Study On The Degradation Of Pharmaceutical Wastewater By Three-dimensional Electrode Reactor

With the development of the pharmaceutical industry in China, pharmaceutical wastewater had gradually become one of the important pollution sources. Because of complex composition, high organic content, toxicity, deep color and high salt content, poor biodegradability, especially intermittent emissions, pharmaceutical wastewater was belong to difficult treatment industrial wastewater. Today, how to disposal such wastewater has become a problem of environmental protection. The three-dimensional electrode method has become a new water treatment technology in recent years, and it is one of the hot spot of current research.This thesis focuses on the difficulties of pharmaceutical wastewater treatment carry out the laws of the degradation of pharmaceutical wastewater by three-dimensional electrode, the kinetics and mechanism of degradation of COD and pollutants, discusses the actual effectiveness and practicality of the degradation of artificial pharmaceutical wastewater by three-dimensional electrode. It will provide new technical reference and theoretical basis for pharmaceutical wastewater reuse and discharge, and has important theoretical basis and practical value. We selected four drugs available in the laboratory and common in the pharmaceutical industry(lidocaine hydrochloride, benzoic acid, sodium benzoate, ciprofloxacin hydrochloride)as the object of study, and prepare an analog pharmaceutical wastewater, use the three-dimensional electrode method for processing.Firstly, the static adsorption influence of particle electrode was studied which used in the three-dimensional electrode method on pharmaceutical wastewater. The result shows that the static adsorption efficiency of particle electrode on pharmaceutical wastewater is not high, it not reach20%.Therefore, we considered that the adsorption effects of the particle electrode on the pharmaceutical wastewater was not significant.The experiment was carried out to treat single ingredient artificial wastewater using three-dimensional electrode. The effects of operating conditions on the removal efficiency of artificial pharmaceutical wastewater, such as the electrode distance, voltage, amount of wastewater, and the electrolytic time are also investigated. The result shows that the removal efficiency increase with the electrolytic time increases. The extreme value of the effect of electrode distance and voltage on the pharmaceutical wastewater removal efficiency is the best electrode distance and best voltage. By orthogonal test, we can get the best removal condition of three kinds of pharmaceutical wastewater processing by three-dimensional electrode method. The best removal condition of the lidocaine hydrochloride wastewater as follows, the electrode distance is2cm,the voltage is40V, the amount of wastewater is440mL, the electrolysis time is90min, the removal ratio is62.6%; The best removal condition of the sodium benzoate wastewater as follows:the electrode distance is4cm,the voltage is45V, the amount of wastewater is440mL, the electrolysis time is75min, the removal ratio is66.1%; The best removal condition of the ciprofloxacin hydrochloride wastewater as follows, the electrode distance is4cm,the voltage is35V, the amount of wastewater is500mL, the electrolysis time is60min, the removal ratio is88.9%.Carry out a comparative study on three-dimensional electrode and two-dimensional electrode processing artificial benzoic acid wastewater. The results show that the best removal condition of the benzoic acid wastewater processing by three-dimensional electrode as follows, the electrode distance is4cm,the voltage is45V, the amount of wastewater is250mL, the electrolysis time is90min, the removal ratio is30.5%and the COD removal ratio is70.5%, the kinetics of degradation is first-order reaction; the best removal condition of the benzoic acid wastewater processing by two-dimensional electrode is:the electrode distance is4cm,the voltage is45V, the dosage of NaCl is0.6g/L, the removal ratio is83.0%, the kinetics of degradation is zero-order reaction.The study of degradation kinetics shows that the kinetics of degradation of lidocaine hydrochloride wastewater is second-order reaction, the kinetics of degradation of sodium benzoate wastewater expressed as three-order reaction, the degradation reaction of ciprofloxacin hydrochloride wastewater by three-dimensional electrode is second-order reaction.Experiment study on the degradation of mixing pharmaceutical wastewater by three-dimensional electrode method, the results show that (1) when the lidocaine hydrochloride and sodium benzoate mixed with mass ratio of1:1and2:1, the removal ratio of lidocaine hydrochloride reached70.8%and63.9%,the removal ratios are higher than that individually treated under the respective optimum conditions.(2)The removal ratio of COD of different concentrations of wastewater which mixed with four drugs, is different under different processing conditions. Under the best removal condition of the lidocaine hydrochloride wastewater processing by three-dimensional electrode, the highest removal ratio is89.4%. The five kinds of wastewater all can achieve removal effect under the best removal condition of the ciprofloxacin hydrochloride wastewater processing by three-dimensional electrode. The COD removal ratios are82.4%,76.1%,85.9%,78.2%,82.4%.The degradation mechanism of the pharmaceutical wastewater were studied by three-dimensional electrode. First, the UV absorption spectrum of artificial wastewater with electrolysis time was measured, the result showed that the intensity of UV absorption was reduced with the electrolytic time increases indicating that the pollutant concentration is gradually reduced. Infrared spectrum of the drugs and the floe produced by electrolysis of the pharmaceutical wastewater is analyzed. The infrared spectroscopy analysis shows that the infrared absorption of groups in the organics like benzene ring, the long carbon chain and the N-containing moieties such as amino significantly reduced, indicating those groups broken down into small molecules of CO2N2and H2O during the preferred electrolysis conditions process.The elemental analysis showed that the C/N value of two drugs lidocaine hydrochloride and ciprofloxacin hydrochloride decline in the processing. The removal ratios of N, C, H in lidocaine hydrochloride are reduced98.59%,65.41%,75.56%; the removal ratios of N, C, H in ciprofloxacin hydrochloride are reduced31.72%,29.65%,16.19%. It has proved the results of infrared spectroscopic analysis. During the Pharmaceuticals wastewater by electrolysis, the structure of organic is destroyed, resulting in C, N two elements content greatly reduced, respectively, into small molecules like CO2, N2and H2O,then escaped.