National Health Environment Association

A NOTE FROM CHARLES SENN

Former Chairman of the National Health Environment Association

​Note: MR. CHARLES SENN, NOW RETIRED, IS THE FORMER CHAIRMAN OF THE NATIONAL HEALTH ENVIRONMENT ASSOCIATION FOR THE STUDY OF ON SITE SYSTEMS FOR THE FEDERAL ENVIRONMENTAL PROTECTION AGENCY, FORMER HEALTH DIRECTOR FOR THE CITY OF LOS ANGELES, FORMER PROFESSOR OF SANITARY ENGINEERING AT U.C.L.A. AND INDEPENDENT ENVIRONMENTAL CONSULTANT.

Report on Study and Observations of Sewage Treatment System of
by Charles L. Senn, P.E., R.S.
​Environmental Consultant

It is clear from tests and repeated observations that the effluent is far superior to that of a septic tanks.

C. Observations

In addition to the experiences of many observers, noted above and included in the appendix, the following conditions were noted:

The efficiency of the current system in distributing the liquid so it is available to plant roots, in certain soils, was apparent from the luxuriant growth of vegetation which outlined the distribution system at the Riverside residence.

Further, whereas it was nearly impossible to force a round-nosed shovel into the hard, dry decomposed granite soil adjacent to the distribution system, one could spade almost any part of the area over the pipes with ease and the soil was uniformly moist.

Unlike digging near effluent from a septic tank, the soil had a natural soil odor.

The most serious problem with most extended aeration system is the need for fairly frequent removal of excess activated sludge. It has been noted that this type system tends to produce more sludge volume of a septic tank.

Probably due to the daily alternating of aerobic and anaerobic cycles of the Sewer King unit, there is practically no build-up of sludge and no carry-over of sludge through the effluent. One possible explanation is that the activated sludge produced during the aerobic cycle is anaerobically digested during the 18 hour period during which the aerator is off. Further study must be made to better understand the phenomenon but it is noted that the aerobic cycle results in a high degree of nitrification occurs with the nitrogenous material converting to nitrogen gas and carbonaceous material converting to nitrogen gas and carbonaceous material converting to carbon dioxide.

Sincerely,
Charles L. Senn, P.E., R.S.