Study On Treatment Of Sweet Potato Starch Wastewater By Compound Bacteria

The wastewater produced in traditional sweet potato's starch production contains many plenty of starch,protein,sugar,fat and other organic substances.It contained a amount of organic matters and the acidity value is very high,which could easily cause serious water and air pollution if it directly discharged.In this study,acid-resistant strains were selected from sweet potato starch wastewater by biofortification.With COD reduction as the main objective,the efficiency of acid-resistant microorganisms in the biochemical treatment of sweet potato starch processing wastewater with low pH was discussed.The specific research contents and results are as follows:(1)Pollution characteristics of sweet potato starch wastewaterThis study mainly adopted the conventional detection methods in water pollution treatment to detect the basic of sweet potato starch wastewater.COD 15000-20000 mg/L,total nitrogen 70-80 mg/L,total phosphorus 40-50 mg/L,ammonia nitrogen 25-30 mg/L.After precipitation,the amount of SS in the starch wastewater was still more than 1300 mg/L,and the total solids in the wastewater was more than 3000 mg/L,indicating that the starch wastewater contained more soluble starch and insoluble impurities.The total sugar and protein content were 0.63 mg/mL and 4.68 mg/mL,respectively,indicating that sweet potato starch wastewater has biochemical properties.(2)Separation and purification of acid-resistant bacteria and screening of high-efficiency starch wastewater treatment bacteriaNine culturable strains were isolated and purified from the waste water of sweet potato starch by plate coating method.According to the test of wastewater treatment capacity,the treatment of sweet potato starch wastewater for 6 days under the condition of inoculation amount of 5%,room temperature and 120 r/min showed that A,B,C and d had better COD removal efficiency,and the COD removal rate was more than 50%,among which,the COD removal rate of A could reach 52.2%.The physiological and biochemical characteristics of 4 strains of starch wastewater treatment were understood through physiological and biochemical experiments and the test of wastewater treatment capacity.Bacterium A has the ability to hydrolyze soluble starch in starch wastewater and utilize glucose,and the decomposition and utilization of glucose will not produce organic acids,thus reducing the pH value of wastewater.Finally,bacterium A was selected as the efficient strain to treat starch wastewater.(3)Effect of strain A a on starch wastewater treatmentThe optimal treatment conditions for bacteria A were: the temperature was 20?,the initial pH was 3.0,the inoculation amount was 1%,and in a conical flask with 20% liquid content,120 r/min.Under these conditions,bacteria A treated sweet potato starch wastewater for 5 days,and the removal rates of COD,total nitrogen and total phosphorus reached 57.17%,34.09% and 54.16%,respectively.The results indicated that bacteria A could effectively reduce the concentration of pollutants in sweet potato starch wastewater.(4)Effect of compound bacteria on starch wastewater treatment.Bacteria(A-B)were selected as the compound bacteria system for the treatment of starch wastewater.The better process conditions of the compound bacteria(A-B)were: the bacterial age was 24 h,the treatment temperature was 30?,the initial pH was 4.0,the inoculation ratio was 1:1,the liquid content was 20%,and the treatment efficiency was 120 r/min.Under this process conditions,the treatment efficiency of the compound bacteria(A-B)in the treatment of sweet potato starch wastewater for 5 days was the highest.The removal rates of COD,ammonia nitrogen and total phosphorus reached 98.36%,68.37% and 18.86%,respectively.The results indicated that bacteria(A-B)could effectively reduce the concentration of pollutants in sweet potato starch wastewater.The treatment conditions of the compound bacteria(A-B)were optimized by orthogonal test,and the optimal treatment combination of the compound bacteria(A-B)was obtained: the treatment temperature was 33,the initial pH was 4.5,and the inoculation ratio was 1.5:1.