Ecology As The Source Of Inspiration In Design

The hypothesis that has emerged from the examination of the history of the use of wetlands for wastewater treatment is that the technology primarily evolved from ecologists working on applied problems, rather than from engineers discovering ecosystems as useful systems. If this hypothesis is true, it suggests that the field of ecological engineering has a unique approach compared with other forms of engineering. It is not just a variation of environmental engineering but a whole new branch of engineering, and perhaps of ecology. Detailed descriptions of the design

Reef Slope

Paragoniolithon conicum Porolithon onkodes

Porolithon onkodes Laurencia spp. Caulerpa racemosa

Rubble Crest Caulerpa racemosa Yamadaella coennomyce Endolithic cyanophytes (Enteromorpha sp.) Gelidiella acerosa

Lagoon

Hormothamnion enteromotphoides | Sanid Oscillatotia bonnemaisonii J Species

Halimeda cylindracea Caulerpa serrulata Caulerpa sertularioides Ceratodictyon spongiosum Lithophyllum molluccense ) on Bommies Lithophyllum kotchyanum and most of the species listed for the reef flate

Reef Slope

Paragoniolithon conicum Porolithon onkodes

Porolithon onkodes Laurencia spp. Caulerpa racemosa

Rubble Crest Caulerpa racemosa Yamadaella coennomyce Endolithic cyanophytes (Enteromorpha sp.) Gelidiella acerosa

Reef Flat

Halimeda discoidea Halimeda opuntia Caulerpa racemosa Boodlea composita Chlorodesmis fastigiata Dictyosphaeria spp. Padina australis Lobophora variegata Dictyota bartayresii Chnoospora fastigiata Hydroclathrus clathrus Turbinara ornata Sargassum spp. Caulerpa cupressoides Valonia ventricosa Hypnea spp. Laurencia spp. Gliffordia spp. Feldmannia spp. Ceramium spp. Gelidiella acerosa Bryopsis sp. Polysiphonia spp. Leveillea jungermannoides Lophosiphonia spp. Calothrix crustacea Ralfsia sp. Peyssonellia sp. Lyngbya spp.

Lagoon

Hormothamnion enteromotphoides | Sanid Oscillatotia bonnemaisonii J Species

Halimeda cylindracea Caulerpa serrulata Caulerpa sertularioides Ceratodictyon spongiosum Lithophyllum molluccense ) on Bommies Lithophyllum kotchyanum and most of the species listed for the reef flate

"Turf1' Species

FIGURE 2.25 Cross-section through a coral reef showing the distribution of algae. Note the location of the algal rim (reef crest) where algal turfs can be found. (From Berner, T. 1990. Coral Reefs: Ecosystems of the World. Vol. 25. Z. Dubinsky (ed.). Elsevier, Amsterdam, the Netherlands. With permission.)

histories of two variations on the treatment wetland technology are presented to further explore this idea.

Algal Turf Scrubbers

Walter Adey has developed a unique wastewater treatment system, termed algal turf scrubbers, which utlize algae to strip pollutants out of water (Adey and Loveland, 1998). Although there is a long history of trials employing algae for wastewater treatment in the sanitary engineering field (Bartsch, 1961; Gotaas et al., 1954; Laliberte et al., 1994; Oswald, 1988; Oswald et al., 1957; Wong and Tam, 1998), Adey came upon his version of technology from studies of basic ecology. Adey is a coral reef ecologist who published much work, especially on algae, in the 1970s (Adey, 1973, 1978; Adey and Burke, 1976; Connor and Adey, 1977). Algae are the most important primary producers on coral reefs and they occupy many microhabitats (Figure 2.25). The algal turf scrubber technology is based on Adey's adaptation of algal turfs from coral reefs (Adey and Goertemiller, 1987; Adey and Hackney, 1989; Adey and Loveland, 1998). Algal turfs are short, moss-like mats of algal filaments covering hard surfaces found at the reef crest where wave energy is highest (Figure 2.26). Adey created artificial algal turfs by growing the algae on a screen in a shallow trough over which water was passed (Figure 2.27), with artificial lights

FIGURE 2.26 The reef crest on the barrier reef of Belize.
Caulerpa Adey
FIGURE 2.27 View of an algal turf scrubber unit. (From Adey, W. H. and K. Loveland. 1998. Dynamic Aquaria, 2nd ed. Academic Press, San Diego, CA. With permission.)

and wave energy generated by a surge bucket. The algae grow very quickly and strip nutrients out of the flowing water through uptake. By scraping the algae off the screens periodically, nutrients are permanently removed from the system and water quality is improved.

