Silica removal from newsprint mill effluents with aluminum salts



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Latour Romero, Isabel and Miranda Carreño, Rubén and Blanco Suárez, Ángeles (2013) Silica removal from newsprint mill effluents with aluminum salts. Chemical Engineering Journal, 230 . pp. 522-531. ISSN 1385-8947

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The main obstacle for the implementation of reverse osmosis (RO) in a treatment chain to reuse the effluent of a newsprint mill as fresh water is the high silica content of the water, which produces severe scaling on the membrane, thus, limiting its recovery. Coagulation is one of the preferred methods to reduce silica concentration. Five
aluminum based coagulants have been tested at five dosages (500-2500 ppm) and three pHs (8.3, 9.5 and 10.5). All products showed their best efficiency at the highest dosage and pH, with the exception of alum, that was more efficient at intermediate dosages. A combination of a polyaluminum nitrate sulphate with a cationic quaternary polyamine PANS-PA2), was the most efficient and versatile coagulant. It removed 97% of silica (5 ppm residual silica) at the optimal conditions (pH 10.5, 2500 ppm) and it was very efficient (76% silica removal) at pH 8.3, avoiding the need of any pH adjustment, and minimizing the conductivity and pH increase of the treated waters as well as obtaining some removal of the organic colloidal matter (≈25%).

Item Type:Article
Uncontrolled Keywords:Reverse osmosis; Silica; Scaling; Effluent reuse; Coagulation; Aluminum
Subjects:Sciences > Chemistry > Paper industry
Sciences > Chemistry > Chemical engineering
Sciences > Chemistry > Environmental conditions
Sciences > Chemistry > Chemistry, Technical
ID Code:26407
Deposited On:28 Nov 2014 09:37
Last Modified:28 Nov 2014 09:37

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