| The key of reducing water resources demanded for the petroleum industry development is reduce complementary quantity of fresh water in the circulating cooling water system. Due to the deficiency of water resources worldwide, refinery wastewater reuse after advanced treatment as circulating cooling water has gained more and more attention.In view of the characteristics of circulating cooling water system, the static experiment was designed. Biofouling formation was accelerated quickly by timing drain concentration. The growth curve of the biofouling was made and the development mechanism was discussed. The capability and component of biofouling which was effected by nutritional substances(BOD5,NH4+-N,TP)and granule was investigated from orthogonal experiment,a series of physiological and biochemical experiment and Polymerase Chain Reaction(PCR). The capability and component of biofouling, cauterization and fouling which was effected by operational conditions(velocity of flow, temperature) were investigated from dynamic simulation experiment.The results are as follow.The concentration and proportion of extra-cellular polymeric substances in the biofouling was changed when the proportion of nutritional substances was changed. The major microbe species was changed. The appearance color was different.Carbon was the most influencing factor for extra-cellular polymeric substances. The concentration of extra-cellular polymeric substances and the wet weight of biofouling were least whene the concentrations of BOD5,NH4+-N,TP were 5mg/L,10mg/L,1mg/L, respectively. This concentration proportion of carbon , nitrogen and phosphorus was the worst condition for biofouling growth.The concentration of particles(CaCO3) can accelerate the development of biofouling. Concentration of extra-cellular polymeric substances, wet weight of biofouling and the detachment ratio of the biofouling were most whene the concentration of particles was 70 mg/L in the circulating cooling water.This was befitting whene the concentration of particles was 50mg/L .The operational conditions(velocity of flow, temperature) can affect on the capability and component of biofouling and the corrosion and fouling of equipment. The concentration of extra-cellular polymeric substances was height, mechanical intensity was strong,and the biofouling quantity ,instantaneous fouling resistance, deposition rate and fouling thickness were lowest whene velocity of flow was 1.0m.s-1and temperature was 30℃.So, The velocity of flow and temperature was suitable for circulating cooling water when they were 1.0m/s, 30℃, respectively.The biofouling can aggravate corrosion of metal. Stainless steel made against microbe development mostly. Carbon steel was in the next place. Plastic material could hasten microbe development mostly. |
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