Application of High Efficiency Filter in Chemical Water Treatment

Compared with the filter with quartz sand as the filter material, the high-efficiency fiber filter with fiber as the filter material has the characteristics of high filtration efficiency, fast filtration speed, large sewage interception capacity, large periodic water production, and low self-consumption water. The existing problems in the original technological process are eliminated, and there are higher economic and social benefits. If the cleaning technology of the filter material can be improved.
The raw water filtration system is an important part of chemical water treatment in textile mills. The quality of raw water directly affects the normal operation of subsequent equipment and the water quality of desalinated water, which is related to the quality of fiber tow. The maximum output of the original system design of the soft water station is 420t/h. Due to the needs of the expansion project, the amount of desalted water supplied externally increases, the amount of raw water increases accordingly and the water quality requirements increase. The original 7 machines with a processing capacity of 60t/h The filter can no longer meet the production demand, and there are problems in the system, so the transformation has become inevitable. After investigation and full demonstration, it was decided to adopt a new type of bundled soft filler — a pressure-type high-efficiency fiber filter with polypropylene fiber material as the filter material.

1 Process status and problem analysis of production system

1 The original process flow

Primary water is sent to the soft water station after rough filtration by the water plant. The turbidity of the water after rough filtration in the water plant is 1.5~3mg/L. Because the turbidity is too high, it cannot be directly softened, so the soft water station must be filtered by a mechanical filter. , softened by the softening tank to make desalted water and sent to the production workshop. The mechanical filter uses granular quartz sand as the filter material, and is pressurized by a clean water pump to form a constant velocity pressure mechanical filter. Then desalinated water is produced by subsequent water treatment equipment (desalted water treatment system).

2 Problems in the original system

  1. Due to the deterioration of the incoming water quality of the system, 7 sets of mechanical filters have serious sludge accumulation, which affects the supply of desalinated water; it is often necessary to shut down one for maintenance, and the water output of 6 sets of mechanical filters cannot guarantee the production water, which reduces the ion exchange The periodic water production volume of the device increases the cost of water production.
  2. The backwashing of the mechanical filter consumes a lot of self-water and is difficult to operate. It is very easy to cause a large amount of quartz sand to be taken away during the backwashing or backwashing. After that, the filtering effect is obviously reduced, and it has to be stopped for maintenance, resulting in great waste.
  3. The processing capacity of the mechanical filter is 60t/h, and the granular filter material is used for filtering. The filtration accuracy is limited by the particle size of the filter material, the turbidity of the effluent is high, and the cleaning operation of the filter material is too heavy; it is easy to generate plate volume and replace The filter material is frequent and labor-intensive.

2 Feasibility Analysis

In order to solve the problems existing in the original system, after research and analysis, we have transformed the quartz sand mechanical filter into a high-efficiency fiber filter based on the principle of leading technology. The design output of a single high-efficiency fiber filter is 90t/h.
The working principle of the high-efficiency fiber filter: The high-efficiency fiber filter is a bundle of puffed fiber filaments (D20-50μm) with heavy pendants hanging from the lower end, suspended on a porous plate set on the upper part of the filter as a filter medium filter equipment. There are several capsules in the part of the fiber bundles close to the porous plate. When filtering, water is first filled into the capsules to form a pressurized chamber, and the surrounding fiber bundles are forcibly squeezed to make them dense, and then the water flows through the fibers from bottom to top. Pores for upward flow.
When cleaning, first drain the water in the bag, cancel the extrusion of the fiber bundles, and restore the fiber bundles to their bulky state under the combined action of gravity and the elasticity of the puffed fibers, and then scrub with air and water. Since the fiber used as a filter material is a flexible and soft material, the diameter of the filter material can reach tens of microns, and there are a large number of gap spaces in the filter material layer. Different fiber porosity can be obtained under the extrusion conditions of the bundle, and the efficiency and resistance of the filter can be controlled within the set range, which solves the problem of traditional filter equipment such as valveless filter, siphon filter, mechanical filter, etc. All use granular filter materials such as quartz sand for filtration, and the filtration accuracy is limited by the large particle size of the filter material. The small diameter of the filter material greatly increases the specific surface area and surface free energy of the filter material, increases the contact opportunity between the impurity particles in the water and the filter material and the adsorption capacity of the filter material, thereby improving the filtration efficiency and interception capacity.

