Widespread contamination of groundwater by chlorinated ethenes and their biological dechlorination products necessitates the reliable monitoring of liquid matrices; current methods approved by the U.S. Environmental Protection Agency (EPA) require a minimum of 5 mL of sample volume and cannot simultaneously detect all transformative products. This paper reports on the simultaneous detection of six chlorinated ethenes and ethene itself, using a liquid sample volume of 1 mL by concentrating the compounds onto an 85-µm carboxen-polydimenthylsiloxane solid-phase microextraction fiber in 5 min and subsequent chromatographic analysis in 9.15 min. Linear increases in signal response were obtained over three orders of magnitude (∼0.05 to ∼50 µM) for simultaneous analysis with coefficient of determination (R²) values of ≥ 0.99. The detection limits of the method (1.3–6 µg/L) were at or below the maximum contaminant levels specified by the EPA. Matrix spike studies with groundwater and mineral medium showed recovery rates between 79–108%. The utility of the method was demonstrated in lab-scale sediment flow-through columns assessing the bioremediation potential of chlorinated ethene-contaminated groundwater. Owing to its low sample volume requirements, good sensitivity and broad target analyte range, the method is suitable for routine compliance monitoring and is particularly attractive for interpreting the bench-scale feasibility studies that are commonly performed during the remedial design stage of groundwater cleanup projects.

Widespread use of halogenated organic compounds for commercial and industrial purposes makes halogenated organic pollutants (HOPs) a global challenge for environmental quality. Current wastewater treatment plants (WWTPs) are successful at reducing chemical oxygen demand (COD), but the removal of HOPs often is poor. Since HOPs are xenobiotics, the biodegradation of HOPs is usually limited in the WWTPs. The current methods for HOPs treatments (e.g., chemical, photochemical, electrochemical, and biological methods) do have their limitations for practical applications. Therefore, a combination of catalytic and biological treatment methods may overcome the challenges of HOPs removal.This dissertation investigated a novel catalytic and biological synergistic platform to treat HOPs. 4-chlorophenol (4-CP) and halogenated herbicides were used as model pollutants for the HOPs removal tests. The biological part of experiments documented successful co-oxidation of HOPs and analog non-halogenated organic pollutants (OPs) (as the primary substrates) in the continuous operation of O2-based membrane biofilm reactor (O2-MBfR). In the first stage of the synergistic platform, HOPs were reductively dehalogenated to less toxic and more biodegradable OPs during continuous operation of a H2-based membrane catalytic-film reactor (H2-MCfR). The synergistic platform experiments demonstrated that OPs generated in the H2-MCfR were used as the primary substrates to support the co-oxidation of HOPs in the subsequent O2-MBfR. Once at least 90% conversation of HOPs to OPs was achieved in the H2-MCfR, the products (OPs to HOPs mole ratio >9) in the effluent could be completely mineralized through co-oxidation in O2-MBfR. By using H2 gas as the primary substrate, instead adding the analog OP, the synergistic platform greatly reduced chemical costs and carbon-dioxide emissions during HOPs co-oxidation.