Solutions to fouling in power station condensers

The chlorine use was banned in the Italian Lagoon of Venice, as a consequence, alternative antifouling treatments had to be tested, optimised and, finally, adopted. Now, chlorine dioxide is in use in many plants instead of sodium hypochlorite. Peracetic acid (as antislime) and ammonium quaternary salts (as molluschicide) are also employed in some cases. The treatments are often combined with in-service mechanical cleaning, reducing significantly their cost. The dosage of the alternative oxidant products, now in use, has been optimised by the electrochemical monitoring system BIOX. As requested by Italian regulation, toxicity tests were performed and passed successfully before the adoption of each new treatment. Furthermore, new type of treatments, based on electrochemical low production of oxidant, were also preliminary tested, without significant production of trihalomethanes. The present paper illustrates some detail about the new treatments.