Treatment of ammonia nitrogen wastewater

With such high ammonia nitrogen levels, ammonia can be distilled back to recover ammonia water for reuse in production.

This post was last edited by yjqin1 on 2015-7-15 12:02. What is the quality of this ammonia-nitrogen wastewater? What is the final acceptable level for ammonia nitrogen? This range of ammonia nitrogen levels is not suitable for biochemical or oxidation processes; a separation process is required. For a simple ammonium salt solution, traditional membrane separation processes such as nanofiltration (in the case of ammonium sulfate or diammonium hydrogen phosphate), reverse osmosis, or electrodialysis can be considered. If the water quality is complex, then it is necessary to consider removing ammonia (rather than ammonium) directly. The physical processes that can be employed include stripping (also known as desorption or gas lift), distillation (also known as vaporization or gas lift), or gas-phase membrane separation processes. If the water quality is suitable, I recommend using the gas membrane process. Characteristics of the ammonia removal process using a gaseous membrane method: 1. The capital investment is low, falling between that of stripping (also known as desorption or gas lift) and distillation (also known as vaporization or gas lift) ； 2. By-products can be selected as sulfuric acid, ammonium chloride, **, diammonium hydrogen phosphate, or ammonia water, ammonia gas, or even liquid ammonia. It entirely depends on the customer’s needs, allowing for flexibility ； 3. Operating costs are extremely low; if the by-product is an ammonium salt, the electricity consumption is less than 10% of that in conventional stripping processes, with no heat consumption required ； If the by-product is 5-18% ammonia water, the heat consumption is only 20-30% of that in a conventional stripping process, with almost no electricity consumption ； 4. The ammonia nitrogen level in the treated wastewater can be reduced to 50 mg/L, 15 mg/L, or even 5 mg/L, depending on the customer’s requirements ； 5. The gas-phase membrane method for ammonia removal has no specific requirements regarding the COD value, salt content, or types of salts in wastewater ； As long as the surface tension of the wastewater is high enough ； 6. Existing pretreatment techniques can raise the surface tension of wastewater to a predetermined value in order to meet the feed requirements of gas-phase membrane equipment ； 7. Of course, if the wastewater is neutral or even acidic, alkaline substances need to be added to raise the pH to between 10 and 12, so that ammonia exists in molecular form, as a free substance, or as volatile ammonia. This is necessary; distillation (stripping) and desorption (stripping) also require such an increase in pH value. 8. The gas-phase membrane ammonia removal process allows slaked lime to be used in place of sodium hydroxide to raise the pH of the feed solution; by doing so, chemical costs are reduced by nearly 3 times. In the stripping process, if slaked lime is used to raise the pH, there is a risk of tower blockage caused by the reaction between calcium hydroxide and carbon dioxide in the air to form calcium carbonate precipitate ； If slaked lime is used to raise the pH during the stripping process, there is a risk of tower blockage due to the decreased solubility of calcium hydroxide at high temperatures. In the gas-phase membrane process, the feed solution does not need to come into contact with (external, fresh) air; by adding slaked lime and then filtering, there is no risk of sediment contaminating the membrane ； 9. As long as the preprocessing is done properly and the operations are carried out correctly, the core gas membrane equipment can be used for over 2 years ； 10. Due to the moderate investment required for gas-phase membrane equipment and extremely low operating costs, as well as its ability to overcome the problem of tower blockage caused by calcium ions, the gas-phase membrane process does not end up being a form of pseudo-environmental protection or fake environmental protection like other ammonia removal processes. If you are interested, please contact me on the site.

It depends on what constitutes the ammonia nitrogen in your sample. If it is in the form of ammonium ions, membrane filtration is the only option available for dealing with such high levels. If it exists as gaseous ammonia, stripping can be used for treatment. If it is in the form of amino acid ions, I recommend using resin adsorption as a solution – it’s simple and convenient. We can discuss this further.

*The AO anion can be removed; it’s no problem to use resin for that. Details can be discussed

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Neither biochemical nor oxidation processes are suitable; a separation process is required

With the MAP method, the sludge produced can be used as fertilizer, or through a pretreatment by stripping followed by the MAP method and biochemical treatment. However, using MAP is costly and generates too much sludge ； When using stripping, the issue of exhaust gas absorption must be taken into account ； It is recommended to use electrolysis for treatment.

I’m not sure how your company plans to address the wastewater issue; if a treatment system is needed, you can get in touch with me.

After treatment using the electrolytic method, where does the ammonia go, or what does it turn into?