In this study,the influence of hydraulic retention time on feasibility,efficiency and membrane foul- ing of slightly polluted surface water treatment by a high concentration PAC-MF bioreactor were investigated. During three months operation,TOC,NH4 + -N,nitrobenzene,and TMP were measured to evaluate the MBR performance. The results show that,when HRT reduces from 3 h to 1 h,removal efficiency of TOC and ammonia-nitrite decrease a little. However,there is little effect of HRT on nitrobenzene. And the optimal hydraulic retention time is 1 h.
A novel NF membrane prepared with poly（amidoamine） （PAMAM） dendrimer and trimesoyl chloride （TMC） by interfacial polymerization on polysulfone （PSF） ultrafiltration membrane was investigated. Field emission scanning electron microcopy （ FESEM）, atomic force micrograph （ AFM ） and contact angle （CA） of pure water on PA and PSF substrate were employed to characterize the chemical and physical properties of membranes. The PAMAM concentration, retention of salt solutions and organics were studied on the performance of the NF membrane. From the analyses of SEM and AFM, the polyamide active skin layers of the composite membranes are dense, rough, and finely dispersed nodular structures, packed tightly by the spherical globules. The contact angle of PA nanofitration membrane decreased after polymerization. The higher PAMAM concentra- tion can result in lower flux and higher rejection. The salt rejection of PA membranes decreases in the order K2 SO4 〉 Na2 SO4 〉 MgSQ 〉 MgC12 〉 CaC12 〉 NaC1, which indicates that the resulting membranes is nagatively charged. The pH increases from 3 to 10 in the feed resulting in the decrease of the flux and the increase of the rejection for NazSO4 solution. The molecular weight cut off （MWCO） of the composite NF membrane is nearly 860 kg/mol. The resulted PA membrane can be used to seoarate small organics and salt solutions.
In the present study,nano-sized TiO2 /Al2O3 modified PVDF membranes (MM) were fabricated and utilized for anionic polyacrylamide ( APAM) separation. The results showed that,compared with PVDF membrane (OM) ,the contact angle of MM decreases from 83. 64° to 67. 42°,which indicates the increase of the hydrophilicity of MM. The relative flux (RF) decline curve of this ultrafiltration of APAM in water with time shows an obvious two stage properties. The cake filtration models were used to predict the performance of different time over the complete range of filtration times. All the four cake models could simulate this UF process to a certain extent,and the suitability of the two kinds of membranes was: cake filtration > intermediate pore blocking > standard pore blocking > complete pore blocking models. However,they became more and more unsuited to this process with time extending. Surface and cross-sectional morphology of membrane was investigated by SEM to make an advanced certificate of this UF mechanism.
