Effect Of Flocculation And Submerged Plant On Improving The Efficiency Of MBR Integrated Equipment In The Treatment Of Starch Wastewater

Starch and starch products in the processing process will produce a high concentration of acid organic wastewater,its composition is complex,treatment is difficult.If not treated or improper treatment will cause the surrounding water pollution,make the water black and smelly,thus bringing great harm to the ecological environment.It is necessary to promote the construction of water ecological civilization,prevent and control water pollution from the source,and explore the effective treatment technology of starch wastewater to make it discharge to the standard.In recent years,Membrane Bioreactor(MBR)has been widely used in sewage treatment due to its strong impact resistance.Integrated MBR and combined MBR have achieved results in many aspects,but the effect of nitrogen and phosphorus removal is still unstable.In this paper,a quick-frozen food factory in Chengjiang town,Beibei district,Chongqing,was taken as the object.Through field investigation and water quality test,it was found that the total nitrogen,total phosphorus and Chemical Oxygen Demand(COD)of the water quality were too high,which were 104.71~123.12 mg/L,98.92~102.67 mg/L,5020~5450mg/L,respectively.Strong acidity,pH value of 3.97~4.39;The water quantity changes greatly,the MBR system load is large,the effluent quality is unstable,and even the equipment occasionally breaks down,resulting in serious pollution.Its main reason is that the enterprise existing large amount of particulate matter in starch wastewater,acid is too strong,which is mainly composed of MBR to existing and heavy burden of wastewater treatment process,MBR and the content of inorganic nitrogen and phosphorus in water also is higher,so the poor treatment effect and effluent water quality of total nitrogen,total phosphorus and COD were22.94~31.27 mg/L,8.29~12.37 mg/L,48.12~62.03 mg/L,can achieve “The Surface WaterEnvironment Quality Standard ”(GB3838-2002)of ? class water discharge.Combined with the present situation,the flocculation and precipitation at the front end were proposed to reduce the particle solids,adjust the pH value,and reduce the impact of water entry on MBR.The idea of using submerged plants to absorb inorganic nitrogen and phosphorus in the MBR effluent was adopted at the rear end,and the existing wastewater treatment system equipment of the enterprise was upgraded.Based on this,under the condition of laboratory,this research studies the single flocculant and compound flocculants for water,total nitrogen,total phosphorus and COD removal efficiency and contrast analysis of the quality of flocculation sediment,and then select the optimal distribution of flocculant polymeric ferric Sulfate(Polyferric Sulfate,PFS)+ PAM(Polyacrylamide,PAM)group conducted laboratory conditions optimization test.Introducing the optimal conditions of flocculation of field operation,at the same time introducing the MBR effluent channels to build good submerged plant,water quality situation continuously monitor each stage of processing and analysis of the removal efficiency of each processing stage,the results show that the front-end introducing the flocculation precipitation and the back-end submerged plant ascension process,significantly improve the MBR membrane treatment effect and improve equipment operation stability,monitoring during system outlet the indicators meet the requirements of water quality ? class the surface.At the same time,the change of microbial community quantity and diversity in water at each treatment stage was analyzed by using Phospholipid Fatty Acid(PLFA)method.The main results are as follows:Construction of the process structure of the upgrading scheme: Firstly,a flocculation sedimentation tank is added at the front end for pretreatment with flocculant to reduce the pressure of the subsequent links;Secondly,an aerobic reaction aeration tank was added between the IC anaerobic reactor(IC)and the integrated oxygen host to increase the aeration oxygen.Finally,an ecological ditch is added for the planting of submerged plants(bitter grass and black algae)to remove inorganic nitrogen and phosphorus pollutants in the water after MBR.The wastewater treatment process was upgraded to the combination process of“flocculation and precipitation pretreatment + anaerobic and aerobic reaction treatment+MBR integrated equipment + submerged plant ecological canal purification treatment”.(1)Under the same test conditions in the laboratory(Reaction system: 1 L.Stirring parameters: stirring for 1 min at 200 r/min;Stirring at 150 r/min for 3 min;Stirring for 6 minat 100 r/min;Standing time: 2 h).The weight of flocculation precipitate and the removal effect of total nitrogen,total phosphorus and COD in starch wastewater were compared and analyzed when three flocculants PAM,PFS and Poly Aluminium Chloride(PAC)were treated separately and two inorganic flocculants(PFS and PAC)were combined with organic flocculant PAM.The results showed that the PFS+PAM group had the best removal effect on total nitrogen and total phosphorus in the combination of the two inorganic flocculants and organic flocculants,and the flocculation precipitate had the highest quality,the removal rate of total nitrogen and total phosphorus was 35.15% and 33.84% respectively,and the weight of flocculation precipitate was 675.1 mg.PAC+PAM group had the best COD removal effect(39.89%).The combined use of inorganic flocculant and organic flocculant has better removal effect of total nitrogen,total phosphorus and COD in water than that of single use,which indicates that the combined use of inorganic and organic flocculant overcomes the shortage of single flocculant and gives play to their respective advantages.(2)The study on the factors affecting the removal of total nitrogen,total phosphorus and COD in starch wastewater by the combination of PFS+PAM showed that the optimal dosage,optimal initial pH value and optimal temperature of water samples in the PFS+PAM group were PFS 120 mg/L and PAM 20mg/L,respectively,at 9,25 ?.Under optimized conditions,the PFS+PAM compounding treatment had the highest removal rates of total nitrogen,total phosphorus and COD in the water body,which were 42.96%,51.94% and 52.91%,respectively.This indicated that the PFS+PAM compounding treatment could effectively remove total nitrogen,total phosphorus and COD in the water body of starch wastewater,which alleviated the pressure for the later stages of treatment.(3)The monitoring period,the system of the water without the Suspended solid,Suspended Solids,SS)average concentrations of ammonia nitrogen in 0.46 mg/L,pH stability in 7.89~8.21,the average removal rate of 98.58% of total nitrogen,total phosphorus,the average COD removal rate of more than 99%.System outlet main pollutant concentrations reach “The surface water environment quality standard ”(GB3838-2002)of ? class water discharge standard,satisfy the requirement of enterprise standards.(4)PLFA analysis was conducted on the water bodies in different treatment stages of starch wastewater from a quick-frozen food factory.It was found that the microbial structure of the water body changed,the microbial communities in each treatment stage were significantlydifferent,and the PLFA contents and types of various microbial communities were also different.With the progress of treatment,the pollutants in starch wastewater(Total nitrogen,Total phosphorus,COD,etc.)gradually decreased,which showed a positive correlation with the content of PLFA in each treatment stage.Above all,flocculation precipitation and the submerged plant combination of MBR integration equipment starchy wastewater treatment have promote role,“flocculation precipitation pretreatment + anaerobic aerobic reaction processing + MBR integration +submerged plant ecological ditch purification treatment” the combination of the process can be used as starch wastewater treatment process based on enterprise upgrading technology solutions.