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DTRO (disc Tube Reverse Osmosis Membrane System) Process Description
- Aug 02, 2018 -

DTRO (disc tube reverse osmosis membrane system) process description

Most of the organic matter and nitrogen pollutants in the MBR effluent have been removed, but they are still far from the emission standards. At the same time, the water still contains a lot of pollutants such as organic matter and scale ions, which is an important hidden danger for the subsequent stable operation of membrane separation equipment. The emission standard is high, and the new standard also has the requirement of total nitrogen index. The membrane system is required to have a high rejection rate for nitrates. This design adopts DTRO (disc tube anti-pollution ability and high recovery rate). Osmotic membrane system).

The landfill leachate has complex composition and various kinds of insoluble salts such as calcium, magnesium, barium and silicon. These insoluble inorganic salts are concentrated in high concentration after entering the reverse osmosis system. When the concentration exceeds the solubility under the conditions, the film will be in the film. The surface is fouled. Adjusting the pH value of the raw water can effectively prevent the scaling of the carbonate inorganic salt, so the pH of the raw water must be adjusted before entering the reverse osmosis.

The MBR effluent is pumped into the DTRO membrane column through the DTRO feed pump. At the same time, acid is added from the acid storage tank to adjust the pH value, and reflux mixing is performed to achieve a balanced pH value. The DTRO system inlet water line is equipped with a pH sensor. The PLC determines the pH value of the raw water and automatically adjusts the metering pump frequency to adjust the acid addition amount, and finally makes the pH value of the raw liquid before entering the reverse osmosis reach 6.1-6.5. The original water pump after adjusting the pH is put into the DTRO membrane column. There are 1 set of DTRO system. Each set of equipment is equipped with 2 sets of security bag filters. The inlet and outlet sides have pressure sensors to automatically detect the pressure difference. When the pressure difference exceeds The system prompts to replace the filter bag when there is a certain pressure difference. Two security bag filters are operated in parallel and the filter bag can be replaced online. The security filter has an accuracy of 50 μm to provide the last protective barrier to the membrane. The raw water flowing through the security bag filter directly enters the high pressure plunger pump. The effluent after being pressurized by the high pressure pump enters the DTRO membrane column, and the first membrane is directly supplied by the high pressure pump. Each membrane membrane is equipped with an on-line circulation pump, and a part of the membrane outlet is returned to the inlet of the online pump through an on-line circulation pump. Ensure sufficient flow and flow rate on the membrane surface to avoid membrane fouling.

The membrane water is divided into two parts, a concentrate and a permeate. The end of the concentrate has a pressure regulating valve for controlling the pressure in the membrane group to produce the necessary water recovery. The concentrated liquid is discharged into the concentrated liquid pool, waiting for treatment, and the permeate enters the clean water storage tank to meet the needs of self-cleaning. The excess water is discharged into the water regulating tank, and is discharged into the receiving water body through the pump room in the pool, and the system recovery rate is 80. %.

The reverse osmosis system is medium-pressure reverse osmosis, and a disc-type reverse osmosis membrane is used. The average working pressure of the disc-type reverse osmosis membrane is 30-70 bar, and the maximum pressure limit of medium-pressure reverse osmosis is 70 bar. Since the influent is ultrafiltration, the yield of the clear liquid can reach 80%. The DTRO system has 1 unit, and the whole system has a total of 70 disc-type reverse osmosis membrane columns, with a total membrane area of 658, 3 m2.

The DTRO unit has the following ancillary facilities:

(1) CIP online cleaning facility

CIP online cleaning facility for flushing, cleansing and chemical cleaning of reverse osmosis units;

(2) Acidic dosing facilities

In order to prevent inorganic scale formation during reverse osmosis operation, an acid dosing facility is provided for adjusting the pH value of the reverse osmosis system;

(3) Scale inhibitor dosage facility

Scale inhibitor dosing facilities are also used to prevent the formation of inorganic scale during reverse osmosis operation.

The leachate is pretreated by a membrane biochemical reactor with a complete biological denitrification. The ultrafiltration water contains no suspended solids and biodegradable organic matter, which largely avoids the inorganic and organic fouling of the reverse osmosis membrane. It can reduce the cleaning frequency of the reverse osmosis membrane and enable the reverse osmosis system to operate at a relatively low pressure, prolonging the service life of the reverse osmosis membrane.