JustBob, according to Dr. John H. Timothy Winneberger, Ph.D in his book, “Septic Tank Systems-A Consultants Toolkit”, the first septic tank systems were developed in France. In the introduction of Chapter 1 of Volume 2 of his book, he writes;
“The invention of the household septic tank has been credited to Louis M. Mouras of Vesoul, France. His friend, Abbe Moigno, editor of Cosmos les Mondes, a scientific journal, assisted with studies of the device which Mouras constructed in about 1860. Mouras and Moigno published on the “Fosse Mouras, la vidangeuse automatique,” which was patented 2 September, 1881. In English, the septic tank was the Mouras Automatic Scavenger.
Despite the satisfactory performance of any device, hucksters are always ready to provide products claimed to make things better yet. Perhaps the first proprietary additive came in 1878. Alexander Muller then applied for patent right for a process by which wastewaters were claimed to be biologically treated in septic tanks, by excluding air and adding yeast and other fermenting substances. Perhaps the popular misbelief that yeast should be added to septic tanks could be traced to Muller.”