Liquid purification or separation – Processes – Treatment by living organism
Patent
1985-01-02
1986-12-16
Wyse, Tom
Liquid purification or separation
Processes
Treatment by living organism
210629, 210207, C02F 312
Patent
active
046295658
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention pertains to a process for the biological and, optionally, the chemical treatment of sewage using aeration in aeration basins arranged concentrically within a basin, secondary settling basins and sludge collection as well as an installation for carrying out the process.
The design of biological sewage treatment installations in a number of stages with an activation stage and at least one secondary settling stage is known. These installations have the disadvantage that they manifest a large floor space requirement. In the case of flocculation installations, compact sewage treatment plants such as FR-A 1,081,214 are known, in which the intermingling with the flocculator takes place in a central basin and the secondary settling in a surrounding ring basin. In addition, a two-stage treatment plant of tower design is known from CH-A 462,273, in which a treatment of the sewage is achieved though precipitation.
SUMMARY OF THE INVENTION
The invention has set for itself the task of creating a compact biological sewage treatment installation which is arranged in a container, whereby the container holds both activation and secondary settling basins and the aeration takes place above the activation basin through circulation of the contents of the basin and the secondary settling basin operates according to the system of up-current classification or according to fluidized bed filtration.
The process according to the invention is characterized by the fact that the sludge from the secondary settling basin is collected at a central point and, preferably by means of a pump, is conveyed to a separation device such as, e.g., a centribugal separator in which the sludge is separated into return sludge and excess sludge which is to be channeled off; that the return sludge is aerated before being directed to the ring-shaped aeration basin and that sewage is withdrawn from the activation basin, optionally mixed with fresh sewage and, finally, mixed with the aerated sludge from the secondary settling basin and that the mixture, after retention in the activation basin, is directed to the secondary settling basin. In the case of sewage with a particularly high biological or chemical oxygen requirement, the process is expanded in such a way that the activation basin is designed in two sections, whereby in the first section the intermixing and, particularly, the aeration of circulation liquid, rotation liquid and return sludge and, at the transition of the first into the second activation section, an additional aeration of the sewage takes place, and in the second section the degasifying is carried out and, finally, the degasified sewage is directed by way of a flow-off conduit to a central sedimentation channel into the secondary settling basin.
The installation according to the invention for carrying out the process is characterized by the fact that a conical or truncated cone-shaped inset in the form of a funnel is provided concentrically in a cylindrical basin, whose point or base surface is arranged at or above the bottom of the basin and whose outer casing leaves open a circular secondary settling basin, so as to provide in the inset a base sludge reamer and/or a central sludge chamber into which a suction pipe of a sludge pump extends, the pressure conduit of which is connected to a separation device such as, e.g., a centrifugal separator, manifesting an overflow and an underflow, whereby in the underflow a control valve is provided and the under- or overflow discharges into an aerator in the circular space between the inset and the basin.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is shown schematically and in examples in the attached FIGS. 1 to 4.
FIGS. 1 and 2 show in vertical plan and in section a sewage basin according to the invention;
FIGS. 3 and 4 show, in similar representation, a constructive variant to the preceding.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1 a cylindrical basin is shown inwhich a truncated conical inset 2 is arranged in the for
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patent: 3733263 (1973-05-01), Mardt
patent: 3753897 (1973-08-01), Lin et al.
patent: 3799346 (1974-03-01), Freese
patent: 3959124 (1976-05-01), Tchobanoglous
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Hell Walter
Hillinger Bruno
Waagner-Biro AG
Wyse Tom
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