1 Traditional biological nitrification and denitrification technology
The traditional biological nitrification and denitrification nitrogen removal process includes two stages: nitrification and denitrification. The nitrification process refers to the oxidation of ammonia nitrogen into nitrate nitrogen and nitrite nitrogen under aerobic conditions, facilitated by nitrate and nitrite bacteria.;Under anaerobic conditions, denitrifying bacteria convert nitrate and nitrite nitrogen into nitrogen gas, thereby achieving denitrification.
In traditional biological nitrification-denitrification methods, more mature approaches include:A/O Please provide the Chinese content to be translated.A2/O French,SBRBatch processing methods, contact oxidation, and other techniques offer stable effectiveness, simple operation, non-generation of secondary pollution, and low costs. However, these methods also have their drawbacks, such as the need to supplement corresponding carbon sources to facilitate the removal of ammonia nitrogen, which increases operation costs.;When the carbon-nitrogen ratio is low, digestion liquid reflux is required, which increases the reaction tank volume and energy consumption.;Low concentration of nitrifying bacteria, high alkali dosing in the system, etc.
ThroughA/O Membrane bioreactor treats ammonia nitrogen in the effluent of a refinery's flotation pond, experimental results indicate that when ammonia nitrogen andCOD Volume loads vary respectively.0.04~0.08、0.30~0.84 kg/(m3·d)At the time of processing, the ammonia nitrogen quality concentration in the treated water is less than5 mg/L。
2 New Bio-Denitrification Technology
(1)Short Path Nitritation-De硝ritation Technology. Short Path Nitritation-De硝ritation involves conducting the process within a single reactor. Initially, under aerobic conditions, ammonia is oxidized to nitrite by ammonia-oxidizing bacteria, preventing the further oxidation of nitrite. Subsequently, in an anaerobic environment, nitrite is denitrified to nitrogen gas using organic matter or an external carbon source as an electron donor.
Short-range nitrification and denitrification has the following advantages compared to traditional biological denitrification: For the activated sludge process, it can save...25%Increased oxygen supply, reduced energy consumption.;Reduce carbon source while potentially increasing the total nitrogen removal efficiency.;Enhanced reaction speed, reduced reaction time, and minimized reactor volume. However, due to the close relationship between nitrosomonas and nitrobacter, changes in any influencing factor simultaneously impact both types of bacteria, and there are also interdependencies among these factors, making it challenging to control the conditions for short-term nitrification and denitrification. Currently, the technology for short-term nitrification and denitrification is still in the experimental stage of artificial water distribution, and the theoretical explanations for this phenomenon are not yet sufficient.
(2)Simultaneous Nitrification and Denitrification Technology. This refers to the simultaneous occurrence of nitrification and denitrification within the same reactor.(SND)Dissolved oxygen in wastewater is limited by diffusion rates, resulting in higher concentrations on the surface of microbial flocs or biofilms, which is conducive to the growth and reproduction of aerobic nitrifying and ammonifying bacteria. As one moves deeper into the flocs or membrane, the dissolved oxygen concentration decreases, creating anaerobic zones. Denitrifying bacteria then become predominant, leading to simultaneous nitrification and denitrification processes.
Zou Lianpei et al.26A study was conducted on simultaneous nitrification and denitrification phenomena in a membrane bioreactor system, with experimental results indicating that...DO Please provide the Chinese content to be translated.1mg/L，C/N=30，pH=7.2
At the moment,COD、NH4+-N、TN Removal rates vary96%、95%、92%Presently within the scope, the reactor's conditions are adjusted to either increase or decrease.DO After concentration,TN Removal rates will decline.
The nitrification-denitrification method conserves reactor space, reduces reaction time, and offers low energy consumption and cost savings. However, the research on simultaneous nitrification-denitrification is still in the laboratory phase, with further studies needed on its mechanism and kinetic model, making its industrial application challenging to achieve.
(3)Anaerobic Ammonium Oxidation Technology. Anaerobic ammonium oxidation is a process in which microorganisms operate under anaerobic or anoxic conditions.NH4+ For electronic acceptor, withNO2- OrNO3- For electronic donorsNH4+、NO2- OrNO3- ConvertedN2The process.
Process and Anaerobic Ammonium Oxidation Technology IntegrationThe effectiveness of "middle-aged and elderly" waste leachate, experimental results show that the anaerobic ammonium oxidation reactor can be initiated in sludge with nitrifying activity.;Inflow ammonia nitrogen and nitrite nitrogen mass concentrations do not exceed250 mg/L Under certain conditions, the removal rates for ammonia nitrogen and nitrite nitrogen can reach80%And90%As of now,SHARONResearch on the anaerobic ammonia oxidation coupled process is still in the laboratory stage, and further adjustment and optimization of process conditions are needed to enhance the efficiency of the coupled process in removing total nitrogen from actual high ammonia-nitrogen wastewater.
Anaerobic Ammonium Oxidation (Anammox) technology can significantly reduce the aeration energy consumption in nitrification, eliminate the need for exogenous electron donors in denitrification, and save neutralizing agents required in traditional nitrification-denitrification processes. It also produces less sludge. However, to date, its reaction mechanism, involved microorganisms, and operational parameters are not yet clear.
1 Reverse Osmosis Technology
Reverse osmosis technology is a method that separates solutes from solvents by utilizing a semi-permeable membrane under pressures greater than the osmotic pressure of the solution. It boasts advantages such as low energy consumption, advanced technology, and easy operation and maintenance.
During the treatment of ammonia-nitrogen wastewater using reverse osmosis technology, the equipment applies sufficient pressure, allowing water to pass through a selective membrane and be separated as industrial pure water. On the other side of the membrane, the concentration of the ammonia-nitrogen solution increases accordingly, becoming a concentrated liquid that can be further processed and reused. In actual operation, the reverse osmosis pressure applied is directly proportional to the concentration of the solution; as the ammonia-nitrogen concentration rises, the energy consumption required by the reverse osmosis unit increases, while its efficiency decreases.29〕。
Potassium carbonate production facilityNH4Cl Our company's news content is missing; therefore, there is no translation required.NH4ClWastewater treatment processes have been researched, with the experimental setup employing reverse osmosis membranes.(NTR-70SWCS4)Filter Machines. The results indicate that during the treatment of ammonia-nitrogen wastewater using reverse osmosis membrane technology, the appropriate concentration of ammonium chloride is60g/L Below, under these concentration conditions, the equipment's denitrification efficiency is relatively high, generally greater than97%All technical specifications have been met and are ready for actual production operations.
2 Electrodialysis
Electrodialysis is a process that separates ions from an electrolyte solution under the action of an external direct current electric field, utilizing the selective permeability of ion exchange membranes. The electrodialysis method can separate ammonia nitrogen from wastewater, and it has the advantages of low initial investment, low energy and reagent consumption, simple operation, high water utilization rate, and no secondary pollution by-products.
