SE9602670L - Wastewater treatment plants - Google Patents

Abstract

Sewage treatment plant has a sludge separator (1) for mechanically purifying sewage arriving from an external source and a bio-chamber above a base section (9) inside a housing (5) which contains a bed (8) of large surface area particles and a distributor (6) for water supplied from the sludge separator using a pump (12). Microorganisms aid to biologically degrade contaminants in the water as it flows through the bed. A recirculation pipe (11) linked to the bio-chamber returns biologically purified water to the sludge separator. The pump is incorporated into the same housing as the bio-chamber, below the water level in a trough or vessel (7`) beneath the bio-chamber base section, to allow water to be pumped intermittently to the distributor. The recirculation pipe is used only as an evacuation pipe from the bio-chamber and all water that passes through the bed is returned to the sludge separator, which itself is only ever used for separating sludge. An outlet pipe (14) for supplying purified water to a recipient is connected to the pump trough so that water can be supplied directly (i.e. without any post-sedimentation step) to a recipient in an amount proportional to the quantity of contaminated water received by the sludge separator. Intermittent pumping is regulated so that the pump starts up \- 4 times per hour and the down or pause time in between two successive start-ups is \} 25% of its operation time.