Agriculture Reference
In-Depth Information
chemicals must not be mixed with each other unless
under the express instructions of a competent person.
All chemical containers must be clearly labelled with
product-specific identification and safety information as
per EU standards. Hygiene chemicals should be stored
safely and systematically; dilution and dosing should
where possible be automated. Automation has the dual
advantage of reducing risk and contributing to valida-
tion and consistency. Safety data sheets on all chemicals
must be available which conform to EU legislation. All
equipment must be properly maintained.
Total counts: week 24
350
Unacceptable
300
250
200
150
Excellent
100
50
0
Monday
Conveyors
Cutting boards
Slicers
Tuesday
Wednesday
Thursday
Friday
Figure 5.13
Example graph showing trend analysis of total
counts over time for sample points on different surfaces
(Reproduced with permission from Ecolab. © Ecolab).
Effluent and external odour control
It is beyond the scope of this discussion to deal in depth
with these two complex hygiene-related issues. A num-
ber of general points, however, may be usefully made.
Effluent systems
in meat plants may be affected by the
misuse of some detergents and disinfectants. If 'high-
volume slugs' of concentrate chemicals are left to drain
that have very high or low pH, they may (if not neutral-
ised in the balance tank) upset the balance within the
microbiological population in biological treatment
plants. The same is true for chlorine, quats and some
other disinfectants. If a treatment plant is undersized
for the effluent it receives at peak periods, especially the
balance tank section, it is possible for 'breakthrough'
of organics and surfactants to occur. This means that
instead of being fully biodegraded in the plant, mole-
cules survive to give possible foaming problems (espe-
cially where aeration occurs), high COD/BOD and
increased suspended and dissolved solids. This may
result in higher charges from the water authorities or
possible penalties.
It is important in the factory pre-clean to remove
as much organic matter as possible, for example, food
residues, from production areas before detergents are
applied. These larger pieces of organic material are not
readily biodegradable and may block or blind the bio-
logical treatment plant. No bio-plant likes varying BOD
loadings. Steady conditions are preferred if 'shedding' of
filamentous growth is to be avoided. In activated sludge
plants, the sudden ingress of high-COD material will
result in low dissolved oxygen levels, thus potentially
turning the plant anaerobic (with resulting malodours)
or, by increasing the potential for filamentous growth,
causing settlement problems in the final clarifier.
By definition, cleaning chemicals will dissolve, emul-
sify and disperse organic materials and carry perhaps
excessive amounts to the effluent plant. It is also impor-
tant not to discharge sudden, very large quantities of
heavily loaded water, such as from scald tanks or cook-
ing kettles. The risk is even higher if the water is hot, as
should be reported regularly to management and fed
back to the cleaning team for remedial action. In relation
to surface hygiene, microbiological methods are useful
for validating cleaning and disinfection procedures, but
they do not provide useful data for daily real-time moni-
toring; however, they are used for long-term monitoring
of surface population trends. Figure 5.13 shows the infor-
mation that may be gained from monitoring over time;
the limits in the graph are not meant to be representative
of any particular process type.
Training
Training of all operatives and managers involved in plant
cleaning is
critically important
. It helps develop and
maintain a high self-esteem and status in the cleaning
team (too often seen, wrongly, as less skilled than pro-
duction workers) and a problem-solving, self-assessing
quality attitude to the job. Training should cover the
theoretical background in sufficient depth, particularly
the microscopic 'enemy, the risks of re-contamination,
the importance of procedures and the safe use of chemi-
cals and equipment. Practical, on-the-job training
should be continuous, especially when new plant or
equipment is introduced or procedures are changed. For
protection of due diligence, training should be recorded
on the personnel records of those trained.
Safety
Industrial detergents and disinfectants are generally,
because of the nature of the job they are designed to do,
more concentrated and extreme in pH than domestic
products. They should always be applied using the cor-
rect protective wear: gloves, goggles (or full-face protec-
tor), apron, boots, etc. In areas where high aerosol levels
may be created, with a risk of heavy microbial contami-
nation, a suitable facemask should be worn. Different
