Research finds common coagulant could corrode sewers

摘要

A research team at the University of Queensland have discovered that a common coagulant used in drinking water treatment can be a prime contributor to global sewer corrosion. Aluminium sulphate (alum) is widely used as a coagulant as it is relatively cheap and widely available. The aluminium binds to particles in water and is removed as part of the treatment process, but the soluble sulphate remains in the treated drinking water. The paper, published in the journal Science, reveals that the coagulant is the main source of over 50% of the sulphate found in wastewater, which in turn is indirectly the primary source of hydrogen sulphide. This gas is well known as the cause of rapid degradation in concrete sewers, sometimes reducing their life by up to 90%. The mechanism for the degradation is the presence of microbes on sewer walls that take up the hydrogen sulphide and oxidise it to form sulphuric acid, an extremely powerful agent for corroding concrete.