| Water pollution comes mainly from industry sewage, municipal sewage andgarbage, agricultural non-point source pollution. Industry sewage is one of the mainsources of pollutants in water environment, which mainly from chemical,pharmaceutical, food and food processing, coking industry. And pharmaceuticalindustry is the most serious on the impact of water pollution in our country. Thepharmaceutical industry is divided into six categories: Chemical Synthesis, BiologicalEngineering, Fermentation, Extraction, Chinese Traditional Medicine and Mixing andFormulating. Chemical Synthesis pharmaceutical wastewater is more difficult to dealwith, because of its characteristics: high concentration of organic matter, high saltcontent, pH value changes, and hard biological degradation. It is difficult to meetdischarge standards using biological method to treat pharmaceutical waste water; weneed to improve the biodegradability of wastewater by pretreatment, so that making thebiochemical treatment more effective. So developing cost-effective pharmaceuticalwastewater pretreatment technology is urgent.Based on a comprehensive discussion of pharmaceutical wastewater pretreatmenttechnology, taking a Chemical Synthetic pharmaceutical wastewater as research object,this thesis used iron carbon micro-electrolysis technology followed by Fenton reagentoxidation technique to treat the pharmaceutical wastewater, which comprises thefollowing four aspects: the best operating condition and treatment effect of iron carbonmicro-electrolysis technology and Fenton reagent oxidation; the best treatment effect ofcombined process: iron carbon micro-electrolysis technology followed by Fentonreagent oxidation; and reaction kinetics of the two pretreatment technology.In this study, iron scrap and granular activated carbon were used as materials ofmicro-electrolysis to pretreat the pharmaceutical wastewater. Through single-factorexperiment and orthogonal experiment analysis, the best operation conditions of ironcarbon micro electrolysis technology were confirmed: mass ratio of iron and carbon is2:3, iron-carbon dosage is500g/L, reaction time is2h, the pH value is2.2.Under thisconditions, the CODCrremoval rate of the wastewater can reach above60%, CODCrconcentration decreased from30000to10840mg/L~11440mg/L. The orthogonalexperiment showed that, the order of various main factors affecting the effect of theiron-carbon micro-electrolysis is the total amount of iron and carbon, mass ratio of ironand carbon, reaction time, pH value; of which influencing the experiment results most significantly is iron carbon total dosage (significant level0.01), influencing theexperiment results significantly are mass ratio of iron and carbon, reaction time(significant level0.05),influencing the experiment results general significantly are pHvalue (significant level0.10). Iron carbon micro-electrolysis process has good treatmenteffect on the pharmaceutical wastewater.30%hydrogen peroxide and ferrous sulfate reagent were used as materials of Fentonreagent oxidation to pretreat the pharmaceutical wastewater. Through single-factorexperiment and orthogonal experiment analysis, the best operation conditions of Fentonreagent oxidation were confirmed: pH value is3, H2O2/Fe2+molar ratio is30:1, H2O2dosage is28mL/L, and reaction time is100min. Under this conditions, the CODCrremoval rate of the wastewater can reach above25%, the effluent CODCrreached22360mg/L~23360mg/L. The orthogonal experiment showed that: the order of variousmain factors affecting the effect of Fenton reagent oxidation is pH value, H2O2/Fe2+molar ratio, H2O2dosage, reaction time; of which influencing the experiment resultssignificantly are pH value and H2O2/Fe2+molar ratio (significant level0.05), andinfluencing the experiment results general significantly are H2O2dosage and reactiontime (significant level0.10).In order to further reduce CODCrconcentration of the pharmaceutical wastewater,reduce the load of equipment in subsequent biological treatment, iron-carbonmicro-electrolysis treatment followed by Fenton oxidation treatment was used toenhance the treatment result of the wastewater in this study. Taking effluent water ofiron carbon micro electrolysis under the optimum operation condition, adjusting theeffluent water’s pH to3.5, then adding12mL/L H2O2as the oxidant, after oxidation for80minutes, the CODCrremoval rate reached above70%, CODCrreduced to about8000mg/L, and the treated wastewater biodegradability increased to0.43.Finally, kinetics of the combined process treating the pharmaceutical wastewaterhad been done a preliminary study: CODCrdegradation reaction by iron carbonmicro-electrolysis obeys approximately the pseudo-first-order reaction kinetics. treatingthe effluent of iron carbon micro-electrolysis as research object, and organic matterconcentration and initial concentration of hydrogen peroxide as factors influencing thereaction rate, the reaction kinetics model by Fenton was derived. |
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