Membrane technology for reducing total nitrogen in wastewater
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If the total nitrogen content in wastewater is high and cannot be degraded using conventional biochemical methods, could membrane technology be considered for separation? Anyone with experience in this area, please share your insights. Thank you.
I was wondering whether, after a series of treatments, desalination technology could be used in a certain step of wastewater treatment! :handshake
I’m very interested in knowing what the current status of membrane treatment for wastewater is.
Is there anyone skilled? Everyone, learn * it
If separation is to be achieved solely through membranes, such as RO membranes, it depends on whether it is ammonia or molecules with a higher molecular weight. If it is ammonia or ammonium ions with low molecular weights, the retention rate of the membrane is very low, around 50%.
The MBR process can be used; through biochemical treatment and membrane treatment, the treated water can be reused. Many manufacturers are currently employing this process for such reuse purposes
Please refer to my main post on “Various new membrane technologies for the removal/recycling of ammonia, ammonium, or amines from ammonia-containing (ammonium or amine) wastewater””
Simply, as a reply, post it again. There are 5 new membrane separation technologies that can be applied to separate ammonia (or volatile amines)–water systems, ammonium–water systems, and (ammonia + ammonium)–water systems. 1. Support gas film process (also known as membrane permeation absorption, which essentially combines two towers – a stripping tower and an acid absorption tower – on a microscopic level): Hydrophobic microporous hollow fiber membranes are used, with an aqueous solution of ammonia (or volatile amines) flowing on one side of the membrane and dilute sulfuric acid, dilute hydrochloric acid, or dilute phosphoric acid flowing on the other side. The highly volatile ammonia (or volatile amines) pass through the gas film and are chemically absorbed into the acid solution, thereby resulting in an enriched solution. Advantages: It is extremely effective and suitable for the recovery of ammonia (or volatile amines) at low or very low concentrations (10–2000 ppm), allowing the wastewater to meet discharge standards or to be reused. No heating, pressurization, or vacuum operation is required. Disadvantages: The by-product obtained is an ammonium salt; if ammonia (or amines) is to be reused, alkalis such as sodium hydroxide or calcium hydroxide must be added, followed by processes like distillation to obtain a high-concentration ammonia (or amine) solution; it is not very suitable for high-concentration situations. This process can also be used directly for the recovery of ammonia (or amines) from exhaust gases. Note that, regardless of what is stated in academic papers, acid solutions with a concentration of over 20% should not be used as absorbents, as otherwise the acid solution will eventually be diluted by the water migrating from the wastewater. Furthermore, all organic amines with a carbon count of 8 or less (whether primary, secondary, or tertiary amines) have a relative volatility in dilute aqueous solutions that is 3–5 times greater than that of ammonia, making them easier to separate from ammonia. The most ideal hydrophobic micropores for ammonia removal in hollow fiber membranes should be circular pores with a diameter of 0.02 micrometers on the membrane wall, rather than the flat-pore membranes produced by the stretching method currently used in China (0.2x0.02 micrometers). The market for this law in the domestic market is large, with annual contract values exceeding 10 million yuan. 2. Vacuum membrane distillation process (corresponding to vacuum stripping): A hydrophobic microporous membrane is used, with the ammonia (amine) aqueous solution flowing on one side of the membrane while a vacuum is created on the other side. Advantages: It requires only a low-temperature heat source for heating, offers high removal efficiency, and the concentration ratio can reach 20–80% of the relative volatility of ammonia (amine) to water. Disadvantages: There is significant temperature gradient polarization, large amounts of water evaporate, the feed liquid needs to be heated multiple times; to achieve high recovery rates, multiple components must be connected in series, and several vacuum pumps are required to produce a highly concentrated product. Some of the less concentrated product also has to be returned to the feed liquid. The exhaust gases from the vacuum pumps also pose pollution concerns. This process is suitable for ammonia concentrations ranging from 500 to 10,000 ppm. 3. Membrane-induced condensation: Its principle is similar to that of gas-gap membrane distillation. Ammonia (amines) in the condensate flowing through each membrane module can be concentrated by a factor of 3–15. This process requires only a low-temperature heat source and cooling water; it does not necessitate high temperatures or vacuum conditions. By connecting multiple modules in series, high recovery rates (50%–99.99%) can be achieved, and the condensed liquid at lower concentrations can be reused in the feed solution. Of course, further concentration requires conventional distillation or the fourth membrane process mentioned below. This process is suitable for ammonia concentrations ranging from 500 to 10,000 ppm.
