The problems of traditional biological denitrification in the treatment of landfill leachate

The traditional biological denitrification technology in the treatment of landfill leachate includes two stages: nitrification and denitrification. Firstly, the landfill leachate is oxidized to nitrite or nitrate by aerobic nitrifying bacteria under aerobic conditions. Then, under anaerobic conditions, denitrifying bacteria are used to reduce nitrite or nitrate to nitrogen and escape, thereby achieving the goal of denitrification. The traditional biological denitrification process adopts a combination of aerobic and anaerobic treatment processes, with representative ones being A/O and SBR processes. The traditional nitrification denitrification process plays a certain role in biological denitrification, but there are still many problems.

Treatment of landfill leachate

1. The proliferation rate of nitrifying bacteria is slow, making it difficult to maintain high biological concentrations, resulting in long hydraulic retention time, low volumetric load, increased investment and operating costs.

2. In traditional denitrification processes, denitrification requires a certain organic carbon source, and a large part of COD in landfill leachate is removed during the nitrification process. Therefore, additional carbon sources are often added during denitrification, increasing treatment costs.

3. Complete nitrification of ammonia nitrogen requires a large amount of oxygen, resulting in increased power costs.

To neutralize the acidity generated during the nitrification process, it is necessary to add alkali for neutralization, which increases the treatment cost.

5. In order to maintain a high biological concentration and achieve good denitrification results, the system must carry out nitrification liquid and sludge reflux to increase power consumption and operating costs.

6. The operation control is relatively complex, etc.

Therefore, studying new ideas, technologies, and appropriate control conditions for denitrification in the treatment process of landfill leachate is one of the core issues in effectively removing nitrogen pollutants from landfill leachate.