Suspended Filler Used In Sewage Treatment Plant Upgrade And Demonstration Research Projects

’With the development of Socio-economic and the acceleration of urbanization process, water pollution in China is more and more serious, and serious damage was made to the water environment. Therefore, more attention has been paied to water environment pollution control, the discharge standards of wastewater treatment plant was carried out more stringently. Many WWTTPs (wastewater treatment plants) need upgrading according to the current situation of China’s waste water treatment plants operation, especially in northern China. To resolve instability of WWTTPs’effluent ammonia, we propose a solution by using suspended filler in existing sewage treatment processes. The suspended filler plays an important role in the enhancement of nitrification and microbial enrichment. Tracking and monitoring of the WWTTPs treatment effect has been taken after the demonstration projects’upgrading.As the core of the MBBR process, the suspended carrier’s selection is vital to the process’operation performance. The selection of suspended filler and the influencing factors of the nitrification enhancement were discussed. A SBR pilot plant was built to test the suspended filler’s applicability in the sewage treatment process. And the demonstration WWTTPs’operation performance was tracking and monitoring before and after the upgrading.Suspended filler doesn’t only affcets the HRT of the waste water; it also plays an important role in reducing energy consumption, especially the energy consumption in aeration tank. Accord to the fluidization experiments’results, suspended filler that density less than1g/cm3(0.94-0.97g/cm3) is easier to to fluidizing, while suspended filler that density more than1g/cm3(1.00-1.05g/cm3) caused higher aeration rate and more energy consumption. In the investigation of oxygen transfer efficiency, the results turn out that suspended filler that density less than1g/cm3is more efficiency.Nitrification rate and the fill rate of suspended filler are in good quadratic function relationship. The nitrification rate of composite system of active sludge and suspended filler biofilm reach the highest as the fill rate reached75%. However, while the fill rate reached a certain degree the fluidization of suspended filler became harder. In consideration of fluidization, energy consumption, and nitrification rate of suspended filler at high fill rate, the reasonable limits of fill rate should be30%-50%.During the operation of the SBR pilot plant, the operation cycle was carried out at8h,6h and4h, respectively. The operation performance turns out that the operation cycle6h was stable and efficiency. Operation stages during a cycle are inflowing, stirring, aeration, sediment, effluenting and standing, and corresponding time are22min,120min,120min,30min,38min and30min. The removal rate of COD、TN、 NH4+-N are88%,74%and96%, while the aeration rate and the fill rate are20-25m3/h and30%.The enhancement of nitrification rate in composite system was more obvious with lower temperature(11-15℃). Nitrification rate in the composite system was even more than100%higher than it in the active sludge system. Ehancement in the higher temperature is not so clear.The relationship between temperature and nitrification rates is in line with Arrhenius equation in the heating and cooling during experiment of composite system and active sludge system. The relationship can be expressed as rT=r(20)·(?)(T-20). In the heating process(?)=1.0385in the composite system, lower than it in active sludge system; while in the cooling process,(?)=1.1659in the composite system, lower than it in active sludge system, which means that heating process the nitrification rate in the composite system varied more intensely, and cooling process nitrification rate in the composite system varied less.Composite system was favorable to low temperatures, eapecially in winter. After the upgrading, ammonia of demonstration WWTTPs effluent keeps staying lower than5.0mg/L. Energy in the aeration tank was lower after upgrading, since the application of suspended filler enhanced the transfer efficiency. Investigation of energy consumption in Jining WWTTP’s aeratation tank has showed that aeration rate was reduced to69452m3/d,6.1%lower than before. Especially in January-February when the temprerature is low, aeration rate was even cut off by29%.’Biomass and proportion of nitrobacteria of suspended filler and active sludge were both tested. The test results showed that biomass on suspended filler were more than30%in composite system, and Luchun WWTTP’s even reached59%. Results of plate count method showed that nitrobacteria were more active in the suspended filler than it in the active sludge. By using FISH (fluorescent in situ hybridization) the proportion of nitrobacteria of suspended filler and active sludge was tested.The results showed that the nitrobacteria proportion of suspended filler was higher than it in active sludge, which is more than55%, the supreme proportion of nitrobacteria in suspended filler can reach73.3%.