1
Don M Vandervelde, Glenn J Helm: Process and apparatus for a biological reactor to purify water. March 5, 1991: US04997568 (40 worldwide citation)

A system and method to remove pathogenic organisms and other suspended and dissolved containments from sewage or other contaminated water by an inexpensive, nearly maintenance free device. Principles of operation include new effective methods whioch combine synergistically, suspended and fixed film ...


2
Don M Vandervelde, Glenn J Helm: System for treating sewage or other fluids. January 25, 1994: US05281332 (15 worldwide citation)

A method and device for complete treatment of septic tank effluent or other contaminated water by contriving for it to flow in an ultra-thin film over a surface treatment medium such as fabric or sand. It provides diffusive aeration, biological reaction and physical filtration on a molecular scale.


3
Don M Vandervelde, Glenn J Helm: Method for treating sewage and other liquids. R Reams Goodloe Jr, May 27, 1997: US05632896 (12 worldwide citation)

A method for complete treatment of septic tank effluent or other contaminated liquid by contriving for it to flow in an ultra-thin film over a surface treatment medium such as fabric or sand. It provides diffusive aeration, biological reaction and physical filtration on a molecular scale.



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