Thanks for the Activated Sludge

Kindly wishes, from the preface of the book Sewerage and Sewage Treatment, by Harold Eaton Babbitt (published by John Wiley and Sons, New York,1922):

[The author wishes to express his thanks] to Mr. Paul Hansen, consulting engineer, of Chicago, and to Mr. Langdon Pearse, Sanitary Engineer of the Sanitary District of Chicago, for their help on the section covering the treatment of sewage; and to Professor Edward Bartow, Professor of Chemistry at the University of Iowa, for his review of the chapter on Activated Sludge; in general his thanks are due to all others who have furnished suggestions, illustrations, or quotations, acknowledgments of which have been included in the text.