Abstract
This research focused on a model setup fed with underground water pumped into a water supply network. The scope of the research included a long- and a short-term stagnation of water in the setup and a water flow of 0.1 m/s. The water supplied into the system gradually lost its corrosive properties and developed calcium carbonate precipitation capability. These processes indicated that cement components migrate from the lining into the water. Apart from the primary components, the presence of the following trace elements was found: iron (399.6 ppb), magnesium (17.8 ppm), zinc (26.9 ppb), barium (22.6 ppb), boron (21.6 ppb), sodium (10.8 ppm), gallium (2.1 ppb). At early stages of the operation, recorded quantities were not significant. Leaching of the trace elements from cement increased after water was chlorinated. In turn, the highest percent increases were observed in the case of zinc (217%), boron (19%) and gallium (12%), whereas the increase for sodium, iron, barium and magnesium in water was insignificant (reaching a few percent). A repeated analysis of samples of stagnant water in the setup showed that most of trace elements were below the detectability level. Final concentrations of all elements identified in the water after its contact with internal cement mortar lining were much lower than the limit values set out for drinking water.
Highlights
Ductile iron is an alloy of iron and carbon in which, during solidification of the casting—owing to the addition of small amounts of magnesium or cerium—graphite nodules are produced
Values of the Langelier Saturation Index (LSI) indicated that water introduced into the setup gradually lost its corrosive properties and the calcium-carbonate balance was observed
The aim of this research was to examine the impact of cement-mortar lining covering the interior surfaces of ductile iron water conduits on the quality of water conveyed in these conduits
Summary
Ductile iron is an alloy of iron and carbon in which, during solidification of the casting—owing to the addition of small amounts of magnesium or cerium—graphite nodules are produced. This form of graphite improves the mechanical properties of the material when compared to grey cast iron. Ductile iron pipes display higher plasticity, which makes them survive local strain without cracking and produces only local pipe deformations. These pipes are highly resistant to lateral stress and high internal pressure. In the case of the water intended for consumption, linings made of Portland cement or alumina cement are usually employed for contact with water characterized by greater corrosivity
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