Microorganisms Mixed With Calcium Carbonate Scale To Generate The Dynamic Behavior Of The Water System

Fouling is one of the problems widely existing in many fields. It wastes energy and damages human being's health. There are several types of fouling in practical processes, which interact, effect and usually mix together on heat-exchanger surfaces and biomaterials in man's urethra, blood vessel and so on.A new experimental device was designed to investigate the mixed fouling梞icrobial and calcium carbonate (CaCO3) fouling common in water systems. In the experiment, the concentration of pseudomonas fluorescens was kept constant, but the saturation level of CaCO3 was altered with different levels. Then the change regularities of the characteristics of mixed fouling growth curves, its growth period, average mass etc were studied on different material surfaces. Meantime, the dynamic behavior of the mixed fouling growth was observed and recorded by means of micro-video technology. The mixed fouling structures and properties were investigated and its formation mechanism was analyzed.The results show that the average mass of the mixed fouling is less than that of the biofouling. In the unsaturated CaCO3 solution, the average mixed fouling mass is little; but in the saturated CaCO3 solution, with the saturation level of CaCO3 and bulk velocity increasing, the average mass and induction period of the mixed fouling reduce. The mixed fouling mass on non-metallic material surfaces is more than that on metal material surfaces. It has been also found that CaCO3 particles were adsorbed to the surfaces firstly, then microbes. The existence of CO32- and Ca2+ inhibits the activity of bacteria in some degree, so the bacteria secrete less slime and catch less CaCO3 particles.Finally, a comprehensive evaluation and prediction model was built with neural network method. The induction period and average mixed fouling mass on different materials were calculated according to the chemical compositions of solid materials, bulk velocity and the saturation level of CaCO3. It shows that the model could evaluate and predict the mixed fouling development well under different conditions.