EVALUATING REVERSE OSMOSIS TREATMENT FOR REMOVAL OF COMPOUNDS FROM RECOVERY CONDENSATES AT A BLEACHED KRAFT MILL THAT AFFECT FISH HORMONE CONTROL

摘要

Irving Pulp & Paper Ltd. (IPP) is a 900 tonne/day bleached kraft pulp mill located in New Brunswick, Canada, which employs in-plant process technologies rather than end-of-pipe secondary treatment to meet its effluent regulations. Using artificial stream and laboratory studies, we identified clean condensates from the pulping side of mill operations as a source of contaminants that depressed steroid hormone levels in the mummichog (Fundulus heteroclitus), an endemic fish species in the Bay of Fundy. The potential of this condensate stream to depress reproductive steroids was removed by reverse osmosis (RO) treatment, which likely resulted in a final mill effluent that did not cause hormone disruptions in mummichogs at an environmentally-relevant concentration (1%). In the present work, mummichogs were exposed to RO feed (clean condensates from the 5th effect evaporator) and the concentrate and permeate effluents formed by the RO system. Results confirm RO is accumulating the steroid depressing compounds in the concentrate. Plant phytosterols and black liquor have been eliminated as causative agents and present work is focusing on the chemical characterization of the RO process streams. Horizon objectives include identifying the responsible compounds and determining the applicability of RO treatment to the pulping industry.