Evaluation of Chemical Clarification Polymers and Methods for Removal of Dissolved Metals from CDF Effluent

摘要

Clarification processes used to separate solid and liquid phases in the dredging slurry discharged to confined disposal facilities (CDFs) have typically consisted of sedimentation and chemical flocculation. Clarification is intended for removal of solids from CDF effluent, and in doing so, much of the metals contamination is also removed with the solids. Likewise, the ability of the chemical flocculation to remove dissolved phase contaminants should also be considered, since this may be an important, simultaneous benefit. As effluent discharge standards become more stringent, the benefits of new chemical flocculation agents may outweigh their added costs. The ability of polymers to remove dissolved metals as well as solids from dredging applications should be considered. Polymer flocculants for dredging application were previously investigated in screening tests (Wang and Chen 1977, Jones et al. 1978, Schroeder 1983, Wade 1988). The Engineer Manual on Confined Disposal of Dredged Material (U.S. Army Corps of Engineers (USACE) 1987) provides guidance on CDF effluent clarification and lists several polymers as possible candidates in chemical coagulation applications.