Increased Resistance of Nitrite-Admixed Concrete to Microbially Induced Corrosion in Real Sewers

Abstract

Microbially induced concrete corrosion is a major deterioration process in sewers, causing a huge economic burden, and improved mitigating technologies are required. This study reports a novel and promising effective solution to attenuate the corrosion in sewers using calcium nitrite-admixed concrete. This strategy aims to suppress the development and activity of corrosion-inducing microorganisms with the antimicrobial free nitrous acid, which is generated in situ from calcium nitrite that is added to the concrete. Concrete coupons with calcium nitrite as an admixture were exposed in a sewer manhole, together with control coupons that had no nitrite admixture, for 18 months. The corrosion process was monitored by measuring the surface pH, corrosion product composition, concrete corrosion loss, and the microbial community on the corrosion layer. During the exposure, the corrosion loss of the admixed concrete coupons was 30% lower than that of the control coupons. The sulfide uptake rate of the admixed concrete was also 30% lower, leading to a higher surface pH (0.5–0.6 unit), in comparison to that of the control coupons. A negative correlation between the calcium nitrite admixture in concrete and the abundance of sulfide-oxidizing microorganisms was determined by DNA sequencing. The results obtained in this field study demonstrated that this novel use of calcium nitrite as an admixture in concrete is a promising strategy to mitigate the microbially induced corrosion in sewers.

Improving wastewater management using free nitrous acid (FNA)

“…Compared with conventional approaches, FNA spraying is more costeffective and environmentally-friendly to mitigate the sewer corrosion as nitrite is cheap and the residual nitrite is biodegradable in wastewater. Aside from mitigation/rehabilitation of the corrosion in existing sewers, in a recent study, FNA achieved a long-lasting effect on inhibiting the growth and activity of acidophilic SOM on the concrete surface by blending calcium nitrite into concrete (Li et al 2019). With the nitrite admixed concrete, around 30% reduction in sulfide uptake rate was observed in comparison to the concrete without the nitrite admixture, during 18 months of exposure in a real sewer system (Li et al 2019).…”

“…Aside from mitigation/rehabilitation of the corrosion in existing sewers, in a recent study, FNA achieved a long-lasting effect on inhibiting the growth and activity of acidophilic SOM on the concrete surface by blending calcium nitrite into concrete (Li et al 2019). With the nitrite admixed concrete, around 30% reduction in sulfide uptake rate was observed in comparison to the concrete without the nitrite admixture, during 18 months of exposure in a real sewer system (Li et al 2019). This was accompanied by the same level of reduction in concrete loss (due to corrosion) measured when the admixture was present.…”

Enhancing Concrete and Mortar Properties and Durability Using Pristine Graphene Particles

“…All of the moulds were let to cure for 24 h at ambient temperature. Later, demoulding was carried out and they were cured for 28 days in a solution of lime and water [53]. Different concrete and mortar coupons were prepared for different mechanical and durability tests.…”

The Effect of Liquid Slurry-Enhanced Corrosion on the Phase Composition of Selected Portland Cement Pastes

“…Softening of the concrete surface exposed to sewerage has been reported during normal usage. A solution to this problem could be the addition of nitrites to concrete mixes [14].…”