| The water resources are developed and polluted more and more severely with the development of economy. To maintain the persistent progression of the country's economy, we should protect the water resources. At the same time, we should strengthen the treatment of the polluted area. The methods of treatment basically include physical, chemical and biological methods in all. Due to the restriction of the physical and the chemical methods in some fields, they aren't greeted more than the biological method. Compared to them, the biological method has the merits of little energy exhaustion, high purification level and can be used persistently, etc. Biofilm is immobilized on the surface of some carrier and dispose deleterious substance by the microbe on the surface of the carrier. According to different carriers, the biofilm has many types. Choosing suitable carrier and promoting the transmission of nutrition was the key of biofilm technics. The experiment was done according to these problems. Usually, the carriers include plastic, stone and so on. The structure of the biofilm formed is aerobic layer, anoxic layer and anaerobic layer from the inner to the outside. The microbe on the surface of the hollow fibre membrane got oxygen permeated from the inner side so that the structure was different from the traditional type and the efficiency of oxygen usage was heightened. It was known from the experiment that the ORP of the biofilm on the surface of the hollow fibre membrane made of "PES"was +210mV and the DO in the solution was 4.4 mg/L. The microbe would adhere to the surface of the hollow fibre membrane after it was formed in the activated sludge one week. This type of biofilm could dispose of low concentrated organic wastewater well and the removal efficiency could reach 70%. The microbe on the surface included Vorticella,Epistylis,Carchesium etc and one layer of white filar biofilm was formed that is Sphaerotilus film. This type of biofilm was aerobic inside so that it could adhere to the carrier closely. Different concentrated FeCl3, WST and PAM were used to treat with membrane to shorten the length of the microbe's adhesion time. The time was shortened because the fibre treated with had static gravitation and glutinosity. The experiment before biofilm formation proved that high concentrated chemical could restrain the growth of the microbe while some microbe would adapt slowly and grow quickly after. The result of biofilm formation on the treated fibre showed that the fibre treated by FeCl3 would adsorb a film of microbe after few minutes and the fibre treated by WST and PAM would adsorb a film of microbe after 1～2 days. So the adsorption time was shortened. After the biofilm formed successfully, the activity of it was about 34.6mgO2/gMLSS.h and the depth of it was about 3mm. The former reactor (Example: Figure 3.1) only prolonged the HRT through adding some baffles and the water flowed laminarly. So some dead angle and short flow would occur. At the same time the nutrition diffusion efficiency was low because the lack of disturbance due to the bubbleless aeration. We used "Hgh Eficiency Tiny Eddy Coagulation Theory"to design new reactor (Example: Figure 1.2).The reactor included a few of chambers and one board was installed in the bottom of each chamber. The board was apertured so that the water stired strongly and the effection of nutrition diffusion was intensified. In the experiment, we used ink to watch on the water flow. The water would disorganize after it flew through the pores of the board. "Smoke-feathered Shape"water flow would be clearly observed after each pore. Additionally, the water would diffuse to the center from the pores around because the pressure inside was comparatively low. Thus the nutrition could diffuse to the microbe on the surface of the hollow fibre membrane better. To solve the problem that microbe were difficult to attach because the surface of hollow fibre membrane was smooth, PVA was used to embed the microbe on the surface of the hollow fibre membrane in this experiment. The run of the embeded membrane in the new type reactor proved that the removal efficiency could reach 90%. The removal efficiency of Ammonia was good... |
