the kind of impurities that are found in the water. This can differ very much for different types of water. In which ways is polluted water treated? Settling Before the purification process begins some contaminants, such as oil, can be settled in a settling tank. They can then be removed easily, after they have reached the bottom of the tank. Removal of dangerous microorganisms Often polluted water has to be freed from microorganisms. The water is than disinfected, usually by means of chlorination. Removal of dissolved solids Microrganisms are not only a threat to water; they can also be an advantage when it comes to water purification processes. They can convert harmful contaminants to harmless substances. This biological purification process usually takes a long time and it is only used for water that is polluted with contaminants that the microrganisms, usually bacteria, can convert. Physical/ chemical techniques
To avoid bacteria spreading, then it is important to stick to biosafety rules. It is hardly recommended to wear nonabsorbing protective clothes and gloves, because it is hard to avoid contact with ocular secretions and epiphora harbouring bacteria, when handlers and veterinarians are doing close- up examination. Moraxella bovis can easily infuse into the clothing of farmers performing such check-ups. Hands, clothing and tools used to examine the eye should be disinfected after next research of the animal (Angelos, 2018). Cattle can recover without treatment, but it is different individually. Some more stronger cattle recover spontaneously from the disease, while in others the disease becomes chronic (Postma et al., 2007). However, animals with no clinical signs can infect healthy animals, therefore animal handlers should be careful and take it into account. To avoid spreading over the farm then it is important to focus on the recovery
tamination of the finished product appears to Suggested frequencies are shown in Table mostly be due to L. monocytogenes strains 15.3. already present in the plant environment It has been shown that L. monocytogenes (Be¯ rzin¸š et al. 2007). This experience con- can become established and persist in floor firmed the results obtained by other authors drains. Therefore, drains should be cleaned (Norton et al. 2001; Hoffman et al. 2003). and disinfected in a manner that prevents Both persistent and nonpersistent strains contamination of other surfaces in the room. were isolated from pork products produced Solid forms of disinfectants (e.g., blocks of in seven different plants. QUATs) can be placed in drains to help Previous studies have shown that persis- control bacterial growth. Floor drains should tent L. monocytogenes strains can often be not be cleaned during production. High-
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