Humic acid removal by chemical coagulation, electrocoagulation and ultrafiltration
Sakarinen, Ekaterina (2016)
Sakarinen, Ekaterina
Yrkeshögskolan Arcada
2016
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-201605046275
https://urn.fi/URN:NBN:fi:amk-201605046275
Tiivistelmä
This thesis work aimed to establish experimental procedures and compare different methods for removing humic acid (HA) from water. Three methods were investigated: chemical coagulation (CC), electrocoagulation (EC) and ultrafiltration (UF). The topic was approached by reviewing the relevant literature and performing experiments. The literature review reported here provides an overview of current experimental methods, defines HA and describes the analytical methods used to quantify HA. For the practical part of this work, experiments were held to establish CC, EC and UF procedures aiming for the highest removal rates of moderately concentrated synthetic HA. The effects of working solution pH, coagulation and flocculation times, chemical coagulant dosage and current applied on HA removal rates were investigated. HA removal values exceeding 95% were reached by EC and by CC techniques under optimum conditions and after floc removal by gravitational or centrifuge settling. UF did not achieve similarly high removal efficiencies of floc: the flocs seemed to break under pressure, which let some of them pass through the membrane and reform afterwards. An attempt was made to quantify the sizes of coagulated flocs with a microscope in order to estimate their strength. Accurate estimation of floc dimensions, however, was not possible from captured images due to the destructive sampling technique and difficulties in defining individual floc boundaries. The concentrations of HA in all samples were measured by UV-Vis spectrophotometry.