An Audacious Idea

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The use of wetlands for wastewater treatment was begun in the early 1970s. Whose idea was this? It is important to understand the origin of this application since it will reveal information on the nature of ecological engineering. One hypothesis is that the origin of treatment wetlands was a result of the technological progress of sanitary engineering systems (Figure 2.9). This is a reasonable hypothesis in that the pathways require no especially dramatic technical jumps and in each case ecosystems are used to consume the sewage. Of course, sewage was originally just released into streams as Streeter and Phelps had studied in the early 1900s. This is exactly the same approach taken with wetlands in the 1970s but with one treatment ecosystem (the river) being changed for another (the wetland). Although this hypothesis is reasonable, there is much more to the history.

Rather than a gradual progression of technological steps, there was an explosion of ideas, all at about the same time, for combining wetlands and sewage for waste-

Use of Wetlands for Wastewater Treatment

Use of Wetlands for Wastewater Treatment

Dumping Raw Sewage in rivers

FIGURE 2.9 Hypothetical pathways of technological evolution of the use of wetlands for wastewater treatment from sanitary engineering systems.

Georgia salt marsh (Haines 1979)

Wisconsin constructed marsh (Fetter et al., 1976)

Canadian marsh (Hartland-Rowe and Wright 1975)

South Florida marsh (Steward and Ornes 1975)

Georgia salt marsh (Haines 1979)

Wisconsin constructed marsh (Fetter et al., 1976)

Canadian marsh (Hartland-Rowe and Wright 1975)

South Florida marsh (Steward and Ornes 1975)

New Jersey tidal marsh (Whigham and Simpson 1976)

Canadian mesocosm (Lakshman 1979)

Michigan peat wetland (Tilton and Kadlec 1979)

South Carolina river swamp (Kitchens et al., 1975)

Canadian Ontario marsh (Murdoch and Capobianco 1979)

Mississippi constructed marsh (Wolverton et al., 1976)

Massachusetts salt marsh (Valiela et al., 1973)

Michigan peat wetland (Tilton and Kadlec 1979)

South Carolina river swamp (Kitchens et al., 1975)

Canadian Ontario marsh (Murdoch and Capobianco 1979)

New Jersey tidal marsh (Whigham and Simpson 1976)

Mississippi constructed marsh (Wolverton et al., 1976)

Canadian mesocosm (Lakshman 1979)

Florida cypress domes (Odum et al., 1977a)

Massachusetts salt marsh (Valiela et al., 1973)

Minnesota constructed peat bed (Osborne 1975)

FIGURE 2.10 The "big-bang" model of a technological explosion of early treatment wetland projects.

water treatment (Figure 2.10). An examination of the literature shows that, starting in the early 1970s and extending through the decade, a large number of studies were conducted over a relatively short period of time to test wetlands as a system for wastewater treatment. This is shown in Figure 2.10 with references scattered around a central core of possible antecedent studies. The model that is represented in this figure is a kind of "big bang" explosion of creative trials of the idea of using wetlands for wastewater treatment. This kind of model has been proposed by Kauffman (1995) for technological jumps. He uses an analogy with the evolutionary explosion that took place at the start of the Cambrian era when many of the modern taxonomic groups of organisms appeared suddenly in a kind of creative explosion of biodiversity. In the same sense there was an explosion of studies on wetlands for wastewater treatment in the 1970s and the present state of the art in this technology traces back to this creative time.

What might have triggered this explosion of studies? Several authors have proposed that the Clean Water Act, which was passed in 1972, may have been an important influence (Knight, 1995; Reed et al., 1995). The most significant aspect of this legislation may have been the shifting emphasis in research funding towards alternative treatment technologies. However, the general intention of the Act was to reduce pollutant loads to natural systems, not to increase them as occurs when treating wastewater with wetlands. It seems unlikely, moreover, that either an act of legislation or even increased research funding were the actual triggers to the explosion of studies, because these are not strong motivators of scientific advancement. In fact, there must have been a kind of sociopolitical resistance against putting wastewater into natural wetlands from several sources in the early 1970s. First, the environmental movement was growing, and environmentalists sought to preserve wilderness and to oppose any changes in natural systems caused by human actions. This movement took definite form with the first Earth Day celebration in April 1970, almost at the exact beginning of trials of wastewater treatment with wetlands. Second, society as a whole in the U.S. had just come to recognize cultural eutroph-ication as a significant issue (Bartsch, 1971; Beeton and Edmondson, 1972; Hutchinson, 1973; Likens 1972). Eutrophication, or the aging of an aquatic ecosystem through filling in with inorganic and organic sediments, is a natural phenomenon (actually a form of ecological succession). However, humans can accelerate this process through additions of nitrogen and phosphorus found in various kinds of wastewater (i.e., cultural eutrophication). Finally, in addition to the obstacles mentioned above, there was a normal resistance to the idea of using wetlands to treat wastewater, resistance that always occurs when a new technology is introduced. This was led by sanitary engineers who utilized conventional treatment technologies and by government officials who regulate the industry, and it continues in the present. Thus, the use of wetlands to treat domestic sewage was an audacious idea in the early 1970s, which faced many hurdles (Figure 2.11). The only positive influence may have been the first energy crisis in 1973, which provided the incentive for reducing costs in many sectors of the economy (K. Ewel, personal communication). In retrospect, it seems somewhat amazing that the idea was allowed to be tested at all.

