| In recent years,the requirement of wastewater discharge in pharmaceutical industry is becoming more and more strict,the conventional biochemical secondary treatment is difficult to achieve the target of treatment,no matter what way the wastewater is discharged,it is necessary to take measures to strengthen the effect of wastewater treatment.In advanced treatment of wastewater,enhanced flocculation is a simple,economical and reliable process.Based on the effect of potassium permanganate and several inorganic flocculants on the advanced treatment of pharmaceutical wastewater,the form of potassium permanganate oxidation compound polymer inorganic flocculants was proposed to optimize the advanced treatment effect,and the strengthening mechanism was explored.The economy and practicability of the compound process are also discussed.It was found that the initial dosage of potassium permanganate,pH value of solution and mixing reaction time had effects on the removal rate of COD,the utilization rate of potassium permanganate and the chroma of effluent,but the effect of temperature on the treatment effect was not obvious.The results showed that under neutral condition,the potassium permanganate utilization ratio was the highest when the dosage of potassium permanganate was in 10mg/L,and the utilization rate of potassium permanganate decreased significantly and the chroma of effluent increased significantly when the dosage of potassium permanganate continued to increase.Reducing the pH value of the solution can effectively increase the utilization rate of potassium permanganate and the removal rate of COD,and the reaction time can be further shortened.In the advanced treatment of pharmaceutical wastewater with several kinds of inorganic flocculants,the removal efficiency of COD and turbidity of polymer flocculants PFS and PAC is better than that of aluminum sulfate and ferric chloride,while the addition of PAM can significantly improve the turbidity removal efficiency.On the other hand,the addition of flocculant PFS and PAC can significantly reduce the pH value of the solution and keep the pH value around 3.35,while that of PAC can keep the pH value around 5.8.The compound flocculant was composed of three forms: KMnO4-PAC,KMnO4-PFS and KMnO4-PFS-PAC.The optimized results showed that the optimum mass fraction of KMnO4 in KMnO4-PFS was 15%,and the optimum proportion of KMnO4-PFS-PAC was 14.95% KMnO4,41.63% PAC and 43.42% PFS.The optimum mass fraction of KMnO4 in KMnO4-PAC was 10%.However,for different kinds of wastewater,the treatment effect of several complex forms is different,when the specific gravity of refractory substances in water increases,the treatment effect will weaken.Compared with KMnO4-PFS flocculant and KMnO4-PAC flocculant,the removal effect of KMnO4-PFS-PAC on COD and turbidity is between the optimum ratio of COD and turbidity,and the utilization ratio of potassium permanganate is also between the optimum ratio of KMnO4-PFS flocculant and KMnO4-PAC compound flocculant.However,in the advanced treatment of pharmaceutical wastewater,KMnO4-PFS complex flocculant has the best treatment effect,but it is found that the treatment cost of KMnO4-PFS-PAC is 0.2732 yuan / ton when the preliminary economic cost accounting is carried out.It was found that the introduction of inorganic flocculant improved the oxidation ability of potassium permanganate and the utilization rate of potassium permanganate.But the addition of potassium permanganate weakens the neutralization ability of flocculant,and the turbidity removal rate can be maintained at more than 75% by adding PAM to assist coagulation. |
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