The pharmaceutical industry wastewater mainly includes antibiotic production wastewater and synthetic drug production wastewater. The pharmaceutical industry wastewater mainly includes four categories: antibiotic production wastewater, synthetic drug production wastewater, Chinese patent medicine production wastewater, washing water and washing wastewater from various preparation processes. The wastewater is characterized by complex composition, high organic content, high toxicity, deep color, high salt content, especially poor biochemical properties and intermittent discharge. It is an industrial wastewater that is difficult to treat. With the development of my country’s pharmaceutical industry, pharmaceutical wastewater has gradually become one of the important pollution sources.
1. Treatment method of pharmaceutical wastewater
The treatment methods of pharmaceutical wastewater can be summarized as: physical chemical treatment, chemical treatment, biochemical treatment and combination treatment of various methods, each treatment method has its own advantages and disadvantages.
Physical and chemical treatment
According to the water quality characteristics of pharmaceutical wastewater, physicochemical treatment needs to be used as a pre-treatment or post-treatment process for biochemical treatment. The currently used physical and chemical treatment methods mainly include coagulation, air flotation, adsorption, ammonia stripping, electrolysis, ion exchange and membrane separation.
coagulation
This technology is a water treatment method widely used at home and abroad. It is widely used in the pre-treatment and post-treatment of medical wastewater, such as aluminum sulfate and polyferric sulfate in traditional Chinese medicine wastewater. The key to efficient coagulation treatment is the correct selection and addition of coagulants with excellent performance. In recent years, the development direction of coagulants has changed from low-molecular to high-molecular polymers, and from single-component to composite functionalization [3]. Liu Minghua et al. [4] treated the COD, SS and chromaticity of the waste liquid with a pH of 6.5 and a flocculant dosage of 300 mg/L with a high-efficiency composite flocculant F-1. The removal rates were 69.7%, 96.4% and 87.5%, respectively.
air flotation
Air flotation generally includes various forms such as aeration air flotation, dissolved air flotation, chemical air flotation, and electrolytic air flotation. Xinchang Pharmaceutical Factory uses CAF vortex air flotation device to pretreat pharmaceutical wastewater. The average removal rate of COD is about 25% with suitable chemicals.
adsorption method
Commonly used adsorbents are activated carbon, activated coal, humic acid, adsorption resin, etc. Wuhan Jianmin Pharmaceutical Factory uses coal ash adsorption – secondary aerobic biological treatment process to treat wastewater. The results showed that the COD removal rate of adsorption pretreatment was 41.1%, and the BOD5/COD ratio was improved.
Membrane separation
Membrane technologies include reverse osmosis, nanofiltration and fiber membranes to recover useful materials and reduce overall organic emissions. The main features of this technology are simple equipment, convenient operation, no phase change and chemical change, high processing efficiency and energy saving. Juanna et al. used nanofiltration membranes to separate cinnamycin wastewater. It was found that the inhibitory effect of lincomycin on microorganisms in wastewater was reduced, and cinnamycin was recovered.
electrolysis
The method has the advantages of high efficiency, simple operation and the like, and the electrolytic decolorization effect is good. Li Ying [8] carried out electrolytic pretreatment on riboflavin supernatant, and the removal rates of COD, SS and chroma reached 71%, 83% and 67%, respectively.
chemical treatment
When chemical methods are used, the excessive use of certain reagents is likely to cause secondary pollution of water bodies. Therefore, relevant experimental research work should be done before design. Chemical methods include iron-carbon method, chemical redox method (Fenton reagent, H2O2, O3), deep oxidation technology, etc.
Iron carbon method
The industrial operation shows that using Fe-C as a pretreatment step for pharmaceutical wastewater can greatly improve the biodegradability of the effluent. Lou Maoxing uses iron-micro-electrolysis-anaerobic-aerobic-air flotation combined treatment to treat the wastewater of pharmaceutical intermediates such as erythromycin and ciprofloxacin. The COD removal rate after treatment with iron and carbon was 20%. %, and the final effluent complies with the national first-class standard of “Integrated Wastewater Discharge Standard” (GB8978-1996).