4. Membrane distillation: A new type of efficient and energy-saving heat-driven membrane process that replaces conventional (vacuum) distillation. It overcomes the shortcomings of the aforementioned membrane processes, offering better economic efficiency and safer operation: no high temperatures or pressures are required, there is no need for vacuum conditions, and it can handle feed solutions of various concentrations to produce ammonia solutions with very high concentrations. This process is suitable for ammonia concentrations ranging from 10 ppm to 10%. It only requires a low-temperature heat source; if heat energy must be converted into low-pressure steam (although the thermal value may differ), the heat consumption is 0.05–0.15 tons of steam per ton of wastewater. In systems involving diamines such as ethylenediamine-water, propylenediamine-water, or hydrazine hydrate-water, the relative volatility of the diamines to water remains extremely close to 1 across the entire concentration range, or an azeotrope may form. Membrane distillation provides additional selectivity, allowing it to be used even for separating systems like ethylenediamine-water, propylenediamine-water, or hydrazine hydrate-water where the relative volatility is very low or an azeotrope exists.
5. A new type of efficient and energy-saving heat-driven membrane process that replaces multi-effect evaporation for the concentration and recovery of ammonium salts: If wastewater contains both ammonia and ammonium salts, it is recommended to first use one of the aforementioned techniques to remove ammonia, and then use the technique described below to concentrate and recover the ammonium salts along with high-quality water. Another process we have developed can be used to concentrate various salt/alkali/sugar aqueous solutions to high concentrations while simultaneously recovering fresh water. This process requires no high temperature, high pressure, or negative pressure (or vacuum) to operate, and it is noise-free. This process can use a low-temperature heat source (60–120 degrees) as a driving force, but its heat efficiency (water production ratio) is better than that of multi-stage flash evaporation and multi-effect evaporation. The electrolyte concentration in the fresh water produced by this process can be as low as less than 1 ppm, with typical values ranging from 10 to 100 ppm. Another feature of this process is that the equipment used is mostly made of plastic, which completely eliminates the corrosion problems associated with multi-stage flash evaporation and multi-effect evaporation processes. The equipment used in this process is relatively compact, similar to that used in reverse osmosis; therefore, for a given separation task, the volume of the equipment required is much smaller than that needed for multi-stage flash evaporation and multi-effect evaporation. As mentioned earlier, even in the absence of high temperature and pressure or negative pressure (or vacuum), the thermal efficiency of this process remains better than that of multi-stage flashing and multi-effect evaporation. For example, the water production ratio of this process is generally between 8 and 12, while that of triple-effect evaporation is below 3. Moreover, the heat values used are different. The membrane processes mentioned above are not limited to the ammonia-water system; they are also suitable for separating low-molecular-weight organic amines in systems consisting of small-molecule volatile organic amines (with 8 atoms or fewer) and water. The characteristics of such systems are as follows: the relative volatility of amines to water is about 3–5 times that of ammonia to water (at low amine concentrations), and their basicity is about 10 times greater (based on the dissociation constant). In systems involving diamines, such as ethylenediamine-water, propanediamine-water, or hydrazine hydrate-water, the relative volatility of these diamines to water remains extremely close to 1 across the entire concentration range, or an azeotrope is formed. The fourth process can even be used for separating ethylenediamine-water, propanediamine-water, and hydrazine hydrate-water systems where the relative volatility is very low throughout the concentration range or where an azeotrope exists. Those interested in these processes can contact: yjqin1@yahoo.com or yqin@chembrane.com
4. Membrane distillation: A new type of efficient and energy-saving heat-driven membrane process that replaces conventional (vacuum) distillation. It overcomes the shortcomings of the aforementioned membrane processes, offering better economic efficiency and safer operation: no high temperatures or pressures are required, there is no need for vacuum conditions, and it can handle feed solutions of various concentrations to produce ammonia solutions with very high concentrations. This process is suitable for ammonia concentrations ranging from 10 ppm to 10%. It only requires a low-temperature heat source; if heat energy must be converted into low-pressure steam (although the thermal value may differ), the heat consumption is 0.05–0.15 tons of steam per ton of wastewater. In systems involving diamines such as ethylenediamine-water, propylenediamine-water, or hydrazine hydrate-water, the relative volatility of the diamines to water remains extremely close to 1 across the entire concentration range, or an azeotrope may form. Membrane distillation provides additional selectivity, allowing it to be used even for separating systems like ethylenediamine-water, propylenediamine-water, or hydrazine hydrate-water where the relative volatility is very low or an azeotrope exists.
