HydroBwt-LSG Filter


HydroBwt-LSG vertical auto backwash ballast water filter is mainly used in the filtration process of ship ballast water systems.

The structure is as follows:

  • Cylinder.
  • Water inlet and outlet and sewage outlet.
  • Differential pressure transmitter. Between the water inlet and outlet.
  • Wedge wire self-cleaning screen.
  • Geared motor.
  • Swing arm.
  • PLC electric control box.
  • Pneumatic control valve.

Ship ballast water: Ship ballast water is a balanced and stable ballast. It is mainly to ensure the navigation safety of the ship when it is empty.
Ballast water treatment system: Ship ballast water contains a large number of bacteria, viruses, and various marine animals and plants. Accompanying the navigation of ships and the discharge of ballast water. Pests in the water can survive and cause damage to local ecosystems. Therefore, ballast water treatment is very important. The ballast water treatment system mainly includes two major units: one is the filtration unit and the other is the sterilization unit.
HydroBwt-LSG vertical ballast water filter: It is controlled by electromechanical integration technology such as PLC. A filtration technology with an automatic backwash function designed based on hydraulic principles. The filter control system can automatically control the use of filtered clear liquid or an external cleaning system to clean the filter layer according to pressure difference changes or time settings. Keep the filter in normal filtering status. It has the characteristics of non-disassembly and cleaning of the filter layer, continuous filtration, unattended, water saving, and energy saving.

HydroBwt-LSG Auto Backwash Ballast Water Filter Guide

HydroBwt-LSG vertical auto backwash ballast water filter mainly appears in the first stage of treatment in the system. Its function is to remove larger particles, algae and microorganisms from the water, with a filtration accuracy of 50 microns. HydroBwt-LSG uses a wedge wire candle filter whose structure is suitable for backwashing.
After running for a period of time, there will be a large amount of material in the filter, causing the pressure drop inside and outside the filter to increase. When reaching a certain pressure drop value, the system backwash device starts. Use the filtered water to backwash the filter screen and wash the material trapped inside the filter screen into the sewage pipe for discharge.

HydroBwt-LSG backwash filter mainly relies on the back pressure of the system when backwashing. Normally, the back pressure is above 0.4MPa to ensure thorough backwashing. In the ship’s ballast water treatment system, the back pressure of the system is very low. Usually between 0.2 and 0.3MPa, and during backwashing, this causes the automatic backwashing filter element to not be backwashed clean. As a result, the pressure difference between the inlet and outlet has been very high, and the injection of ballast water cannot be completed. Eventually, the ship was unable to leave the port, causing huge losses to the shipowner.


  • Add a centrifugal pump to the sewage outlet.
    Add a centrifugal pump to the drain outlet of the filter. When the pressure difference reaches the set value, the backwash program starts and the drain valve opens. At this time, through the signal output by the pressure difference transmitter, the centrifugal pump at the sewage outlet starts. After starting the centrifugal pump, negative pressure forms at the sewage outlet. Therefore, it is equivalent to artificially increasing the back pressure of the backwash system, making the backwash more thorough. When the backwash cycle ends, the PLC electronic control system will send a signal to stop the centrifugal pump. At the same time, the centrifugal pump stopped working.
  • Add a backwash pump externally.
    Since the backwash back pressure is low and the backwash is incomplete, in order to increase the back pressure during backwash, some manufacturers will install a backwash pump outside the automatic backwash filter.
    The inlet of the centrifugal pump is connected to the outlet of the automatic backwash filter through a pipeline, while the outlet of the centrifugal pump is connected to the filter cylinder.
    When the pressure difference reaches the set value, the drain valve at the drain outlet opens. At the same time, the external centrifugal pump is started, and the clean water returns to the cylinder of the automatic backwash filter. Increase backwash back pressure to make backwash more thorough. End the backwash process, close the drain valve at the sewage outlet, and at the same time, the backwash pump stops working.


Ship ballast water treatment systems mainly appear on ships, and ships, especially oil tankers, have special electrical process requirements and installation site restrictions. As a result, the above designs have the following shortcomings:

  • Whether it is a centrifugal pump at the sewage outlet or an external backwash pump, a certain amount of space is required. Due to the limited space on board, the application of the above solution is difficult.
  • The requirements for electrical technology on ocean-going ships, especially ocean-going tankers, are very strict. Many require the explosion-proof category to be intrinsically safe. Therefore, if the above solution is adopted, it will be difficult to buy a centrifugal pump that meets the conditions of use.
  • The centrifugal pump and supporting pipeline valves will inevitably increase the cost.

To solve the above problems, we have developed a new HydroBwt-LSG auto backwash ballast water filter. Its features are as follows:

  • The process is simple and reliable, and takes up little space. 
  • Easily meet the electrical process requirements on board. 
  • No cost increase.