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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