Treatment of pharmaceutical wastewater

2021-03-09


Pharmaceutical industry wastewater treatment methods can be summarized as follows: physical and chemical treatment, chemical treatment, biochemical treatment and the combination of a variety of methods.
 
1. According to the characteristics of pharmaceutical wastewater quality, physicochemical treatment should be used as the pretreatment or post-treatment process of biochemical treatment. At present, the physicochemical treatment methods mainly include coagulation, air flotation, adsorption, ammonia stripping, electrolysis, ion exchange and membrane separation.
 
(1) Coagulation is a kind of water treatment method widely used at home and abroad. It is widely used in the pretreatment and post-treatment of pharmaceutical wastewater, such as aluminum sulfate and polymerized ferric sulfate for traditional Chinese medicine wastewater. The key of high efficiency coagulation treatment is to select and add coagulant with good performance. In recent years, the development direction of coagulant is from low molecular to polymer, from single functional component to composite.
 
(2) Air floatation air floatation usually includes aeration air floatation, dissolved air floatation, chemical air floatation and electrolytic air floatation. In Xinchang pharmaceutical factory, CAF cavitation air floatation device was used to pretreat pharmaceutical wastewater. With proper chemicals, the average removal rate of COD was about 25%.
 
(3) Adsorbents commonly used in adsorption method include activated carbon, activated coal, humic acid, adsorption resin, etc. A pharmaceutical factory used coal ash adsorption two-stage aerobic biological treatment process to treat its wastewater. The results showed that the removal rate of COD was 41.1%, and the BOD5 / COD ratio was increased.
 
(4) Membrane separation technology, including reverse osmosis, nanofiltration and fiber membrane, can recover useful substances and reduce the total amount of organic matter emissions. The main features of this technology are simple equipment, convenient operation, no phase change and chemical change, high treatment efficiency and energy saving. Juana et al. Used nanofiltration membrane to separate lincomycin wastewater, and found that it not only reduced the inhibition of lincomycin on microorganisms, but also recovered lincomycin.
 
(5) Electrolysis has been paid more and more attention because of its high efficiency and easy operation. At the same time, electrolysis has good decolorization effect. Li Ying pretreated riboflavin supernatant by electrolysis, and the removal rates of COD, SS and chroma were 71%, 83% and 67% respectively.
 
 
 
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2. Chemical treatment chemical methods include iron carbon method, chemical oxidation-reduction method (Fenton reagent, H2O2, O3), deep oxidation technology, etc.
(1) The industrial operation of iron carbon process shows that the biodegradability of the effluent can be greatly improved by using Fe-C as the pretreatment step of pharmaceutical wastewater. The combined process of iron carbon micro electrolysis anaerobic aerobic air flotation was used to treat the wastewater from pharmaceutical intermediate production. The COD removal rate was 20% after iron carbon treatment.
(2) The combination of ferrous salt and H2O2 in Fenton reagent treatment process is called Fenton reagent, which can effectively remove refractory organic compounds that cannot be removed by traditional wastewater treatment technology. With the deepening of the research, ultraviolet (UV) and oxalate (C2O4 -) were introduced into Fenton reagent, which greatly enhanced its oxidation ability. Using TiO2 as catalyst, 9 w low pressure mercury lamp as light source, Fenton reagent was used to treat pharmaceutical wastewater. The effect of complete decolorization and COD removal rate of 92.3% were achieved, and the compound was reduced from 8.05 mg / L to 0.41 mg / L. This method can improve the biodegradability of wastewater and has a good removal rate of COD.
(3) Oxidation technology, also known as advanced oxidation technology, mainly includes electrochemical oxidation, wet oxidation, supercritical water oxidation, photocatalytic oxidation and ultrasonic degradation. Among them, the UV catalytic oxidation technology has the advantages of novel, high efficiency and non selectivity to wastewater, especially suitable for the degradation of unsaturated hydrocarbons, and the reaction conditions are relatively mild, without secondary pollution, so it has a good application prospect. Compared with ultraviolet, heat, pressure and other treatment methods, ultrasonic treatment of organic matter is more direct and requires less equipment. As a new treatment method, it is receiving more and more attention.
3. Biochemical treatment biochemical treatment technology is widely used in pharmaceutical wastewater treatment, including aerobic biological method, anaerobic biological method, aerobic anaerobic and other combination methods.
 
(1) As pharmaceutical wastewater is mostly high concentration organic wastewater, aerobic biological treatment generally needs to dilute the original solution, so the power consumption is large, and the biodegradability of wastewater is poor, so it is difficult to meet the discharge standard after direct biochemical treatment. Therefore, there are not many aerobic treatment alone, which generally requires pretreatment. Common aerobic biological treatment methods include activated sludge process, deep well aeration process, adsorption biodegradation process (AB process), contact oxidation process, sequencing batch batch batch reactor (SBR process), cyclic activated sludge process (CASS process), etc.
 
(2) At present, anaerobic biological treatment is mainly used to treat high concentration organic wastewater at home and abroad, but the COD of effluent is still high after single anaerobic treatment, which generally needs post-treatment (such as aerobic biological treatment). At present, it is still necessary to strengthen the development and design of high-efficiency anaerobic reactor and carry out in-depth research on operating conditions. The successful applications in the treatment of pharmaceutical wastewater include anaerobic sludge bed (UASB), anaerobic combined bed (UBF), anaerobic baffled reactor (ABR), hydrolysis, etc.
 
(3) Anaerobic aerobic and other combined treatment processes are often unable to meet the requirements due to single aerobic treatment or anaerobic treatment. However, anaerobic aerobic, hydrolytic acidification aerobic and other combined processes are obviously superior to single treatment method in improving the biodegradability, impact resistance, investment cost and treatment effect of wastewater, so they are widely used in engineering practice Universal application.