AXIOMS OF ECOLOGICAL ENGINEERING


The notion that human beings can design incredible processes such as ecosystems has been described as the height of hubris by some; ecosystems are too complex, the argument goes, and our knowledge too incomplete. In reality, we design ecosystems every time we start a bulldozer or tractor, every time we change land use or reroute stream flow.

We just do not design explicitly, and the consequences are apparent. Designing ecosystem services should be approached with a deep sense of humility and respect for what we do not know.

In order to ensure that this philosophy is embodied in the practice of ecological design, we propose the following three axioms of ecological engineering:

1. Everything is connected
2. Everything is changing
3. We are all in this together

The first two axioms are fundamental principles of systems ecology described by H. T. Odum (1988) and are the foundation of ecological design. They are critical for understanding and conceptualizing solutions to the challenges of developing sustainable design strategies.

The interconnectedness of all biotic and abiotic processes throughout the biosphere is demonstrated by the effects of urban land use on almost every aspect of ecosystem function, from climate to hydrology to biodiversity. Everything is changing, and the rate of change is increasing.

Changes in the biosphere are being driven by changes in global climate, land use, and human population, among other factors.

The third axiom, embodied by the Cherokee cultural ideal gadugi, roughly translated as “we are all in this together,” is a normative claim that connects ecosystem theory with sustainability. This is the essence of the ecological engineering ethics.

DRINKING WATER PLANT PROCESS SELECTION


Fundamental Precepts

Experience has taught us the following fundamental precepts in process selection (MWH, 2005):

1. The raw water quality of every source is different.

2. Raw water quality is variable.

3. There is no standard water treatment plant design that is applicable to all sources.

4. For every source, a number of treatment process alternatives are available.

5. Site conditions often limit the types of treatment process that can be used.

6. Retrofitting and upgrading of existing plants requires creative solutions that are not presented in standard textbooks such as this one.

7. Pilot plant testing is highly recommended in the selection of retrofit and upgrade alternatives.

8. Pilot plant testing requires careful planning and execution to obtain useful design and operating criteria.

9. It is essential that the multibarrier concept be a feature of all designs.

10. Operator experience is invaluable in developing a design.

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