Mr. POWELL. No; they passed first into an inclosed chamber, where the
bacteria destroyed it.
Mr. HATTON. I should imagine, from what you say, that must be the
process by which both the aerobic and the anaerobic bacteria are the
destroyers.
Mr. POWELL. Exactly.
Mr. HATTON. We do not want any anaerobic bacteria in our process,
because it produces septic action, which is inimical to our process,
because it absorbs the oxygen and interferes with the efficiency of
the process.
Mr. POWELL. Can you take the sludge from the Imhoff tank and use
it, or treat it the same as you are treating the sludge there in
Milwaukee now?
Mr. HATTON. We can; but the trouble is that the sludge from the
Imhoff tank, as we have found it in Milwaukee, only contains about
from 1 to 1½ per cent of ammoniacal nitrogen at most, and that does
not pay for its recovery. I want to say another thing about this
which is of interest. There is no odor about the operation of the
plant at all. You can stand over one of the tanks as it is being
aerated and have no odor come to you, or no odor throughout the
entire plant, unless you let the sludge stay undried.
Mr. TAWNEY. To what do you attribute the lower percentage in the
sludge taken from the Imhoff tanks?
Mr. HATTON. The fermentation process removes the ammonias from the
sludge. Well, practically all the reduction of the sludge in the
Imhoff tank proposition is the fermentation process, and of course
that removes a large portion of fertilizer values in the sludge.
Mr. MAGRATH. Are there any weak features in this process that you
look forward to correcting?
Mr. HATTON. There are some problems which we are investigating, with
a view of getting a more economical use of the air, and thus a lower
cost of operation, and that problem concerns the diffusion of the air
in the tanks. We are trying out three methods of diffusion. We are
not prepared to say yet which is the most economical. I am giving you
the figures based upon that which we have used, and our whole efforts
now are being directed to reducing the amount of air used. That is
the principal point which we are investigating at the present time.
Mr. TAWNEY. How does the operating cost of your system compare with
the operating cost of the Imhoff tanks?
Mr. POWELL. The operating cost of the Imhoff tank is considerably
less than the operating cost of our tanks. They have no air to pay
for, and very little plant attendance to pay for.
Mr. MAGRATH. As I understand you, the cost to the municipality under
your system is less than the cost under the other system?
Mr. HATTON. The cost of the Imhoff tank, you mean?
Mr. MAGRATH. Yes.
Mr. HATTON. That is true of installations of any magnitude.
Mr. TAWNEY. Installation, but not operation?
Mr. HATTON. On both--that is, taking into consideration the value of
the sludge recovered.
Mr. MAGRATH. Your system costs the municipality less than the other
system?
Mr. HATTON. Providing they sell the sludge. I want to make it plain
to you gentlemen that I am not giving you this information as it may
pertain to Detroit or Buffalo or any other city, but as it concerns
Milwaukee, because I am not in a position to speak of it here, not
knowing your situation.
Mr. TAWNEY. You state that you recently had your plant examined by a
number of the leading consulting sanitary engineers of the country,
and that while they all agreed that your system was successful, so
far as purification of sewage was concerned, they expressed doubt as
to the disposing of the sludge. On what do they base their skepticism
or doubt with reference to the sludge disposal?
Mr. HATTON. Past experience.
Mr. TAWNEY. Your past experience?
Mr. HATTON. No; past experience of the sanitary engineers who have
expressed that doubt. As I started to say, or I think I did say at
the beginning of my remarks, that disposition of the sludge was the
greatest problem, both in Europe and America, and this was so easy,
apparently, to dispose of, that they were from Missouri and had to be
shown.
Mr. TAWNEY. After seeing the way in which you disposed of sludge in
Milwaukee plant, did that satisfy them or remove their doubts as to
the efficiency of your method?
Mr. HATTON. They have not seen it yet.
Mr. TAWNEY. I thought you said they personally visited it.
Mr. HATTON. They have personally visited it. We put it in operation,
but our press broke down. We have only put this portion of it in
operation in the last two weeks, and it is only now we have begun to
dry it; we did not have a dryer before.
Mr. MIGNAULT. Do you use the rotary dryer?
Mr. HATTON. The rotary direct dryer.
Mr. MAGRATH. I interrupted you when you were about to say that in 90
days you would demonstrate something, and you stopped.
Mr. HATTON. I told these engineers that in 90 days I would
demonstrate the possibilities of disposing of the sludge, but I have
already demonstrated it before the end of the 90 days. I think I said
that at Syracuse some time ago in an address I delivered.
Mr. MAGRATH. In an address made, I think, in 1915 you expressed some
doubt as to the efficacy of your method in winter months?
Mr. HATTON. Yes; I did; and in order to try out this system in
Milwaukee during the winter months was the purpose of building this
1,600,000-gallon plant which we are now operating; that was the
primary object of building that plant, which cost us $65,000, and we
got it in operation the first week in January and we have operated
it since continuously with temperatures as low as 20° below zero,
with a clear effluent during the cold winter months coming out of the
plant as that effluent which you see there in that bottle. We had
no freezing and no trouble with ice. We had, of course, much lower
nitrates in our effluent than we had in the summer months; in fact,
we had very little nitrates, but we kept up the stability about 104
to 110 hours’ average; some of them went up higher. We go on the
basis of 5 days’ stability test instead of 10 days. The American
Public Health Association suggest that five days is all we need.
You ask me about the relative cost of the Imhoff tank installation
and operating as compared with the activated sludge. Our
investigations in Milwaukee show that the cost of the Imhoff tank,
without sterilization, is $6.20 per million gallons--that includes
all overhead charges--as against $7.81 for the activated sludge. The
cost of the Imhoff tank----
Mr. TAWNEY. Is that an estimated or actual cost?
