The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
How To Design And Install Plumbing
SPRINKLE OR TRICKLE FILTER SEWAGE DISPOSAL PLANT
The sprinkle and trickle filter treatment of sewage embodies many principles of the activated sludge process and is commonly used by smaller municipalities. The one disadvantage of this kind of sewage treatment lies in the fact that its building and equipment require an unusually large area of ground. It is efficient, however, in the purification of sewage, attaining an 85 to 95 per cent range of correction. Fig. 8 illustrates the course of travel of the raw sewage in this type of plant as follows:
1. The lines with one arrow indicate the route the sewage takes as it passes through the clarifier, where it is separated.
2. The lines with two arrows indicate the course the sludge takes to its final disposition.
3. The lines with one arrow and one circle show the course the liquid content of the sewage takes as it is treated.
Coarse Screen House. The raw sewage enters the large or coarse screen house where the larger particles of nonsoluble materials are screened and carried into a device which cuts them into small pieces. The cut materials are returned to the raw sewage and conveyed to the next stage of the treatment process. A comminutor identical with the one used in the activated sludge process may be used to replace this stage of treatment.
Primary Clarifiers. The clarifier consists of a large concrete tank equipped with baflBe plates on opposite ends of the unit. The bottom of the tank is pitched to one point and connected to a sludge well located below the pump house, where a sludge pump is provided.
The sludge is a heavy black mixture which settles to the bottom of the tank and is scraped from the bottom by means of a mechanical agitator of the rotary or drag variety. The liquid sewage is carried under the outlet baffle plate into a clear water well located below the pump-house floor. The well is provided with large centrifugal pumps. The effluent is now divided into two parts, sludge and liquid, and each part undergoes individual treatment.
Digester. From the sludge well below the pump-house floor the settled sludge is pumped into the digester. This unit is identical with that discussed in the activated sludge process.
Sludge Drier or Drier Bed. The nonsoluble sludge is drawn at various intervals from the digester onto a bed of sand, to be dried as in the activated sludge process. In some instances an area of open ground is used for this operation.
