Tertiary Treatment of Industrial Waste and
Lake Restoration
A Similarity in Approach
BRIAN P.J. HIGGINS, Graduate Research Assistant
ROBERT L. IRVINE, Associate Professor
SUDHIR C MOHLEJI, Doctoral Student
Department of Civil Engineering
University of Notre Dame
Notre Dame, Indiana 46556
INTRODUCTION
Tertiary treatment of wastewater involves something beyond conventional primary
and secondary treatment. It may include additional suspended solids removal with
microscreening or chemical clarification, organic carbon removal with activated carbon or
direct oxidation, inorganic removal with ion exchange or reverse osmosis and nutrient
removal with precipitation or biological denitrification. Research and development of
various tertiary treatment operations and processes has advanced quite rapidly during the
past decade and easily goes beyond the examples listed above. Considerable work in the
area of lake restoration has paralleled these efforts in tertiary treatment. In fact many lake
restoration techniques are simple applications of results from tertiary treatment studies.
The purpose of this paper is to give a detailed description of one lake restoration technique
which may have possible direct application to tertiary treatment of wastewaters. This
technique involves the use of fly ash, the nation's seventh most abundant "raw material" (1),
and the ability of fly ash to remove phosphorus from waters. A brief review of lake
restoration procedures will be presented, however, before the details of fly ash treatment are
discussed.
LAKE RESTORATION PROCEDURES
Man, through this quest for growth and expansion, has managed to accelerate the
natural process of eutrophication in lakes to the point that a review of 425 lakes (2)
indicated that they could not be restored with cursory protective actions alone. Lake
restoration procedures that have been used with varying degrees of success include the
following (3):
1. Control of aquatic plants using chemical, mechanical, physical and biological means.
In each case an attempt is made either to eliminate an unwanted plant or to reduce the
competitive advantage of this plant so that a more balanced biological population
will develop.
2. Reduction of nutrient input by either diversion of the high nutrient load flows or
treatment of the primary nutrient sources. In either case the objective is to reduce the
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