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Use of pH, contact time, chlorine dose, temperature on the formation of trihalomethane and some empirical models for predicting trihalomethane formation
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.ORCID iD: 0000-0001-8241-2225
2006 (English)In: WIT Transactions on Ecology and the Environment, 2006, 411-421 p.Conference paper, Published paper (Refereed)
Abstract [en]

An empirical model for predicting trihalomethane (THMs) formation, using linear and nonlinear regression, was carried out using a database built when the influence of enhanced coagulation on the formation of THMs was studied. These experiments were done under different conditions of pH, temperature, chlorine dosages and contact time; and two types of coagulation (enhanced and conventional). This database was first used to compare the formation of trihalomethane obtained in these experiments with some existing predictive models. Because the values measured experimentally did not agree enough with the values from the predictive models for both coagulation types, new ones were developed using the results of enhanced coagulation experiments. In order to test the predictive capacity of the models, both linear and non-linear models, were used to predict the formation of THMs using the database obtained from the conventional coagulation experiments. The nonlinear model gave best results in comparison with the linear model. The results were statistically validated by analysis of variance and other statistics parameters.

Place, publisher, year, edition, pages
2006. 411-421 p.
Series
WIT Transactions on Ecology and the Environment, ISSN 1743-3541 ; 95
Keyword [en]
Anova, Empirical model, Natural organic matter, Statistic, Trihalomethane
National Category
Environmental Sciences
Identifiers
URN: urn:nbn:se:kth:diva-8988DOI: 10.2495/WP060411ISI: 000242618600041Scopus ID: 2-s2.0-36148947859ISBN: 9781845640422 (print)OAI: oai:DiVA.org:kth-8988DiVA: diva2:14511
Conference
8th International Conference on Modelling, Monitoring and Management of Water Pollution, WATER POLLUTION 2006, WP06; Bologna; 4 September 2006 through 6 September 2006
Note

QC 20101129

Available from: 2006-01-16 Created: 2006-01-16 Last updated: 2017-03-24Bibliographically approved
In thesis
1. Removal of natural organic matter by enhanced coagulation in Nicaragua
Open this publication in new window or tab >>Removal of natural organic matter by enhanced coagulation in Nicaragua
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

The existence of trihalomethanes (THMs) in a drinking water plant of Nicaragua has been investigated in order to see whether the concentration exceeded the maximum contaminant level recommended by the environmental protection agency of the United States (USEPA) and the Nicaragua guidelines. The influence of pH, temperature, chlorine dose and contact time on the formation of THMs were studied. The contents of organic matter measured by surrogate parameters such as total organic carbon, dissolved organic carbon, ultraviolet absorbance and specific ultraviolet absorbance were also determined in order to show which type of organic matter is most reactive with chlorine to form THMs. Models developed by other researchers to predict the formation of trihalomethanes were tested to see whether they can be used to estimate the trihalomethane concentration. In addition, empirical models were development to predict the THM concentration of the drinking water plant analysed. The raw water was treated by conventional and enhanced coagulation and these processes were compared with regard to the removal of natural organic matter (NOM). The significance of the results was assessed using statistic procedures.

The average concentration of THMs found at the facility is below the USEPA and Nicaragua guideline values. Nevertheless the maximum contaminant level set by USEPA is sometimes exceeded in the rainy season when the raw water is rich in humic substances. Comparison between the water treated by conventional and enhanced coagulation shows that enhanced coagulation considerably diminished the trihalomethane formation and the value after enhanced coagulation never exceeded the guidelines. This is because enhanced coagulation considerably decreases the organic matter due to the high coagulant dose applied. The study of the trihalomethane formation when varying pH, time, temperature and chlorine dose using water treated by conventional and enhanced coagulation showed that higher doses of chlorine, higher pH, higher temperature and a longer time increases the formation of THMs. However, combinations of two and three factors are the opposite. The predicted THM formation equations cannot be used for the water at this facility, since the results shown that the measured THM differs significantly from the THM concentration predicted. Two empirical models were developed from the data for enhanced coagulation, using linear and non-linear regression. These models were tested using the database obtained with conventional coagulation. The non-linear model was shown to be able to predict the formation of THMs in the Boaco drinking water plant.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 56 p.
Series
Trita-KET, ISSN 1104-3466 ; 225
Keyword
drinking water, surrogate parameters, enhanced coagulation, natural organic matter
National Category
Environmental Sciences
Identifiers
urn:nbn:se:kth:diva-586 (URN)
Presentation
2006-01-26, Sal Q25, Osquldas väg 6, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20101129Available from: 2006-01-16 Created: 2006-01-16 Last updated: 2011-02-14Bibliographically approved

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