Controlling organics in brewing water.
The author describes the evaluation of procedures for the treatment of municipal water supplies in order to ensure their brewing quality. Raw water contains humic substances categorised as total organic carbon (TOC) and largely unidentified. These may react with chlorine, following the normal water chlorination process to form chlorinated compounds. The primary water treatment approach in the brewery has been the use of granular activated carbon in order to control taste and odour problems and to strip chlorine from the water. Frequent variation in inlet water quality both with respect to TOC loading and to the range of compounds present often leads to reduced organic adsorption and to unpredictable desorption so that full time protection cannot be guaranteed. Pretreatment methods were tried aimed at reducing the organic load in the incoming water with a view to improving the consistency and efficiency of carbon treatment. Ozonation and aeration of the water, attempted first on laboratory scale and subsequently on full scale, gave a more consistent, higher quality water. Ozonation resulted in the oxidation of phenolics and other compounds and reduced TOC by 50% to 60%. Aeration led to 80% reduction in trihalometanes and eliminated 95% of the residual O3. The result was that the activated carbon showed increased adsorption capacity and decreased desorption potential.
Keywords: brewing liquor hydrocarbon ozone pollution