Li Xuan, Johnson Ian, Mueller Kara, Wilkie Simeon, Hanzic Lucija, Bond Philip L, O'Moore Liza, Yuan Zhiguo, Jiang Guangming
Advanced Water Management Centre, the University of Queensland, Australia; School of Civil, Mining & Environmental Engineering, University of Wollongong, Australia.
Council of the City of Gold Coast, Gold Coast, QLD 4211, Australia.
Sci Total Environ. 2022 Feb 1;806(Pt 3):151328. doi: 10.1016/j.scitotenv.2021.151328. Epub 2021 Oct 28.
Microbially influenced concrete corrosion (MICC) in sewers is caused by the activity of sulfide-oxidizing microorganisms (SOMs) on concrete surfaces, which greatly deteriorates the integrity of sewers. Surface treatment of corroded concrete by spraying chemicals is a low-cost and non-intrusive strategy. This study systematically evaluated the spray of nitrite solution in corrosion mitigation and re-establishment in a real sewer manhole. Two types of concrete were exposed at three heights within the sewer manhole for 21 months. Nitrite spray was applied at the 6th month for half of the coupons which had developed active corrosion. The corrosion development was monitored by measuring the surface pH, corrosion product composition, sulfide uptake rate, concrete corrosion loss, and the microbial community on the corrosion layer. Free nitrous acid (FNA, i.e. HNO), formed by spraying a nitrite solution on acidic corrosion surfaces, was shown to inhibit the activity of SOMs. The nitrite spray reduced the corrosion loss of concrete at all heights by 40-90% for six months. The sulfide uptake rate of sprayed coupons was also reduced by about 35%, leading to 1-2 units higher surface pH, comparing to the control coupons. The microbial community analysis revealed a reduced abundance of SOMs on nitrite sprayed coupons. The long-term monitoring also showed that the corrosion mitigation effect became negligible in 15 months after the spray. The results consistently demonstrated the effectiveness of nitrite spray on the MICC mitigation and identified the re-application frequencies for full scale applications.
下水道中微生物影响的混凝土腐蚀（MICC）是由混凝土表面硫化物氧化微生物（SOMs）的活动引起的，这极大地破坏了下水道的完整性。通过喷洒化学药剂对腐蚀的混凝土进行表面处理是一种低成本且非侵入性的策略。本研究系统评估了在实际下水道检修孔中喷洒亚硝酸盐溶液对减缓腐蚀和恢复原状的效果。两种类型的混凝土在下水道检修孔内的三个高度处暴露21个月。在第6个月时，对已出现活性腐蚀的一半试块喷洒亚硝酸盐。通过测量表面pH值、腐蚀产物成分、硫化物吸收速率、混凝土腐蚀损失以及腐蚀层上的微生物群落来监测腐蚀发展情况。在酸性腐蚀表面喷洒亚硝酸盐溶液形成的游离亚硝酸（FNA，即HNO）被证明可抑制SOMs的活性。亚硝酸盐喷洒在六个月内使所有高度处的混凝土腐蚀损失降低了40 - 90%。与对照试块相比，喷洒试块的硫化物吸收速率也降低了约35%，导致表面pH值高出1 - 2个单位。微生物群落分析显示，喷洒亚硝酸盐的试块上SOMs的丰度降低。长期监测还表明，喷洒后15个月，腐蚀减缓效果变得微不足道。结果一致证明了亚硝酸盐喷洒对减轻MICC的有效性，并确定了全规模应用的重新喷洒频率。
