• Lars R. Bennedsen
  • Jens Muff
4. semester, Kemiteknik, Kandidat (Kandidatuddannelse)
The present thesis considers two closely related topics. The first is contributions to a tender for an examination project called by the Danish EPA concerning tests of alternative techniques for treatment of swimming pool water. The tender was prepared by a consortium between Rambøll A/S and Scan Research A/S, and the project group has evaluated the applicability of a newly developed test trailer to conduct the required tests on swimming pools. The ozone as well as the electrochemical treatment system installed in the trailer were found to be applicable. A search for commercial applications on the Danish swimming pool market and an evaluation of the collected manufacturer experiences revealed that especially UV treatment of swimming pool water is well documented, and the treatment system installed in MarseillisborgCentrets Svømmebad was identified as very applicable as test installation. The second topic is electrochemical treatment of swimming pool water, a technique widely used in Greece, but not implemented in Denmark. Laboratory investigations revealed the chlorine production rate to be 1.69·10-4 mol/min·A in a 0.9 % NaCl electrolyte with a current efficiency of 55 % and energy efficiencies of 6-12 %. The efficiencies were enhanced by increasing NaCl concentration. The cathodic production rate of hydrogen gas was determined to be 3.82·10-4 mol/min·A, and the ratio of 2.3:1 to the chlorine production strongly indicates the formation of other oxidants. By the experimental method of bleaching p-nitroso-dimethylaniline (RNO), the formation of hydroxyl radicals was demonstrated. Ozone is another feasible oxidant expected to be identified in subsequent investigations. Through the bleaching tests, a synergetic effect was found by the presence of chloride in the electrolyte and the electrochemical treatment. In an electrochemical disinfection experiment, a linear logarithmic reduction of E. coli was found, and with a contact time of 0.33 s, a log-3 reduction was obtained at a current of 9 A in a 0.9 % NaCl electrolyte. By model calculations, the disinfection caused by the produced chlorine was estimated to less be than 1 %. A full scale electrochemical treatment system for a 32 m3 swimming pool was dimensioned, and the power consumption was estimated to 2.3 kWh/day. On the basis of the experimental work and the literature study, the project group considers the electrochemical technique as being very well suited for treatment of swimming pool water in Denmark.
Antal sider154
Udgivende institutionAalborg Universitet
ID: 17125979