Study On Preparation And Application Of Fly Ash Biological Padding

With the development of science and industrial technology, more and more wastewater into waters, and threat the human health and quality of life. Any single wastewater treatment technology can not satisfied with the increasing requirement of emissions. More comprehensive treatment technology of domestic wastewater and industrial waste water becomes the mainstream of today's water treatment technology, and bio-contact oxidation process is a great potential method in wastewater biological treatment technology. Bio-contact oxidation process has obvious advantages in dealing with waste-water which containing bio-degradable material and substances which can restraint the growth of microorganisms. In system of bio-contact oxidation process, material,specific surface area and pore structure of filler are the determinants of bio-contact oxidation's processing performance. Pore filler with best performance can gather more microbiology, fixed more spawn, and improve the concentration of oxygen. Thus, improve the anti-force capability of the system. Impact of this study is prepare a kind of filler for bio-contact oxidation with high chemical stability, high biological affinity and high porosity, then film on the surface of these particles to degradate the printing and dyeing wastewater and research the mechanism. The research contents are as follows:1. Selected fly ash, zeolite, bentonite as raw materials, with industrial starch as binder, design a kind of technical system for preparing porous multiple fly ash particles materials. Determine the optimum technological conditions through the Single factor experiment, and the conditions is:fly ash:zeolite=3:7, the percentage of binder is 10%, the percentage of bentonite is 35%, calcination temperature is 600℃, calcination time is 2h.In the best preparation process conditions, porous multiple fly ash particles materials has good physical and chemical properties, the volume density is 1.12kg/m3, uniformity of size, few cracks, dissipation rate is 0.87%, have no dissipation in the static water, decolorization rate of azo wastewater is 98.82%.2. Conduct an morphology on porous multiple fly ash particles materials which prepared under the optimum technological conditions through the SEM. As can be seen that the porous structure on the surface of composite materials is obvious. The pore showing widespread distribution and in different shapes. The aperture between 6μm and 90μm. These holes will provides a high surface chemical activity, at the same time it greatly increased the porosity of composite materials. So its unique surface structure provides the prerequisites for adsorpt degradation the refractory azo dyes in printing and dyeing wastewater. By the material's physical performance test we can see that the porous composite material of fly ash has high compressive strength, specific surface area, porosity and low dissipation rates, these can be prerequisite conditions for recycling.3. Use the porous materials as filler of the bio-contact oxidation unit to do the biofilm experiments, in two weeks time the surface of substrate formed a layer of bio-film and the thickness is greater than 0.2mm.The wastewater's removal rates of COD and BOD reached 55% and 70%,this show the success of bio-film experiments. And then use this device deal with the simulate printing and dyeing waste-water. Under the optimum technological conditions:initial concentration of wastewater is100mg/L, PH is 7, concentration of carbon is 1g/L, concentration nitrogen is 3g/L, dosage of porous materials is 100g/L,when the time of degradation come to 30minutes,the decolorization rate come to 97% and more, the removal rates of COD come to 85% and more.4. Microbial degradation kinetics of azo dyes conform to hyperbolic model. The higher of the initial concentration of azo dyes, the faster of the degradation reaction rate. When the reaction rate constant k of microbial degradation of azo dye was the largest, and the half-life was the shortest.5. Microbial degradation of azo dyes can be divided into three phases:Stage I, chromogenic C-N bond and N-N bond in the molecular structure of azo dyes rupture, escape from the solution forms of N2; StageⅡ, structure with high biological activity generate into intermediate product of aromatic amines with the biodegradation, and the intermediate products accumulation of energy, continues to degrade; StageⅢ, intermediate products with nitrogen-containing structures continue to degrade until the complete decomposition.The results show that:Under the same conditions, the ecolorization and degradation rate of printing and dyeing wastewater, on the one hand depends on the adsorption-oxidation of the porous materials; On the other hand depends on the effect of environmental factors, including nutrient content in wastewater, temperature, ph and DO of the wastewater; In addition, depends on the characterization of organic be degradated.