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再生水营养物质含量丰富,微生物来源广泛,其输运管网微生物腐蚀尤为严重。采用铸铁Ⅱ型标准腐蚀挂片和某城市污水处理厂出水,利用电化学测试、SEM-EDS等技术,考察了15 d培养期内未杀菌和杀菌条件下再生水中铸铁材料的微生物电化学腐蚀特性及腐蚀产物形貌和元素组成特征。电化学结果表明,与杀菌体系相比,未杀菌体系中生物膜对铸铁材料的腐蚀有先促进后抑制的特性。生物膜在前期形成过程中促进阴极反应从而加速铸铁的腐蚀;后期稳定生长的生物膜会增加溶液中侵蚀性粒子向铸铁表面扩散的电阻,对后期铸铁材料的腐蚀起到抑制作用。表面分析结果表明,生物膜可以缓解铸铁表面的均匀腐蚀,但会产生更为严重的局部点蚀;所形成的腐蚀层中P、Fe元素含量较高,有助于缓解铸铁材料表面的均匀腐蚀。
The reclaimed water is rich in nutrients and has a wide range of microorganisms. The microbial corrosion of transport pipelines is particularly serious. Cast iron Ⅱ standard corrosion coupons and a city sewage treatment plant effluent, the use of electrochemical tests, SEM-EDS and other techniques to study the 15 d culture period of non-germicidal and germicidal conditions of reclaimed water in the iron cast iron material electrochemical corrosion characteristics And corrosion products morphology and elemental composition characteristics. Electrochemical results show that compared with the bactericidal system, the non-bactericidal system biofilm corrosion of cast iron materials first promote the inhibition of the characteristics. The biofilm promotes the cathode reaction in the early formation process to accelerate the corrosion of the cast iron. The biofilm that grows steadily in the late stage will increase the resistance of the aggressive particles in the solution to the surface of the cast iron, thus inhibiting the corrosion of the later cast iron material. The results of surface analysis show that the biofilm can reduce the uniform corrosion on the surface of cast iron but lead to more serious local pitting corrosion. The higher content of P and Fe in the formed corrosion layer helps to alleviate the uniform corrosion on the surface of cast iron .