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Ammonia removal from wastewater by membrane contactor process will thrive in the future


Release time:

2024-04-07

The advantages of PTFE membrane deamination, such as its efficiency in deamination, lower energy consumption, reduced operating costs, and higher investment benefits, are significantly superior to traditional methods. Although it requires higher influent water quality than traditional methods, its many advantages make it irresistible.

Ammonia removal from wastewater by membrane contactor process will thrive in the future

After we had completed several membrane deamination projects and they had been running successfully for a couple of years, we decided to introduce this membrane contactor process worldwide because it has some advantages that users cannot resist.

The primary method for treating wastewater with high concentrations of ammonia nitrogen has always involved the use of an air-stripping tower or steam stripping. An efficiently operated air-stripping tower can remove approximately 80-90% of ammonia nitrogen. However, during winters, especially in colder areas, the performance of the stripping tower deteriorates. Moreover, if the wastewater contains volatile organic matter or other environmentally harmful gases such as hydrogen sulfide, discharging it into the air can lead to environmental pollution. Additionally, the stripping tower occupies a large space and consumes a considerable amount of energy.

On the other hand, steam stripping deamination has a remarkable deamination effect, and its removal rate is also high. In most cases, ammonia nitrogen can be reduced to emission standards, and ammonia water can be obtained as a by-product. However, it has certain drawbacks. Firstly, it requires a significant initial investment, and secondly, it consumes a lot of energy, necessitating the use of a large amount of steam, which is difficult to manage in a factory without steam. Besides, the ongoing global carbon emission reduction and carbon neutrality situation has led to restrictions on the use of steam generated using fossil energy.

Membrane contactors have been utilized for over 20 years to treat high-concentration ammonia nitrogen wastewater. However, this technology has not been widely adopted. The first deamination membrane used in the industry was made of PP material. The diameter of the fiber membrane was approximately 0.3mm, which allowed for a large number of membrane filaments to be filled in a membrane module. This design provided high specific surface area and high degassing efficiency. However, the pollution resistance of PP material is inadequate. It can maintain good operating conditions for several years in pure water, but when it comes to industry wastewater, particularly when it contains organic matter, oxidants, and suspended particles, the service life of the membrane would become very short. The organic matter reacts with the PP membrane, causing it to swell and destroying the hydrophobicity of its surface. Oxidants such as hydrogen peroxide, ozone, etc., will corrode the PP membrane, while particulate matter in the water will stick to the membrane surface, causing clogging and scaling. Despite the benefits of membrane deamination, such as high deamination efficiency, low operating costs, no secondary pollution, and low investment, it is still unable to adapt to the complex and diverse composition of wastewater

.PTFE is a material that has many advantages. It is resistant to various corrosions, including acids, alkalis, oxidants, and organic matter. It has low surface energy, which makes it very smooth and difficult for pollutants to adhere to its surface. It is also the most hydrophobic plastic and is the best natural raw material for gaseous membrane production. However, the processability of PTFE is relatively poor. Currently, only a few manufacturers of hollow fiber membranes can produce them, and their minimum diameter can only be 0.8mm. Compared with degassing membranes made of pp material, its degassing efficiency per unit volume is relatively low. Nonetheless, the low degassing efficiency of the PTFE membrane is compensated by its excellent anti-corrosion and anti-pollution properties in the field of deamination of industrial wastewater. This makes the use of membrane deamination process for industrial high ammonia nitrogen wastewater a realistic and feasible solution.

Over the past few years, we have been promoting the use of PTFE deamination membranes in China. We are pleased with the results we have seen in real-world applications, which have reinforced our confidence in promoting it worldwide. Here are some examples of how PTFE deamination membranes have been utilized across three different fields:

The pharmaceutical industry was the first to adopt PTFE deamination membranes. Wastewater in this industry typically contains high levels of organic matter and solvent components. Additionally, these wastewater streams often contain volatile organic compounds (VOCs), which pose a risk of secondary pollution and are prohibited by Chinese regulations. Making it unsuitable for treatment via air-stripping. Steam stripping or evaporation with mechanical vapor recompression (MVR) are the only viable treatment options, but they consume a lot of energy and require significant upfront investment. In situations where the volume of water is relatively small, these methods can be very cost-ineffective. Some manufacturers attempted to use PP deamination membranes, but these had a short lifespan, with the membrane contactor failing in about six months. After switching to PTFE deamination membranes, the lifespan of the membrane contactor was significantly extended. The first pharmaceutical factory to switch to PTFE deamination membranes has been operating successfully for over two years.

In the lithium battery and hydrometallurgy industries, there is a significant amount of high-concentration ammonia nitrogen wastewater containing heavy metals. This wastewater doesn't have organic matter, but the deamination process leads to heavy metal decomplexation and precipitation of tiny particles. In the past, blowing and stripping methods were used to remove ammonia, but these methods have high energy consumption and carbon emissions. Nowadays, membrane deamination is gaining popularity in this industry. However, the PP membrane has a short service life, and users have started exploring PTFE deamination membranes. Although the PTFE deamination membrane is more expensive, it has excellent anti-fouling properties, and some manufacturers have started using it to treat high-ammonia nitrogen wastewater.

The semiconductor industry also produces a large amount of high-ammonia nitrogen wastewater containing hydrogen peroxide. The use of PP deamination membranes in this industry results in a short lifespan. However, experimental tests have shown that the PTFE deamination membrane can replace the PP deamination membrane and significantly extend its service life.

We are currently living in an age of constant development and change. Water treatment technology has progressed into the era of membranes. PTFE deamination membrane addresses the limitations of PP deamination membrane, which has a short service life. It fully utilizes the benefits of membrane deamination compared to traditional air-stripping and steam-stripping. The advantages of PTFE membrane deamination, such as its efficiency in deamination, lower energy consumption, reduced operating costs, and higher investment benefits, are significantly superior to traditional methods. Although it requires higher influent water quality than traditional methods, its many advantages make it irresistible.