The effect of iron corrosion in cast iron pipes on the microbiological quality of drinking water: a laboratory and field investigation

Abstract

Iron pipelines are commonly used in old drinking water distribution systems, adding rust to pipe-borne water. Chlorine added to water for disinfection could react with iron that leaches from these iron pipelines, thereby reducing available free chlorine for disinfection. The consumption of dissolved chlorine by iron and consequent effects on the microbiological quality of drinking water were investigated, by spiking Serratia marcescens and Escherichia coli into different known mixtures of Fe 2+ and chlorine. Twenty seven water samples were collected from three water supply systems at the University of Peradeniya, Sri Lanka and investigated for its iron content, residual chlorine and microbial quality. The selected water distribution system is 60 years old and is corroded to a large extent, adding rust to the pipe-bone water. The results indicated that the rate of chlorine consumption in water was directly proportional to the content of Fe 2+ ion in water. The Fe 2+ concentration in drinking water in iron pipelines ranged from <0.01 to 0.64 mg/L, while the desired residual chlorine levels were not obtained. Both total and fecal coliforms were detected in some samples indicating that the disinfection was not effective due to chlorine consumption in the distribution system. It was also observed that a high level of ferrous ions in water was inhibitory to microorganisms by forming iron-bacteria clumps in water.

Effect of sodium silicate on drinking water biofilm development

“…This may present a risk when silicate is used as a water treatment additive. 4. Orthophosphate promoted biofilm growth, but it did not disrupt the community structure in comparison to the biofilms exposed to silicates.…”

“…1,2 Corrosion by-products can react with disinfectant, neutralizing it before it can inactivate microorganisms in the bulk water or biofilm. 1,3,4 To mitigate corrosion, drinking water treatment plants apply corrosion inhibitors while making adjustments to pH and alkalinity. According to a 2019 corrosion control survey, 54% of utilities in the US utilize a phosphate-based corrosion inhibitor.…”

Corrosion resistance of commonly used plumbing materials for water distribution systems exposed to disinfection treatments

“…The formation of this excessively thick, rough corrosion scale explains the reduction in corrosion rate over time, but it is detrimental for water systems because it obstructs the flow passage of the pipes. Furthermore, these conditions might increase the risk of bacteria proliferation, because it has been demonstrated that they cause a consumption of disinfectant [5,26].…”

Salophen Anchored Silver Nanoparticle as Nanoprobe Designed for Selective Sensing and Antibacterial Activity

“…Specifically, the identification of Fe 2 + and Cu 2 + ions, considered as heavy metal ions, is vital due to their existence in wastewater originated from the various industrial plants. [19][20][21] The taste, colour and aroma of water are generally influenced by the presence of surplus iron in water. Excess intake of iron containing water poses harmful consequences such as liver cancer, diabetes, alzheimer's disease, and other diseases.…”