Quantification and identification of pharmaceuticals and their treatment by-products in drinking water and wastewater by LC/MS/MS

Current analytical methods have focused on analyzing pharmaceuticals in the environment including wastewater, however, wastewater flow is not homogeneous and depending on the size of the municipal wastewater treatment plant (WWTP), short-term variations can be extremely significant. Therefore, while the biodegradability and physico-chemical properties of the transformed compounds are important factors that determine the observed concentrations of micro-contaminants in wastewater, diurnal variations can be influenced significantly by the frequency of sample collection and the type of sampling mode performed. Grab and different composite sampling methods for a full scale WWTP were performed for selected pharmaceuticals in order to investigate concentrations and mass loadings variation in the influent and the effluent. As expected, all the target pharmaceuticals were highly variable and dependent on the time and location of sampling, but flow rates of the model WWTP did not influence the variability of concentrations when compared concentrations and mass loadings variability. The best way to reduce any uncertainties regarding pharmaceutical sampling and analysis from any environmental samples is to adopt an automatic analysis system on site and to analyze them in real time, but since it is not available now, the best way to collect a representative samples is likely through compositing methods. Comparing different composite sampling methods, flow-weighted and time-weighted compositing methods were not significant different. Therefore, either compositing method can be adopted for wastewater sampling for the analysis of pharmaceuticals according to the results of this work.;The biological fate of trimethoprim (TMP; 1 &mgr;g/L--1 mg/L), a pharmaceutical with mid to high removal rates by WWTPs equipped with a tertiary treatment system that includes a nitrification step, was evaluated in flow through reactors containing: an ammonia oxidizing bacterial (AOB) culture; two enriched heterotrophic cultures devoid of nitrifier activity; and nitrifying activated sludge (NAS) cultures. AOBs did not biotransform TMP whereas the heterotrophic cultures biotransformed TMP. Heterotrophic dioxygenase activity did not enhance removal of TMP, and the basal expression of these enzymes was sufficient to achieve the high degree of transformation observed at TMP concentrations ≤ 1 mg/L. The importance of AOBs in removing TMP was evaluated further by performing NAS experiments at lower feed concentrations (500--1,000 ng/L), and TMP removal was not affected by AOB inhibition.;Carbamazepine (CBZ) is one of the most persistent pharmaceutical compounds in wastewater effluents due to its resistance to biodegradation-based conventional treatment. Advanced oxidation can efficiently degrade CBZ, but the toxicity and persistence of the oxidation products may be more relevant than those of the parent. This study sets out to determine whether the products of the advanced oxidation of CBZ can be biotransformed and ultimately mineralized by developing a novel methodology to assess these sequential treatment processes. The methodology traces the transformation products of the 14C labeled CBZ during UV-hydrogen peroxide advanced oxidation and subsequent biotransformation of mixed, undefined cultures using liquid scintillation counting, and by liquid chromatography with radioactivity and UV detectors and, a mass spectrometer. The results indicate that the oxidation by-products of CBZ containing a hydroxyl or carbonyl group can be fully mineralized by a mixed bacterial inoculum. A tertiary treatment approach that includes oxidation and biotransformation has the potential to synergistically mineralize persistent pharmaceutical compounds in wastewater treatment plant effluents. This methodology can be applied to assess the mineralization potential of other persistent organic contaminants.;Water filters can serve as an additional treatment step at the point-of-consumption to further remove trace levels of pharmaceuticals and other drinking water contaminants from water. Two representative commercial faucet-style water filters were tested, each claiming to have the ability to remove some organic compounds after having filtered100 gallons of water. The water filters were connected to the tap water system and 1 mL of a 100 ppb pharmaceutical mixture was injected into the filters to collect a 1 L sample of filter-treated tap water after 0, 50, 100, 200, and 300 gallons of water had passed through the filter. The removal efficiencies for both brands of filters displayed more than 97% removal of all target pharmaceuticals after filtering 100 gallons of tap water. The removal efficiencies beyond the filter's capacity, however, decreased for carisoprodol (CRP), meprobamate (MPB), and sulfamethoxazole (SMX) to 74∼95% for both filters [A] and [B] after 300 gallons of tap water had passed through the filters. Removal of two chlorinated by-products of trimethoprim (TMP) were also investigated and their removal efficiencies were 82∼93% after 100 gallons of tap water had been filtered, while the removal efficiencies for both filters were drastically decreased up to 40% and 69% for filter [A] and [B], respectively, after 200 gallons of tap water had been filtered. (Abstract shortened by UMI.)...