5. A new type of efficient and energy-saving heat-driven membrane process that replaces multi-effect evaporation for the concentration and recovery of ammonium salts: If wastewater contains both ammonia and ammonium salts, it is recommended to first use one of the aforementioned techniques to remove ammonia, and then use the technique described below to concentrate and recover the ammonium salts along with high-quality water. Another process we have developed can be used to concentrate various salt/alkali/sugar aqueous solutions to high concentrations while simultaneously recovering fresh water. This process requires no high temperature, high pressure, or negative pressure (or vacuum) to operate, and it is noise-free. This process can use a low-temperature heat source (60–120 degrees) as a driving force, but its heat efficiency (water production ratio) is better than that of multi-stage flash evaporation and multi-effect evaporation. The electrolyte concentration in the fresh water produced by this process can be as low as less than 1 ppm, with typical values ranging from 10 to 100 ppm. Another feature of this process is that the equipment used is mostly made of plastic, which completely eliminates the corrosion problems associated with multi-stage flash evaporation and multi-effect evaporation processes. The equipment used in this process is relatively compact, similar to that used in reverse osmosis; therefore, for a given separation task, the volume of the equipment required is much smaller than that needed for multi-stage flash evaporation and multi-effect evaporation. As mentioned earlier, even in the absence of high temperature and pressure or negative pressure (or vacuum), the thermal efficiency of this process remains better than that of multi-stage flashing and multi-effect evaporation. For example, the water production ratio of this process is generally between 8 and 12, while that of triple-effect evaporation is below 3. Moreover, the heat values used are different. The membrane processes mentioned above are not limited to the ammonia-water system; they are also suitable for separating low-molecular-weight organic amines in systems consisting of small-molecule volatile organic amines (with 8 atoms or fewer) and water. The characteristics of such systems are as follows: the relative volatility of amines to water is about 3–5 times that of ammonia to water (at low amine concentrations), and their basicity is about 10 times greater (based on the dissociation constant). In systems involving diamines, such as ethylenediamine-water, propanediamine-water, or hydrazine hydrate-water, the relative volatility of these diamines to water remains extremely close to 1 across the entire concentration range, or an azeotrope is formed. The fourth process can even be used for separating ethylenediamine-water, propanediamine-water, and hydrazine hydrate-water systems where the relative volatility is very low throughout the concentration range or where an azeotrope exists. Those interested in these processes can contact: yjqin1@yahoo.com or yqin@chembrane.com
Ammonia nitrogen can be treated using membrane bioreactors, while seawater desalination generally employs nanofiltration
Currently, reverse osmosis is the most common method used for seawater desalination, depending on the level of purification required
The wastewater can first be pre-treated using membranes, and then sent to the biochemical tank; the portion that has been concentrated by the membranes can be dried and burned.
Take a good look at it; thanks to the original poster. This post was last edited by chc1125 on 2008-11-3 at 16:53.]
The view from the 11th floor is debatable. For ammonia ions, the rejection rate of reverse osmosis membranes is very low. Other microfiltration, ultrafiltration, and nanofiltration membranes are almost ineffective. Electrodialysis is even more expensive. Even if reverse osmosis can retain ammonium ions, concentrating ammonia to at most 3-4% requires 70 atmospheres of pressure. It’s impossible to use ammonium salts such as sulfuric acid an and ammonium chloride with a concentration of 10% or less for incineration. Therefore, since the wastewater is mainly composed of free ammonia, it is best to use the gas film process that I developed. This results in contract values of tens of millions per year in the domestic market. If it is mainly ammonium salts and the concentration is above 1%, membrane-based multi-effect evaporation is the best choice. This post was last edited by chc1125 on 2008-11-3 16:54]