Study On Preparation Of The Magnetic Porous Ceramisite With Sludge And Its Application On Wastewater Treatment

The waste sludge is a kind of solid waste,what has a huge number and complex components. The waste sludge must be handled and disposed properly in order to prevent secondary pollution. The waste sludge was used to produce the porous ceramic, that was a good way to use of the waste sludge. Biological contact oxidation process is a more practical method of wastewater treatment, what has been applied to a variety of wastewater treatment. Physical and chemical properties of the water which was magnetized will be changed, the magnetic field can increase the biological activity of microorganisms in water,and improve the ability of microorganisms to the adsorption and degradation of organic pollutants and the effect of the biological wastewater treatment significantly.This dissertation includes the study of using waste sludge to prepare the porous ceramics,optimization of the production process,magnetic modified sludge ceramsite fille,a nd treatment of coking wastewater, landfill leachate application to the experimental study. The main conclusions were gained as follows:(1).The porous ceramic is preparated by sewage sludge, flocculation sludge as the main raw material, quartz, coal as auxiliary materials. Orthogonal and uniform design, the various factors affect the performance of porous ceramic, find the regression equation and the optimum conditions. The preparation of porous ceramic optimized formula is that municipal sewage sludge16.67%,quartz33.33%,sludge flocculation25%,the amount of coal25%,the particles of coal0.1mm～0.9mm, conversion time of150min, firing temperature of1230℃.The regression equation and the optimum conditions are found by uniform design, the system of various factors on the properties of porous ceramics. The porous ceramic according to the optimal formula performance is water absorption of57.2%, porosity of60.89%, bulk density of1.065g/m3, compressive strength of1.8MPa, acid resistance of97.1%and alkali resistance of98.3%.(2).The chemically pure magnetite (Fe3O4), which was selectted as the magnetic species, was uniformly mixed with porous ceramics and sodium silicate in accordance with the mass ratio of porous ceramics:sodium silicate:magnetic=X:270:10. A certain magnetic field strength of the magnetic carrier was verbbed after a specific process. At the time of X=200, the magnetic field strength is30～40mGs; at the time of X=400, the magnetic field strength is80～100mGs. The magnetic carrier is applied to the biofilm reactor for the treatment trials of coking wastewater and landfill leachate, in order to verificate the advantage of the magnetic carriers in wastewater treatment. (3).The modified porous ceramisite was applied to the treatment of coking wastewater in a biofilm reactor. The results of comparative experiment showed that, removal efficiencies for COD and NH3-N in the porous ceramisite biofilm reactor were25%～30%higher than that in activated sludge reactor; and15%～20%higher than in bilfilm reactor without biocarrier. Under conditions of aeration flow1.5L/min, aeration duration10h/d, temperature25～30℃, removal efficiencies for both COD and NH3-N in the porous ceramisite biofilm reactor were about90%and the COD and NH3-N of effluent can satisfy the professional emission standard (grade two) of industrial wastewater of PR China(GB18918-2002).(4).At the aeration rate of3L/min, aeration time per day for16h, and landfill leachate was processed by magnetic carrier biofilm reactor, and the removal of COD, NH3-N, lead and hexavalent chromium in the supernatant is more than90%. The concentration in effluent of COD is61.92～65.75mg/L; ammonia nitrogen is22.324.27mg/L; lead is0.0988～0.0621mg/L; hexavalent chromium is0.0471～0.0354mg/L. The indicators have reached the national life Landfill Pollution Control Standard (GB16889-2008) requirements. Compared to the with nonmagnetic carrier and conventional activated sludge process, the MLSS in the biofilm reactor with magnetic carrier was reduced from34.34g/L to28.72g/L, the amount in the biofilm reactor with magnetic carrier was reduced from43.91g to33.86g, which showed that magnetic field could improve the efficiency of sludge reduction.