FAq

What are the main applications of nanofiltration water treatment equipment in sewage treatment?

1. Softening: Membrane softening water mainly uses the selective permeability of nanofiltration membranes to soften water with different valence states. While removing hardness, membrane softening can also remove turbidity, chromaticity and organic matter, and its effluent water quality is significantly better than other softening processes. Moreover, membrane softening has the advantages of no need for regeneration, no pollution, simple operation, and less land occupation, and has obvious social and economic benefits.
Membrane softening is very common in the United States. In the past 10 years, new softening water plants in Florida have adopted membrane softening to replace conventional lime softening and ion exchange processes. In recent years, with the continuous improvement of nanofiltration performance and the continuous decline in the price of nanofiltration membrane components, membrane softening has been superior to or close to conventional methods in terms of investment, operation, and maintenance.

2. Used to remove organic matter in water: In addition to softening, nanofiltration membranes are mostly used for decolorization, removal of natural and synthetic organic matter (such as pesticides), trihalomethanes, disinfection byproducts (trihalomethanes and haloacetic acids) and their precursors and volatile organic matter in drinking water treatment, to ensure the biological stability of drinking water, etc.

3. Removal of trihalomethanes: Studies have shown that nanofiltration membranes can remove most of the toxic and harmful organic matter and Ames mutagens in water, making the mutagenicity ratio MR values ​​of TA98 and TA100 strains less than 2 at each test dose, and the Ames test results are negative. Further research will examine the interception characteristics of nanofiltration technology for endocrine disrupting substances in drinking water to provide a basis for safe drinking water.

4. Removal of disinfection byproducts and their precursors: Disinfection byproducts mainly include trihalomethanes (THMs), haloacetic acids (HAAs) and possible trichloroacetaldehyde hydroxide (CH). Foreign scientific and technological workers have conducted extensive research in this regard. The average retention rates of nanofiltration membranes for the precursors of these three disinfection by-products are 97%, 94% and 86% respectively. By selecting appropriate nanofiltration membranes, the quality of drinking water can meet higher standards for safe drinking water quality.

5. Removal of volatile organic compounds (VOCs): It has a high removal rate for trace volatile organic compounds in drinking water.

6. Application in piped drinking water: Nanofiltration can intercept ions with a valence of more than two and other particles, and only water molecules and some monovalent ions (such as sodium, potassium, and chloride ions) are passed through. Nanofiltration can be used to produce direct drinking water, and a certain amount of ions are still retained in the effluent, and the treatment cost can be reduced.

What is the main role of the TUF device in the process of wastewater softening?

The TUF device is a type of tubular membrane with a filtration accuracy of 50nm. It is mainly used in the process of wastewater softening to separate solids and liquids. The membrane component adopts a unique tubular support structure, and the membrane layer is fully anchored or chemically bonded to the sintered porous plastic. The component is designed as a cross-flow filtration mode, and its filtration pore size range belongs to the microfiltration and ultrafiltration range. And POREX tubular membrane components have excellent chemical resistance, temperature resistance and friction resistance.
Technical features of TUF device
1. Remove heavy metals (Ca2+, Mg2+, Ba2+, Sr2+)
2. A recovery rate of 10 to 20 times or more can be obtained
3. Strong, durable and washable membrane on the market
4. Super chemical resistance PH 0-14
5. Friction resistance, suitable for solid-liquid separation of coarse particles
6. Microporous membrane, providing excellent filtered water quality and low SDI (generally less than 0.5 NTU)
7. Large channel, cross-flow circulation, allowing high solid load, no pre-treatment required
8. Components are specially designed for wastewater treatment, with a service life of 5-10 years

Daily maintenance precautions for DTRO membranes

1. Regularly check the water quality of landfill leachate
The water quality of landfill leachate fluctuates greatly, and the raw water quality needs to be regularly analyzed and checked during the treatment process

2. Regularly check the water quality of the single membrane module
DTRO membrane modules are all in parallel mode. During normal operation, the conductivity of the produced water generally does not change much. If the conductivity of the produced water is found to increase during operation, the conductivity of the produced water of the single membrane module can be checked. If the conductivity is higher than the conductivity of the discharge, the single membrane module can be isolated and disassembled for inspection. Generally, the O-ring is detached or the membrane If the membrane is damaged, it can be replaced to restore the performance of the membrane assembly.

