A New Process for Pharmaceutical Wastewater Treatment

Pharmaceutical industrial wastewater mainly includes antibiotic production wastewater, synthetic drug production wastewater, traditional Chinese patent medicines and simple preparations production wastewater, and washing water and flushing wastewater in the production process of various preparations. The characteristics of its wastewater are complex composition, high organic content, high toxicity, deep color and high salt content, especially poor biochemical properties and intermittent discharge, making it difficult to treat industrial wastewater. With the development of China's pharmaceutical industry, pharmaceutical wastewater has gradually become one of the important sources of pollution. How to treat this type of wastewater is a difficult problem in environmental protection today.
The treatment technologies for pharmaceutical wastewater can be summarized as follows: physical and chemical treatment, chemical treatment, biochemical treatment, and combination treatment of multiple methods. Each treatment method has its own advantages and disadvantages. Most pharmaceutical wastewater has characteristics such as high organic concentration, high chromaticity, difficult to degrade and toxic substances to microorganisms, complex water quality components, and poor biodegradability.
1、 Physical and chemical treatment
According to the water quality characteristics of pharmaceutical wastewater, physical and chemical treatment is required as a pre-treatment or post-treatment process for biochemical treatment in its treatment process. The current physical and chemical treatment methods mainly include coagulation, air flotation, adsorption, ammonia stripping, electrolysis, ion exchange, and membrane separation. 
1. The air flotation method usually includes various forms such as inflatable air flotation, dissolved air flotation, chemical air flotation, and electrolytic air flotation. The CAF concave air flotation device is used for pre-treatment of pharmaceutical wastewater, and the average COD removal rate is about 25% with appropriate chemical combinations. 
2. Coagulation method is a commonly used water quality treatment method both domestically and internationally. It is widely used in the pre-treatment and post-treatment of pharmaceutical wastewater, such as aluminum sulfate and polymeric iron sulfate used in traditional Chinese medicine wastewater. The key to efficient coagulation treatment lies in the appropriate selection and addition of high-performance coagulants. In recent years, the development direction of coagulants has shifted from low molecular weight to polymeric polymers, and from single component functional type to composite type. Liu Minghua et al. used a highly efficient composite flocculant F-1 developed by him to treat wastewater from the production of urgent syrup. At a pH of 6.5 and a flocculant dosage of 300mg/L, the removal rates of COD, SS, and chromaticity in the wastewater reached 69.7%, 96.4%, and 87.5%, respectively. Its performance was significantly better than that of single flocculants such as PAC (powdered activated carbon) and polyacrylamide (PAM). 
3. Membrane separation technology includes reverse osmosis, nanofiltration membranes, and fiber membranes, which can recover useful substances and reduce the total amount of organic matter emissions. The main characteristics of this technology are simple equipment, convenient operation, no phase change or chemical change, high processing efficiency, and energy conservation. The separation experiment of lincomycin wastewater using nanofiltration membrane found that it not only reduced the inhibitory effect of lincomycin on microorganisms in the wastewater, but also recovered lincomycin. 
4. The commonly used adsorbents in adsorption methods include activated carbon, activated coal, humic acids, adsorption resins, etc. Using coal ash adsorption two-stage aerobic biological treatment process to treat its wastewater. The results showed that the adsorption pretreatment achieved a COD removal rate of 41.1% in wastewater and increased the BOD5/COD value. 
5. The electrolysis method has been highly valued for its high efficiency and ease of operation in treating wastewater, and it also has good decolorization effects. The iron carbon electrolysis+efficient anaerobic GBIC treatment unit has a good effluent effect. The electrolysis method is used to pretreat the riboflavin supernatant, and the removal rates of COD, SS, and chromaticity reach 71%, 83%, and 67%, respectively. 
2、 Chemical treatment
When applying chemical methods, excessive use of certain reagents can easily lead to secondary pollution of water, so relevant experimental research should be done well before design. Chemical methods include iron carbon method, chemical oxidation-reduction method (Fenton reagent, H2O2, O3), deep oxidation technology, etc. 
1. The industrial operation of the iron carbon method shows that using Fe-C as a pre-treatment step for pharmaceutical wastewater can greatly improve the biodegradability of its effluent. The combined treatment process of iron charcoal micro electrolysis anaerobic aerobic air flotation is used to treat pharmaceutical intermediate production wastewater such as erythromycin and ciprofloxacin hydrochloride. The COD removal rate after iron charcoal treatment reaches 20%, and the final effluent meets the first level standard of the Comprehensive Wastewater Discharge Standard (GB8978-1996). 
