The study and modeling of atrazine fate in buffer strips soil

Study on degradation and sorption of atrazine within different species of grass-hedges Vegetative Buffer Strips (VBS) (big bluestem (Andropogon geradi), switchgrass (Panicum virgatum L.), and eastern gamagrass (Tripsacum dactyloides L.)) was conducted. Over seven years eastern gamagrass appeared to be accumulating organic C in both the surface 15 and 15--30 cm soil depths. Soil under eastern gamagrass had the highest mineralization rate of atrazine and the highest atrazine-degrader populations. Atrazine was degraded rapidly in eastern gamagrass soil with the atrazine half-life of 10 days. Atrazine adsorbed to thatch more readily than VBS soil. These data suggested that eastern gamagrass should be used preferential to big bluestem grass and switchgrass for establishing grass-hedges VBS;Preferential flow of bromide and atrazine in the 5 and 9-year-old switchgrass Riparian Buffer Strips (RBS) and their adjacent cropped areas were observed. However, there was little difference in transport characteristics between these two RBS soils and their adjacent cropped soils. Despite similar texture and organic C contents, atrazine sorption was greater in RBS soils than adjacent cropped area soils. Greater sorption would lessen the potential leaching of atrazine to groundwater. Degradation of atrazine was slower under switchgrass RBS compared to the adjacent cropped soil. The rapid degradation of atrazine in the corn-soybean soil adjacent to the 5-year-old RBS was due to a larger population of atrazine-degrading microorganisms, which were also responsible for rapid mineralization of atrazine;Simulation results of atrazine fate after entry into the RBS using the Root Zone Water Quality Model (RZWQM) indicated that the RBS would retain about 79--94% of atrazine in runoff from the adjacent cornfield. The RZWQM predicted very low atrazine concentrations in seepage (\u3c3 mug L --1). Our results suggested that RZWQM underpredicted leaching in the soil profile. Further modifications of the leaching subroutine are needed to correctly predicted pesticide loss in the seepage. Atrazine loss in runoff leaving the RBS was mostly sensitive to macropore size and plant residue load, but less sensitive to organic matter content. However, further study of the relationship between macroporosity and runoff losses of pesticides effectively are needed to verify the model sensitivity to macropores

Alkalinity of Cassava Wastewater Feed in Anodic Enhance Electricity Generation by a Single Chamber Microbial Fuel Cells

This study was demonstrated that the alkaline feeding in the anode chamber could enhance the electricity generation from a single chamber microbial fuel cell (SCMFC). The SCMFC was operated in batch mode. The substrate was cassava wastewater from a flour factory in Roi-Et province, Thailand and the concentration of COD value was controlled between 1,086 ± 50.06 mg/L. The pHs were varied from acidicity (pH 5.0 and 6.0), neutral (pH 7.0) and alkalinity (pH 8.0 and 9.0) by adding NaOH. The temperature was controlled at 30oC. The maximum power density could be generated to 22.19 W/m3 from pH feed at 9.0. Whereas at pH feed of 8.0, the second highest power density at 16.70 W/m3 was gained. The maximum efficiency of COD removal (92.83 ± 1.37%) was obtained from pH of 8.0. The maximum of coulombic efficiency (CE) was 47.8% which was obtained from pH feed of 9.0. The alkalinity feed enhanced the power generation by increasing the alkalinity and conductivity in the anode chamber more than other feeds. It was also found that the pH feed which was nearly close to neutral would enhance the wastewater treatment by SCMFC

Photo-fermentational hydrogen production of Rhodobacter sp. KKU-PS1 isolated from an UASB reactor

Background: In this study, the detection of nifH and nifD by a polymerase chain reaction assaywas used to screen the potential photosynthetic bacteria capable of producing hydrogen from five different environmental sources. Efficiency of photo-hydrogen production is highly dependent on the culture conditions. Initial pH, temperature and illumination intensity were optimized for maximal hydrogen production using response surface methodology with central composite design. Results: Rhodobacter sp. KKU-PS1 (GenBank Accession No. KC478552) was isolated from the methane fermentation broth of an UASB reactor. Malic acid was the favored carbon source while Na-glutamate was the best nitrogen source. The optimum conditions for simultaneously maximizing the cumulative hydrogen production (Hmax) and hydrogen production rate (Rm) from malic acid were an initial of pH 7.0, a temperature of 25.6\ub0C, and an illumination intensity of 2500 lx. Hmax and Rm levels of 1264 ml H2/l and 6.8 ml H2/L-h were obtained, respectively. The optimum initial pH and temperature were further used to optimize the illumination intensity for hydrogen production. An illumination intensity of 7500 lx gave the highest values of Hmax (1339 ml H2/l) and Rm (12.0 ml H2/L-h) with a hydrogen yield and substrate conversion efficiency of 3.88 mol H2/molmalate and 64.7%, respectively. Conclusions: KKU-PS1 can produce hydrogen from at least 8 types of organic acids. By optimizing pH and temperature, a maximal hydrogen production by this strain was obtained. Additionally, by optimizing the light intensity, Rm was increased by approximately two fold and the lag phase of hydrogen productionwas shortened

Biohydrogen production by Thermoanaerobacterium thermosaccharolyticum KKU-ED1: Culture conditions optimization using mixed xylose/arabinose as substrate

