The Desalination Of Penicillin Wastewater

In the production of penicillin using fermentation method, a large amount of wastewater is produced at the same time. The raffinate of extraction process is the main source of the wastewater, which is of high concentration of salinity and organics. The existence of sulfate makes the anaerobic reaction to be unable, so the biological treatment of wastewater cannot be performed. If the wastewater is not treated with a efficient method, the production will not proceed. So the wastewater desalination becomes the bottleneck of restricting the production process.A process for recycling sulfate from the penicillin wastewater was developed. Firstly, most of the organic matter was removed by adsorption and pH regulation, and then the sodium sulfate was recycled by solventing-out crystallization. The whole process is of practical significance to penicillin wastewater treatment of the pharmaceutical industry.The main content of this research work and the corresponding results are as follows:(1) The thermodynamics related to solventing-out crystallization of sodium sulfate were studied in this paper. The solubility of sodium sulfate in the mixture of methanol and water at 10,20,30,40,50 ℃ was determined, and an empirical model was proposed to relate the experimental data, and the parameters were obtained by fitting. The influence of operating conditions on the width of metastable zone was studied. It was shown that, the width of sodium sulfate metastable zone decreases with methanol content and the import rate of methanol.(2) The crystallization kinetics of sodium sulfate in solventing-out crystallization was investigated. The ASL model was used to relate the data, the nucleation and growth rate of sodium sulfate are shown as follows:(3) A new desalination process of penicillin wastewater was developed and experimentally studied. The optimized operating conditions are as follows:the amount of activated carbon should be 3-6g/L, pH of the wastewater should be adjusted to perform reaction precipitation, the concentration of sodium sulfate in concentrated wastewater should be as high as possible, unless crystallize, the crude product of sodium sulfate should be dissolved in the water to recrystallize. A experimental process using the optimized operating conditions was carried out, the result showed that the total yield was 72.33%, the purity of sodium sulfate was 95.45%, which matched the Ⅱ class qualified product of sodium sulfate in Chinese standard.