Kefeng Zhang

Research on the Treatment for Ozone-Flocculation Filter from Yellow River

This paper mainly based on the new processes of ozone-floating filter and ozone floatation which were tested in the water from the Queshan Reservoir. The process of ozone floating filter stated that little influence ccurred when the raw water was pre-treated by the ozone. UV254(Ultraviolet Rays)was removed in large amount (76.47%) if the ozone oxidation had been adopted. The removal rate could achieve 100% when the air flotation and activated carbon filtration were used. Ozone oxidation has good effects on the removal of COD（Chemical Oxygen Demand）Mn, the total removal rate was increased 7.0% in average rather than the technology without ozone, and the final content in the effluent was 1.87mg/L. in the new technology, ozone flotation did little job to decreasing turbidity. And the great progress was the removal of UV254 through the strong ability of oxidation. The removal rate was increased 9.80% in average rather than floating filter technology.

Research on CFD numerical simulation and flow field characteristics of countercurrent-cocurrent dissolved Air flotation

Countercurrent-cocurrent dissolved air flotation (CCDAF), the popular water purification device, which consists of collision and adhesion contact zones, showed favorable flotation conditions for micro-bubble adhesion and stability. In this study, computational fluid dynamics (CFD) numerical simulation was employed to confirm that the unique CCDAF configuration create reasonable and that the flow field characteristics were good no matter for single phase or gas-liquid two-phase conditions. In addition, the turbulence of the flow field was enhanced with the increasing influent load; the swirling was remarkably reduced with the increase of gas holdup. Meanwhile, a thick micro-bubble filter layer was formed in the separation zone, which favored bubble-flocs agglomerating and rising. The force analysis also showed that the cross section within the tank contribute to the uniformity of the bottom water collection as well as enlargement of the bottom outflow area, therefore improving the overall flotation performance. The simulation results revealed for the CCDAF process can provide technical guidance for engineering design and application.

Investigate of in situ sludge reduction in sequencing batch biofilm reactor: Performances, mechanisms and comparison of different carriers

Biofilm is an effective simultaneous denitrification and in situ sludge reduction system, and the characteristics of different biofilm carrier have important implications for biofilm growth and in situ sludge reduction. In this study, the performance and mechanism of in situ sludge reduction were compared between FSC-SBBR and SC-SBBR with constructed by composite floating spherical carriers (FSC) and multi-faceted polyethylene suspension carriers (SC), respectively. The variation of EPS concentration indicated that the biofilm formation of FSC was faster than SC. Compared with SCSBBR, the FSC-SBBR yielded 0.16 g MLSS/g COD, almost 27.27% less sludge. The average removal rates of COD and NH4+-N were 93.39% and 96.66%, respectively, which were 5.21% and 1.43% higher than the average removal rate of SC-SBBR. Investigation of the mechanisms of sludge reduction revealed that, energy uncoupling metabolism and sludge decay were the main factors for sludge reduction inducing 43.13% and 49.65% less sludge, respectively, in FSC-SBBR. EEM fluorescence spectroscopy and SUVA analysis showed that the hydrolytic capacity of biofilm attached in FSC was stronger than those of SC, and the hydrolysis of EPS released more DOM contributed to lysis-cryptic growth metabolism. In additional, Bacteroidetes and Mizugakiibacter associated with sludge reduction were the dominant phylum and genus in FCS-SBBR. Thus, the effect of simultaneous in situ sludge reduction and pollutant removal in FSC-SBBR was better.

The Research of the Flofilter Technology with Micro-Flocculation and GAC Sand to Treat Eutrophic Water

The water quality characteristics of Jinan Queshan reservoir (which derived from Yellow River) are low turbidity and algal bloom. Based on those characteristics， the flofilter technology with flotation and filtration was developed, which was conducted to dispose of the eutrophic water with the algal bloom from Queshan Reservoir. The tested result stated that the removing rate of total algae was 72.01%~81.45% through the flofilter technology when the dose of PAFC (Al3+) was 2mg/L,and the average removing rate was 76.31%.The total removing rate of chlorophyll was 62.29%~79.51%, and the average rate related was 71.26%. The effluent turbidity was 0.03~0.39 NTU, and the average value was 0.24NTU. The flofilter technology has the positive effects on the removing rate of CODMn and UV254 during the stage of algal bloom. The amount of CODMn in the effluent was 0.52~1.72mg/L, the average value was 1.26mg/L.The UV254 in the effluent was 0.003~0.029cm-1, and the average removing rate was 77.02%, and the test showed the flofilter has a significant effect on water purification.

Influence of Pre-Ozonation on Coagulation of Micro-Polluted Surface Water from Yellow River

Although ozone was widely used before coagulation in water treatment, the influence of pre-ozonation on the coagulation for removal of particle and natural organic matter (NOM) from micro-polluted surface water is still unclear. A pilot investigation of the influence of pre-ozonation on coagulation of the micro-polluted surface water from Queshan reservoir which derived from Yellow River was carried out in this paper. The results showed that the coagulation for particle and NOM removal of the micro-polluted Yellow River water was enhanced greatly after ozone oxidation and the optimized coagulation efficiency was observed at ozone dosage 3.0 mg/L. Moreover, the enhanced coagulation under the influence of pre-ozonation was compared with the traditional one in terms of coagulation efficiency, whereas the removal efficiency of turbidity, color index, UV254 and CODMn were increased in 24%, 27%, 35%, and 15% respectively.