Fenton’s reagent processing
The combination of ferrous salt and H2O2 is called Fenton’s reagent, which can effectively remove the refractory organic matter that cannot be removed by traditional wastewater treatment technology. With the deepening of research, ultraviolet light (UV), oxalate (C2O42-), etc. were introduced into Fenton’s reagent, which greatly enhanced the oxidation ability. Using TiO2 as a catalyst and a 9W low-pressure mercury lamp as a light source, the pharmaceutical wastewater was treated with Fenton’s reagent, the decolorization rate was 100%, the COD removal rate was 92.3%, and the nitrobenzene compound decreased from 8.05mg/L. 0.41 mg/L.
Oxidation
The method can improve the biodegradability of wastewater and has a better removal rate of COD. For example, three antibiotic wastewaters such as Balcioglu were treated by ozone oxidation. The results showed that the ozonation of wastewater not only increased the BOD5/COD ratio, but also the COD removal rate was above 75%.
Oxidation technology
Also known as advanced oxidation technology, it brings together the latest research results of modern light, electricity, sound, magnetism, materials and other similar disciplines, including electrochemical oxidation, wet oxidation, supercritical water oxidation, photocatalytic oxidation and ultrasonic degradation. Among them, ultraviolet photocatalytic oxidation technology has the advantages of novelty, high efficiency, and no selectivity to wastewater, and is especially suitable for the degradation of unsaturated hydrocarbons. Compared with treatment methods such as ultraviolet rays, heating, and pressure, ultrasonic treatment of organic matter is more direct and requires less equipment. As a new type of treatment, more and more attention has been paid. Xiao Guangquan et al. [13] used ultrasonic-aerobic biological contact method to treat pharmaceutical wastewater. Ultrasonic treatment was carried out for 60 s and the power was 200 w, and the total COD removal rate of the wastewater was 96%.
Biochemical treatment
Biochemical treatment technology is a widely used pharmaceutical wastewater treatment technology, including aerobic biological method, anaerobic biological method, and aerobic-anaerobic combined method.
Aerobic biological treatment
Since most of the pharmaceutical wastewater is high-concentration organic wastewater, it is generally necessary to dilute the stock solution during aerobic biological treatment. Therefore, the power consumption is large, the wastewater can be biochemically treated, and it is difficult to discharge directly up to the standard after biochemical treatment. Therefore, aerobic use alone. There are few treatments available and general pretreatment is required. Commonly used aerobic biological treatment methods include activated sludge method, deep well aeration method, adsorption biodegradation method (AB method), contact oxidation method, sequencing batch batch activated sludge method (SBR method), circulating activated sludge method, etc. . (CASS method) and so on.
Deep well aeration method
Deep well aeration is a high-speed activated sludge system. The method has high oxygen utilization rate, small floor space, good treatment effect, low investment, low operating cost, no sludge bulking and less sludge production. In addition, its thermal insulation effect is good, and the treatment is not affected by climatic conditions, which can ensure the effect of winter sewage treatment in northern regions. After the high-concentration organic wastewater from the Northeast Pharmaceutical Factory was biochemically treated by the deep well aeration tank, the COD removal rate reached 92.7%. It can be seen that the processing efficiency is very high, which is extremely beneficial to the next processing. play a decisive role.
AB method
The AB method is an ultra-high-load activated sludge method. The removal rate of BOD5, COD, SS, phosphorus and ammonia nitrogen by AB process is generally higher than that of conventional activated sludge process. Its outstanding advantages are the high load of the A section, the strong anti-shock load capacity, and the large buffering effect on pH value and toxic substances. It is especially suitable for treating sewage with high concentration and large changes in water quality and quantity. The method of Yang Junshi et al. uses the hydrolysis acidification-AB biological method to treat antibiotic wastewater, which has a short process flow, energy saving, and the treatment cost is lower than the chemical flocculation-biological treatment method of similar wastewater.
biological contact oxidation
This technology combines the advantages of activated sludge method and biofilm method, and has the advantages of high volume load, low sludge production, strong impact resistance, stable process operation and convenient management. Many projects adopt a two-stage method, aiming to domesticate dominant strains at different stages, give full play to the synergistic effect between different microbial populations, and improve biochemical effects and shock resistance. In engineering, anaerobic digestion and acidification are often used as a pretreatment step, and a contact oxidation process is used to treat pharmaceutical wastewater. Harbin North Pharmaceutical Factory adopts hydrolysis acidification-two-stage biological contact oxidation process to treat pharmaceutical wastewater. The operation results show that the treatment effect is stable and the process combination is reasonable. With the gradual maturity of the process technology, the application fields are also more extensive.