3 Implementation

1 Process flow

Before the filter is operated, the bladder is filled with water to ensure that the pressurized chamber reaches the set pressure. When the filter is started, it must be pre-run, and it can be put into operation after the water turbidity is qualified. During the operation of the filter, the adjustment of the flow rate must be stable to prevent the sudden change in the flow rate from causing the filtered product to be “brought out” and cause the turbidity of the effluent to exceed the standard. The cleaning process of the filter is: capsule drainage → open the exhaust valve, backwash inlet valve and backwash drain valve → open the compressed air valve for backwash (backwash for 25~35 minutes) → open the positive wash inlet valve and positive discharge valve ( Positive washing for 15~25 minutes) Perform positive washing → close the compressed air valve and positive washing inlet valve, and wait for five steps.

2 Operating status

The filtration system has been put into use in the water treatment system since October 15, 2008. In order to grasp the operation rules and make the filtration system operate safely, efficiently and reasonably, we have tested the operation cycle of the filter.
Three-parameter control is adopted for single filter failure control:

  1. Inlet and outlet pressure difference ≥ 0.1MPa;
  2. Outlet water turbidity ≥ 1mg/L;
  3. Set period cumulative water production. Satisfying one of them confirms its failure.

Because incoming water is affected by seasons, spring and autumn have heavy rainfall, and the turbidity of the effluent from the water field is somewhat high, so the periodic water production volume is also different. A single periodic water production volume between 3000 and 4000t can ensure the quality of the effluent water. The maximum turbidity of the incoming water is 5mg/L, and the minimum is only 1.2mg/L, but the turbidity of the effluent can meet the requirements. Filters are capable of retaining in any case. Protect the subsequent process.

4 Economic and social benefits

The raw water system has been transformed and operated for four and a half years, solving the problems existing in the original process, improving the quality and quantity of effluent water, and reducing production costs.

  1. Calculation of water consumption: The high-efficiency fiber filter produces a large amount of water periodically, and the water consumption of backwashing is small, which reduces water consumption and sewage discharge.
    High-efficiency filter annual backwash water volume = single backwash water consumption x annual backwash number = 80 x 1278 = 102240t
    Annual backwash water volume of mechanical filter = single backwash water consumption × annual backwash number rate = 60 × 2555 = 153300t
    Annual water saving of high-efficiency filter = (annual backwash water volume of mechanical filter – annual backwash water volume of high-efficiency filter) = 153300-102240 = 51060t
    Saving sewage charges throughout the year = 2.87×51060≈147,000 yuan
  2. Process effect: The quality of the effluent water from the high-efficiency fiber filter has been improved, making the turbidity of the effluent stable and less than 0.7mg/L, reducing the burden on the cation exchanger, effectively increasing the periodic water production of the ion exchanger, and reducing salt Consumption, reducing the staining of the resin.
  3. The number of backwashing is reduced, the mechanical filter is backwashed every 24 hours, and the high-efficiency filter is backwashed once every 48 hours, which reduces the labor intensity of workers.
  4. It solves the heavy labor such as frequent maintenance of mechanical filters and replacement of filter materials. During the four and a half years of transformation, it has not been stopped for maintenance, which saves maintenance costs and reduces the labor intensity of workers.

Xi’an CHIWATEC Water Treatment Technology is a high-tech enterprise specialized in various water processing devices. Aside from these individual products, which cover a number of types and series, we can also help with related comprehensive engineering projects. Thanks to our hard work and dedication upon our founding, we are now one of the fastest-developing water treatment equipment manufacturers in Western China.

Further reading

Water Treatment Systems & Reverse Osmosis in Pharmaceutical

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