H.Y. Chien

Application of surfactant enhanced permanganate oxidation and bidegradation of trichloroethylene in groundwater.

The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated solvents found in groundwater contamination. The main objectives of this study were to evaluate the feasibility of using non-ionic surfactant Simple Green (SG) to enhance the oxidative dechlorination of TCE by potassium permanganate (KMnO4) employing a continuous stir batch reactor system (CSBR) and column experiments. The effect of using surfactant SG to enhance the biodegradation of TCE via aerobic cometabolism was also examined. Results from CSBR experiments revealed that combination of KMnO4 with surfactant SG significantly enhanced contaminant removal, particularly when the surfactant SG concentrated at its CMC. TCE degradation rates ranged from 74.1% to 85.7% without addition of surfactant SG while TCE degradation rates increased to ranging from 83.8% to 96.3% with presence of 0.1wt% SG. Furthermore, results from column experiments showed that TCE was degraded from 38.1microM to 6.2microM in equivalent to 83.7% of TCE oxidation during first 560min reaction. This study has also demonstrated that the addition of surfactant SG is a feasible method to enhance bioremediation efficiency for TCE contaminated groundwater. The complete TCE degradation was detected after 75 days of incubation with both 0.01 and 0.1wt% of surfactant SG addition. Results revealed that surfactant enhanced chemical oxidation and bioremediation technology is one of feasible approaches to clean up TCE contaminated groundwater.

Assessing of natural attenuation and intrinsic bioremediation rates at a petroleum-hydrocarbon spill site: laboratory and field studies.

Natural attenuation is a passive remedial approach that depends upon natural processes to degrade and dissipate contaminants in soil and groundwater. Intrinsic bioremediation is believed to be the major process among the natural attenuation mechanisms that account for the reduction of contaminant concentrations. In this study, a mass flux approach was used to calculate the contaminant mass reduction at a petroleum-hydrocarbon spill site. The mass flux technique is a simplified mass balance procedure, which is accomplished using the differences in total contaminant mass flux across two cross sections of the contaminant plume. The mass flux calculation results show that up to 86% of the dissolved total benzene, toluene, ethylbenzene, and xylene (BTEX) isomers removal was observed via natural attenuation at this site. Evidence for the occurrence of natural attenuation was the decreased contaminant mass flux through the plume cross sections along the transport path and limited spreading of the BTEX plume. Evi...

Clean up of petroleum-hydrocarbon contaminated soils using enhanced bioremediation system: laboratory feasibility study.

The objective of this study was to assess the potential of applying enhanced bioremediation on the treatment of petroleum-hydrocarbon contaminated soils. Microcosm experiments were conducted to determine the optimal biodegradation conditions. The control factors included oxygen content, nutrient addition, addition of commercially available mixed microbial inocula, addition of wood chip and rice husk mixtures (volume ratio=1:1 ) as bulking agents, and addition of organic amendments (chicken manures). Results indicate that the supplement of microbial inocula or chicken manures could significantly increase the microbial populations in soils, and thus enhance the efficiency of total petroleum hydrocarbon (TPH) removal (initial TPH=5,500 mg/kg ). The highest first-order TPH decay rate and removal ratio were approximately 0.015  day−1 and 85%, respectively, observed in microcosms containing microbial inocula (mass ratio of soil to inocula=50:1 ), nutrient, and bulking agent (volume ratio of soil to bulking agen...

Evaluation of biological stability and corrosion potential in drinking water distribution systems: a case study

The appearance of assimilable organic carbon (AOC), microbial regrowth, disinfection by-products (DBPs), and pipe corrosion in drinking water distribution systems are among those major safe drinking water issues in many countries. The water distribution system of Cheng-Ching Lake Water Treatment Plant (CCLWTP) was selected in this study to evaluate the: (1) fate and transport of AOC, DBPs [e.g., trihalomethanes (THMs), haloacetic acids (HAAs)], and other organic carbon indicators in the selected distribution system, (2) correlations between AOC (or DBPs) and major water quality parameters [e.g. dissolved oxygen (DO), free residual chlorine, and bacteria, and (3) causes and significance of corrosion problems of the water pipes in this system. In this study, seasonal water samples were collected from 13 representative locations in the distribution system for analyses of AOC, DBPs, and other water quality indicators. Results indicate that residual free chlorine concentrations in the distribution system met the drinking water standards (0.2 to 1 mg l−1) established by Taiwan Environmental Protection Administration (TEPA). Results show that AOC measurements correlated positively with total organic carbon (TOC) and UV-254 (an organic indicator) values in this system. Moreover, AOC concentrations at some locations were higher than the 50 μg acetate-C l−1 standard established by Taiwan Water Company. This indicates that the microbial regrowth might be a potential water quality problem in this system. Higher DO measurements (>5.7 mg l−1) might cause the aerobic biodegradation of THMs and HAAs in the system, and thus, low THMs (<0.035 mg l−1) and HAAs (<0.019 mg l−1) concentrations were observed at all sampling locations. Results from the observed negative Langelier Saturation Index (LSI) values, higher Ryznar Stability Index (RSI) values, and high Fe3+concentrations at some pipe-end locations indicate that highly oxidative and corrosive conditions occurred. This reveals that pipe replacement should be considered at these locations. These findings would be helpful in managing the water distribution system for maintaining a safe drinking water quality.

Evaluation of Enhanced Reductive Dechlorination of Trichloroethylene Using Gene Analysis: Pilot-Scale Study

AbstractThe industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. The objective of this pilot-scale study was to evaluate the effectiveness of an in situ reductive dechlorination process to remediate TCE-contaminated groundwater at a TCE-spill site using specific gene analysis. An injection well was installed inside the TCE plume for substrate and inocula injection. Brown sugar and anaerobic activated sludge (collected from an industrial wastewater-treatment plant with influent containing TCE) as electron donor (primary substrate) and inocula, respectively, were injected to enhance the TCE biodegradation rate through anaerobic reductive dechlorination. Three monitor wells were installed downgradient of the injection well along the groundwater flow path to monitor the TCE degradation trend. Polymerase chain reaction (PCR) analytical results reveal that the major TCE degrader (Dehalococcoides) and TCE-degrading genes (vcrA and tceA)...