Summary
Washing represents a key part of any zoohygiene sanitation program. High-pressure washing above 120 bar results in the transfer of contaminated aerosol over long distances. Pressure washing with cold water without pre-wetting is the least effective. The washing with hot water is more effective, but also much more expensive than other methods. Pre-wetting of pens can facilitate the washing significantly.
Using the right wetting agent for pre-wetting has proven to be most effective because it can disrupt biofilm and residues of fat and protein deposits. In addition, the use of a non-ionic surfactant on absorbent surface (wood, concrete, plastic) also achieves the impact of micropores in the material, far below the surface. This reduces the adhesion of organic residues for the next lot. In addition, this allows the use cold water at pressures up to 100 bar for subsequent washing of surfaces.
Keywords: biosecurity at farm, high-pressure washing, stable cleaning, zoohygiene, microorganisms, preventive measures, spreading of microorganisms by air
 
Introduction
Cleaning and washing of the stables after the departure of pigs represent the most effective step to reduce infection pressure between the lots. Correct realization of wet cleaning also has a decisive effect on the effectiveness of disinfectants. On the other hand, this stage of the disinfection program poses the risk of potential contamination of the halls on site and even outside the farm. The results of our and foreign experimental works show that cleaning can be efficiently carried out by simple pressure washing (<100 bar) with cold water, with a considerable savings of time and water consumption.
 
The aim of work
The aim of the experiment was to compare different washing methods and to determine the optimal ratio between cleaning efficiency and time consumption. The secondary objective was to determine the potential range of the aerosol particles depending on the applied pressure.
 
Material and methods
The monitoring was carried out in pig production - pre-fattening category. Individual runs were used on the farm. Pre-fattening halls were divided into 2 x 4 equal sections.
The study was performed on 8 pens, each time after the pigs were departed. The materials in the pens were as follows: plastic floor grates, concrete floors, full plastic fence in combination with galvanized fence, wall surface - tiles in combination with plaster, ceilings - trapezoidal sheet.
 
Each section had the following dimensions: l = 8.0m; w = 10.0m; h = 2.3m.
So the section area (S) was: S = 3 x l x w + 2 x (l x h + w x h) = 322.8m2.
The coefficient of technological area (kt) was set at 1.45; e.g. Skt = 468.1m2.

 The time required for perfect cleaning was compared with the following washing methods:
1) Without pre-wetting
2) With water pre-wetting or non-ionic surfactant soaking or with combination of both
3) Washing with cold water
4) Washing with hot water
 
The washing with cold water was performed using Comet K901, high-pressure water apparatus (without pre-wetting after calibration at 21l/min at 160bar; after pre-wetting at 18l/min at 100 bar) with a straight nozzle. The washing with hot water was performed using Comet KE K901, high-pressure water cleaner with heating (without pre-wetting after calibration at 16 l/min at 150bar; after pre-wetting at 14 l/min at 100 bar) at temperature of 90°C and with a straight nozzle. Water pre-wetting was performed with cold water 1 day before washing. Pre-soaking with ShiftTM, alkaline non-ionic detergent, was performed 30 60 minutes before washing. The combined pre-wetting was performed with water 2 hours prior to the application of Shift surfactant and subsequent washing 30-60 minutes after its application.

 Results and discussion
The test results are shown in Tables 1 and 2 below.

Table 1: Dependence of aerosol and dust particle range on their size

Table 2: Average consumption for section washing using different methods

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When washing with cold water only, without surfactant or pre-wetting, the average time consumption per section was 6 hours and 52 minutes. Hot water shortened this time by 23.3%. The negative effect of hot water was the mist created, which caused very low visibility to the operator. Water pre-wetting 24 hours in advance brought a reduction of 9.1% for cold and 27.0% for hot water. Using Shift surfactant with cold water shortened the washing time by 52 minutes (e.g. by 12.5%); hot water with surfactant by 1 h 56 m (28.1%). Combined water pre-wetting + subsequent use of surfactant shortened the washing with cold water even by 46.2%, with hot water by 48.7%.
Soaking the surfaces with an alkaline surfactant by means of a foam application to dilute the dried organic impurities before the pressure washing affected the time much more significantly when the floors were previously wetted with water. When working with cold water, the washing process was shortened by almost half. An interesting moment was the discovery that using the right alkaline surfactant greatly speeds up the washing process and even allows almost identical times to be obtained for both hot and cold water when combined with water pre-wetting.

Time consumption can be divided according to categories based on the following key:
49% in fattening, 31% in farrowing and 20% in pre-fattening. These values can be reduced by combined pre-wetting with water and using of an alkaline non-ionic surfactant, namely by up to 48.7%.
Interesting were also the results of time consumption calculated per square meter in relation to water consumption. The time required for the washing of 1m2 was evaluated for about 1 hour, which means an average water consumption of 20 l/min, e.g. 1,200 l/year/m2. The table above shows that the water consumption can be reduced by up to 49.3%.
 
Conclusion
Pre-wetting of pens prior to their high-pressure washing is recommended by experts worldwide. Such a way of cleaning offers many advantages to farms. The most significant benefits of prewashing with an alkaline surfactant are as follows:
1) reduction of working time and water consumption for cleaning between lots by almost half
2) water pre-wetting can take place overnight
3) reduction of water consumption used for washing
4) reduction of slurry production (limits for slurry removal)
 
References
NOVÁK, P. (2005): Prevence v chovu prasat; 12-13;
TITTL, K., NOVÁK, P., MALÁ G. (2011): Does biosecurity have any influence on the health and profitability in pig farm?
TITTL, K., NOVÁK, P. (2009): Disinfection, an Integral Part of Animal Biosecurity on Farm. In Proceedings of the XIV.ISAH Congress 2009, Vechta, Germany. 927-930.