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pH and Particle Structure Effects on Silica Removal by Coagulation
Author(s) -
Hermosilla D.,
Ordóñez R.,
Blanco L.,
de la Fuente E.,
Blanco Á.
Publication year - 2012
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.201100527
Subject(s) - coagulation , chemistry , effluent , chemical engineering , particle size , chemical oxygen demand , particle (ecology) , reverse osmosis , chromatography , pulp and paper industry , environmental engineering , wastewater , membrane , environmental science , biochemistry , psychology , oceanography , psychiatry , engineering , geology
Coagulation is presented as an efficient alternative to reduce the silica content in effluents from recovered‐paper mills that are intended to be recycled by a final reverse‐osmosis (RO) step. Coagulation pretreatment by several polyaluminum chlorides (PACls) or FeCl 3 was optimized prior to the RO process. PACls with low alumina content and high basicity achieved almost a 100 % removal of silica at pH 10.5. A good reduction of the silica content was attained without regulating the pH by adding one of these PACls. Silica removal was related to the structure of the produced clots in which cylindrical particles produced higher silica removal. All coagulants removed more than 50 % of the chemical oxygen demand (COD).