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City of Milwaukee v. Activated Sludge Inc.

March 2, 1934


Appeal from the District Court of the United States for the Eastern District of Wisconsin; Ferdinand A. Geiger, Judge.

Author: Sparks

Before EVANS, SPARKS, and FITZHENRY, Circuit Judges.

SPARKS, Circuit Judge.

This is an appeal from a decree of the District Court holding the following United States patents issued to Walter Jones valid, and that appellant has infringed the following enumerated claims:

Claims 2, 3, 7, 11, and 13 of No. 1,247,540 issued November 20, 1917, on application filed October 9, 1914.*fn1

Claims 2 and 8 of No. 1,282,587 issued October 22, 1918, on application filed November 7, 1916 (a division of the application resulting in United States patent No. 1,247,540).*fn2

Claims 5, 8, and 9 of No. 1,247,542 issued November 20, 1917, on application filed October 18, 1915.*fn3

Claims 3, 7, 8, 9, and 10 of reissue No. 15,140 issued July 5, 1921, on application filed August 11, 1919.*fn4 (The original patent, No. 1,247,543 on which this patent was based was issued November 20, 1917, on application filed October 18, 1915.)

For brevity we shall adopt appellant's method of referring to the Jones United States patents by the last three digits of their respective numbers. All of these patents pertain to the treatment of sewage by aeration. No. 587 relates to apparatus, and the others relate to process. It is admitted that 542 and 140 pertain to and depend upon the "Activated Sludge Process." As to 540 and 587, appellee claims the same dependence, and appellant denies it.

It is claimed by appellee that the patents referred to are based upon certain British patents which were issued to Jones, that is to say: United States patent 540 is based on three British patents, 22,952, 729, and 19,916; No. 587 is based on British 19,916; No. 542 is based on British 22,737; and No. 140 is based on British 22,736. It is further claimed by appellee that the American patents are entitled to effective filing dates as of the dates of the applications for the British patents upon which the American patents are respectively said to be based.

Prior to 1912 bio-chemists generally understood certain processes of nature which are collectively designated as the "nitrogen cycle." In order to comprehend the subject matter before us, and the contentions of the parties with respect to the claims in suit, it is necessary to describe that cycle in a general way, for it was by consideration of the natural laws therein involved that the successful disposal of sewage was attained.

Plant life grows by absorbing carbon dioxide from the air and food from the earth. That food must include certain simple nitrogenous compounds, such as nitrates and nitrites, which in turn are converted by the plants into more complex nitrogenous compounds. Plants become the food of animals whose life and digestive processes convert the nitrogenous compounds of the plants into still more complex nitrogenous compounds.When an animal dies, a process of putrefaction sets in, converting the most complex nitrogenous compounds of animal tissue into simpler ones, more or less soluble in water. Those compounds in solution are carried by the water into the earth where they are further reduced and converted into nitrates and nitrites ready again to become the food of plants. Of course much plant life dies and decays without ever being used as animal food, and in that case its nitrogenous compounds are more directly reduced. Again, animal life does not necessarily have to die in order to start the process of conversion. The animal's excreta during life immediately become the subject of putrefaction, degradation, and conversion to the simpler nitrogenous compounds. The intermediate products of putrefaction are inimical to the existence of both plants and animals, hence it is essential that the putrefaction of both animal and vegetable life be followed by a process of purification by which it may be converted into the simple and wholesome compounds. Purification is largely a matter of oxidation which may be effected in time by exposure to air, or to running water which contains air, but oxidation by mere exposure to air is a very slow and offensive process.

For many years prior to the disclosures of the patents in suit it was known that bacteria performed an essential part in nature's processes of putrefaction and purification. It was known that anaerobic bacteria, those which live out of contact with air, attack animal bodies soon after their death, and promote the putrefactive processes which result in the conversion of the very complex nitrogenous compounds into the simpler and more soluble ones such as ammonias, amidos, and aminos. These in turn are acted upon through processes of purification by aerobic bacteria, which thrive in the presence of air, and are converted into the nitrates and nitrites to be used again as plant food. It was also known that the absence of air was inimical to the life processes of aerobic bacteria, while the presence of it was inimical to the anaerobic.

Appellee correctly defines purification of sewage as the conversion of the putrescent and putrescible, and perhaps other more or less complex nitrogenous, carbonaceous and sulphurous compounds into simpler compounds which are wholesome and inoffensive. This action involves ultimately the oxidation of the compounds, and a sufficient degree of oxidation means adequate purification. When all or a great proportion of the total nitrogen is reduced to nitrates and nitrites it is said that a sufficiently complete purification has been effected. This is not because the nitrogenous compounds are the only ones which require oxidation, but because they are the most difficult to oxidize, and when that is accomplished the carbonaceous and sulphurous compounds will of necessity have been sufficiently oxidized.

