STUDIES ON ACID BOILING WATER - OR CIRCULATION CLEANING FOR MILKING INSTALLATIONS

Milking installations are cleaned by circulation cleaning using water of a temperature between 40-60-degrees-C or acid boiling water of 95-1 00-degrees-C. The effect and the cost of both processes were examined on 64 dairy farms, of which 16 used circulation cleaning and 48 acid b oiling water cleaning. On 4 farms, respectively, the cleaning effect w as tested using bioluminescence measurements at the individual parts o f the milking installations. On another dairy farm (K.) both cleaning systems were alternatively used and examined. The hygienic quality of raw milk from the farms which used circulation cleaning and acid boili ng water cleaning was, in both cases, satisfactory (34.500 and 31.400 bacteria). However, if the cleaning effect was measured on the basis o f the remaining biomass in the milking installations, critical compone nts were found for both systems. The organic deposits could be differe ntly well removed from the individual parts of the milking installatio ns, depending on the surface quality and material. Terminal unit, milk pipeline, recorder jars and liner barrels could be cleaned satisfacto rily. Mouth pieces and claws and mainly their top parts showed higher degrees of contamination. In the experiment acid boiling water cleanin g was found to be markedly more susceptible to uneven water distributi on compared with circulation cleaning. Too low input water temperature s and low flow velocities in the milk pipeline as a result of too smal l supply line cross sections impaired, with this procedure, the cleani ng effect. In milking installations, in which application of the acid was not adapted to the degree of water hardness, scale and biomass dep osits were found. With circulation cleaning the results were unsatisfa ctory, if there was no regular change between acid and alkaline cleani ng agents and application was not adapted to water hardness. Further, old liners and defective cluster mounting systems and rinsing connecti ons could impair the cleaning effect. Related to the surfaces to be cl eaned the energy expenditure was approximately identical (1.7 and 1.6 kWh/m2 per cleaning) for both processes, also water consumption differ ed practically not (21.0 and 20.0 l/m2). On the other hand, 72.3 g/m2 chemicals were required for circulation cleaning, whilst it was only 6 .6 g/m2 for acid boiling water cleaning. Further, with acid boiling wa ter cleaning consumption of electric energy can, to a far extent, be s hifted to the times of low electricity tariffs.