Grit chambers are intended for extraction and removal highly precipitable particles (grit), which is sized more than 0.15 mm from municipal and industrial wastewater. The grit chambers are intended for use in wastewater with a рН of 6.5 - 8.5.
The spiral of the screw transporter is manufactured from wear-resisting carbon steel; other parts are manufactured from stainless steel AISI 304 or AISI316 on customer demand. The grit chambers can be of 50 or 100 m3/h capacity. The grit chamber is a cone-shaped tank with an inclined transporter for the removal of the precipitated grit.
Inlet and outlet branches are installed on the top of tank. The grit washing units with washing water inlet- and outlet branches are installed at the bottom of conical tank. The mixing device is on the mounted inside of the tank and is driven by a geared motor. Another geared motor drives the screw of the grit transporter. The grit transporter - which consists of a number of cases with rotating screws inside - is mounted to the tank with sn angle of 35°. The rounded case of the grit transporter is protected by wear resistant polymer inserts. The case sections are connected by flange couplings.
Wastewater is fed at the inlet zone of the conical tank and swirls along tank walls by means of the mixing device rotation. Grit slips along the walls of the conical tank and reaches the grit washing unit. Clarified wastewater is directed to the outlet branch for subsequent treatment stages. Grit is washed by pressure water in the grit washing unit. Grit is agitated by the mixer to improve the grit washing process. Washing water is drained to the subsequent treatment stages while the grit is collected at the tank's bottom. From here it is removed to the discharge zone by the screw conveyor. The grit is discharged into the storage container or onto the transporter.
Automation of the grit chamber operation can be time based. All grit chamber geared motors (mixing devices and transporter) are equipped with electrical protection. Alarm systems of the normal operation indication and emergency stops are provided.It is possible to transfer equipment status data to a higher level automated process control system depending on the client’s requirements. The screw can be reversed in order to address jams and congestion.
|Wastewater feed rate, [m/s]||0,6...0,8|
|Reatined particles diameter, more than [mm]||0,2...0,25|
|Drive power of mixing device, [kW]||0,18|
|Drive power of screw conveyor, [kW]||2,2|
|Diameter of conveyor screw, [mm]||190|