Abstract
Deep insight into the forces driving chloramine decay in different material of pipes is the key to take sound actions to cope with the pipe water quality deterioration. By using the newly developed RTCDM (refined Total Chloramine Decay Model) and pipe section reactor, the role of four typical pipes in disinfection chemistry was qualitatively and quantitatively compared, and the mechanism of pipe wall mediated chloramine decay was further described. As for the four typical pipes studied, the ability of deteriorating water quality, especially for accelerating TCR decay was in the order of cast iron pipe > steel pipe > cement lined ductile iron pipe > polypropylene-random pipe. Cast iron pipe, cement lined ductile iron pipe, and steel pipe with long serving age are characterized by one or two driven forces leading to TCR decay. Aged cast iron pipe could consume chloramine by Fe(0) and microbe (especially for nitrifier) spreading over the inner wall. Aged steel pipe is characterized by aggressive electrochemical corrosion and weak nitrification. Lime and gypsum leaching is the main cause, and nitrification/denitrification may also occur in aged cement lined ductile iron pipe. Polypropylene-random pipe has minimum effect on disinfection chemistry. This knowledge is of value in speculating the reasons leading to TCR loss in the full scale distribution system.
Electrochemical Corrosion Damage Detection Test of Steel Pipe Based on Piezoelectric Ceramics
