Dear John Todd
I am very interested in your technology - especially the re-use potential included in the concept.

I would however like your comments on a paper presented at the 5th Int. Conf, on Wetlands Systems for Water Pollution Control held in Vienna 1996. The paper is authored by S.C. Reed, J. Salisbury, L. Fillmore and R.K. Bastian, and is entitled: "An evaluation of the 'Living Machine' wastewater treatment concept".  The paper describes the results and conclusions of an EPA funded independent evaluation of the technology, based on studies in a 150 m3/day system constructed in Frederick, MD.  I would like your comments to the conclusions listed below:

(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 plants do, however provide a pleasing aesthetic environment which can significantly enhance public acceptance as a waste
treatment process.

(2) The residuals (sludge and plant material) produced by the 'Living Machine' are equivalent to that produced by an equivalent sized extended aeration process.

(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.

(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.

(5) The 'Living Machine' can be accurately described as an extended aeration unit followed by a nitrification filter followed by a denitrification filter.  These are all well understood and widely used conventional technologies. The claims that the 'Living Machine' is a unique and distinct technology are not warranted.

I look forward to hear your responses to these statements.

Dr Hans Brix
Department of Plant Ecology, Institute of Biological Sciences
University of Aarhus, Nordlandsvej 68, DK-8240 Risskov (DENMARK)
Tel. +45 8942 4714 (direct line); +45 8942 4700 (switchboard)
Fax. +45 8942 4747
Email: Hans.Brix@biology.aau.dk
Department Homepage: http://botanik.aau.dk/ecology/
EUREED Homepage: http://botanik.aau.dk/eureed/