Edward A. Paterson, chemical engineer, London, England, appeared before the commission and said:
After I received the telegram from the secretary of the Canadian section of the commission asking me to come here I cabled to London for certain plans and models and additional samples, as I only had a few samples on this side and a few notes. These samples and reports have not yet got here, I suppose owing to the war conditions. I therefore have to rely upon rough laboratory notes, which I hope to augment with further information as soon as the data arrive here. I hope you will excuse me for not having the short report which I have made in fuller detail. I shall be glad to give you more interesting information later.
I may state, first, that my remarks are purely from the British point of view; I am not at all familiar with the conditions on this side, except as to a few of the plants, such as the Baltimore plant and others, where they have erected up-to-date plants for the collection of the solids. I have been investigating this matter for about six years purely from the point of view of the disposal of the solids, and I have looked upon it from the utilization point of converting waste products into a commercial enterprise. Our difficulty in Great Britain is that we have an enormous accumulation of what we call sludge cake or sewage cake, which comes mostly from the filter press, and in some cases it is taken out to sea and in others it is disposed of on the land and in other cases they burn it. In England alone we have enormous quantities of this material, which costs from 1 shilling to 5 shillings—that is, from 25 cents to $1.25—per ton of wet sludge. When I refer to “wet sludge,” I mean sludge that contains from 50 to 60 per cent of water.
As to the raw material, the process to which I will refer deals with the raw sewage which has been precipitated or agglomerated by means of lime, “ferro-alumina,” or other agent, and rendered solid either by filter pressing or “lagooning” at the sewage-disposal works. This solid material contains on an average 50 to 55 per cent moisture and must, owing to its nature, be quickly disposed of, because for about six months in the year it becomes extremely offensive, and they have in England a very small area in which to dispose of it. It has to be taken away by railway trains and in boats and such like conveyances. In Great Britain the amount of solid material—containing 50 per cent moisture—produced by each 1,000 inhabitants is approximately 100 tons per annum, and, for the purposes of this report, those towns in the United Kingdom having a population of over 100,000 people produce annually 1,800,000 tons.
In disposing of it we look upon it from the commercial point of view, and, therefore, the composition of the sewage is very important.
The composition of raw sewage, of course, must vary very considerably, depending on the time of year and the district which it is derived from—trades waste, and so forth, e. g., paper factories, iron works, dye works, render it very complex, and an ever-varying mixture, but the following analysis will give a very general idea of its character and composition in Great Britain:
Analysis of raw sewage per 100,000 parts as solids.
| In solution, 125.4 | } 188.3 |
| In suspension, 62.9 | |
| Chlorine | 8.9 |
| Free ammonia | 2.1 |
| Organic (albuminoid). Ammonia | 76.0 |
I have a sample here of the material that is generally produced at the sewage works.
(Sample produced and shown to the commissioners.)