Excerpt from Methods and Devices for Bacterial Treatment of Sewage To draw a clear distinction between the engineering problem and the biological problem is not to undervalue the work of the biologist and the chemist. Unless their work had been done, the engineering applications of it could not be made, or, if they were made, they would be entirely empirical, and in con sequence uneconomical. But it should not be thought that the engineer can afford to be altogether ignorant of the sciences of biology and chemistry. It is essential for him to understand something of both of these sciences in order that he may be intelligent in applying the principles derived from them. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.