title: Influence of the apparent molecular size of aquatic humic substances on colour removal by coagulation and filtration.
abstract: This study aims to verify the influence of the apparent molecular size of aquatic humic substances (AHSs) on the effectiveness of coagulation with aluminium sulphate and ferric chloride. Coagulation-filtration tests using the jar test and bench-scale sand filters were carried out with water samples having a true colour of approximately 100 Hazen units and prepared with AHSs of different molecular sizes. Stability diagrams are presented showing regions of > or = 90% and > or = 95% apparent colour removal delineated for each water sample using plots of total metal ion concentration (Al3+ and Fe3+) versus coagulation pH. To achieve the same degree of colour removal, the water samples with smaller apparent molecular sizes and a higher percentage of fulvic acids required higher dosages of both aluminium sulphate and ferric chloride.
authors.affiliation: Institute of Chemistry of São Carlos, University of São Paulo, São Carlos, Brazil. elisloboda@hotmail.com
authors.forename: Eliane Sloboda
authors.initials: ES
authors.lastname: Rigobello
authors.forename: Angela Di Bernardo
authors.initials: AD
authors.lastname: Dantas
authors.forename: Luiz
authors.initials: L
authors.lastname: Di Bernardo
authors.forename: Eny Maria
authors.initials: EM
authors.lastname: Vieira
mesh_terms: D000534:Alum Compounds / Q000737:chemistry; D001578:Benzopyrans / Q000032:analysis; D002712:Chlorides / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D005374:Filtration; D006812:Humic Substances / Q000032:analysis*; D008970:Molecular Weight; D013056:Spectrophotometry, Ultraviolet; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D000534:Alum Compounds; D001578:Benzopyrans; D002712:Chlorides; D005290:Ferric Compounds; D006812:Humic Substances; C041524:aluminum sulfate; C024555:ferric chloride; C005023:fulvic acid