▊▊ 概要
The environment is the basis for our survival and development. It provides the air, water, soil, energy, resources and so on that we need。However, with the rapid development and consumption of human society, the environment is facing more and more serious pollution and destruction, resulting in climate change, biodiversity loss, resource depletion and other problems, threatening the health and well-being of humans and other living things。Protecting the environment is not only our responsibility and obligation, but also our interests and needs。
Today we'll talk about itWastewater treatment technology of biopharmaceutical enterprises。
Usually in the biopharmaceutical enterprises sewage discharge pollutants contain a large number of organic pollutants, which are mainly amino acids, glucose, protein, fat, etc。These organic matter will lead to the increase of chemical oxygen demand, and the higher the chemical oxygen demand, the more serious the organic matter pollution in the water, which will lead to a large number of aquatic organisms die, and the ecosystem is seriously damaged。
COD and ammonia nitrogen are the most important indicators in the wastewater discharge requirements of the biopharmaceutical industry. How to choose the appropriate wastewater treatment process to remove COD and ammonia nitrogen from the water and meet the discharge requirements has become the focus of common attention。
▊▊ Noun interpretation
▊▊ Interpretation of regulations
According to the requirements of GB8978-1996 "Comprehensive Sewage Discharge Standard", the three-level discharge standard of COD is 1000 mg/L
The national standard emission standards in Table 1 are relatively relaxed，Table 2 landmarks are more stringent，And the biopharmaceutical industry is generally a key pollutant discharge unit，Local ecology and environment bureaus will focus on management，Beijing, for example, requires an online monitoring system，Continuous monitoring of sewage discharge indicators，And upload data online，Complete real-time monitoring)。
▊▊ The purpose of selecting suitable wastewater treatment process
(1) With high quality, high efficiency, low consumption, environmental protection and energy saving as the fundamental purpose;
(2) The process flow is smooth, the general drawing and process layout are reasonable, the operation is reliable, and the maintenance is convenient;
(3) Follow the principle of self-control that is advanced, mature, reliable, practical, and conducive to reducing control in order to improve labor productivity;
(4) Control the scale of construction, reduce the amount of engineering and save investment;
▊▊ The choice of sewage treatment process
There are many methods to remove COD, such as precipitation, adsorption, chemical coagulation, electrochemical method, oxidation method, biological method, micro-electrolysis and so on。In short, the removal or decomposition of organic matter in sewage。
In line with the purpose of controlling the scale of construction, reducing the amount of engineering and saving investment, the fastest and most effective reduction of COD indicators is usually usedBiochemical processThat is, the method of combining biological method and physical method is processed。
The economical treatment method of low concentration organic wastewater is biochemical treatment method, mainlyTraditional activated sludge process, A/O, A2/O, SBR, CASS, etcEach has its own characteristics and application conditions, in the selection, should be a comprehensive consideration of water quality and water discharge, climate and other local conditions。
The following is a brief introduction to the commonly used sewage treatment process:
1. Traditional activated sludge process
The traditional activated sludge process has been used in the early days and has been used until now。It is mainly composed of aeration tank, secondary sedimentation tank, aeration system and sludge return system。After the primary sedimentation tank, the wastewater enters the aeration tank together with the backflow sludge at the bottom of the secondary sedimentation tank, and the wastewater flows in the form of push flow to the end of the tank。The aeration tank is filled with air through the aeration system，Its function is to oxygenate sewage，It also makes the sewage and activated sludge in the aeration tank in a state of intense agitation，Make activated sludge and sewage in full contact，Suspended solids and colloids in wastewater are adsorbed by activated sludge，The soluble organic matter in the wastewater is used by the microorganisms in the activated sludge as nutrition for their own reproduction，Metabolic conversion into biological cells，And oxidized to the final product (mainly CO2)。Insoluble organic matter needs to be converted to dissolved organic matter before it can be metabolized and utilized。The waste water is thus purified。After purification, the wastewater and activated sludge are separated in the secondary sedimentation tank, and the upper level of the effluent is discharged. Part of the separated and concentrated sludge is returned to the aeration tank to ensure a certain concentration of activated sludge in the aeration tank, and the rest is residual sludge and discharged by the system。
Advantages of the traditional activated sludge method:
1) With mature operation experience, reliable operation and convenient management。
2) The treatment effect is reliable and the effluent quality is guaranteed。
Disadvantages of the traditional activated sludge method:
1) The process cannot be changed flexibly。
2) Large power consumption。
2, A/O process
The A/O process is a processing technology pioneered in the early 1980s，This method uses anoxic-aerobic series process，The denitrification - nitrification reaction is carried out continuously，An anoxic/aerobic system where BOD5 removal is done in the same pool as denitrification for nitrogen removal，Also known as pre-denitrification system，At the same time due to the general use of mixed liquid reflux，Therefore, it can also be called cyclic nitrogen removal system。
The main advantages of using A/O system are as follows:
1) The process is simple and easy to operate and manage;
2) Anoxic and aerobic alternating operation is conducive to improving the sludge settling performance, filamentous bacteria are not easy to multiply, and sludge swelling will not occur;
