Occurrence and partitioning of antibiotic compounds found in the water column and bottom sediments from a stream receiving two wastewater treatment plant effluents in northern New Jersey, 2008.

An urban watershed in northern New Jersey was studied to determine the presence of four classes of antibiotic compounds (macrolides, fluoroquinolones, sulfonamides, and tetracyclines) and six degradates in the water column and bottom sediments upstream and downstream from the discharges of two wastewater treatment plants (WWTPs) and a drinking-water intake (DWI). Many antibiotic compounds in the four classes not removed by conventional WWTPs enter receiving waters and partition to stream sediments. Samples were collected at nine sampling locations on 2 days in September 2008.

Efficiency of conventional drinking-water-treatment processes in removal of pharmaceuticals and other organic compounds.

Samples of water and sediment from a conventional drinking-water-treatment (DWT) plant were analyzed for 113 organic compounds (OCs) that included pharmaceuticals, detergent degradates, flame retardants and plasticizers, polycyclic aromatic hydrocarbons (PAHs), fragrances and flavorants, pesticides and an insect repellent, and plant and animal steroids. 45 of these compounds were detected in samples of source water and 34 were detected in samples of settled sludge and (or) filter-backwash sediments. The average percent removal of these compounds was calculated from their average concentration in time-composited water samples collected after clarification, disinfection (chlorination), and granular-activated-carbon (GAC) filtration.

Persistence of pharmaceuticals and other organic compounds in chlorinated drinking water as a function of time.

Ninety eight pharmaceuticals and other organic compounds (POOCs) that were amended to samples of chlorinated drinking-water were extracted and analyzed 1, 3, 6, 8, and 10 days after amendment to determine whether the total chlorine residual reacted with the amended POOCs in drinking water in a time frame similar to the residence time of drinking water in a water distribution system. Results indicated that if all 98 were present in the finished drinking water from a drinking-water treatment plant using free chlorine at 1.2 mg/L as the distribution system disinfectant residual, 52 POOCs would be present in the drinking water after 10 days at approximately the same concentration as in the newly finished drinking water.