Coagulation of humic waters for diffused pollution control and the influence of coagulant type on DOC fractions removed

JOURNAL OF ENVIRONMENTAL MANAGEMENT

卷:181

Article

Heiderscheidt, Elisangela¹  Leiviskae, Tiina²  Klove, Bjorn¹ 

[1] Univ Oulu, Fac Technol, Water Resources & Environm Engn, Oulu 90014, Finland

[2] Univ Oulu, Fac Technol, Chem Proc Engn, Oulu 90014, Finland

关键词: Organic polymers;    Coagulation;    DOC fractionation;    LC-OCD-OND;    Organic nitrogen;   

DOI  :  10.1016/j.jenvman.2016.06.043

来源: Elsevier

【 摘 要 】

This study examined the suitability of organic coagulants for treatment of typically humic peat extraction runoff water by comparing their performance with that of ferric sulphate (FS). The influence of coagulant type on dissolved organic carbon (DOC) fractions removed was analysed in detail using LC-OCD-OND (size exclusion liquid chromatography coupled with organic carbon and organic nitrogen detection) fractionation techniques. In general, lower coagulant dosage was needed under acidic (pH 4.5) than neutral (pH 6.5) conditions. Chitosan (Chit) and poly (diallyldimethyl) ammonium chloride (pDMAC) required significantly lower dosage (40-55%) than FS for acceptable purification, while a tannin-based coagulant (Tan2) required substantially higher dosage (55-75%) independent of water pH. FS demonstrated the best removal of DOC (<81%) and phosphorus (<93%) followed by pDMAC, while Chit and Tan2 achieved the highest removal of suspended solids (SS) (<58%), with flocs formed by Tan2 presenting the best settling properties. Higher molecular weight (MW) DOC fractions were more efficiently removed by all coagulants, with FS being the most efficient (biopolymers 69% and humic substances 91%), followed by Tan2. FS also displayed satisfactory removal of lower MW fractions (building blocks similar to 46% and low MW neutrals 62%). Overall, FS was the best performing coagulant. Nevertheless, the organic polymers demonstrated satisfactory overall performance, achieving purification rates mostly inside the requirements set by Finnish environmental authorities. (C) 2016 Published by Elsevier Ltd.

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