Mud cleaning equipment - mud scraper and thickener
In order to ensure the normal operation of the sedimentation tank, the sludge deposited in the sedimentation tank must be cleaned continuously or regularly. The mechanical method is commonly used for sludge removal. According to the method of sludge removal, the sludge removal machinery can be divided into sludge scraper and sludge suction machine.
Sludge scraper is a device that scrapes the sludge in the sedimentation tank to a centralized position (or the sludge collecting bucket at the inlet end of the sedimentation tank). It is mainly used in the primary sedimentation tank of the sewage treatment plant. It is called a thickener when it is used in the gravity sludge thickener. Commonly used mud scrapers include chain scraper mud scraper, truss truck mud scraper and rotary mud scraper and thickener.
(1) Chain scraper
The chain scraper type mud scraper is equipped with a scraper at a certain interval on two main chains. Two chains with the same number of sections are connected into a closed ring, and the drive device drives the drive sprocket to rotate. The chain slowly rotates under the support of the guide sprocket and guide rail, and drives the scraper to move. The scraper scrapes the settled sludge into the sludge hopper at the tank bottom, and the scraper on the return trip at the water surface leads the scum into the sludge tank.
(2) Truss type mud scraper
Truss type mud scraper is installed on the rectangular advection sedimentation tank with reciprocating motion. Each operation cycle includes one working stroke and one non working return stroke. The advantages of the mud scraper are:; In the working stroke, only the mud scraper and scum scraper are immersed in the water, while in the return stroke, the whole machine is raised out of the water, which brings great convenience to maintenance; As the sludge scraping and slag scraping are both positively driven, the sludge stays at the bottom of the tank for a short time and the working efficiency of the sludge scraper is high. The disadvantage is that the movement is more complex and the failure rate is relatively high.
(3) Rotary mud scraper and thickener
The rotary mud scraper and thickener used in the radial flow sedimentation tank and the round sludge thickening tank, in addition to the role of mud scraping and preventing sludge hardening, also uses many longitudinal bars to stir the sludge in the tank to promote the separation of mud and water.
The structural difference between rotary thickener and rotary mud scraper is that a number of longitudinal bars are added above the inclined plate mud scraper, with spacing of 100~300mm. Through the stirring action when the grid slowly rotates, it can promote the agglomeration of sludge particles and accelerate the sludge settling process. In terms of operation management, the mud feeding shall be operated continuously to maintain the fluidity of mud. If there is mud in the tank after a long shutdown due to maintenance and other reasons, special attention shall be paid to restart. The mud at the bottom of the tank may cause great resistance.
4.5.2 Sludge suction machine
The sludge suction machine is a mechanical equipment that sucks out the sludge settled at the bottom of the tank. It is generally used in the secondary sedimentation tank to suck out the activated sludge and return it to the aeration tank. Most of the suction dredgers are assisted by the mud scraper during the suction process, so they are also called the mud scraper suction dredgers. The suction methods of the suction dredger are as follows.
(1) Static pressure type
It is applicable to rotary mud scraper.
This device connects the upper ends of several mud suction pipes with a mud collecting tank. The mud collecting tank is semi immersed in water to make its bottom lower than the water surface of the sedimentation tank. A conical valve is installed at the connection part between each mud suction pipe and the mud collecting tank. When the tank is full, open the conical valve. The pressure formed by the liquid level difference makes the activated sludge at the bottom of the tank continuously flow into the sludge sump through the sludge suction pipe, and then flow into the distribution well or back to the sludge pump house through the central sludge tank from the sludge sump.
The advantage of static pressure sludge suction is that it is easy to operate. The sludge suction capacity of each sludge suction pipe can be controlled by a cone valve as long as the liquid level in the pool is higher than that in the central sludge tank. The disadvantage is that due to the structure * * *, the liquid level difference cannot be large, especially the pressure difference of the suction pipe near the edge is smaller. It is difficult to absorb the thicker sludge, and sometimes it is necessary to use other methods to forcibly lift the sludge. In addition, static pressure sludge suction cannot be used for truss truck type sludge suction machine.
Air stripping is an auxiliary means of static pressure sludge suction. Its main function is to dredge the blocked sludge suction pipe. When the sludge at the bottom of the tank becomes thick due to a fault shutdown, a large number of rising bubbles help to mix the sludge with water and help the sludge flow upward. The air source of the air stripping device comes from two aspects: one is the active type, which uses the air pump installed on each sludge suction machine to supply air; The other is passive type, that is, the pressure air is directly introduced from the pipe in the blower room, which requires laying pipes at the bottom of the pool. The pressure air is led from the bridge to the lower end of the suction pipe with one hose.
(2) Siphon type
The sludge is pumped into the central tank at the bottom of the radial flow tank or the side sludge tank of the horizontal flow tank by using the siphon principle. The condition for forming siphon is that the liquid level at the siphon outlet should be lower than that in the sedimentation tank. In this way, the siphon is initially filled with water.
(3) Pump suction type
One or several sewage pumps are installed on the sludge suction machine to directly absorb sludge at the bottom of the tank. In this way, the liquid level can be raised to the aeration tank, so there is no need for liquid level difference. The sludge can be pumped by opening the water pump, and even the return sludge pump and excess sludge pump are omitted. If the emptying system of the sedimentation tank fails, these pumps can empty the water in the tank to be used as the emptying pump.
(4) Static pressure type, siphon type and pump suction type are used for sludge suction
The static pressure sludge suction principle is used to make the sludge flow into the sludge collecting tank automatically, and then the siphon or suction pump is used to suck the sludge from the sludge tank to the outside of the tank. This method has a wide range of applications. It can also be used on the truss truck type sludge suction machine that is not suitable for static pressure sludge suction. It can also use air lift to help lift the sludge and use a cone valve to regulate the sludge flow and concentration.
Rotary sludge suction machine and truss truck type sludge suction machine are commonly used. The former is used for radial flow secondary sedimentation tank, and the latter is used for horizontal flow secondary sedimentation tank.
Jiangsu Dawei Environmental Protection Technology Co., Ltd., a manufacturer of screw folding machine, screw folding sludge dehydrator, manual and automatic flocculation device, mud scraper, conveyor and grating, welcome to call for consultation.