E. B. Klein The “Kharkovkommunochistvod” State Municipal enterprise, Kharkov, Ukraine;
M. S. Bolotskikh, V. P. Ivanov Kharkov State Technical University of construction and architecture, Ukraine

INTENSIFICATION OF OPERATION OF SLUDGE BEDS EQUIPPED WITH DRAINAGE SYSTEMS

The present paper describes a new device of suction-pressurizing type used to intensify water drain on sludge drying beds equipped with drainage systems.

At the “Bezlyudovsky” sewage biological purification complex, city of Kharkov, sludge drying beds on artificial foundations with horizontal and vertical drainage are in operation. For horizontal drainage, the Ekopolimer drainage elements are used, stacked in rows with the interval of 6 m into special drainage channels in the form of flumes of reinforced concrete. Drainage elements are stacked with the gradient of 0.002 on sand beds and further covered with crushed stone, gravel and river sand.

Usage of the Ekopolimer drainage elements instead of perforated tube drains allowed to improve water-receiving capabilities of the drainage system and increase the sludge bed efficiency. At the same time, there occurs sealing of drainage elements and crumbling, which results in reduction of draining elements water-receiving capabilities and the production of the sludge drying bed in general. To solve this problem, the “Kharkovkommunochistvod” State Municipal enterprise together with Kharkov State Technical University of construction and architecture suggested a system of intensified water drain on sludge beds by vacuumization of horizontal drains and removal of liquids from them, as well as drains and crumbling regeneration by regular expulsion with compressed air.

For this purpose, a special device of suction-pressurizing type (VNU-1) has been developed. The device consists of a homing station (See Fig.), suction-pressurizing pipeline 7 and by-wash 16. Homing station consists of frame 1 with centrifugal pumping unit 4, built-in pump 2, circulation tank 3, connecting and stop valves are mounted on it.

Centrifugal pumping unit is used to feed ‘working’ water to the jet pump. Jet pump is used to drain evacuation and liquid removal when working in evacuating mode as well as for supplying compressed air into the drains, expulsing, drains and crumbling regeneration in pressurizing mode. Circulation tank is used to provide circulation of the ‘working’ liquid as well as the air collector for collection and feeding of compressed air into drains when working in pressurizing mode.

Fig. Device of suction-pressurizing type VNU-1

1 – frame; 2 – jet pump; 3 – circulation tank; 4 – centrifugal pumping unit; 5 – pressurizing pipeline; 6 – valve; 7 – suction-pressurizing sleeve; 8 – valve; 9 – relief; 10 – cutoff plate; 11 – vacuum meter; 12, 13 – manometers; 14 – air duct; 15 – cutoff plate; 16 – relief sleeve.

The device operates in the following manner. During drains evacuation and liquid removal (suction mode) cutoff plates 10 and 15 are opened, valves 6 and 8 are closed. At the same time, jet pump created vacuum, evacuates liquid from the drains and feeds it to the circulation tank. The liquid from the circulation tank is further drained through sleeve 16.

When compressed air is fed into drains, during expulsion or drain and crumbling regeneration (pressurizing mode) cutoff plates 10 and 15 are closed, valves 6 and 8 are opened. Atmosphere air is sucked by the jet pump, fed under pressure to the circulation tank and further forwarded along air duct 14 through valve 8 to the drains.

Periodic change of suction and pressurizing modes helps to intensify the process of sediment drying on sludge beds and increase their efficiency.

Industrial testing of the created device is scheduled for the current year with the purpose of determining optimum modes of its operation and the most rational usage areas.