Digester Start-Up at Cobourg, Ontario
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Transcript of Digester Start-Up at Cobourg, Ontario
Digester Start-Up at Cobourg, OntarioAuthor(s): Charles HicksSource: Sewage and Industrial Wastes, Vol. 31, No. 1 (Jan., 1959), pp. 117-118Published by: Water Environment FederationStable URL: http://www.jstor.org/stable/25033807 .
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Vol. 31, No. 1 DIGESTER START-UP 117
water system and scum removal piping are a considerable help in removing scum. All elutriation-unit scum is
pumped to the secondary digestion tanks.
Wash water settling basins and screens were placed in operation in
May. Results from the use of these new facilities are good.
Sludge Disposal
Vacuum filtration of the digested sludge was normal. Bucket elevators
and chemical feeding equipment re
quired considerable maintenance. The stainless steel filtrate pump operated satisfactorily.
Sludge cake is disposed of by incin eration. Smoke difficulties were ex
perienced, particularly during the summer. The incinerators and ash
system required a great deal of work. Ash system improvements were started in December.
Plant Performance
The over-all removals of suspended solids and BOD were appreciably better than during previous years. This reflects the effect of the new aera
tion facilities and other units placed in operation in 1954 and 1955.
The appearance of the plant grounds was vastly improved by grading and
grassing. A dedication ceremony and
open house for the new facilities were held in October.
Operating and maintenance costs in
creased approximately $47,500 over
1954.
Operation data for 1955 are sum marized in Table IV.
Industrial Wastes Control Unit
John R. Wolfs, Engineer-in-Charge
Industrial waste problems have re
ceived increased attention as their seriousness became more apparent.
The Industrial Wastes Control Unit was created in September 1954 and
organized its program during 1955. The problem of treating acid wastes
is one of the most troublesome. Nine
teen companies were notified to stop the discharge of this waste to the sewers. Outcome of this enforcement
depends on the results of a pilot-plant installation of the Blaw-Knox Ruthner
Process for treating the waste, at Niles, Ohio.
Various phases of the waste control
program are inspection and testing of sewer flows, stream and lake pollution sampling, and general public relations
with industry. The need for expanded services of
this section is very apparent and its establishment has been an important step forward in improving the opera tion and administration of the sewage disposal program in Cleveland.
DIGESTER START-UP AT COBOURG, ONTARIO By Charles Hicks
Superintendent, Cooourg Sewage Treatment Plant, C ob our g, Ont., Canada
During the winter of 1956 the di
gester at the Cobourg, Ont., sewage treatment plant was inspected and cleaned. Because of the cold weather it took approximately two months to
complete the job. The digester has a 50-ft diameter and 19-ft side-water
depth. It is equipped with two sets of internal heating coils, two internal
mixers of the draft-tube type, recircu
lation facilities, and a temperature control device located at about mid
depth. The unit has a fixed cover. The digester had been in continuous
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118 SEWAGE AND INDUSTRIAL WASTES January 1959
service for six years prior to cleaning.
Inspection revealed that only about 12
in. of scum and 2 cu. yd of grit and
sand had accumulated. In starting the unit, about 12 ft of
fresh water and 500 lb of lime were
added. The auxiliary boiler was then fired and the temperature of the water was raised to 90?F. No seed sludge was available. For the first week
sludge from the primary clarifier was
added for two 10-min periods each
day. Digester contents were recircu
lated for about 6 hr each day. The
second week raw sludge pumping was
increased to two 20-min periods each
day. By the 16th day sufficient gas was available to fire the boiler. Care was taken to add only thick sludge during the start-up.
Normal digester operation over the
years has consisted of maintenance of a liquid temperature of about 90?F, sludge recirculation for about 4 hr a
day, and internal mixing for three 2-hr
periods each day. On the basis of past experience this schedule appears to be a good one.
TIPS AND QUIPS
Sewage Flocculation *
A few months ago at the Little Miami Sewage Works, Cincinnati, Ohio, preliminary tests were made to
determine if operation of the paddle wheel agitators would cause better set
tling efficiencies. In these tests sew
age was pumped from the plant aera
tion channel to two 50-gal plastic drums. The contents of one drum were agitated slowly with a wooden
paddle for 20 min. No chemicals were
added. After stirring, the contents were allowed to settle for 2 hr. The second drum of sewage was not stirred but was allowed to settle for 2 hr 20
min. Tests showed that suspended solids removal was 14 per cent better for the stirred sewage.
While it is doubtful that compar able increases can be obtained on a
plant scale, the tests were sufficiently encouraging to warrant the use of the flocculators for full-scale evaluation.
I have no technical and no univer
sity education, and have just had to
pick up a few things as I went along.
Winston Churchill
* Bulletin of the Sewage Disposal Section,
Cincinnati, Ohio, Sept. 1958.
Day in Court f
A few months ago a court decision was handed down concerning the dis
charge of treated sewage by the com
munity of Rolla, N. Dak. Rolla is a
community of 1200 people that has
recognized its responsibility in the matter of pollution abatement. A
satisfactory lagoon system was con
structed there about four years ago.
During the past year a downstream landowner sought to prevent the town from discharging its well-treated efflu ent to the watercourse which flows
through his land and, if possible, se cure damages for the discharge of the treated wastes. The Rolla installation had met all requirements of law in
regard to plan approval and opera tion. After hearing the testimony the
judge ruled in favor of the town, stating that Rolla had the right to
discharge sewage into a defined water
course, providing adequate treatment was provided.
Intelligent ignorance is the first re
quirement in research.
Charles F. Kettering
t Official Bulletin, North Dakota Water
and Sewage Works Conf., 26, 3, 1 (1958).
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