| During the industrial production of potato starch,potato starch wastewater will be produced,and it will increase by a certain amount every year.The starch wastewater is rich in organic matter and belongs to high concentration of organic wastewater.After the initial fermentation of recycling,part of the protein products can be recovered,but the remaining fermentation liquid still belongs to high-concentration organic wastewater and needs to be continued to be treated.On this basis,the fermentation broth of potato potato residue juice was taken as the source of effluent for experimental treatment,the organic wastewater was treated in the early stage by anaerobic treatment method,and the composite bacteria group was constructed by biological method for treatment,and the fermentation process was optimized by response surface optimization method.It not only avoids the secondary pollution in the conventional treatment process,but also contributes to environmental protection,reduces the cost of wastewater treatment and improves the economic value of potatoes.In this study,13 strains of bacteria capable of anaerobic fermentation were screened from the anaerobic activated sludge.After re-screening,6 strains of bacteria capable of highly degrading COD were screened,including D2,S2,DF1,S36,C2 and CF3.After morphological and molecular biological identification,all strains screened were identified as bacillus.The growth characteristics of the strains were analyzed,and the results showed that the optimal growth temperature of each strain was 28?31 ?,the optimal Na Cl concentration was 1%,and the optimal pH range was 6.0?7.0.The growth curve of6 strains was measured,and it was found that 4 h? 22 h was the logarithmic growth period.Six dominant strains were used to construct composite flora,and antagonistic effects were found in the confrontation between CF3 and S36.Apart from the combination of CF3 and S36,each of the three combinations was matched with each other,leaving 17 combinations.It was found that C2+CF3+DF1 combination had the best treatment effect,and the COD degradation rate reached 59.22% on the 3rd day.The inoculation ratio of each strain found that the inoculation ratio of C2:CF3:DF1 was 2:2:1.The optimal level was determined by single factor experiment as follows: time was3 d,temperature was 31 ?,pH was 7,inoculation amount was 5%,and rotation speed was 180 r/min.Through the analysis of response surface experiment results,the regression of the model is extremely significant.The significance order of the influence of each single factor on the degradation rate of COD is:time>temperature>pH>inoculation amount>rotation speed,the primary term of COD degradation rate of time and temperature reached significant level,while the secondary term of COD degradation rate of time,temperature and inoculation amount all reached extremely significant level,but the interaction between each factor was not significant.The optimum fermentation conditions were as follows: time 3.13 d,temperature 31.9 ?,pH 6.96,inoculant quantity 4.71% and rotation speed 200 r/min.Under this optimization condition,the COD degradation rate was verified to be 75.99%,with a small deviation compared with the predicted value(76.7036%)of the model.It was found that the degradation rate of COD after optimization was 1.2 times that before optimization. |
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