The core reason for excessive ammonia nitrogen
The reasons for excessive ammonia nitrogen in wastewater can be mainly divided into four categories, covering the entire process of water inlet, process, operation and maintenance, and are also industry pain points (such as emergency treatment methods for excessive ammonia nitrogen in wastewater and reasons for excessive ammonia nitrogen in industrial wastewater). One issue is abnormal inflow load. In industries such as chemical, pharmaceutical, aquaculture, and landfill leachate, the concentration of ammonia nitrogen in the wastewater itself is high. If it is not pre treated and directly enters the treatment system, it is highly likely to exceed the process capacity, resulting in effluent exceeding the standard; The second issue is the imbalance of the biochemical system, where nitrifying bacteria are the core of degrading ammonia nitrogen. When the water temperature is too low (below 15 ℃), the dissolved oxygen is insufficient, the pH value deviates from the appropriate range of 7.5-8.5, or the sludge ages and the sludge concentration is too low, the activity of nitrifying bacteria decreases, and the efficiency of ammonia nitrogen conversion is significantly reduced; Thirdly, the process design is unreasonable, with some Wastewater treatment plants having insufficient residence time, unclear oxygen deficient and aerobic zoning, and insufficient internal reflux ratio, resulting in insufficient nitrification reaction; The fourth is the impact of load shock. Intermittent production by enterprises, non-standard addition of chemicals, or sudden influx of high concentration wastewater can directly damage system stability and cause short-term ammonia nitrogen exceedance.
Solution to excessive ammonia nitrogen
In response to the issue of excessive ammonia nitrogen, the mainstream solution in the industry follows the principle of "biochemistry as the main solution, physical-chemical as the auxiliary solution, and emergency replenishment". It is flexibly matched according to the concentration, water volume, and industry characteristics of the wastewater, taking into account the compliance effect and cost control, and adapting to the actual needs of different enterprises.
Biochemical treatment is the preferred and most economical way for low to medium concentration ammonia nitrogen wastewater, suitable for large water volume and long-term stable compliance requirements. Common processes include A/O, A ²/O, SBR, oxidation ditch, etc. The core is to oxidize ammonia nitrogen to nitrate through nitrifying bacteria, and then reduce it to nitrogen gas through denitrifying bacteria to achieve ammonia nitrogen removal. If ammonia nitrogen exceeds the standard in the biochemical system, the operating parameters can be quickly optimized: control the dissolved oxygen in the aerobic section at 2-4mg/L to provide sufficient oxygen for nitrifying bacteria; Adjust the pH value to the appropriate range and add acid-base regulators if necessary; Extend the sludge age to 15-25 days to avoid the loss of nitrifying bacteria; Reasonably adjust the internal reflux ratio to improve denitrification efficiency. If the system activity is insufficient, professional ammonia nitrogen degrading bacterial agents can be added. Follow the standardized operation of ammonia nitrogen degrading bacterial agents, quickly activate microorganisms, shorten system recovery time, and are suitable for low temperature, start-up, or emergency scenarios.
Physical and chemical treatment is often used for high concentration ammonia nitrogen pretreatment, emergency compliance or deep treatment, to solve the pain points of difficult to meet biochemical treatment standards. The blow off method adjusts the pH value of the wastewater to above 10 and combines aeration to blow out ammonia nitrogen in the form of ammonia gas. It is suitable for the pretreatment of high concentration wastewater with ammonia nitrogen concentration>500mg/L; The breakpoint chlorination method uses chlorine gas to oxidize ammonia nitrogen into nitrogen gas, with a fast reaction rate that can take effect in 1-2 hours, making it suitable for emergency compliance; Deep treatment can use ion exchange method, membrane separation technology or efficient ammonia nitrogen adsorption materials to further reduce effluent ammonia nitrogen, meet ultra-low emission standards, and adapt to enterprises with strict environmental protection requirements.
Daily operation and maintenance are the key to avoiding repeated exceedance of ammonia nitrogen, and are also the core points of concern for enterprises. Enterprises need to regularly monitor key indicators such as influent water quality, dissolved oxygen, pH value, sludge concentration, and adjust operating parameters in advance according to water volume fluctuations; It is strictly prohibited for toxic and harmful substances to enter the biochemical pool to protect the microbial community; Establish emergency response plans, add microbial agents or auxiliary agents in advance during high load periods to prevent the risk of exceeding standards. Different industries require different solutions, with a focus on enhancing the stability of the biochemical system for municipal wastewater. Livestock wastewater needs to undergo solid-liquid separation pretreatment, while chemical wastewater needs to be treated with pre-treatment to remove toxic substances and improve treatment efficiency.
