Date of Award

Spring 1985

Project Type

Dissertation

Program or Major

Engineering

Degree Name

Doctor of Philosophy

Abstract

Because of the ever increasing concern over the health effects associated with aluminum, this study was designed to determine the behavior of aluminum in a water treatment facility using alum in the coagulation process. The plant chosen was the Arthur Rollins Water Treatment Facility located in Durham, New Hampshire. Laboratory jar tests, as well as actual monitoring, were conducted. The important parameters examined included pH, temperature and fluoride. Also, a comparison between natural river water and a colored model water was performed in the laboratory.

Aluminum was determined using both the Atomic Absorption Spectrophotometry (AAS) method and the Eriochrome Cyanine R method which can detect aluminum in the low ppb range. The latter method was also used by the operator of the water treatment plant.

The results from the jar tests indicated that the soluble aluminum concentration was affected by pH, temperature and fluoride. The most important parameter in the partitioning of aluminum was pH. The amount of soluble aluminum can vary as much as one hundred fold by changing the pH one unit. The minimum soluble aluminum concentration occurred at a higher pH when the temperature decreased from 25 to 5(DEGREES)C. Colored model water (humic acid) showed a close relationship with natural water in terms of its effect on the solubility of aluminum. The fluoride ion is an important factor in increasing the amount of soluble aluminum in a pH of less than 7. However, the fluoride addition took place after the filtration and should not have affected the performance of this plant. These parameters have different magnitudes of effect on the partitioning of aluminum. However, a water treatment plant deals with a combination of these parameters in a given time. It is of utmost importance to minimize the soluble aluminum concentration due to the fact that sedimentation and filtration units are not able to remove this portion of aluminum and this would end up in the finished water.

The monitoring of the water treatment plant confirms that the total aluminum concentration in the finished water was usually well above that of the raw water.

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