Performance of a biotrickling filter employing Thiobacillus thioparus immobilized on polyurethane foam for hydrogen sulfide removal

The removal of hydrogen sulfide [H[2]S] from contaminated airstream was studied in a biotrickling filter [BTF] packed with open-pore polyurethane foam as a carrier of Thiobacillus thioparus [DSMZ5368] with counter current gas/liquid flows. The effect of operating parameters on BTF performance was studied. Experiments were performed at different Empty Bed Residence Times [EBRT] from 9 to 45 seconds, and different initial H[2]S concentration from 25 to 85 ppm. The results showed reasonable performance of the BTF, in H[2]S removal from the synthetic gas stream. However, the performance was somewhat lower than other studies in BTF in which either Thiobacillus thioparus with other packings or polyurethane foam with other microbial cultures were used. The effect of liquid recirculation rate [LRR] in the range of 175-525 ml/min [0.46-1.34 m/h] on BTF performance was also studied. Results showed that increasing LRR from 175 to 350 mL/min resulted in significant enhancement of H2S removal efficiency, but further increase in LRR up to 525 mL/min had an insignificant effect. H[2]S elimination at different heights of the bed was studied and it was found that decrease in EBRT results in more homogeneous removal of the pollutant in BTF. Determination of microbial species in the BTF after 100 days performance showed that during BTF operation the only H[2]S degrading specie was Thiobacillus thioparus

use of a submerged membrane bioreactor for the treatment of a styrene containing synthetic wastewater

In this study, the potential of a membrane bioreactor for treating styrene contaminated synthetic wastewater, with COD that simulated a petrochemical wastewater, was evaluated and compared with previous studies. At hydraulic retention times of 18 and 24 hours, the removal efficiency of COD and styrene was consistently higher than 99%. More significantly no styrene was detected in the exhaust air, which meant that, at both hydraulic retention times, the mechanism of styrene removal in the membrane bioreactor was exclusively through biodegradation. The lower contribution of stripping to overall styrene removal obtained in the present work compared to that previously reported for traditional activated sludge processes was attributed to the higher Mixed Liquor Suspended Solids [MLSS] that can be achieved in a membrane bioreactor. Decrease of hydraulic retention time from 24 h to 18 h also resulted in significant increase in the rate of membrane fouling as quantified by transmembrane pressure gradiant. This was attributed to decrease in extracellular polymeric substance concentration which resulted in sludge deflocculation. As a consequence, the particle size distribution of the activated sludge shifted to lower mean particle sizes and the increase in the percentage of smaller particles resulted in increase in the rate of membrane fouling

Production of rhamnolipids by pseudomonas aeruginosa growing on carbon sources

Arhamnolipid producing bacterium, Pseudomonas aeruginosa was previously isolated from Iranian oil over years. Isolated strain was identified by morphological, biochemical, physiological and 16 sr RNA [1]. Glycolipid production by isolated bacterium using sugar beet molasses as a carbon and energy source was investigated. Biosurfactant production was quantified by surface tension reduction, Critical Micelle Dilution [CMD], Emulsification Capacity [EC], and Thin Layer Chromatogeraphy. biosurfactants during growth on waste Dates as the primary carbon and nitrogen sources, respectively. After 48 h of growth the culture supernatant fluid had a rhamnose concentration of 0.18 g/L and surface tension was reduced to 20 mN/m [%].[reduced the interfacial tension against crude oil from 21 mN/m to 0,47 mN/m] Result from the study showed that the growth of the bacteria using molasses as carbon sources is growth-associated. The specific production rate of rhamnolipid with 2%, 4%, 6%, 8% and 10% of molasses are 0.00065; 4.556; 8.94; 8.85; and 9.09. respectively The yield of rhamnolipid per biomass with 2%,4%,6%,8% and 10% molasses are 0.003;0.009;0.053;0.041 and 0.213 respectively. The production of rhamnolipid [0.0531 g rhamnolipid/g biomass] is higher compare to the culture grown in aerobic condition [0.04 g rhamnolipid/g biomass].The rhamnolipids were able to form stable emulsions with n-alkanes, aromatics, crude oil and olive oil. These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes

Environmental importance of rhamnolipid production from molasses as a carbon source

Rhamnolipid has been known as biosurfactant which is produced by Pseudomonas aeruginosa in fermentation process. Several carbon sources such as ethanol, glucose, vegetable oil and hydrocarbon have been used to produce rhamnolipid. In this study, we are trying to use molasses which is a waste product from sugar industry as carbon source to produce rhamnolipid. The bacterium which was previously isolated from Iranian oil over years Glycolipid production by isolated bacterium using sugar beet molasses as a carbon and energy source was investigated. Result from the study showed that the growth of the bacteria using molasses as carbon sources is growth-associated. The specific production rate of rhamnolipid with 2%, 4%, 6%, 8% and 10% of molasses are 0.00065, 4.556, 8.94, 8.85, and 9.09 respectively. The yield of rhamnolipid per biomass with 2%, 4%, 6%, 8% and 10% molasses are 0.003, 0.009, 0.053, 0.041 and 0.213 respectively. The production of rhamnolipid [0.0531 g. rhamnolipid/g biomass] is higher compare to the culture grown in aerobic condition [0.04 g. rhamnolipid/g biomass]. These studies indicate that renewable, relatively inexpensive and easily available resources can be used for important biotechnological processes