Ozonation of brewing water.
Egan, L.H., Taylor, K.R. and Hahn, C.W.
Ozone possesses advantages over other disinfectants, such as chlorine, due to its high electronegative oxidation potential, its rapid rate of reaction at levels of 0.5 ppm towards bacteria and organic compounds and its greater solubility in water than oxygen. Ozone has been used to treat two types of water supply, denoted A and B, at a Colorado brewery for the last 2 years and has given total sterility and removed all objectionable tastes in the water. Water A is employed for brewing, blending and product purging and is obtained from springs in the brewery grounds. The water is pumped to a contact chamber where ozone is bubbled in, then through a diatomaceous filter to a secondary contact chamber. Water B is surface water and is used for barley steeping, washing and utility purposes. It is collected and stored in lakes before pumping through a microstrainer to the contact chamber, then to a sand filter and chlorinated. Water leaving the treatment plant has a residual ozone content of 1 ppm. This residual ozone can cause severe corrosion problems if water containing it is heated to 80 degrees C and passed through a piping system such as of 304L stainless steel 6" schedule 5 pipe. Pinhole leaks were found at welds and bends sections of the piping. Various methods of removing the residual ozone such as use of a spraying chamber, vacuum deaerator or activated carbon tower, were found to be unsatisfactory but the addition of sodium metabisulphite to the water just before heating to give a final concentration of 2 ppm, removed the ozone. A Welsbach generator producing up to 225 lbm/day O3, supplied the ozone.
Keywords: effluent treatment ozone water