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Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Suzette Burckhard

Abstract

A decommissioned water treatment plant located on Lake Kampeska, Watertown, SD, was modified to biologically remove phosphorus from the lake’s water by cultivating and harvesting algae. The nutrient levels in the lake have been measured and determined to be excessive, and have made the waters prone to algae blooms. The treatment plant operates as a research facility to demonstrate a possible method of lake restoration in northern climates. The Lake Kampeska Phosphorus Removal Plant has been experiencing below expected levels of phosphorus removal. Bench scale laboratory testing was requested to study the requirements to optimize plant operation. The primary objective of this research project was to determine the effective nitrogen and phosphorus concentrations needed to allow for efficient phosphorus removal by the natural occurring algae from Lake Kampeska at different temperatures. A nutrient diffusing substrata (NDS) test evaluated the limiting nutrients in the natural lake water. Ammonium chloride, potassium nitrate, and sodium nitrate were used as nitrogen source and potassium phosphate was used as a phosphorus source. Sodium nitrate exhibited superior growth effects as a source for nitrogen compared to the other nitrogen containing chemicals. Potassium phosphate showed inhibitory effects as both a singular chemical and in addition to any nitrogen source tested. xi Nitrogen to phosphorus ratios were evaluated using a bench-scale batch test and multiple ratios created by the addition of sodium nitrate. The batch tests performed at 23o C, investigated a wide range of N:P mass ratios including 2:1, 3:1, 5:1, 7:1, 10:1, 12:1 15:1, 20:1, and 50:1. Any mass ratio above 7:1 generally reached a phosphorus limiting state where nitrogen removal ceased or slowed considerably. However, mass ratios of 3:1 or below generally reached a nitrogen limiting state where phosphorus removal ceased or slowed considerably. Temperature effects were analyzed on both the NDS tests and the batch tests. NDS tests performed at water temperatures between 19 to 16o C showed chlorophyll a levels up to 10 times larger than when performed at water temperatures between 10 to 4o C. At the colder temperature, the algae took longer to cultivate and remove nutrients, however the N:P ratio for both nitrogen and phosphorus reduction effectiveness remained the same. Overall, assessments performed on the natural algae from Lake Kampeska with an in-situ NDS test at the pilot plant and bench-scale batch test at SDSU showed promising results for optimizing the pilot plant performance. This research project showed that the addition of sodium nitrate can enhance algal cultivation. Additionally, the algae can produce both nitrogen and phosphorus reduction over a range of temperatures.

Library of Congress Subject Headings

Water--Purification--Phosphate removal--South Dakota--Kampeska, Lake
Water--Phosphorus content--South Dakota--Kampeska, Lake
Bioreactors--South Dakota--Kampeska, Lake
Algae--South Dakota--Kampeska, Lake

Description

Includes bibliographical references (pages 56-59)

Format

application/pdf

Number of Pages

88

Publisher

South Dakota State University

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Rights Statement

In Copyright