The use of wetlands to treat wastewater came from an intellectually courageous group of ecologists who saw the positive dimension of the idea (as a form of ecological engineering) and who were not held back by the negative dimension (that it represented intentional pollution of a natural ecosystem type in order to treat wastewater). The concept seems to have arisen from at least four specific antecedent

Introduction of the Clean Water Act by the U.S. Congress .

Normal resistance to new technologies

Use of wetlands for wastewater treatment in the U.S.

First Earth Day and growing awareness about water pollution by society

First energy crisis

FIGURE 2.11 Causal diagram of sociopolitical influences on the development of the treatment wetland technology in the U.S. during the early 1970s.

activities that appeared in the late 1960s, as shown in the center of Figure 2.10. Bastian and Hammer (1993), Kadlec and Knight (1996), and Knight (1995) provide some discussion of the history of the treatment wetland technology, and they note the possible early influence of several of these antecedent works. These early initiatives are especially important because they predate the early 1970s explosion of studies. Short descriptions of these are given below:

1. Tinicum Marsh is a natural, freshwater tidal marsh near Philadelphia, PA. It is dominated by wild rice (Zizania aquatica) and common reed (Phrag-mites australis) and has been highly altered by a variety of human impacts. In the late 1960s the marsh became the focus of a conservation struggle over its value as open space within the urban setting and several studies were conducted on its ecology. One study by Ruth Patrick reviewed the marsh's ability to improve water quality. The findings showed significant reductions in BOD and in nitrogen and phosphorus from the effluent discharge of a nearby sewage treatment plant. The data on water quality improvement owing to the marsh became one of the political arguments for preserving it as urban open space. This example of an inadvertent discharge was the first of many similar studies made in the 1970s. Information on Tinicum Marsh is given by McCormick (1971), by Goodwin and Niering (1975), and in an original contract report by Grant and Patrick

2. Water hyacinths (Eichhornia crassipes) are floating plants of tropical origin that have very high productivity. This quality causes them to act as weeds in clogging waterways and much research has gone into developing methods for controlling their growth. In the late 1960s and early 1970s a number of workers sought to take advantage of the water hyacinth's fast growth rates by testing out possible wastewater treatment designs (Boyd, 1970; Rogers and Davis, 1972; Scarsbrook and Davis, 1971; Sheffield, 1967; Steward, 1970). The concept is to grow water hyacinths on sewage effluent and periodically harvest their biomass. Large amounts of nutrient could be stripped from the water as a result of uptake

driven by the high productivity. These early studies were continued through the 1970s (Cornwell et al., 1977; Taylor and Steward, 1978; Wooten and Dodd, 1976), and they also led to modifications such as by Wolverton and McDonald (1979a, 1979b).

3. Professor Kathe Seidel was a German scientist who started experimenting with the use of wetland plants for various kinds of wastewater treatment in the 1950s at the Max Planck Institute. Seidel seems to have been the first worker to test the concept of treatment wetlands and she published extensively in German (Seidel, 1966). Unfortunately, her work did not become widely known to western scientists until a publication appeared in English in the early 1970s (Seidel, 1976).

4. H. T. Odum ran a large project, which began in 1968, on testing the effects of domestic sewage on estuarine ecosystems at Morehead City, NC (H. T. Odum, 1985, 1989b). Experimental ponds that received sewage were compared with control ponds that received fresh water. The results indicated that sewage ponds had lower diversity of species and other characteristics of cultural eutrophication (algal blooms, extremes in oxygen concentrations) relative to controls, but both systems self-organized ecological structure and function with available species. This experiment did not deal with treating sewage specifically but rather with sewage effects as a pollutant. This focus is indicated by H. T. Odum's placement of the study in his text on microcosms (Beyers and H. T. Odum, 1993) not under the "wastes" chapter but under the chapter on "ponds and pools." However, H. T. Odum's later project on cypress swamps for wastewater treatment in the 1970s (Ewel and H. T. Odum, 1984) clearly traces back to the Morehead City project, as noted by Knight (1995), who served as a young research assistant studying the estuarine ponds. H. T. Odum seems to have had even earlier premonitions on the treatment wetland idea while working on the Texas coast in the 1950s, as indicated by the following quote from Montague and H. T. Odum (1997):

A serendipitous example one of us (HTO) has observed over some years is the sewage waste outflow from a small treatment plant at Port Aransas, Texas. Wastes were released to a bare sand flat starting about 1950. As the population grew, wastes increased. Now there is an expansive marsh with a zonation of species outward from the outfall. Freshwater cattail marsh occurs immediately around the outfall. Beyond that is a saltmarsh of Spartina and Juncus through which the wastewaters drain before reaching adjacent coastal waters.

These four projects or lines of research seem to have set the stage for or actually triggered the explosion of studies in the 1970s. Apparently, the idea arose in scientists' minds to try wetlands for wastewater treatment and then positive feedback occurred as other scientists got caught up in trying the approach with different kinds of designs. Table 2.1 summarizes the early published studies according to their basic research design. Although there is a balanced representation between types of studies, the inadvertent experiment was the most common kind of study. In this approach

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