I would like to add to Michael Shaw's responses to Dr. Hans Brix's questions of last week. I apologize for the delayed response...

>(1) The plants used on and in the 'Living Machine' provide a marginal
>contribution to treatment and are not essential for realization of process treatment goals.

The authors of this study reached this conclusion by comparing the area of several types of planted reactors (including open aerobic cells, clarifiers, and Ecological Fluidized Beds, or EFB's) with the area of the total greenhouse. However, they failed to note that treatment performance was only one goal of the Demonstration AEES project. The greenhouse was specifically constructed to accomodate tours, and made handicap accessible. Therefore, the size (and cost) of the greenhouse was far greater than would be necessary for a purely performance-oriented Living Machine.

>(3) The life cycle costs of the 'Living Machine' appear to be comparable to
>conventional technologies at flow rates less than 200 m3/d. At flow rates
>higher than 200 m3/d the 'Living Machine' becomes more expensive. At 3785
>m3/d the costs of the 'Living Machine' is 50 percent higher than
>conventional technology.

Once again, the demonstration-nature of this project prevents meaningful comparisons. As Michael stated, a number of Living Machines have since been built for private-sector clients to treat high-strength industrial wastes. These systems offer clients an extremely cost-effective choice to achieve environmental excellence.

>(4) Solar energy plays an incidental role in the 'Living Machine' process.
>The 'Living Machine' utilizes the same mechanical energy sources (at the
>same levels) and the same chemicals as conventional wastewater treatment systems.

While solar energy provided only a portion of the energy inputs to the Maryland system, other Living Machines have been built that rely entirely on solar energy. Restorer 1, the floating Living Machine placed on Flax Pond in Harwich, Massachusetts in 1992, has been powered entirely by renewable energy resources. Initially, a wind turbine was used to power the 12-volt air compressors on board. This has since been replaced with a photovoltaic system, making this Living Machine entirely solar-powered, from its mechanics to its extensive rhizofiltration cells. During the first two years of its operation, the Restorer Living Machine assisted in the digestion of 19,000 cubic meters of anoxic sediments, greatly improving benthic diversity. Additionally, we estimate that the Restorer removes more than 5 kg of ammonia from the pond through denitrification each year in its EFB's.

Although many improvements in Flax Pond are difficult to quantify (the Restorer is an extremely open, nonlinear system, 78,000 gallons of landfill leachate continue to enter the pond each day, and the pond also received other ecological augmentations), this solar-powered system achieved more with solar energy than any other lake-treatment strategy I know of. One could easily design Living Machines for industrial and municipal waste treatment to be as completely solar-powered as the Flax Pond system.

-----Richard Boylan-----
        -----Ocean Arks International-----
                -----Lake Restoration Project Manager-----