Adey came upon this technology while trying to design large coral reef aquaria for research and exhibit purposes (see Chapter 5). His challenge was to maintain narrow water quality conditions necessary for survival of the sensitive coral reef organisms. Adey's (1987) description of the discovery of the algal turf scrubber, after many unsuccessful trials of commercially available filter systems, reveals the basic ecological knowledge embodied in the design:

Finally, I decided to try to remove a piece of the primary photosynthetic component, the algal turf from the reef itself, and to allow that plant community to develop and photosynthesize under appropriately high light intensity in a side branch of the entire system, during hours when the reef was in darkness.

From our experience with both the wild and the microcosm algal turfs, we concluded that we might make this work if, along with high light intensity, we supplied wave action, water flow, a porous surface (to prevent overgrazing) and constant harvesting (to prevent community succession). Thus, we created a device called "the algal turf scrubber" and attached it to the 7 kl system late in 1979. The algal turf scrubber was extraordinary successful, in that it achieved primary production rates characteristic of a wild reef, and also simulated the effects of high-quality ocean water by adding oxygen to the system and scrubbing nutrients from it. Most important, it could be operated at night, when water quality is likely to decline, and it was controllable in many ways, since by adjusting light, wave action, water flow and harvest rates we could maintain water chemistry in the microcosm reef much as ocean flow maintains it in the wild.

An algal turf scrubber was attached to Adey's coral reef model to simulate a larger body of water that would normally surround a reef and buffer its water quality. Specifically, the scrubber is lighted in a cycle opposite to the model reef so that oxygen would be supplied during the night and so that nutrients and CO2 released by nighttime respiration would be taken up. These critical functions allowed a high diversity of animal life to survive in the model reef. Adey patented the technology in 1982 and applied it to a number of living ecosystem models (Adey and Loveland, 1998). He later scaled the design up in size and applied algal turf scrubbers to a variety of types of wastewaters (Adey et al., 1993, 1996; Blankenship, 1997; Craggs et al., 1996). Overall, this represents an excellent example of ecological engineering by utilizing ecological knowledge and the principle of preadaptation. Specifically, Adey recognized that the natural algal turf was preadapted for wastewater treatment. The design process used by Adey is proposed in Figure 2.28. He studied natural algal turfs on coral reefs (references shown in the upper box) and then had a creative inspiration that allowed him to use the natural system in an engineered design to treat wastewater (references shown in the lower box). The creative inspiration is shown by the arrow connecting studies of the natural system with examples of engineered designs. This kind of insight is the essence of ecological engineering!

Living Machines

John Todd has developed a unique wastewater treatment system, termed the living machine, which is the product of a long design history (Guterstam and Todd, 1990; Todd, 1988a, 1988b, 1990, 1991; Todd and Todd, 1994). The development of the design started at the New Alchemy Institute on Cape Cod, which Todd helped create in the early 1970s. The New Alchemy Institute was an organization devoted to developing and demonstrating integrated environmental technologies involving energy systems, architecture, and sustainable agriculture (Todd and Todd, 1980, see Chapter 9). One of the principal elements in these integrated systems was aquaculture. Especially with William McLarney and Ronald Zweig, Todd tried many configurations of fish culture tanks (McLarney and Todd, 1977; Zweig, 1986; Zweig et al., 1981). He settled on a large cylindrical tank (up to 1000 gal or 3790 l capacity)

Adey, W.H. and R. Burke, 1976. Holocene bioherms (algal ridges and bank barrier reefs) of the eastern Caribbean. Geol. Soc. of Am. Bull., 87:95-109.

Connor, J.L. and W.H. Adey, 1977. The benthic algal composition, standing crop, and productivity of a Caribbean algal ridge. Atoll Res. Bull., 211.

Adey, W.H., 1978. Algal ridges of the Caribbean Sea and West Indies. Phycologia, 17:361-367.