Background: Biological hydrogen production by microorganisms can be divided into two main categories i.e. photosynthetic organisms that produce hydrogen using light as energy source and anaerobic bacteria that produce hydrogen via dark fermentation. Dark fermentative hydrogen production by anaerobic bacteria has the advantages of a higher HPR without illumination and of the capability to convert various kinds of substrate. Results: Thermophilic hydrogen producer was isolated from elephant dung and identified as Thermoanaerobacterium thermosaccharolyticum KKU-ED1 by 16S rRNA gene analysis, which was further used to produce hydrogen from mixed pentose sugar i.e., xylose/arabinose. The optimum conditions for hydrogen production from mixed xylose/arabinose by KKU-ED1 were a 1:1 xylose/arabinose mixture at the total concentration of 5 g/L, initial pH of 6.5 and temperature of 55\ubaC. Under the optimum conditions, hydrogen from sugar derived from acid-hydrolyzed sugarcane bagasse at a reducing sugar concentration were achieved. Soluble metabolite product (SMP) was predominantly acetic acid indicating the acetate-type fermentation. Conclusions: The strain KKU-ED1 appeared to be a suitable candidate for thermophilic fermentative hydrogen production from hemicellulosic fraction of lignocellulosic materials due to its ability to use various types of carbon sources

Photo-hydrogen and lipid production from lactate, acetate, butyrate, and sugar manufacturing wastewater with an alternative nitrogen source by Rhodobacter sp. KKU-PS1

Photo-hydrogen and lipid production from individual synthetic volatile fatty acids (VFAs) and sugar manufacturing wastewater (SMW) by Rhodobacter sp. KKU-PS1 with sodium glutamate or Aji-L (i.e., waste from the process of crystallizing monosodium glutamate) as a nitrogen source was investigated. Using individual synthetic VFAs, the maximum hydrogen production was achieved with Aji-L as a nitrogen source rather than sodium glutamate. The maximum hydrogen production was 1,727, 754 and 1,353 mL H2/L, respectively, using 25 mM of lactate, 40 mM of acetate and 15mM of butyrate as substrates. Under these conditions, lipid was produced in the range of 10.6–16.9% (w/w). Subsequently, photo-hydrogen and lipid production from SMW using Aji-L as nitrogen source was conducted. Maximal hydrogen production and hydrogen yields of 1,672 mL H2/L and 1.92 mol H2/mol substrate, respectively, were obtained. Additionally, lipid content and lipid production of 21.3% (w/w) and 475 mg lipid/L were achieved. The analysis of the lipid and fatty acid components revealed that triacyglycerol (TAG) and C18:1 methyl ester were the main lipid and fatty acid components, respectively, found in Rhodobacter sp. KKU-PS1 cells

Biochemical Methane Potential (BMP) of Cattle Manure, Chicken Manure, Rice Straw, and Hornwort in Mesophilic Mono-digestion

Biochemical Methane Potential (BMP) assay was used to investigate the potential of methane production from agricultural wastes and weed. The objective of the study is to investigate the methane production potential from cattle manure, chicken manure, rice straw, and hornwort (Ceratophyllum demersum). The result of the study can be used to choose the most suitable substrate for renewable energy generation as well as to prioritize waste treatment to reduce Greenhouse Gases (GHGs) emission from waste. Cattle manure (CWM), chicken manure (CHM), rice straw (RSW), and hornwort (HNW) were used as substrates for batch anaerobic digestion under mesophilic condition at 35 °C using 500 mL glass bottles and working volume of 350 mL with substrate at inoculum to substrate ratio (ISR) of 1:1 based on Volatile Solids (VS) weight (g VS). Parameters observed including biogas production, biogas composition, methane production, and specific methane yield. Results showed that among four substrates, RSW had the highest total biogas production of 3773.33 mL, while the lowest was CHM with 1443.00 mL. In term of the biogas composition, HNW had the highest methane proportion of 66.68% among all substrates used, while RSW had the lowest proportion (62.50%). Furthermore, the highest methane production was from RSW at 2135.52 mL and the lowest was from CHM at 736.28 mL. In addition, the highest specific methane yield was obtained from RSW with a total of 331.99 NmL CH4/g VS, while CHM had the lowest yield with 114.55 NmL CH4/g VS. From results of the study, RSW was found to be a very promising substrate for a potential source of renewable energy with a high methane yield

Evaluation of xylose-utilising yeasts for xylitol production from second generation ethanol vinasse and effect of agitation intensity in flask-scale xylitol production

This study aimed to select a yeast strain that effectively utilises xylose to produce xylitol from the vinasse of ethanol broth obtained from the fermentation of sugarcane bagasse hydrolysate. Eleven strains of xylose-fermenting yeasts were evaluated for their abilities to utilise xylose and produce xylitol. Two strains that showed outstanding performance in the semi-defined xylose medium were selected for further testing with a vinasse medium. Candida guilliermondii TISTR 5068 showed a superior xylitol production of 7.03 ± 0.08 g/L with the xylitol yield of 0.70 g/ gxylose when cultured in bagasse-based ethanol vinasse. The strain was further tested for its xylitol production performance when cultured at four different agitation intensities. Excessive agitation resulted in a rapid xylitol production rate but caused xylitol consumption once the xylose was depleted. Moderate agitation resulted in the highest xylitol yield of 0.79 g/gxylose. The results of this study have provided important information for the development of the xylitol production process using waste streams from cellulosic ethanol production

Bio-hydrogen and Methane Production from Lignocellulosic Materials

This chapter covers the information on bio-hydrogen and methane production from lignocellulosic materials. Pretreatment methods of lignocellulosic materials and the factors affecting bio-hydrogen production, both dark- and photo-fermentation, and methane production are addressed. Last but not least, the processes for bio-hydrogen and methane production from lignocellulosic materials are discussed