title: Chemical treatment response to variations in non-point pollution water quality: results of a factorial design experiment.
abstract: Chemical treatment of non-point derived pollution often suffers from undesirable oscillations in purification efficiency due to variations in runoff water quality. This study examined the response of the chemical purification process to variations in water quality using a 2(k) factorial design for runoff water rich in humic substances. The four k factors evaluated and the levels applied were: organic matter as dissolved organic carbon (DOC) (20-70 mg/L), suspended solids (SS) (10-60 mg/L), initial water pH (4.5-7), and applied coagulant dosage (ferric sulphate) (35-100 mg/L). Indicators of purification efficiency were residual concentration of DOC, SS and total phosphorus (tot-P). Analysis of variance and factor effect calculations showed that the initial DOC concentration in raw water samples and its interactions with the coagulant dosage applied exerted the most significant influence on the chemical purification process, substantially affecting the residual concentration of DOC, SS and tot-P. The variations applied to the factors SS and pH only slightly affected purification efficiency. The results can be used in the design of purification systems with high organic matter load variation, e.g. peat extraction runoff.
authors.affiliation: Water Resources and Environmental Engineering Research Group, Faculty of Technology, University of Oulu, P.O. Box 4300, 90014 Oulu, 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, P.O. Box 4300, 90014 Oulu, Finland.
authors.forename: Tiina
authors.initials: T
authors.lastname: Leiviskä
authors.affiliation: Water Resources and Environmental Engineering Research Group, Faculty of Technology, University of Oulu, P.O. Box 4300, 90014 Oulu, Finland.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Kløve
mesh_terms: D002244:Carbon / Q000737:chemistry*; D006801:Humans; D006812:Humic Substances; D015233:Models, Statistical; D010758:Phosphorus / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification; D060753:Water Quality
chemical_list: D006812:Humic Substances; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D002244:Carbon
keywords: Coagulation; Diffuse load; Factorial design; Flocculation; Humic substances