title: Coagulation of humic waters for diffused pollution control and the influence of coagulant type on DOC fractions removed.
abstract: 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 ∼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.
authors.affiliation: Water Resources and Environmental Engineering, Faculty of Technology, University of Oulu, 90014, Finland. Electronic address: elisangela.heiderscheidt@oulu.fi.
authors.forename: Elisangela
authors.initials: E
authors.lastname: Heiderscheidt
authors.affiliation: Chemical Process Engineering, Faculty of Technology, University of Oulu, 90014, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Leiviskä
authors.affiliation: Water Resources and Environmental Engineering, Faculty of Technology, University of Oulu, 90014, Finland.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Kløve
mesh_terms: D001704:Biopolymers / Q000737:chemistry; D002244:Carbon / Q000032:analysis / Q000737:chemistry; D005591:Chemical Fractionation; D048271:Chitosan / Q000737:chemistry; D002850:Chromatography, Gel; D004058:Diffusion; D005290:Ferric Compounds / Q000737:chemistry; D006812:Humic Substances / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen; D010758:Phosphorus / Q000032:analysis; D011095:Polyethylenes / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D014867:Water / Q000032:analysis; D014876:Water Pollution / Q000517:prevention & control*; D018508:Water Purification / Q000379:methods*
chemical_list: D001704:Biopolymers; D005290:Ferric Compounds; D006812:Humic Substances; D011095:Polyethylenes; D000644:Quaternary Ammonium Compounds; D012987:Soil; D014867:Water; C041004:poly-N,N-dimethyl-N,N-diallylammonium chloride; D010758:Phosphorus; C024823:ferric sulfate; D002244:Carbon; D048271:Chitosan; D009584:Nitrogen; D010100:Oxygen
keywords: Coagulation; DOC fractionation; LC-OCD-OND; Organic nitrogen; Organic polymers