Study On Treatment Of Polluted River Water With Combined Packing SBBR

In this study, combined fibrous packing (Model NO.ZH) was added into a Sequencing Batch Reactor (SBR) system. Compared with a conventional SBR, the laboratory-scale Sequencing Batch Biofilm Reactor (SBBR) fed with synthetic polluted river water was designed to investigate the performance of pollution removal. Specific objectives of the research were to investigate the effect of changing conditions on COD_Cr removal, nitrate removal and total nitrogen removal. This study is mainly divided into three parts. Firstly, the optimal operating cycle was defined through orthogonal test. Secondly, effect and removal characteristic of influent NO3--N concentration, pH, C/N, temperature on the pollution removal were studied based on the steady system. Thirdly, the sludge activity of SBR and SBBR including nitrosation activity, nitrification activity and denitrification activity were investigated in batch experimental apparatus. The conclusions of this study can be summaried as follows:(1)According to the orthogonal test (three factors and three levels) and operation condition, the optimal operation cycle was determined: 10 min filling, 4 h first anaerobic stirring, 1 h aeration, 2 h second anaerobic stirring, 50 min settling and drawing for SBR and SBBR. On the optimal operation cycle of the long and steady run, the COD_Cr, NO3--N and total nitrogen removal efficiency of SBR and SBBR were 97.28% and 96.57%, 99.91% and 99.74%, 99.51% and 99.24% respectively.(2)Both in SBR and SBBR, with the increase of influent NO₃^--N concentration, COD_Cr removal efficiency were slightly affected while NO₃^--N and total nitrogen removal efficiency decreased significantly. SBBR showed higher removal rates of NO₃^--N, TN, and more stable operation with higher influent NO3--N concentration.Typical profiles of NH₄+^-N,NO₂^--N, NO₃^--N and COD_Cr concentration in a cycle of SBR and SBBR were hardly affected by the change of influent NO₃^--N concentration. However, there existed discrepancy between SBR and SBBR. Easier nitrite accumulation and higher adsorption of COD_Cr in SBR were observed.(3)The COD_Cr removal efficiency of SBR and SBBR both achieved highest at pH value of 7.0, lowest at 6.0. While NO3--N and total nitrogen removal efficiency achieved highest at 7.0, lowest at 9.0. The effect of influent pH on the performance of pollution removal is a little more remarkable in SBR than that in SBBR.Rates of NO3--N reduction, NO2--N accumulation and NO2--N reduction during NO2--N accumulation phase of denitrification were affected by influent pH. With the changing influent pH, variation of pH in a cycle stayed relatively stable both in SBR and SBBR, with the initial little increase and latter slight decrease, through which a good performance may be achieved.(4)The variety of influent C/N hardly affected the COD_Cr removal efficiency, while the effluent concentration of NO₃^--N and TN increased drastically with the decrease of influent C/N from 5.4 to 2.7. The nitrogen removal efficiency showed no advantage when influent increased from 5.4 to 8.4. Totally, SBBR made a better performance than SBR, especially at C/N of 2.7.(5)With low operation temperation, the pollution removal efficiency hardly decreased in SBBR. Although COD_Cr removal efficiency decreased slightly, a large amount of accumulation of NO₂^--N in effluent was observed in SBR.(6)Due to the high influent NO3--N concentration and long-term anaeration operation conditon, the denitrification activity is higher than the nitrisation activity and the nitrification activity both in SBR and SBBR. The use of nitrate concentration as the sole parameter of the denitrification rate is not accurate, for nitrite accumulates more obviously in SBR than in SBBR.