Nature's process of purifying sewage involved the reduction of dead animal or plant life by putrefaction from its complex forms to the soluble compounds such as the ammonias, amidos and aminos. In these forms they could be dissolved in rain or other water and thus seeped into the earth or flowed over its surface into streams. Here these intermediate compounds came into contact with the aerobic bacteria contained in the surface soil and also upon the surfaces of stones and rocks in running streams. In streams, these aerobic bacteria grew on certain slimy, gelatinous substances adhering to the stones and rocks, and absorbed the air contained in the running water. As a result of the contact between these bacteria and the intermediate nitrogenous compounds, the latter were further reduced to the simpler and more oxidized compounds such as nitrates and nitrites, and in this state, they had attained purification. These natural processes, although extremely slow, were quite adequate to effect requisite purification of a reasonable amount of pollution, but they were much too slow to effect or maintain the purification of streams and lakes into which the sewage of large cities was poured.

How to dispose of abnormal amounts of sewage, caused by the growth of population and industry was a question that confronted the scientist and inventor from very early years, and it was never answered successfully prior to the disclosures out of which this controversy arises. Several methods of artificial sewage disposal were tried such as flowing over large areas of land, and contact filters, which include the trickling and sprinkling systems, through such media as tanks of rock, stone, cork, and sand. All such methods were very slow and expensive and proved to be quite unsatisfactory. Efforts were made to accomplish the desired result by chemical precipitation, but that method was likewise expensive and for that reason its extensive use was prohibited. No bacterial action was involved in it. In all those processes, except precipitation, nature's process was followed or approximated, and in each there remained after aeration and running off the liquid a sludge-like residuum of which no use was made. At the time the patents were issued it was known that this sludge contained both aerobic and anaerobic bacteria, and if permitted to lie dormant it would become septic and fetid because of the activity of the anaerobic bacteria in the absence of air, but if kept in an active state it would become purified by reason of the activity of the aerobic bacteria in the presence of air. Thus the idea of activation of the sludge formed the basis of further experimentation which resulted in the solution of the troublesome question. Its success was found to be dependent upon the fact that all sludge should be kept in active but gentle circulation with the sewage by the introduction of a continuous flow of air.

The patents in suit do not purport to cover the discovery of the bacteria, nor their characteristic activities, but they do claim the method and apparatus by virtue of which conditions are provided under which the aerobic bacteria are permitted to function to the best advantage. In certain experiments referred to, Mr. Eddy in 1903 and 1904, and Mr. Clark in 1912, actually purified sewage by aeration in the presence of sludge, but neither succeeded in reducing his experiments to commercial practice. The reasons for their failure are significant in that they appear to result from differences in the methods used by them and by Jones. Eddy failed because his agitation of the sludge was too violent. Clark seems to have failed because of insufficient circulation, for his idea was to cause the sludge to settle upon many slate surfaces which he had placed in the tank in order to increase the stationary area of the gelatinous slime with which the sewage should come in contact. The deposits on the slate naturally increased in thickness and sloughed off and this in turn fell to the bottom where it lay quiescent and of course became septic. As a result of other laboratory experiments of his, algae were developed in the container and were permitted to grow, and they became enveloped with gelatinous slime, no doubt containing aerobic bacteria. Upon draining the water the algae and sediment were permitted to remain for contact with other fresh sewage. In all his experiments, so far as he professed to know, the bacteria were fixed and stationary, and no results were obtained which warranted commercial use.

Appellee says of the activated sludge system, which it argues is covered by the claims in suit, that it contemplates running sewage into a tank and there mixing it with a quantity of "activated sludge" which is a mixture of many species of aerobic bacteria suspended in water. The bacteria adhere to the surfaces or pores of minute particles or flocs of zoogleol or gelatinous material. The flocculi are suspended in the water and with it form a liquid which flows like water. One of appellant's witnesses described activated sludge to be a "uniform, flocculent suspension of the sewage solids accumulated from the suspended and colloidal solids present in sewage under aerobic conditions. * * * It is rich in aerobic organisms, which have been developed by continued aerobic conditions in successive volumes of sewage." In amplification of that description, Mr. Eddy, in 1921, said,

"The floc is a sponge-like mass or an open-mesh network which in the process of formation may envelop, entrap or entrain colloidal matter and bacteria. The spongelike structure of the floc offers a very large surface area for contact, and this floc appears to be able to absorb colloidal matter, gases, and coloring compounds.When the floc is driven about in the liquid it has a sweeping action by which the colloidal substances may be said to be swept out of the water, or as stated by Philip Morley Parker, the 'process may be regarded as passing a filter through the water in place of passing the water through a filter.' Thus far the process seems to be primarily of a physical nature. It has been demonstrated, however, that it can not be carried out under sterile conditions.

"Just what the action of bacteria and other organisms may be, is a subject which should receive further investigation. One plausible theory is that the bacteria which are contained in the cell-like structure of the floc, feed upon the very finely divided matter and thus relieve the floc of its burden of such substances and restore its faculty of absorption to such an extent that when introduced into the incoming sewage the floc efficiently performs its function of absorbing the colloidal matter which will again be consumed by the living organisms which thus cause its regeneration. Because of these properties the sludge has come to be called 'activated sludge,' a term suggested by Ardern and Lockett."

With this general statement of the earlier attempts at purification of sewage and of the knowledge of bacterial characteristics and their activities with respect to such purification, we shall proceed to describe the method which appellee claims was disclosed for the first time by the Jones patents, and which it ...

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