Characterization of a Bleached Kraft Mill Effluent Discharging to Codorus Creek, Pennsylvania, as Part of a Long-Term Monitoring Study-Chemical, Biological, and Mesocosm Measurements

摘要

Physical, chemical, and biological characterization of activated sludge treated effluent from a bleached kraft mill in Spring Grove, PA, USA was carried out as part of a long-term integrated monitoring study to assess potential effluent effects on Codorus Creek. Although the primary focus of the monitoring study was instream assessment of periphyton, macroinvertebrate, and fish communities, detailed characterization was also carried out to determine effluent quality based on physical-chemical parameters, effluent chronic bioassays, and through the use of streamside mesocosms. Mean values for physical/chemical parameters measured for the effluent were color - 309 PCU, total polyphenols - 6.7 mg/L, conductivity - 1,950 μmhos/cm, total suspended solids - 6.8 mg/L, turbidity - 5.7 NTU, BOD_5 - 4.8 mg/L, COD - 166 mg/L, and TOC - 57 mg/L. Concentrations of resin/fatty acids, phytosterols, and categories of various chlorinated and non-chlorinated organic compounds are reported as well. During the 3 year study period, effluent quality was assessed quarterly using U.S. Environmental Protection Agency procedures with Ceriodaphnia dubia and fathead minnow (Pimephales promelas). The 7-d survival IC25 for fathead minnow and C. dubia were all > 100% effluent with 100% of the fathead minnow growth and all but one of the C. dubia reproduction IC25 values also > 100%. An additional support component for the long-term instream monitoring study was the conduct of a 28-d flow-through mesocosm experiment carried out streamside on Codorus Creek. The study involving native species of periphyton and macroinvertebrates was carried out in replicate 380 L circular tanks with exposures that bracketed the mean effluent concentration (38% v/v) in Codorus Creek and also included the approximate 7Q10 concentration (50% v/v). At the conclusion of 28-d exposure, no significant differences (Kruskal-Wallis) in chlorophyll a or dry weight biomass were indicated at the 10, 20, 50% effluent test concentrations when compared to the control. Macroinvertebrate measurements indicated no significant differences between test concentrations for total biomass or density (Kruskal-Wallis). Combined results from effluent chronic bioassay and mesocosm studies suggest that effluent effects would not occur beyond the edge of the mixing zone at mean or 7Q10 flows on Codorus Creek, an effluent dominated receiving water. As part of an integrated monitoring study, an opportunity is presented to compare these results with those from concurrent instream monitoring.