2. The combination of ferrous salt and H2O2 in the Fenton reagent treatment method is called Fenton reagent, which can effectively remove difficult to degrade organic compounds that cannot be removed by traditional wastewater treatment techniques. With the deepening of research, ultraviolet light (UV) and oxalate (C2O42-) were introduced into Fenton reagents, greatly enhancing their oxidation ability. Using TiO2 as a catalyst and 9W low-pressure mercury lamp as a light source, Fenton reagent was used to treat pharmaceutical wastewater, achieving a decolorization rate of 100% and a COD removal rate of 92.3%. Nitrobenzene compounds were also reduced from 8.05mg/L to 0.41mg/L. 
Pharmaceutical wastewater treatment technology 3, oxidation method. This method can improve the biodegradability of wastewater and has a good removal rate of COD. Balcioglu et al. treated three types of antibiotic wastewater with ozone oxidation, and the results showed that the wastewater treated with ozone oxidation not only increased the ratio of BOD5/COD, but also had a COD removal rate of over 75%. 
3、 Biochemical treatment
Biochemical treatment technology is currently widely used in the treatment of pharmaceutical wastewater, including aerobic biological method, anaerobic biological method, aerobic anaerobic combination method, etc. 
1. Due to the fact that pharmaceutical wastewater is mostly high concentration organic wastewater, aerobic biological treatment generally requires dilution of the original solution, resulting in high power consumption and poor biodegradability of the wastewater, making it difficult to directly treat and discharge it up to standard. Therefore, aerobic treatment alone is not commonly used and generally requires pre-treatment. The 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 batch activated sludge method (SBR method), circulating activated sludge method (CASS method), etc. 
Pharmaceutical wastewater treatment technology
2. Deep well aeration method
Deep well aeration is a high-speed activated sludge system, which has the advantages of high oxygen utilization rate, small footprint, good treatment effect, low investment, low operating cost, no sludge bulking, and low sludge production. In addition, its insulation effect is good, and the treatment is not affected by climate conditions, which can ensure the effectiveness of winter wastewater treatment in northern regions. After biochemical treatment in a deep well aeration tank, the COD removal rate of high concentration organic wastewater reaches 92.7%, indicating that its treatment efficiency is very high and extremely beneficial for the next step of treatment. It plays a decisive role in achieving the effluent standard of process treatment. 
3. AB method belongs to the ultra-high load activated sludge method. The removal efficiency of BOD5, COD, SS, phosphorus, and ammonia nitrogen by AB process is generally higher than that of conventional activated sludge method. Its outstanding advantages are high load capacity in section A, strong resistance to impact load, and significant buffering effect on pH and toxic substances. It is particularly suitable for treating wastewater with high concentration and significant changes in water quality and quantity. The use of hydrolysis acidification AB biological process to treat antibiotic wastewater has a short process flow, energy saving, and lower treatment cost than the chemical flocculation biological method for the same type of wastewater. 
4. The biological contact oxidation method combines the advantages of activated sludge and biofilm methods, and has the advantages of high volumetric load, low sludge yield, strong impact resistance, stable process operation, and convenient management.
Many engineering projects adopt a two-stage approach with the aim of domesticating dominant bacterial strains at different stages, fully leveraging the synergistic effects between different microbial populations, and improving biochemical efficacy and shock resistance. In engineering, anaerobic digestion and acidification are often used as pretreatment processes, and contact oxidation method is used to treat pharmaceutical wastewater. The pharmaceutical wastewater was treated using a hydrolysis acidification two-stage biological contact oxidation process. The operating results showed that the treatment effect of this process was stable and the process combination was reasonable. With the gradual maturity of this process technology, its application fields have also become more extensive. 
5. The SBR method has the advantages of strong impact load resistance, high sludge activity, simple structure, no need for reflux, flexible operation, small footprint, low investment, stable operation, high substrate removal rate, and good denitrification and phosphorus removal effect. It is suitable for treating wastewater with large fluctuations in water quantity and quality. The experiment of SBR process for treating pharmaceutical wastewater shows that aeration time has a significant impact on the treatment effect of this process; Setting up anoxic sections, especially the repeated design of alternating hypoxia and aerobic, can significantly improve the treatment effect; The SBR enhanced treatment process with the addition of PAC in the reaction tank can significantly improve the removal efficiency of the system. In recent years, this process has become increasingly sophisticated and has been widely used in the treatment of pharmaceutical wastewater. The hydrolysis acidification SBR method is used to treat biopharmaceutical wastewater, and the effluent quality meets the first level standard of GB8978-1996. 
In summary, with the development and progress of environmental protection technology and the strengthening of overall environmental supervision, various pharmaceutical companies are facing pressure to meet the discharge standards for sewage environmental treatment. The iron carbon micro electrolysis+efficient anaerobic GBIC treatment unit technology has become an important method for treating pharmaceutical wastewater.