3. Regular cleaning
During the operation of the DTRO membrane assembly, contamination is inevitable, so it needs to be cleaned. The cleaning method is generally chemical cleaning. The DTRO membrane cleaning agent can be used for online cleaning to restore the flux. During the cleaning process, the temperature is generally controlled at 35°C, and the cycle is soaked. The chemical cleaning time is generally 2 hours. If the contamination is particularly serious, the cleaning time can be appropriately extended. The cleaning process is a professional maintenance process, and the operator needs to strictly follow the cleaning operation procedures to ensure the service life of the membrane assembly.

How to calculate the desalination rate and salt permeability of zero-emission DTRO disc-tube reverse osmosis membrane elements?

Zero-emission DTRO is a form of reverse osmosis. It is a membrane component specially used to treat high-concentration sewage. Its core technology is disc-tube membrane column. The reverse osmosis membrane and hydraulic guide plate are stacked together, fixed with a central tie rod and end plate, and then placed in a pressure-resistant casing to form a membrane column. DTRO overcomes the disadvantage that general reverse osmosis systems are prone to clogging when treating leachate, making the system more stable and lower operating costs.

The application of zero-emission DTRO disc-tube reverse osmosis membrane treatment technology in water treatment in power plants in my country has entered the stage of gradual promotion. It has the advantages of high raw water treatment quality, wide application range, economic and environmental protection, and easy maintenance and management. The application of DTRO disc-tube reverse osmosis technology can better solve various water resource problems through efficient purification of unconventional water sources. In water-scarce areas with high energy demand, DTRO disc-tube reverse osmosis technology is a general technology for solving the "water problem". It has the advantages of clean production with low land use and no other pollution, which helps to break through the ecological and environmental bottleneck for the further development of the local economy.

Desalination rate and salt permeability of zero-emission DTRO disc-tube reverse osmosis membrane elements
The principle of desalination rate is to remove the percentage of soluble impurities from the system influent through the DTRO reverse osmosis membrane. The salt permeability refers to the percentage of soluble impurities in the influent that pass through the membrane. The relationship between them is explained by the following expression:
Desalination rate = (1-salinity content of produced water/salinity content of influent) × 100%
Salt permeability = 100%-desalination rate

The desalination rate of the membrane element is determined when the membrane is manufactured. The desalination rate depends on the density of the ultra-thin desalination layer on the surface of the membrane element. The denser the desalination layer, the higher the desalination rate, and the lower the water production. The removal rate of reverse osmosis for different substances is mainly determined by the structure and molecular weight of the substances. The removal rate of high-valent ions and complex monovalent ions can exceed 98%. The removal rate of monovalent ions such as sodium ions, potassium ions, and chloride ions is lower, but it also exceeds 95%. The removal rate of organic matter with a molecular weight greater than 100 can also reach more than 98%, but the removal rate of organic matter with a molecular weight less than 100 is lower.

Storage of zero-emission DTRO disc-tube reverse osmosis membrane elements:
(1) The membrane elements are tested for water flow before leaving the factory, and are stored with 1% sodium sulfite solution, and then vacuum-packed in oxygen-isolating bags.
(2) The membrane elements must always be kept moist. Even when they need to be temporarily opened to confirm the quantity of the same package, they must be opened without damaging the plastic bag, and this state should be kept until use.
(3) The membrane elements are best stored at a low temperature of 5~10℃. When storing in an environment with a temperature exceeding 10℃, choose a well-ventilated place and avoid direct sunlight. The storage temperature should not exceed 35℃.

What are the pollution methods of zero-emission DTRO membrane?

