Valveless Gravity Filter

Overview

The valveless gravity filter is a rapid filter that operates automatically based on the siphon principle. During filtration, the outlet water level remains constant, while the inlet water level rises in the siphon pipe as head loss through the filter media increases. When the water reaches the top of the pipe and forms a siphon flow, the unit automatically backwashes the filter bed. The backwash water is discharged through the siphon pipe.

The filter tank is circular. Units with a flow rate of 20–175 m³/h are shipped to site fully assembled. Units of 200–750 m³/h are prefabricated in several sections and shipped to site for assembly and anti-corrosion treatment. Once loaded with filter media, the unit can be commissioned and put into operation. The manufacturer can also design larger combined units to meet side-stream filtration requirements of recirculating cooling water systems.

Features

Inflow, outflow, backwashing and drainage are all driven hydraulically, with no control valves required. The unit integrates the water distribution tank, filter and backwash tank, resulting in a compact structure, low operating costs and easy management. The user only needs to prepare the foundation and connect the inlet and outlet piping. The unit has a cover and can be installed outdoors; it is lighter than a reinforced concrete filter and can be placed on an elastic asphalt-sand foundation.

1. Self-operating and self-backwashing via siphon, with no need for routine manual operation; low energy consumption, safe and easy to manage.
2. The water distribution tank, filter, U-shaped inlet pipe and drain tank are assembled into one compact unit.
3. Usually made of carbon steel or other materials on request; anti-corrosion treated, precision-fabricated and easy to install.
4. Filter operation requires no separate power source such as water pressure, electricity or compressed air. If spring water flows by gravity from a higher elevation into the system, no lift pump is needed.
5. Equipped with a forced backwash system to actively clean the filter before head loss reaches the allowable limit.
6. Requires little maintenance and has no operating mechanisms subject to significant wear.

Applications

The unit is used to purify surface water for domestic or industrial supply, and to treat cooling water, mine water and recirculating water for reuse, increasing the water reuse rate.

1. Side-stream filtration of recirculating cooling water in the oil and gas, chemical, pharmaceutical, metallurgical, power, light industry, textile and dyeing sectors.
2. Surface water purification; iron and manganese removal from groundwater.
3. Water filtration at urban and township waterworks.
4. Pretreatment ahead of softening or desalination.
5. Water purification for swimming pools, fountains and water features.
6. Removal of suspended solids from process wastewater; polishing filtration of effluent from secondary clarifiers in biological treatment systems.