Trihalomethane formation and remotion in pre-oxidation water treatment processes using chlorine / Formação e remoção de trihalometanos em aguas de abastecimento tratadas, na pre-oxidação, com cloro livre

AUTOR(ES)

Carlos Renato Marmo

DATA DE PUBLICAÇÃO

2005

RESUMO

The present research evaluated, in laboratory scale, the formation of trihalomethanes (THM) produced in oxidation reactions, with free chlorine, of water samples with humic acids, in different concentrations and reaction time. This research also studied the presence of the bromide ion, to evaluate, qualitatively and quantitatively, the different species of THM produced. Trihalomethanes detection was comparatively investigated through two analytical techniques. The gaseous chromatography, indicated for the analysis of such molecules, resulted in the quantification of chloroform, dichlorobromomethane, dibromochloromethane and bromoform. The spectrophotometric technique was evaluated as an alternative methodology to the first one, allowing the expression of the results only in total THM. Static reactors were used to carry out assays of THM removal by adsorption in different concentrations of powdered activated carbon (PAC), followed by coagulation processes with aluminium sulphate, flocculation, sedimentation and filtration. The results indicated that THM formation is directly proportional to the concentrations of chlorine, humic acids, bromide ion and reaction time. The procedure of PAC adsorption, followed by conventional processes of water treatment were effective, showing THM removal from the samples of up to 89%. The increase in PAC concentration from 10 to 150 mg/L, and adsorption reaction time from 60 to 120 minutes, resulted in the best performances. The methodologies for THM based on gaseous chromatography and espectrophotometric presented different results in the laboratory conditions of these assays

ASSUNTO(S)

water purification plants agua - estações de tratamento carvão agua - purificação - oxidação water - purification - chlorination chloroform water - purification - oxidation cloroformio coal agua - purificação - cloração

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