3) Using organic matter in wastewater as denitrification carbon source;
4) Part of the organic matter in the wastewater reduces the load of the subsequent aerobic section and reduces the power consumption through denitrification removal;
5) The alkalinity generated by denitrification can partially meet the demand for alkalinity in the nitrification process, thus reducing the consumption of chemical agents and reducing operating costs。
3A2/O process
1) Working principle
The phosphorus concentration in sewage increased due to the return of phosphorus containing sludge from the sedimentation tank and the release of phosphorus by phosphorus accumulating bacteria under anaerobic conditions.At the same time, some ammonia nitrogen is removed due to the synthesis of cells, and the concentration of ammonia nitrogen in the sewage decreases. In addition, dissolved organic matter is absorbed by microbial cells, and the concentration of COD in the sewage decreases。
The A2/O process can simultaneously complete the removal of organic matter, nitrification and nitrogen removal, and the removal of excessive uptake of phosphorus. The premise of nitrogen removal is that ammonia nitrogen should be completely nitrated. The aerobic pool can complete this function, the anoxic pool can complete the nitrogen removal function, and the anaerobic and aerobic pool can complete the phosphorus removal function。
2) Process characteristics
① The organic coordination of anaerobic, anoxic and aerobic environmental conditions and different types of microbial flora has the function of removing organic matter, nitrogen and phosphorus at the same time。
In the process of simultaneous nitrogen and phosphorus removal, this process is relatively simple, and the total hydraulic residence time is less than that of other similar processes。
③ Under the conditions of anaerobic - anoxic - aerobic alternating operation, filamentous bacteria can not multiply, SVI value is generally less than 100, sludge settling is good, and sludge swelling will not occur。
④ The phosphorus concentration in sludge is high, generally in 2.Above 5%, is conducive to biological phosphorus removal。
4, SBR process
SBR process is a variant of activated sludge process, according to the cycle cycle operation, each cycle cycle process including water intake, reaction (aeration), precipitation, discharge and standby five processes。The influent, reaction, precipitation, discharge and standby of SBR in a single cycle can be controlled。Each process is associated with specific reaction conditions (mixing/resting, aerobic/anaerobic) that promote selective changes in the physical and chemical properties of the effluent。
Advantages of SBR process:
1) Simple process。Compared with the traditional activated sludge process, this process saves the secondary sedimentation tank and the return sludge pump house, and the whole process covers less than half of the traditional activated sludge process.
2) Easy management, sewage treatment system can be controlled by computer management;
3) Saving capital investment in small and medium-sized sewage treatment plants;
4) Good treatment effect。The treatment method of SBR is close to advanced treatment, and the process can form an aerobic, anoxic and anaerobic microbial environment in space or time, which is very conducive to the stable operation of the biological treatment system and can effectively remove P and N. Therefore, the effluent quality of SBR is significantly better than that of traditional activated sludge process and other processes。
5) High degree of localization of equipment。In recent years, China's water industry has developed rapidly, and a lot of new water treatment equipment has been introduced to the market, and the equipment required by SBR has been basically localized。The automatic control technology and water quality monitoring technology of SBR have also been greatly developed, which can meet the realization of SBR process automation。
However, the traditional SBR and its various derivative processes have high requirements for automatic control, and require a large number of electronically controlled valves and mechanical skimmers, which will not be able to operate if there is a slight failure。
5CASS process
Sewage enters the selection area first，The mixture flows back from the main reaction zone to the selection zone，The reflux ratio is generally 20%，Activated sludge in the selected area is mixed and contacted with incoming fresh sewage，To create the conditions for microbial populations to compete for survival under high concentration and high load environment，The microbial population suitable for the system is selected，And effectively inhibit the excessive proliferation of filamentous bacteria，Avoid sludge bulking phenomenon，Improve system stability，This area has the effect of releasing phosphorus，The facultative zone can further promote phosphorus release and denitrification，Achieve the effect of nitrogen removal，Sewage enters the main reaction zone，Removes most organic pollutants and absorbs phosphorus，So as to achieve the role of purifying sewage。
Main advantages of CASS process:
1) The operation of variable containers improves the adaptability to water quality and water quantity fluctuations and the flexibility of operation;
2) Good settling performance;
3) Good nitrogen and phosphorus removal effect;
4) Simple process, low civil construction and investment, high degree of automation。
▊▊ 结语
Human beings have only one earth, and protecting the ecological environment and promoting sustainable development is our common responsibility。
Since the 18th National Congress of the Party，习近平总书记多次在不同国际场合发表重要讲话，Profoundly clarify the importance of protecting the global ecological environment，Advocate harmonious coexistence between man and nature，Call on the world to jointly promote ecological and environmental governance，On many occasions, we have offered China's proposals, solutions, wisdom and strength on jointly building a beautiful planet and a community with a shared future for mankind，It demonstrates China's responsibility as a major country in global environmental governance and ecological civilization construction。
