Experimental Research On The Biochemical Capability Of Landfill Leachate And Numerical Simulation Of UV-Fenton Reactor

Light Fenton technology has advantages in degradation efficiency, range ofapplication and cost. Especially, it applies to the advanced treatment of landfillleachate. In this paper, the leachate from the oxidation ditch of a landfill was treatedto improve its biodegradability. The main test indexes were BOD5/COD and theremoval of COD. Based on the light Fenton technology laboratory test, the feasibilityof improving biodegradability of leachate and the factors effecting the treatment werediscussed. Meanwhile, the flow field of the novel UV-Fenton reactor was simulatednumerically, and the effect of aeration on the treatment efficiency was discussed. Theconclusions were as follows:(1) In this paper, the improvement of landfill leachate’s biodegradability wasresearched by the method of UV-Fenton at first, and effect of the main factors aboutH2O2dosage, n(H2O2)/n(Fe2+), reaction time, aeration and dosing times of H2O on thetreat efficiency was analyzed. The results showed that when the H2O2dosage was10mmol/L, n(H2O2)/n(Fe2+) was1, reaction time was2hours, aeration was2L/minand dosing time of H2O2was forth, the index B/C would reach to0.42, and theremoval of COD would be60%. On this condition, the follow-up treatment’s burdenof removing COD was reduced, and the B/C of leachate would be improved to morethan0.3, and the biodegradability of leachate was improved effectively, which createda good condition for the further biochemical treatment.(2) The three dimensional unsteady gas-water two phase flow in the reactor wassimulated by CFD software FLUENT in this paper. The flow characteristic of aerationof2L/min and4L/min were simulated, and the distribution of gas volume fractionand liquid velocity were displayed from the result of simulation. The consequenceshowed that two-fluid model could well simulate the flow characteristic of two-phaseflow. The distribution of gas volume fraction and liquid velocity were displayed. Asthe increasing of the aeration speed, the gas volume fraction and liquid velocityincreased, the interaction between gas and liquid was stronger and internal circulationbecame faster. At the beginning of the reaction, the bubble rose perpendicularly, and continuously rose along the quartz pipe wall. The liquid was pulled by thebubble and rose along the quartz pipe wall. Because of the conservation of liquidphase, the liquid out of the sleeve appeared backflow phenomenon, which made theliquid generate internal circulation.(3) In this paper, the result of numerical simulation was compared with the resultof experiment on different aeration, and the consequence showed that the increasingof the aeration speed made the gas volume fraction larger and the interaction betweengas and liquid stronger, which indirectly improved the treatment efficiency.