Chemical synthesis pharmaceutical wastewater treatment process
The nature of wastewater
The plant area is classified and collected according to the nature of the wastewater, and it is divided into four streams of wastewater:
(1) High concentration wastewater. It mainly contains organic substances such as ethanol, DMF (dimethylformamide), toluene, ethyl acetate and dichloromethane.
(2) High salinity wastewater. The salt concentration of saline wastewater is as high as 10%. The main salts are: sodium hydroxide, sodium chloride, sodium bicarbonate, sodium nitrite, hydrochloric acid, triethylamine hydrochloride, phosphoric acid.
(3) Preparation wastewater.
(4) General production wastewater.
According to the analysis of basic data and the technical personnel’s summary of medical wastewater treatment experience, the wastewater in the factory area mainly has the following characteristics: (1) The concentration of high-concentration pollutants is high, most of them have good biodegradability, and some are of average biodegradability. Substances with extremely poor biochemical properties. Because the characteristic pollutants in it are not easy to open the ring, if it is directly biochemically treated, its efficiency is low and the effect is general;
(2) High salinity in some wastewater has an inhibitory effect on bacteria;
(3) The concentration of pollutants in preparation wastewater and general production wastewater is relatively high and low, and the biodegradability is good.
Small test experiments and data
2.1 Experimental route
(1) The purpose of the experiment is to verify the technological process suitable for this wastewater treatment.
(2) Experimental objects: 1) High concentration wastewater; 2) High salinity wastewater.
(3) Experimental route:
High concentration wastewater – evaporation – ↓
High salinity wastewater – evaporation – advanced ozone oxidation – IC anaerobic reactor – aerobic reactor – effluent
2.2 Experimental data and analysis
From the experimental data (Table 1), it can be seen that the two wastewaters have the following characteristics:
(1) The biodegradability of wastewater after advanced ozone oxidation is greatly improved and the treatment effect is stable;
(2) The influence of high salinity and refractory organic matter in wastewater on treatment efficiency has been well resolved after desalination and ozone oxidation;
(3) This route can be used as the main process flow of this wastewater treatment.
Conclusions of the small test experiment The following conclusions can be drawn from the results of the small test experiment:
(1) The biochemical properties of the wastewater after desalination treatment have been greatly improved;
(2) The wastewater contains certain substances, which must be guaranteed for a certain residence time in order to be biodegraded. From the data analysis provided by the owner, this substance is likely to be DMF (dimethylformamide). In practical engineering, other wastewater that has not been treated by MVR must consider the residence time of wastewater in anaerobic and aerobic conditions to ensure sufficient time for DMF to degrade;
(3) After advanced oxidation treatment, the biodegradability of wastewater has been greatly improved;
(4) Since the time of this small test is very tight, only COD is used as the assessment index throughout the experiment, but there is still a certain risk of ammonia nitrogen in this scheme. For example, during the degradation of DMF, a large amount of ammonia nitrogen will be produced.
(5) Experimental route The main process route is recommended for this program.
The actual operation of the new pharmaceutical factory
4.1 Design water quality and discharge standard of wastewater
According to continuous on-site testing and sampling by technicians, combined with the actual operation experience of the old plant and the discharge rule of wastewater, after considering a certain margin, the design water quality and discharge standards (local standards) of this project are shown in Table 2.
4.2 Process flow of new pharmaceutical factory sewage treatment station
The actual process flow of the sewage treatment plant in this project is shown in Figure 1.
4.3 Operation of the sewage treatment station of the newly built pharmaceutical factory
After the completion of biological commissioning in October 2017, the project runs stably, the effluent COD fluctuates around 150mg/L, and the effluent reaches the standard.
5 Conclusion
(1) This project is chemical synthesis wastewater, which is high-concentration, high-salt, and refractory pharmaceutical wastewater. The main treatment process of this project is determined through the comparative analysis of small-scale experiments: wastewater is classified and collected, and high-salt wastewater is desalted and pretreated. After the degradation wastewater is treated by advanced oxidation, it enters the subsequent anaerobic-aerobic treatment unit;
(2) The actual operation of the sewage station of this project is basically consistent with the conclusions of the small test experiment. The recommended process flow of this small test experiment is reasonable. The experimental conclusions have great guiding significance for the qualitative analysis of various types of wastewater and the determination of the project process flow. .