This paper studied the biofilm properties and corrosion behavior of sulfate reducing bacteria （SRB） on stainless steel 316L （SS316L） surface in circulating cooling water system with and without additives including hydroxy ethyl fork phosphonic acid （HEDP）, dodecyl dimethyl benzyl anunonium chlotide （1227） and NaClO. Biochemical technique, electrochemical technology, X-ray photoelectron spectroscopy （XPS） and scanning electron microscope （SEM） were used. The results show that the extracellular polymeric substance （EPS） in biofilm attached on the SS316L surface mainly contain proteins and polysaccharides, the contents are 98 ug.cm-2 and 635ug.cm-2, respectively. The polysaccharides were cut by 1227 about 80%, while 55% by NaCIO. The proteins were reduced by NaCIO about 53%, while only 30% by 1227. The potentiodynamic polarization shows that the corrosion potential of SS316L was enhanced from -0.495 V to -0.390 V by the chemical additive delaying the occurrence of the corrosion. And the corrosion rate was also reduced from 5.19 × 10^-3 mm·a^-1 to 2.42 × 10^-3 mm＇a . But NaCIO stdl caused pitting corrosion after stenhzmg the bacteria, while 1227 can form a protective film on the surface of SS316L. Though HEDP contribute to the bacteria activity, it can enhance the breakdown potential. XPS results confirmed that 1227 can change the value of C：O in the biofilm attached on metal surface, and NaCIO can eliminate the existence of amidogen. This study would provide some recommendations for the selection of chemical additives in the thermal power plant.
Yu Qi Jin Li Rui Liang Sitong Ji Jianxiang Li Meng Liu
