| Ink cleaning wastewater is a typical type of wastewater produced during cleaning all kinds of printing equipment in enterprises,but there have been rare research literatures on its treatment so far.Therefore,based on the characteristics of such emulsion wastewaters containing a large number of refractory organics,high COD concentration and poor biodegradability,acid precipitation demulsification,fenton oxidation,hydrolysis acidification and SBR process were used to treat ink cleaning wastewater.Acid precipitation-fenton's experimental research on ink cleaning wastewater pretreatment showed that the effect of sulfuric acid acidulation was better than hydrochloric acid.When p H=3-4,removal efficiencies of chroma and COD were higher than 90%and 60%,respectively.Though photo-fenton effluent was better than fenton,the fenton oxidation was utilized in the following experiments,considering actual treatment cost and further biochemical needs.The optimum treatment conditions of fenton oxidation were p H=3.5,n(H2O2/Fe2+)=15,H2O2=12m L/L,reaction time 90 min,the total removal efficiency of COD was 92.55%.The orthogonal experiments found that H2O2 dosage was the most prominent effect factor,followed by H2O2/Fe2+molar ratio and p H value.COD concentration of the ink cleaning wastewater reduced to 1200 mg/L,and the B/C value increased to 0.319 after both acidulation and fenton pretreatments.The experiments for both Hydrolysis acidification and SBR process indicated that the hydrolytic acidification reactor was successfully launched after a 22-day consecutive operation of process,with 9h of the optimal HRT.At that time,the removal efficiency of COD in the system was 28%,p H values of the effluent was 6.26,and the accumulation amount of VFAs reached 290.8mg/L.The content of volatile acid components in different HRT was in the order of acetic acid>propionic acid>butyric acid>formic acid.Hydrolysis acidification process increased the B/C value of ink cleaning wastewater from 0.319 to 0.445.The removal efficiencies of COD,NH3-N and TN in the printing ink cleaning wastewater by the hydrolytic acidification SBR combined process reached to 91.16%?83.4%?74.8%,respectively within20 days of stable operation,and the effluent concentration has been up to the discharge standard of water pollutants for printing ink industry.Study on COD kinetics during the combined wastewater treatment process showed that the reaction order of Fenton oxidation reaction was 2.04.The kinetic equation of COD degradation in ink wastewater by fenton method was r=4.28×10-6C2.04.Through the preliminary kinetic analysis of the hydrolysis and acidification reactor based on Monod equation,it revealed that the kinetic parameter K of the hydrolysis and acidification reactor was related to the hydraulic residence time,sludge properties,and the concentration of influent organic matter. |
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