this study, the method of using high concentrated oxygen water to purify the bottom sediment was confirmed to be effective. The high concentrated oxygen dissolver was developed and the lab scale experiment was performed. High rate, high efficiency oxygen dissolver was developed, the optimum running condition of the apparatus and the method of producing high concentrated oxygen water was discussed and determined in this study. In addition, the effective prevention of phosphorus release from anaerobic bottom sediment was also studied. As a result, it is found that high concentrated oxygen water was effective for prevention of phosphorus release from anaerobic bottom sediment. On the basis of the fundamental knowledge from the laboratory-scale study, pilot scale apparatus was set up and the pilot study was carried out. It is showed that the introduction of high concentrated oxygen water did not destroy the thermocline of dam reservoir.

Hydrogen from Photo Fermentation

Hydrogen is considered to be a promising future fuel for the transportation sector due to its zero carbon emissions and high energy capacity by mass. Nevertheless, an energy-saving and environmentally friendly hydrogen production pathway has not yet been achieved on an industrial scale. Hydrogen may be produced from waste streams during photofermentation using purple non-sulfur bacteria (PNSB). This process has unique advantages, such as high hydrogen yield and environment benefits. This chapter provides an overview of PNSB and its enzyme system used in photofermentative hydrogen production, factors affecting fermentation, and hydrogen production from industrial waste, wastewater, and agricultural biomass. Both suspension and immobilized cultures of PNSB used in various types of photobioreactors are discussed in detail. Furthermore, the fluid flow and mass transfer in bioreactors using lattice Boltzmann simulation are presented. Enhancement strategies and perspectives of photofermentative hydrogen production are also outlined.

Drag reduction and shear-induced cells migration behavior of microalgae slurry in tube flow

To optimize the designing of microalgae slurry pumping system and enhance the efficiency of microalgae products production, the flow characteristics of microalgae slurries (Chlorella pyrenoidosa) in tube flow were for the first time investigated combining experiments and numerical simulation. The drag reduction behavior of microalgae slurry in the fully developed laminar flow regime was studied. In addition, the transition Reynolds number of microalgae slurries from laminar flow to turbulent flow was about 1000-1300, which was similar to the expression of two-phase flow. To provide a further understanding of flow feature of microalgae slurries in tube, a two-phase mixture model was proposed by considering the heterogeneity of concentration due to the shear-induced microalgae cells migration behavior. Simulation results revealed that the heterogeneous distribution of concentration was affected by average velocity and volume fraction of microalgae slurries, significantly affecting the flow resistance and flow stability of microalgae slurry in the tube flow.