SBR method
The SBR method has the advantages of strong shock load resistance, high sludge activity, simple structure, no need for backflow, flexible operation, small footprint, low investment, stable operation, high substrate removal rate, and good denitrification and phosphorus removal. . Fluctuating wastewater. Experiments on the treatment of pharmaceutical wastewater by SBR process show that the aeration time has a great influence on the treatment effect of the process; the setting of anoxic sections, especially the repeated design of anaerobic and aerobic, can significantly improve the treatment effect; the SBR enhanced treatment of PAC The process can significantly improve the removal effect of the system. In recent years, the process has become more and more perfect and is widely used in the treatment of pharmaceutical wastewater.
Anaerobic Biological Treatment
At present, the treatment of high-concentration organic wastewater at home and abroad is mainly based on anaerobic method, but the effluent COD is still relatively high after treatment with separate anaerobic method, and post-treatment (such as aerobic biological treatment) is generally required. At present, it is still necessary to strengthen Development and design of high-efficiency anaerobic reactors, and in-depth research on operating conditions. The most successful applications in pharmaceutical wastewater treatment are Upflow Anaerobic Sludge Bed (UASB), Anaerobic Composite Bed (UBF), Anaerobic Baffle Reactor (ABR), hydrolysis, etc.
UASB Act
The UASB reactor has the advantages of high anaerobic digestion efficiency, simple structure, short hydraulic retention time, and no need for a separate sludge return device. When UASB is used in the treatment of kanamycin, chlorin, VC, SD, glucose and other pharmaceutical production wastewater, the SS content is usually not too high to ensure that the COD removal rate is above 85% to 90%. The COD removal rate of the two-stage series UASB can reach more than 90%.
UBF method
Buy Wenning et al. A comparative test was conducted on UASB and UBF. The results show that UBF has the characteristics of good mass transfer and separation effect, various biomass and biological species, high processing efficiency, and strong operation stability. Oxygen bioreactor.
Hydrolysis and acidification
The hydrolysis tank is called a Hydrolyzed Upstream Sludge Bed (HUSB) and is a modified UASB. Compared with the full-process anaerobic tank, the hydrolysis tank has the following advantages: no need for sealing, no stirring, no three-phase separator, which reduces costs and facilitates maintenance; it can degrade macromolecules and non-biodegradable organic substances in sewage into small molecules. The easily biodegradable organic matter improves the biodegradability of the raw water; the reaction is fast, the tank volume is small, the capital construction investment is small, and the sludge volume is reduced. In recent years, the hydrolysis-aerobic process has been widely used in the treatment of pharmaceutical wastewater. For example, a biopharmaceutical factory uses hydrolytic acidification-two-stage biological contact oxidation process to treat pharmaceutical wastewater. The operation is stable and the organic matter removal effect is remarkable. The removal rates of COD, BOD5 SS and SS were 90.7%, 92.4% and 87.6%, respectively.
Anaerobic-aerobic combined treatment process
Since aerobic treatment or anaerobic treatment alone cannot meet the requirements, combined processes such as anaerobic-aerobic, hydrolytic acidification-aerobic treatment improve the biodegradability, impact resistance, investment cost and treatment effect of wastewater. It is widely used in engineering practice because of the performance of single processing method. For example, a pharmaceutical factory uses anaerobic-aerobic process to treat pharmaceutical wastewater, the BOD5 removal rate is 98%, the COD removal rate is 95%, and the treatment effect is stable. Micro-electrolysis-anaerobic hydrolysis-acidification-SBR process is used to treat chemical synthetic pharmaceutical wastewater. The results show that the whole series of processes has strong impact resistance to changes in wastewater quality and quantity, and the COD removal rate can reach 86% to 92%, which is an ideal process choice for the treatment of pharmaceutical wastewater. – Catalytic Oxidation – Contact Oxidation Process. When the COD of the influent is about 12 000 mg/L, the COD of the effluent is less than 300 mg/L; the removal rate of COD in the biologically refractory pharmaceutical wastewater treated by the biofilm-SBR method can reach 87.5%~98.31%, which is much higher than that of single use Treatment effect of biofilm method and SBR method.