Mr. HATTON. That is the cost from the operation of our plant.
Mr. TAWNEY. Actual operation?
Mr. HATTON. Actual operation.
Mr. TAWNEY. Is it not an estimated cost?
Mr. HATTON. No. The cost of the Imhoff tank with sterilization,
reducing the bacteria 85 per cent, was $9.51 per million gallons,
as against $7.81 for the activated sludge. Mark you, the bacterial
removal in the activated sludge was 95.5 per cent for that cost,
whereas the bacterial removal in the Imhoff with chlorination was 85
per cent; and we attempted--and the report is in here--to sterilize
our Imhoff tank effluent to that point comparable with the activated
sludge, and found that the cost of the process was about $14.50 per
million gallons.
Prof. PHELPS. How much chlorine does that represent?
Mr. HATTON. Eight and five-tenths parts, which costs $5 per million
gallons, based on 7 cents per pound; that is 3 cents per pound
less than we were paying for it; and we believed--in fact, we were
assured--that if we bought it by carload lots we could get it for 7
cents per pound at that time.
Mr. POWELL. Now, circumstanced or conditioned as Milwaukee is, how
does the cost of disposing of your sewage, as at present carried on,
compare with what it would be if you dumped it in its raw state into
the lake, that is taking the raw sewage when it comes from the end of
the sewage pipe? Is Milwaukee the gainer or the loser by disposing of
the sewage as you suggest?
Mr. HATTON. Well, undoubtedly the gainer.
Mr. POWELL. That is, by treating the sewage as you treat it, and
disposing of the product, the fertilizer, Milwaukee is the gainer, as
against dumping it in its raw condition into the lake?
Mr. HATTON. Decidedly.
Mr. POWELL. That is something consequential.
Mr. HATTON. Yes.
Mr. TAWNEY. Financially, it is disposing of the sewage at a profit,
as I understand?
Mr. HATTON. Oh, no; I do not want you to think that. We do not get
enough profit out of our sludge to pay for the treatment of the
sewage.
Mr. TAWNEY. That is the inference I drew from your answer.
Mr. MIGNAULT. What you say is that it pays to dispose of the sludge
after the treatment process?
Mr. HATTON. Yes; there is a profit in it, but not sufficient to pay
for the whole cost.
Mr. MIGNAULT. When the sludge has been treated you calculate the cost
of drying it and disposing of it, and you make a profit out of it?
Mr. HATTON. Yes.
Mr. POWELL. Take a million gallons of sewage at the point of
delivery here in Detroit, and assume Detroit to be circumstanced or
conditioned just the same as Milwaukee is from a sewage standpoint,
what would it cost to bring that sewage up to the point at which you
take it for the purpose of manufacturing into fertilizer?
Mr. HATTON. It costs $7.81 per million gallons, and we get therefrom
practically $3. I am taking the lowest estimate now, making a cost of
$4.81 for the treatment of sewage. I think that answers the question.
Mr. TAWNEY. For 1,000,000 gallons?
Mr. HATTON. Yes; per million gallons.
Mr. POWELL. Where does the $3 come in?
Mr. HATTON. It is the profit from the sludge.
Mr. TAWNEY. Deducting the cost of treating it?
Mr. HATTON. Yes.
Mr. POWELL. The actual cost is $4.81.
Mr. HATTON. Yes.
Mr. POWELL. Following up the question Mr. Magrath asked you, to
anticipate any necessary outlays you made for improvements, without
regard to this, taking the machinery as it is to-day, is there
anything that you think would come in to disturb these features and
upset them in the present conditions?
Mr. HATTON. As to the process?
Mr. POWELL. Yes.
Mr. HATTON. Nothing that has been discovered so far.
Mr. POWELL. You do not anticipate anything?
Mr. HATTON. Nothing at all; if I did, sir, I would hardly be
warranted in recommending to my board the expenditure of two and a
half millions for this process. That is the best way to answer that.
We have adopted this process, and are going ahead to build it as soon
as we get our land, which has to be condemned partially.
Mr. MAGRATH. Before you leave the subject, many municipalities, as
you know, dump crude sewage into flowing water, and consequently they
have not arranged their collecting sewers at any particular point. In
the application of this system of yours is it necessary that there
should be a collection of the sewage at some particular point, or
could it be applied quickly to those existing municipalities?
Mr. HATTON. That is one of the features about the process. While it
is always desirable to get one point to dispose of your sewage, where
the cost is considerable for intercepting sewers to get at that one
point it is better to divide up those numbers of points, providing
you can do so without nuisance and at less cost than the intercepting
sewers, and with this process it can be built and operated in the
heart of the city without any nuisance arising. I think that answers
the question, does it not?
Mr. MIGNAULT. Is there any difference in that respect between your
treatment and the Imhoff tank treatment?
Mr. HATTON. I think not. There is no odor that is objectionable about
an Imhoff tank.
Mr. MIGNAULT. I mean as to the necessity of intercepting sewers?
Mr. HATTON. I think not.
Mr. MIGNAULT. In either case, the question of intercepting sewers is
a question to be considered, according to the layout of the ground?
Mr. HATTON. No; not altogether that; according to the layout of
the ground and according to the process which you propose. If, for
instance, you should go beyond the Imhoff tank process and put in
sprinkling filters or nitrifying beds, then you would have to get
outside of the city, in order to prevent the nuisance arising from
those beds.
Mr. MIGNAULT. Perhaps I did not make my meaning clear. Is there any
advantage in your system as to the multiplying of the treatment
works, in order to avoid the construction of intercepting sewers?
Mr. HATTON. Between the two works?
Mr. MIGNAULT. Yes.
Mr. HATTON. No; I think not.
Mr. POWELL. Your process is not affected by atmospheric conditions at
all?