Research On The Factors Of DMBR And The Application Of Domestic Water Treatment

Low-cost coarse pore materials(non-woven fabrics,steel mesh,nylon mesh,polyester mesh)were used as the supporting material in Self-forming Dynamic Membrane Bioreactor(SFDMBR)and the active sludge deposited initially on the supporting material was called self-forming Dynamic Membrane(SFDM),which obtain the similarity effect with the conventional microfiltration/ultrafiltration membrane.The research concerning the properties of activated sludge was of great significance to the formation and operation of SFDM to improve the stability of SFDMBR.Moreover,the removal efficiency of TN and TP by aerobic SFDMBR was so undesirable as to combine the traditional A/O process with SFDMBR was of great significance to the application of SFDMBR.Firstly,the sludge properties were an important factor affecting the operation of DMBR.For this reason,The effect on dynamic membrane(DM)formation and membrane fouling of normal sludge and bulking sludge was investigated from the aspects of extracellular polymeric substances(EPS),relative hydrophobicity(RH),Characteristics of floc shapes.The results showed that the DM formation of normal sludge was faster than the bulking sludge due to the larger particle size and relative hydrophobicity of the normal sludge and the formation time of the DM was 25 min and50 min,respectively.The cake resistance significantly contributed to the filtration resistance,which accounted for 83.91% and 94.87% of total resistance for normal sludge and bulking sludge,respectively.The large number of filamentous bacteria in the bulking sludge resulted in severe cake fouling.Moreover,the more open and irregular morphology and the more EPS concentration,especially carbohydrates concentrationfor the bulking sludge lead to more severe fouling propensity and higher fouling rate than normal sludge.Secondly,the supporting materials played an important role on the filtration behavior and removal efficiency of pollutants by SFDMBR.A SFDMBR using 500μm wire mesh,polyester,nylon mesh as SFDM supporting material was conducted for long-term operation.The results showed that the filtration behavior of polyester mesh was same to that of steel mesh,which is better than that of nylon mesh.It can run continuously for 8 cycles(200 h)and the stable flux is maintained at 60-108 L·(m2·h)-1.The removal efficiency of COD and ammonia nitrogen was 78% and 90%,respectively.The average removal rates of TP were 28%-37%,and the effect of different materials on the removal of pollutants was of little differences.Finally,concerning the low removal rates of TN and TP by DMBR,the A/O process and DMBR process were combined to construct the A/O-DMBR process,Fermentation liquid of food waste(FLFW)was applied as external carbon source to A/O-DMBR to explore the characteristics of nitrogen and phosphate removal and membrane fouling.Results demonstrated that by adding FLFW,the efficiency of nitrogen and phosphate removal,denitrification and PO43--P release in anaerobic tank enhanced significantly.The concentration of NO3--N decreased from 12.2mg/L to0.27mg/L and PO43--P increased from 2.5 mg/L to 3.5 mg/L in anaerobic tank with the FLFW addition,moreover,the removal efficiencies of NH4+-N,TN and TP achieved98%,76.4%,87.9% respectively.The EPS and specific oxygen utilization rate(SOUR)of the activated sludge in membrane tank increased slightly,while the relative hydrophobicity(RH)decreased from 76.5% to 58% after FLFW addition.It increased the formation time of dynamic membrane,whereas had less influence on membrane fouling by adding the FLFW.