Water crisis in Flint, Michigan, USA (2014–2015)

Summary

The city of Flint (Michigan, USA) was supplied with drinking water under the contract from Detroit. In 2014 for reasons of economy it was decided to provide for the temporary drinking water supply by rehabilitating the old water treatment plant that abstracted water from the local Flint River. Laboratory studies of the Flint River water were carried out; however, the corrosiveness index either was not determined or ignored; as a result orthophosphate corrosion inhibitor was not dosed into the water. In the municipal water distribution system and many houses up to now lead pipes and lead-containing fittings have been used. Under the circumstances the concentration of lead in water increased sharply. The existing municipal water quality monitoring system and sampling practice were focused mainly on concealing the low water quality. Numerous complaints of the residents, manifestation of exanthematous disease after using hot water, elevated lead concentrations in children’s blood led to announcing the emergency situation in the city and taking measures to investigate on the federal level the true situation with water contamination with lead.

Key words

potable water , corrosiveness , disinfection byproducts , water crisis , lead contamination , sampling

Study of drinking water aggressiveness in the Samara municipality

Summary

The results of studying corrosion rate and steel pipe passivation time in the water distribution network of the Samara municipality are presented. To determine the rate of corrosion the gravimetrical method was used. Surface (the Volga River) and underground water (treatment facilities of the Kuibyshev Region) was used as a test object. The experimental studies showed that river water was corrosive in relation to steel pipes: the corrosion rate reached 0.1665 g/(m²·h) on the fifth month of exposure so far, whereas the samples had severe pitting (one month) and crater (5 months) injuries. The values of the corrosion rate in underground water were in the range of 0.01–0.06 g/(m²·h), and the investigated samples did not have any significant corrosion injuries. The experiment timing was not enough to complete passivation. By the example of the sample (50 years working service) it was shown that complete passivation of steel pipes with corrosion processes extinction and material integrity maintaining was possible; however, later the interior face of the pipe bottom line became covered with corrosion deposits (7 mm thick). The results of studying the drinking water aggressiveness demonstrate the following: complete passivation of the interior face of steel pipes is provided by the formation of dense corrosive deposits; the growth of the corrosive deposits results in the decline of the pipe capacity; external corrosion of a non-insulated steel pipe under the wet conditions dominates and results in the formation of blue holes. Replacing steel pipe with plastic ones is economically sound.

Key words

corrosiveness , steel water pipes , corrosion injuries , electrochemical corrosion , gravimetric method

Evaluation of the expediency of utility drinking water stabilization

Summary

Statistic, experimental and design data on the parameters influencing Samara tap water corrosiveness in relation to metallic materials of the pipelines are presented. The possibility of using pH correction and dissolved oxygen elimination methods for stabilization and water corrosiveness reduction is shown. The parameters of a pilot plant operation for catalytic deoxygenation are given.

Key words

water stability , Langelier index , corrosiveness , deoxygenation , palladic catalyst