The Research About The Degradation Of2,4-DCP By Aerobic Granular Sludge

Widespread attention has been attracted by the engineering processes by aerobic granularsludge, which has the characteristics of high efficiency and energy conservation since the90s oflast century. Aerobic granular sludge features impact resistance, short settling time andsimultaneous removal of ammonium and phosphorus. Secondary sedimentation tank can beellipsised, so it saves cost. It can also improve the efficiency of simultaneous removal ofammonium and phosphorus. So we can predict that there is a wide range of application prospectsabout this engineering process by aerobic granular sludge in the field of wastewater treatment.2,4-DCP can be produced in all kinds of processes in daily industrial production.2,4-DCP has abad influence on microbes. Generally speaking, wastewater pretreatment needs adopting. So anew technology should be studied to save energy on the area of wastewater containing2,4-DCP.Basic research about aerobic granular sludge has made significant process. The disposal oftoxic and hazardous substance by aerobic granular sludge has become a new hotspot. Forexample, the wastewater which contains heavy metal ion or Aniline was be treated by aerobicgranular sludge. Therefore, the wastewater that contains2,4-DCP was studied, aerobic granularsludge was used in it. It was studied in sequencing batch airlift reactor （SBAR） using a certainpercentage of glucose and sodium acetate as carbon source, inorganic nitrogen and inorganicphosphorus as microbial nitrogen. Vaccination cultivation and degradation of major pollutantswere studied; In the same reactor, due to the addition of2,4-DCP, the simultaneous nitrificationand denitrification was influenced or not. Adsorption experiments were done in order to furtherdetermine the removal of2,4-DCP. Adsorption data were fitted, so that it can provide the basisfor the theory. The experiment content is divided into the following three parts:1) At the early stage, the selection of seed sludge indicated that anaerobic granular sludge issuitable as seed sludge.The aerobic granular sludge has firm structure and smooth surface.Mature aerobic granular sludge is generally spherical or ellipsoid. The color is light yellow.MLSS is about2500mg/L. The average diameter is1.52mm, and the average wet density is1.036g/cm3. Settling velocity is20.2-60.1cm/min. At stable operation stage, the removal rates ofCOD, NH₄⁺-N and TP are concentrated in80%,80%,50%, respectively.2) The experiment of simultaneous nitrification and denitrification showed that inhibition ofnitrifying bacteria gradually strengthened as the increase of concentration of2,4-DCP. However, the concentration of2,4-DCP has no obvious regularity on denitrifying bacteria. At some certainconcentration, it can stimulate the denitrifying bacteria instead. At10mg/L, the rate ofsimultaneous nitrification and denitrification is the highest and the difference between thenitrification rate and denitrification rate is the minimum; the addition of2,4-DCP has theinfluence on the removal rate of COD and NH₄⁺-N. At10mg/L, the COD removal efficiency isthe highest, and the COD removal efficiency decreased with the increase of the concentrationmore than10mg/L. While the removal rate of NH₄⁺-N increased with the increase of2,4-DCPconcentration. In conclusion, we should balance the influence of all kinds of factors when wethink about the engineering application of aerobic granular sludge. The experimental providesbasic theory support for the treatment of wastewater containing2,4-DCP by aerobic granularsludge.3) The result of adsorption experiment showed that aerobic granular sludge has the capacityto adsorb2,4-DCP. The adsorption capacity is about40mg/g. The thermodynamic sorptionbehavior and mechanism showed that Langmuir isotherm models is more suitable for describingthe process of adsorption comparing with the Freundlich and Tempkin equilibrium adsorptionmodel.It is monolayer adsorption; this absorption process is easy to be performed. Flowresistance mainly affected the adsorption process.Pseudo-first-order and pseudo-second-orderwas presented to describe the adsorption process. We found that the pseudo first-order kineticsmodel was best described the adsorption process indicating that the process is physicaladsorption. However, intraparticle diffusion kinetics model can more accurately describe thisprocess. It reflected all stages of the adsorption. At the early stage,2,4-DCP molecules firstgathered around the surface of the aerobic granular sludge,and then went through the pore intothe interior of the particles; Finally, with the increases of internal diffusion resistance, thediffusion rate was declining, and it achieved the adsorption equilibrium stage. It indicates thatthis process is not only controlled by flow resistance. Other kinetic processes should beconsidered.