1. According to the form of pollution:
a. Membrane pore blockage: Membrane pore blockage caused by small molecules.
b. Gel layer on the membrane surface: The formation of a gel layer caused by concentration polarization of macromolecules.
c. Sludge filter cake: Deposition of particulate matter.
d. Floating object entanglement

2. According to the cleanability and recoverability of pollution:
a. Reversible pollution/temporary pollution: Generally refers to the sludge layer deposited on the membrane surface, which can be removed by physical cleaning.
b. Irreversible pollution/long-term pollution: Generally refers to the gel layer and membrane pore blockage on the membrane surface, which can be removed by chemical cleaning.
c. Irreversible pollution/long-term pollution: Generally caused by irreversible adsorption, which cannot be removed by any cleaning means.

Membrane cleaning is to remove the covering on the membrane surface, restore and improve the membrane flux, which can be regarded as the reverse process of membrane pollution. Effective cleaning of the membrane can not only ensure the continuous operation of the system, but also avoid the occurrence of long-term membrane pollution, thereby extending the life of the membrane and reducing operating costs. It should be noted that certain substances in the influent water may react chemically with the membrane surface, causing precipitation and aging of the membrane surface, contaminating the membrane surface or causing the performance of the membrane to deteriorate.

What is the TUF device? Do you know its materials, features and applications?

The TUF device is actually a membrane layer of fluorine-containing polymer cast on the inner wall of a sintered organic polymer porous support tube. The materials of each part are as follows:

1. Membrane shell: PVC or CPVC material. Generally speaking, we directly use Sch40 PVC straight tubes as TUF membrane shells after processing. The diameter of the membrane shell ranges from 1-1/4 inches to 8 inches. This type of membrane shell can be used in most wastewater treatment occasions. In some cases, considering special chemical resistance requirements or improved temperature resistance, CPVC or stainless steel membrane shells may be required.

2. Sintered porous support tube: HDPE (high-density polyethylene) is a commonly used support tube material and is suitable for most occasions. If necessary, PVDF (polyvinylidene fluoride) can also be used to sinter and form a porous support tube.

3. Membrane layer: PVDF material, its chemical properties.

Features of TUF tubular softening membrane:

1. Chemical resistance: The operating pH range is between 0-14, and it can be used for chemical cleaning with high concentrations of acid/alkali/oxidant solutions.

2. Resistance to friction and particulate matter.

3. It can handle extremely high concentrations (up to 5% mass concentration), sometimes even higher.

4. The membrane flux can be restored by chemical cleaning.

5. Extremely long service life: for example, a system has been in use for more than 12 years.

6. Cross-flow filtration operation, which means that the power consumption is higher than other membrane filtration processes.

7. The system using TUF has good tolerance to upstream process failures and fluctuations in influent water quality because there is no unstable coagulation, flocculation and gravity sedimentation equipment upstream.

Industry application of TUF tubular softening membrane:
Tubular filtration membrane system can be used to replace traditional sedimentation tanks or clarification tanks to obtain better water quality. The membrane filter uses a polymer membrane layer to separate and intercept suspended solids from wastewater. This separation process does not require the insoluble matter to form a large and heavy enough alum flower. It can be understood that it only needs to convert the dissolved substance into an insoluble substance, and then it can be separated from the wastewater with high efficiency.
In a water treatment system that includes RO and wastewater reuse RO, TUF can not only be used as an alternative process to the clarifier, but also as an important part of the wastewater reuse RO process. Due to the high quality of the filtered water, the water produced by TUF can be directly sent to the RO system without any further filtration and turbidity removal process. In contrast, if a clarifier is used, the subsequent multi-media filter, filter element filter and hollow fiber ultrafiltration and other turbidity removal equipment are generally required before RO. In other words, TUF can directly connect the wastewater treatment process section (such as the chemical dosing reaction unit) and the RO desalination process section in series very simply. The overall treatment process flow can be greatly shortened, and the reliability of the system is greatly enhanced.
The water treatment system using TUF is quite robust in terms of operating performance, the operation is simple, and it is relatively easy to adapt to changes in the influent water quality and water volume. The chemical dosing reaction part can be automatically put into operation, and TUF automatically enters the operating mode from the standby mode. Just start the circulation pump and open the water production valve, and it can be put into operation in 1 minute.