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Technical analysis of commissioning and operation of centrifugal sludge dewatering machine
- 2020-07-17-

CentrifugalSludge dewatering machineCommissioning and operating technical analysis


As the debugging of sludge dewatering, the main task of its work is to find the operating combination parameters among the sludge, equipment and flocculant according to the existing conditions. The three depend on one party or ignore the other parties. Causes running problems. Control these operating conditions and parameters to ensure long-term stable operation, and make timely and scientific and effective adjustments in the case of changes in the site, so that it still meets the perfect coordination, and achieves good sludge treatment effects and large scale under the condition of low flocculant consumption. High processing efficiency, so as to achieve low operating costs and meet technical and economic requirements.


Flocculant adjustment with changes in sludge properties and concentration


In the initial stage of the process and equipment debugging of the sewage treatment plant, due to the influence of factors such as water quality, water volume, and water treatment process operating status, many changes may occur in the properties of the sludge to be treated. This change affects the effects of the sludge dewatering machine and flocculant. Dependence will fluctuate. Sludge age or sludge storage time will affect sludge properties, such as sludge concentration, sludge organic matter content (or ash content), sludge density, sludge particle size (skeletal structure of sludge itself) The fluctuation of dependence on flocculants and dewatering machines will be more obvious. Therefore, timely adjustments should be made on site according to the situation to ensure normal sludge dewatering operation and management. The sludge dewatering effect and chemical consumption at this stage may be different from the normal operation. This difference will tend to be stable as the on-site water treatment facilities gradually operate normally and the sludge discharge treatment gradually stabilizes.


Even after the sewage treatment plant has achieved normal operation, the actual nature or concentration of the sludge to be treated will change, especially for those sites where there is no sludge thickening tank and the sludge is directly dehydrated. This change may be It will be more frequent, the fluctuation range will be larger, and the relative change range of the sludge thickening tank will be smaller. These situations are often ignored or underestimated. The main reasons for this change are:


A. Due to the change of the influent load of the sewage plant, the residence time of the sedimentation tank (first sedimentation tank or secondary sedimentation tank) changes, and the actual sedimentation time of the suspended solids in the sedimentation tank changes, resulting in changes in the density and concentration of sludge;


B. Due to the change in the sludge flow rate or the sludge discharge cycle discharged from the sedimentation tank to the sludge dewatering workshop, the sludge concentration is actually changing;


C. The sludge changes due to abnormal conditions (such as maintenance, etc.) in the on-site operation, or due to seasonal reasons, especially changes in the nature and concentration of sludge due to climate alternation, etc. These changes are often not easy to observe on the surface, and easy to be ignored, but a simple calculation will know the possible impact of the magnitude of this change.


Take the concentration of sludge to be treated as an example: if the moisture content of the sludge discharged to the sludge dewatering workshop changes from 96% to 97%, that is, the solid content changes from 4% to 3%, and the value of the concentration of 1% changes In fact, the relative value range has reached 25%. Since the consumption of flocculant is proportional to the solid content of the sludge to be treated, the consumption of flocculant is also reduced by about 25% during normal operation. If there is no timely adjustment to reduce the amount of flocculant added at this time, under the same sludge flow rate and flocculant flow rate, about 25% of the flocculant will be wasted, and the apparent mud cake status will not change significantly. . Conversely, if the sludge concentration increases, but the flocculant does not increase, the sludge dewatering effect will decrease accordingly.


This kind of change happens unconsciously during the operation of the sewage treatment plant, especially in the scene where there is no sludge thickening tank, the magnitude of this change will be more significant. Therefore, it is necessary to pay attention to this important factor that affects the consumption of flocculant at all times at the site. When the sludge properties change significantly, the applicable flocculant should be adjusted in time to cooperate with the sludge dewatering operation; when the sludge concentration changes, It is necessary to adjust the flocculant supply flow in time to meet the treatment effect and avoid waste.


The specific method is to frequently observe the mud effect, and then appropriately reduce the flocculant working fluid supply flow. You can reduce the flocculant dosing pump frequency by about 0.5-1.0Hz each time, and observe the mud cake and supernatant status and torque data after a few minutes , According to the situation, decide whether to continue to reduce the frequency of the dosing pump until the operating frequency of the economical dosing pump is found, or it can be observed and adjusted by increasing the frequency of the mud pump by about 0.5-1.0 Hz each time. Conversely, when the sludge concentration increases, adjust in the opposite direction.


In addition, because the centrifuge structure determines the higher requirements for the quality of the mud, there should not be a large number of large-size particles and fibrous substances in the mud, otherwise it will easily cause the equipment to block, increase the vibration, and affect the processing efficiency. Therefore, the sludge must be crushed and cut before it enters the centrifuge.