How to properly treat wastewater generated by industrial ammonia?

The wastewater produced by industrial ammonia contains high concentrations of ammonia nitrogen, which poses a serious threat to the environment and ecosystem. Therefore, the correct treatment of these wastewaters is essential for protecting the environment and achieving sustainable development. This article will introduce in detail several methods for the correct treatment of wastewater produced by industrial ammonia, and explore their advantages and disadvantages.

1. Sources and hazards of wastewater

Industrial ammonia wastewater mainly comes from industries such as chemical industry, metallurgy, fertilizer, coal gas, coking, tanning, monosodium glutamate, meat processing and breeding. The ammonia nitrogen in these wastewaters is toxic to fish and some organisms, and when wastewater containing a small amount of ammonia nitrogen is reused in industry, it has a corrosive effect on some metals, especially copper.

II. Correct treatment of wastewater produced by industrial ammonia

1. Blow-off method

Blow-off method is a physical and chemical method. By passing air into the wastewater, the ammonia nitrogen in the wastewater is transferred from the liquid phase to the gas phase, thereby achieving the purpose of removing ammonia nitrogen. The basic principle of this method is the theory of gas-liquid phase equilibrium and mass transfer rate. Under alkaline conditions, ammonium ions are converted into ammonia molecules, and then ammonia molecules are released through ventilation. The blow-off method can be air blow-off or steam blow-off. The steam blow-off method is more efficient, but the energy consumption is large, while the air blow-off method has low energy consumption, simple equipment and convenient operation.

2. Chemical precipitation method

Chemical precipitation method, also known as MAP precipitation method, is to add magnesium compounds and phosphoric acid or hydrogen phosphate to wastewater containing ammonia nitrogen, so that NH4+ in the wastewater reacts with Mg2+ and PO4³⁻ to form magnesium ammonium phosphate precipitate, thereby achieving the purpose of removing ammonia nitrogen. The advantages of this method are good removal efficiency, no temperature restrictions, and simple operation. The precipitated sludge formed can be used as compound fertilizer to achieve waste utilization.

3. Biological method

Biological method is a natural process that uses microorganisms to decompose ammonia nitrogen. This method can be divided into several types:

(1) Traditional nitrification and denitrification method: This method first converts ammonia nitrogen into nitrite and nitrate through nitrifying bacteria, and then converts these substances into nitrogen gas and releases them into the atmosphere through denitrifying bacteria. This method is mature and stable, but the treatment cycle is long.

(2) Short-range nitrification and denitrification: This method controls the conditions so that the nitrification process only proceeds to the nitrite stage, and then removes ammonia nitrogen through the denitrification process. This can save energy, but requires accurate control of operating conditions.

(3) Simultaneous nitrification and denitrification: This method carries out nitrification and denitrification processes simultaneously in the same reactor, which can save space and cost, but has more stringent requirements on operating conditions.

(4) Anaerobic ammonia oxidation: This is a new type of biological treatment technology that directly converts ammonia nitrogen into nitrogen gas through anaerobic ammonia oxidation bacteria, without the participation of oxygen, and with lower energy consumption.

(5) The advantage of the biological method is that it is low in cost and can achieve complete removal of nitrogen. However, this method is greatly affected by environmental factors such as temperature and pH value, and the treatment cycle is longer.

  

Membrane separation method is a physical treatment technology that separates ammonia nitrogen from wastewater through the selective permeability of a semipermeable membrane. This method can effectively remove ammonia nitrogen from wastewater, but it requires high investment and operating costs. Cleaning and replacement of membranes are the main disadvantages of this method, because they gradually lose efficiency over time and require regular maintenance.

5. Ion exchange method

Ion exchange method uses specific resin materials to remove ammonia nitrogen by exchanging ions on the resin with ammonia nitrogen ions in wastewater. This method is simple to operate and is suitable for treating low-concentration ammonia nitrogen wastewater. However, the regeneration and replacement of resins will increase additional costs because the resin will be saturated after a period of use and need to be chemically treated to restore its exchange capacity.

6. Soil irrigation

Soil irrigation is an ecological treatment method that uses soil microorganisms and plant roots to absorb and convert ammonia nitrogen by irrigating wastewater into the soil. This method is low-cost and can be used as a way to utilize waste. However, it requires a large land area and may cause soil and groundwater contamination if not properly managed.

In summary, the correct treatment of wastewater produced by industrial ammonia requires comprehensive consideration of wastewater concentration, treatment cost, environmental impact and operability. Air stripping and chemical precipitation are suitable for the pretreatment of high-concentration ammonia nitrogen wastewater, while biological methods are suitable for the treatment of low-concentration wastewater. Membrane separation and ion exchange are suitable for wastewater treatment under specific conditions, and soil irrigation is an eco-friendly treatment method. If you have any other questions, please call or leave a message for us at Hongchang Industry and Trade!