Document Type

Thesis - Open Access

Award Date

1978

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Dwayne A. Rollag

Abstract

For the past three years or so, a gradual migration of iron and manganese deposits has been observed in the water mains to the west of the East Water Treatment Plant of Brookings, South Dakota. These deposits have been gradually migrating further westward from the plant (8). Routine analyses of the treated water from the East Plant indicate that the iron and manganese levels are within the USPHS recommended limits (9). Consequently, conclusive evidence that this plant is the source of the problem does not exist. However, the analyses are normally conducted on samples collected shortly before backwashing the filters. Thus, it is conceivable that enough iron and manganese could leak through the filters for a time after being placed back into operation from cleaning. If any bacteria exist in the filters, perhaps some iron and manganese may be getting through due to reduction from the insoluble to the soluble form in the filters. Also, maybe the concentrations in the filter effluent, even though below the USPHS recommended limits, are high enough to cause a build-up of deposits in certain stagnant locations in the mains. At any rate, the fact that the complaints initially were from users near the plant and, in later years, from further and further away, strongly suggests that the source of the trouble is the East Plant. The purpose of this investigation was to determine the effectiveness and optimum dosage of potassium permanganate for maximum removal of iron and manganese from the influent of the recarbonation basin, East Water Treatment Plant. Because the East Plant was designed specifically to remove iron and manganese by lime precipitation, a logical solution to the problem would be to increase the pH with a more complete precipitation of those ions. However, previous attempts to do this resulted in stability problems when this water mixed with that from the North Water Treatment Plant. Consequently, other possible solutions were considered. One of these potential solutions was 3 the addition of a strong oxidizing agent such as potassium permanganate to precipitate any unoxidized iron and manganese prior to filtration. To avoid disruption of treatment plant operations, it was decided to evaluate the effectiveness of potassium permanganate on a pilot scale. The effluent from the solids contact basin was selected as the point of application. Thus, the pilot units required were a recarbonation basin and a filter since these were the only units that followed the solids contact basin in the East Plant. Using a pilot plant having the same detention time, filter medium, and filter rate as the East Plant, the objectives of these studies were as follows: 1) To duplicate the performance of the East Plant in terms of iron and manganese concentration in the filter effluent, 2) To evaluate the effectiveness of feeding potassium permanganate on the filtered effluent iron and manganese concentrations, 3) To determine the permanganate dosage that will produce the lowest iron and manganese concentration in the filtered effluent, and 4) To design and estimate the cost of a permanganate feeding system for the East Plant.

Library of Congress Subject Headings

Water -- Purification
Potassium permanganate
Iron
Manganese
Groundwater

Format

application/pdf

Publisher

South Dakota State University

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