Common Faults and Solutions of Screw Press

Blockage or Jamming of the Dewatering Unit


  • Quality issues with the equipment, especially the smoothness of the screw shaft and ring. The screw shaft and ring are the main components of the dewatering unit of the screw press. If the manufacturer cuts corners and skips the step of smoothing the surface of the shaft and ring, the equipment is prone to sludge blockage during operation.

  • Related to the nature of the sludge. Sludge can be categorized into organic and inorganic types. Organic sludge typically has a high organic content, decomposes easily with foul odor, fine particles, low specific gravity, high water content that makes it difficult to dewater, hydrophilic properties with a gel-like structure, and is easily transported through pipelines. In contrast, inorganic sludge exhibits opposite characteristics.
    When a screw press is used to treat sludge with a high content of inorganic matter, or when the sludge particles are coarse with high specific gravity and fast separation of mud and water, while the screw press operates at a lower rotational speed, the sludge may not be expelled from the filter chamber by the time it reaches the end of the screw, resulting in low moisture content and extremely poor flowability of the sludge cake, leading to blockages in the dewatering section.
  • Improper operation. Different models of screw press correspond to different processing capacities. If the amount of sludge entering the screw press significantly exceeds its processing capacity, the screw stacker will operate under overload conditions. Failure to clean and drain the equipment before and after use, resulting in residual sludge adhering to the screw, can also lead to equipment blockages.


  1. Before use, allow the screw press to run empty for about 10 minutes, supplemented by a spraying device. After use, turn off the feed and let the screw press run empty for about 30 minutes to completely drain any residual sludge, and rinse the screw with clean water.

  2. For minor blockages, try reversing the screw press (there is a "frequency conversion reverse" button on the control interface) or activate the spray wash function.

  3. For severe blockages, stop operation immediately, conduct equipment maintenance, flush with plenty of clean water, and if necessary, dismantle the screw shaft to clean off the adhered sludge.
    During operation, minor shaft blockages may occur occasionally, but it is more important to adhere to the equipment's operating requirements and master the correct operation methods to avoid shaft blockage issues.

    Sludge Cake Not Drying Properly


    • Flocculation issues. Due to the unique operating principle of the screw press, wastewater treated by the screw stacker must undergo pretreatment with flocculants. After the wastewater is flocculated and settled, it is then pumped into the equipment for dewatering. Factors such as the compatibility between the flocculant and the wastewater, the proportion of flocculant added, and the solubility of the flocculant will affect the size of the floc in the wastewater.
      If the floc size is too small to meet the feed requirements between the screw blades, it will lead to incomplete dewatering. On the other hand, if the floc size is too large, it will constrain too much water and reduce the dryness of the sludge cake.
    • Improper equipment commissioning. Regarding commissioning: first, adjust the flocculation effect of the wastewater; second, adjust the speed frequency of the main shaft; third, adjust the gap size of the back pressure plate according to the flow rate of the sludge inlet. Professional technicians will adjust the sludge inlet flow rate and the gap size of the back pressure plate based on the characteristics of the wastewater and the size of the floc.


    1. Flocculant adjustment is crucial. First, match the appropriate flocculant based on the characteristics of the wastewater being treated. Then, adjust the proportion of flocculant added according to the speed and size of the floc formation to achieve a good flocculation state of the wastewater after entering the reaction tank.

    2. In addition to flocculant adjustment, adjusting the back pressure plate is also essential. Therefore, after purchasing the screw press, it is best to have professional technicians perform adjustments to achieve better treatment results.


    Twisting and Deformation of Screw Press Blades


    • Equipment quality issues. The press formed by the dynamic and static blades of the screw press experiences relative movement during operation. If the smoothness between the blades is insufficient or the thickness of the blades is insufficient, the inner blades of the screw press may wear or become severely deformed due to mud and sand leakage, leading to decreased dryness of the sludge cake over time.
    • Excessive sludge flow rate. Different models of screw press correspond to different processing capacities. The flow rate of the feed should be adjusted based on the actual processing conditions of the screw press, flocculant adjustment, etc. If the feed flow rate is too high and exceeds the range that the screw press can withstand, the blades of the screw press will operate under overload conditions, leading to deformation.
    • Related to the nature of the sludge. If the sludge contains sand, oil, glue, a large amount of solid waste, or easily dry sludge, it is not only prone to clogging but also causes internal pressure imbalance, resulting in wear and deformation of the screw press blades.


    1. Prevention is key. Before purchasing equipment, do not only focus on the price but also thoroughly understand the product's quality and after-sales service to ensure that the equipment itself is of good quality.

    2. Regarding the feed flow rate, it can be adjusted using valves. During installation, it is preferable to install an overflow pipeline. When the flocculation tank of the screw press is overfilled, it will overflow through the overflow pipeline, reducing the operational load on the screw press blades.

    3. Ensure the concentration of the screw press feed (related to flocculant adjustment). If there are large chunks of slag, metal impurities, etc., a filtering device must be added at the inlet.

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