In addition, with the continuous development of membrane technology, the application research of membrane bioreactor (MBR) in the treatment of pharmaceutical wastewater has gradually deepened. MBR combines the characteristics of membrane separation technology and biological treatment, and has the advantages of high volume load, strong impact resistance, small footprint, and less residual sludge. The anaerobic membrane bioreactor process was used to treat the pharmaceutical intermediate acid chloride wastewater with COD of 25 000 mg/L. The COD removal rate of the system remains above 90%. For the first time, the ability of obligate bacteria to degrade specific organic matter was used. Extractive membrane bioreactors are used to treat industrial wastewater containing 3,4-dichloroaniline. The HRT was 2 h, the removal rate reached 99%, and the ideal treatment effect was obtained. Despite the membrane fouling problem, with the continuous development of membrane technology, MBR will be more widely used in the field of pharmaceutical wastewater treatment.
2. Treatment process and selection of pharmaceutical wastewater
The water quality characteristics of pharmaceutical wastewater make it impossible for most pharmaceutical wastewater to undergo biochemical treatment alone, so necessary pretreatment must be carried out before biochemical treatment. Generally, a regulating tank should be set up to adjust the water quality and pH value, and the physicochemical or chemical method should be used as a pretreatment process according to the actual situation to reduce SS, salinity and part of COD in the water, reduce the biological inhibitory substances in the wastewater, and improve the degradability of the wastewater. to facilitate the subsequent biochemical treatment of wastewater.
The pretreated wastewater can be treated by anaerobic and aerobic processes according to its water quality characteristics. If the effluent requirements are high, the aerobic treatment process should be continued after the aerobic treatment process. The selection of the specific process should comprehensively consider factors such as the nature of the wastewater, the treatment effect of the process, the investment in infrastructure, and the operation and maintenance to make the technology feasible and economical. The whole process route is a combined process of pretreatment-anaerobic-aerobic-(post-treatment). The combined process of hydrolysis adsorption-contact oxidation-filtration is used to treat comprehensive pharmaceutical wastewater containing artificial insulin.
3. Recycling and utilization of useful substances in pharmaceutical wastewater
Promote clean production in the pharmaceutical industry, improve the utilization rate of raw materials, the comprehensive recovery rate of intermediate products and by-products, and reduce or eliminate pollution in the production process through technological transformation. Due to the particularity of some pharmaceutical production processes, wastewater contains a large amount of recyclable materials. For the treatment of such pharmaceutical wastewater, the first step is to strengthen material recovery and comprehensive utilization. For pharmaceutical intermediate wastewater with ammonium salt content as high as 5% to 10%, a fixed wiper film is used for evaporation, concentration and crystallization to recover (NH4)2SO4 and NH4NO3 with a mass fraction of about 30%. Use as fertilizer or reuse. The economic benefits are obvious; a high-tech pharmaceutical company uses the purging method to treat the production wastewater with extremely high formaldehyde content. After the formaldehyde gas is recovered, it can be formulated into a formalin reagent or burned as a boiler heat source. Through the recovery of formaldehyde, the sustainable utilization of resources can be realized, and the investment cost of the treatment station can be recovered within 4 to 5 years, realizing the unification of environmental benefits and economic benefits. However, the composition of general pharmaceutical wastewater is complex, difficult to recycle, the recovery process is complicated, and the cost is high. Therefore, advanced and efficient comprehensive sewage treatment technology is the key to completely solve the sewage problem.
4 Conclusion
There have been many reports on the treatment of pharmaceutical wastewater. However, due to the diversity of raw materials and processes in the pharmaceutical industry, wastewater quality varies widely. Therefore, there is no mature and unified treatment method for pharmaceutical wastewater. Which process route to choose depends on the wastewater. nature. According to the characteristics of wastewater, pretreatment is generally required to improve the biodegradability of wastewater, initially remove pollutants, and then combine with biochemical treatment. At present, the development of an economical and effective composite water treatment device is an urgent problem to be solved.
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Post time: Aug-15-2022