Method and apparatus for tertiary treatment of effluent

Claim 2

The method as called for in claim 2 in which the filtrate which has passed through the filter media is accumulated above the filter media in such quantity as tO backwash the filter at the end of a filtering cycle.

Claim 3

The method as called for in claim 1, wherein floatable solid pollutant particles accumulate on the top of the effluent being introduced into the receptacle, and wherein the settleable solid pollutant particles settle out of the effluent and are accumulated on the bottom of the receptacle.

Claim 4

The method as called for in claim 1, wherein the filter is backwashed by flowing the filtrate downwardly therethrough.

Claim 5

The method of operating the system of claim 1, which comprises the additional steps of backwashing the filter media by withdrawing the contents of the receptacle for reversing the flow of filtrate through the filter media.

Claim 6

The method of operating the system of claim 1, which comprises the steps of backwashing the filter media by lowering the contents of the receptacle below said filter media for gravitationally discharging the clear filtrate downwardly through the filter media.

Claim 7

The method of operating the system of claim 7, wherein the rate at which the contents of the receptacle is lowered is approximately five times the rate at which the effluent from the secondary treatment plant is introduced into the receptacle.

Claim 8

A tertiary treatment plant for treating the effluent from a secondary treatment plant, comprising, in combination, a receptacle having sidewalls and a closed bottom, wall means in the interior of said receptacle, said interior wall means dividing the interior of said receptacle into an inlet chamber and a clearwell chamber, said clearwell chamber defined by fluid impervious sidewalls and a fluid pervious bottom wall, filter media supported on said bottom wall, an effluent inlet in open communication with the inlet chamber in the interior of said receptacle, and a fluid outlet in open communication with the clearwell chamber, said inlet chamber having a predetermined size and volumetric capacity, and a settling rate such as to provide sufficient surface area and volume of effluent therein that the downflow rate of effluent is less than the up-flow rate of floating particles so that the floatable solid pollutant particles and the settleable solid pollutant particles will separate out of the effluent by reason of their different specific gravities, leaving a residual effluent containing substantially only the suspended solid pollutant particles of the original effluent, means for causing the residual effluent containing suspended solid pollutant particles to pass upwardly through the filter media to filter the suspended solid pollutant particles from the residual effluent, and bypass means in an upper portion of said interior wall means for bypassing effluent from the inlet chamber to the outlet when the effluent in the inlet chamber reaches a predetermined level.

Claim 9

The tertiary treatment plant as called for in claim 9 wherein the bottom wall of the clearwell chamber is spaced above the bottom of the receptacle for providing a clear, unobstructed area beneath the filter media in open communication with the interior of the receptacle.

Claim 10

The tertiary treatment plant as called for in claim 9, wherein the filter media is located in the lower half of the receptacle.

Claim 11

A tertiary treatment plant as called for in claim 10 which includes means for evacuating the contents of the inlet chamber whenever the height of the effluent therein reaches a predetermined level, and wherein said evacuation gravitationally releases the entire contents of the clearwell downwardly through the filter media thereby flushing the solid particles entrapped in said media back into the inlet chamber.

Claim 12

The tertiary treatment plant as called for in claim 12, wherein the means for evacuating the contents of the inlet chamber comprises a motor-driven pump having an intake in open communication with the lowermost portion of the receptacle, and means responsive to the level of the contents of the inlet chamber for completing an electrical circuit to the motor of said motor-driven pump whenevEr the level reaches a predetermined height and of maintaining said electrical circuit until the level has been lowered to the bottom of said receptacle.

Claim 13

The tertiary treatment plant as called for in claim 13, wherein is included means for evacuating the contents of the reservoir at a rate approximately five times the rate at which effluent from a secondary treatment plant is introduced into said reservoir.

Claim 14

A tertiary treatment plant as in claim 9, wherein said receptacle sidewalls and closed bottom are substantially rectangular, and said interior wall means and said receptacle wall means define a substantially rectangularly shaped inlet chamber and a substantially rectangularly shaped clearwell chamber, sump means in the bottom of said receptacle in communication with said inlet chamber, and pump means in said sump means for pumping effluent from said inlet chamber.

Claim 15

A tertiary treatment plant for treating the effluent from a secondary treatment plant, comprising in combination, a receptacle having sidewalls and a bottom, wall means in said receptacle dividing said receptacle into an inlet chamber and a clearwell chamber, said clearwell chamber defined by fluid-impervious sidewalls and a fluid-pervious bottom wall, filter media supported on said bottom wall, an effluent inlet in open communication with said inlet chamber, a fluid outlet in open communication with the clearwell chamber, and bypass means in an upper portion of one of said interior wall means establishing a fluid bypass from said inlet chamber to said clearwell chamber in bypassing relationship to said filter media whenever the effluent in said inlet chamber reaches a predetermined level.

Claim 16

A tertiary treatment plant as in claim 16, wherein said interior wall means includes an upstanding fluid-impervious wall spanning said receptacle walls, the lower end of said upstanding wall terminating above said receptacle bottom wall, a substantially horizontal, fluid-pervious bottom wall extending from the lower edge of said upstanding wall to a sidewall of said receptacle for subdividing the receptacle into said inlet chamber and clearwell chamber, said effluent inlet being in open communication with the upper part of said inlet chamber and remote from said clearwell; said fluid outlet being in open communication with the upper part of said clearwell, whereby effluent will pass by gravity downwardly through said inlet chamber and thence upwardly through said filter media.

Claim 17

A device as called for in claim 16 which includes a pump having an inlet in open communication with the bottom-adjacent portion of the receptacle, control means for selectively actuating said pump for evacuating the contents of said receptacle and discharging the contents of the clearwell through the filter media for gravitationally backwashing the filter bed.

Claim 18

A device as called for in claim 18 which includes means for automatically operating said pump whenever the level of the effluent within said receptacle raises above a predetermined level as a result of the impairment of the filter bed to accommodate the free flow of effluent upwardly through said filter bed.

Claim 19

A device as set forth in claim 17 wherein said fluid bypass is in that portion of the upstanding wall at a location above the fluid outlet of said clearwell; said fluid bypass adapted to permit effluent to flow directly from the fluid inlet into the upper portion of said clearwell.

Claim 20

A tertiary treatment plant as in claim 16, wherein an effluent discharge trough is in said clearwell chamber at the upper portion thereof and is in communication at one end with said fluid outlet and at the other end with said fluid bypass so that effluent which flows through said bypass is discharged directly into the effluent discharge trough and outlet.

Claim 21

A tertiary treatment plant as in claim 17, wherein said upstanding wall subdivides the interior of said receptacle into a pair of inlet chambers and a pair of clearwell chambers, each operating independEntly of the other and including a filter media between the inlet chamber and clearwell chamber of each.