Table

Classification of Early Treatment Wetland Studies

(A) Natural Wetlands

(1) Inadvertent Experiment

Wisconsin marsh (Spangler et al., 1976) Wisconsin marsh (Lee et al., 1975)

Canadian Northwest Territories (NWT) marsh (Hartland-Rowe and Wright, 1975)

Canadian Ontario marsh (Murdoch and Capobianco, 1979) South Carolina river swamp (Kitchens et al., 1975) Florida river swamp (Boyt et al., 1977)

(2) Purposeful Additions of Actual Sewage

New Jersey tidal marsh (Whigham and Simpson, 1976) Florida cypress dome (Odum et al., 1977a) Michigan peat wetland (Tilton and Kadlec, 1979) Central Florida marsh (Dolan et al., 1981) North Carolina swamp (Brinson et al., 1984) Georgia saltmarsh (Haines, 1979)

(3) Addition of Simulated Sewage

Massachusetts saltmarsh (Valiela et al., 1973) South Florida marsh (Steward and Ornes, 1975)

(B) Constructed Wetlands

(4) Pilot Scale System

New York constructed marsh (Small, 1975) Minnesota constructed peat bed (Osborne, 1975) Mississippi constructed marsh (Wolverton et al., 1976) Wisconsin constructed marsh (Fetter et al., 1976)

(5) Mesocosm

Canadian Saskatchewan marsh (Lakshman, 1979) Note: References are from Figure 2.10.

a study was made of the performance of a natural wetland that had been receiving sewage for a number of years. The situation arises when sewage is discharged inadvertently (and illegally) into a natural wetland. This kind of study has advantages of showing long-term performance, but there is no experimental control and no replication. All of the other kinds of studies listed in Table 2.1 have various degrees of experimental design, though complications often arose. Particularly interesting are the studies that used simulated sewage. The studies listed in Table 2.1 were field studies, which is ecology at its best. Problems occur in such experiments but they are views of how nature responds in the real world. In each case the systems of wetlands and sewage that emerged were new systems with altered biogeochemistry, different relative abundances of plants, animals and microbes, and new food web structures. The ecosystems self-organize from available components into new systems that are partly engineered and partly natural. The engineered subsystems range from simple deployments of pipes and pumps that discharge sewage into an existing wetland to complicated constructed wetlands that are actually hybrids of machine and ecosystem with multiple units in series and parallel connections and with sophisticated flow regulation devices. Some of the studies, such as the cypress project in Florida, were well funded and resulted in many publications about various aspects of the treatment wetland system. Other studies were represented by only a single publication with little system description except some water quality data. Most of the studies were short term and "died out" while a few continued to develop and are represented in the present-day technology. This seems reminiscent of the early automobile industry in Detroit, Michigan, around the turn of the twentieth century when many new auto designs were built and tested by small and large companies (Clymer, 1960). The innovators in the early automobile industry were mechanics who were able to coevolve with entrepreneurs and who in turn could mold and adapt existing technology (such as bicycles). The innovators of the treatment wetland technology were ecologists who were able to coevolve with engineers and regulators and who could mold and adapt wetland ecosystems with existing conventional wastewater treatment technology. An important exception is Robert Kadlec, who is one of the few early workers trained as an engineer rather than as an ecologist. Kadlec has continued his study of sewage treatment by a natural Michigan peatland for three decades, and he is a leader in creating quantitative design knowledge on treatment wetlands (Kadlec and Knight, 1996).

A kind of modest industry has evolved out of the early wetlands for wastewater treatment studies of the 1970s. Table 2.2 offers a hypothetical description of this evolution with speculations for the future. After the period of "optimism and enthusiasm" of the 1970s, problems with the technology began to appear. The best example may be problems with the capacity for long-term phosphorus uptake that have been reviewed extensively by Curtis Richardson (1985, 1989; Richardson and Craft, 1993). These kinds of problems are being addressed and the field is moving forward. It appears the technology will continue to grow into a viable commercial scale industry that will rival conventional treatment technologies, especially for rural or other relatively specialized situations.

Internet Entrepreneurship Survival Guide

Internet Entrepreneurship Survival Guide

Master The Backwoods of Internet Entrepreneurship All Distilled into a Single Most Powerful Guide! Like a long pole, that can shift a great weight with little effort such is the case with succeeding in business. Your chances of succeeding-as an 'army of one' fall somewhere between zip, zilch and nill.

Get My Free Ebook


Post a comment