Adey, W.H., C. Luckett, and K. Jenson, 1993. Phosphorus removal from natural waters using controlled algal production. Restor. Eco., 1:29-39.

Adey, W. H., C. Luckett, and M. Smith, 1996. Purification of industrially contaminated groundwaters using controlled ecosystems. Ecolog. Eng., 7:191-212.

Craggs, R.J., W.H. Adey, B.K. Jessup, and W.J. Oswald, 1996 A controlled stream mesocosm for tertiary treatment of sewage. Ecol. Eng., 6:149-169.

FIGURE 2.28 The intellectual leap taken by Walter H. Adey in developing the algal turf scrubber technology.

made of translucent material as a basic module (Figure 2.29). Table 2 in Tomorrow Is Our Permanent Address (Todd and Todd, 1980) lists much of the design knowledge embodied in the aquaculture system, labeled as "biologically designed versus engineered closed-system aquacultures." The living machine technology evolved from the basic aquaculture module, first by combining them in series and then by using the series as a sequential wastewater treatment system (Figure 2.30). This basic sequential system has evolved over time with the different modules becoming specialized to perform critical functions. Todd (1990) credits the need for maintaining water quality in the aquaculture systems as a kind of inspiration in the design evolution of living machines for wastewater treatment, as noted in the following quote:

For over fifteen years, beginning at New Alchemy, I had raised fish and had learned innumerable tricks to purify water in order to keep the fish healthy. It seemed logical to use the same biological techniques and apply them to purifying water, sewage and other waste streams. An ecosystem approach, while dramatically different from conventional waste engineering, seemed to me to be the best long-term solution to upgrading water quality not only on Cape Cod, but throughout the country.

This jump is the essei of ecological engineer

This jump is the essei of ecological engineer

This design evolution is discussed further in a paper entitled "Biology as a Basis for Design" (Todd and Todd, 1991), which captures the essence of the technology.

Ecological Engineering

FIGURE 2.29 View of a single tank used in early work on aquaculture by John Todd. (A) Hydroponic vegetables on top of pond. (B) Styrofoam flotation and guides for plants. (C) Central core opening for fish feeding. (D) Mesh cage to prevent fish from eating plant roots. (E) Fish rearing area in pond. (From Zweig, R. D. 1986. Aquaculture Magazine. 12(3):34—40. With permission.)

FIGURE 2.29 View of a single tank used in early work on aquaculture by John Todd. (A) Hydroponic vegetables on top of pond. (B) Styrofoam flotation and guides for plants. (C) Central core opening for fish feeding. (D) Mesh cage to prevent fish from eating plant roots. (E) Fish rearing area in pond. (From Zweig, R. D. 1986. Aquaculture Magazine. 12(3):34—40. With permission.)

Principal Steps of the Wastewater Treatment at the Stensund Aquaculture:

1. Raw Sewage

2. Anaerobic Treatment

3. Aerobic Treatment

4. Phytoplankton-Bacteria Basin

5. Zooplankton Basin

6. Polyculture (Fish, Crayfish, Plants)

' 2-3 are Steps of Mineralization and Detoxification ' 4-6 are Steps of Aquaculture

1. Raw Sewage

2. Anaerobic Treatment

3. Aerobic Treatment

4. Phytoplankton-Bacteria Basin

5. Zooplankton Basin

6. Polyculture (Fish, Crayfish, Plants)

' 2-3 are Steps of Mineralization and Detoxification ' 4-6 are Steps of Aquaculture

FIGURE 2.30 The idea of using a series of tanks for wastewater treatment, with aquaculture at the final stages. (From Guterstam, B. and J. Todd. 1990. Ambio. 19:173-175. With permission.)

FIGURE 2.30 The idea of using a series of tanks for wastewater treatment, with aquaculture at the final stages. (From Guterstam, B. and J. Todd. 1990. Ambio. 19:173-175. With permission.)

A number of living machines have been built and tested (Figure 2.31) with much description presented in Todd's own journal (Josephson, 1995; Josephson et al., 1996). A significant amount of work on living machines has also been done in Sweden (Etnier and Guterstam, 1991; Guterstam, 1996; Guterstam and Todd, 1990).

Caulerpa Adey
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