Characterization and performance of poly-silicic-cation coagulant in treatment of recycled paper wastewater

Abstract

AbstractTertiary treatment of pulp and paper wastewater has become increasingly pressing since stricter legislations were issued by the central government and some provincial governments in China. Coagulation process after biological treatment has been regarded as a techno-economically feasible technology for the high quality effluent. In this paper, a study on preparation and characterization of poly-silicic-cation coagulants (PSiCs) with different Si/(Al + Fe) molar ratios is described. X-ray diffraction, infrared spectra, ultraviolet/visible absorption scanning, and microscopic imaging were used as measures for characterization. Coagulant performance was evaluated using it in papermaking wastewater treatment. The results showed that new complex compounds had formed in the PSiC polymers and the optimal Si/(Al + Fe) molar ratio for the coagulant polymerization was about 0.9, at which the polymerization degree was highest. The content of ionic polymerized bonds and branch-like PSiC units would decrease wh...