Mill hygiene and pest control

by Jonathan Bradshaw
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My late father always claimed that an untidy desk was the sign of an untidy mind, thus judging people’s likely work standards by the appearance of their workspace. The same ethic applies to your mills in that an untidy mill often reflects the character of its management and sends a signal that this place may not be well run. Certainly an untidy and unkempt mill does allow infestation to take hold.

Mill hygiene is not a hot topic in everyday management tasks, but it should rank fairly high when it comes to managers taking that all-important daily walk round the mill site.

In order to set and maintain standards that are acceptable to your customers, it is important to get their views of what they expect. Rather than treat audits as times when you come under the hammer and are criticized for not doing things correctly, millers should take the opportunity to turn the tables and get the customer to define what they require in terms of cleanliness and hygiene standards.

A cleaning schedule is useful to start the discussion, and it should become the bible for cleaning activities, defining what tasks are to be done daily, weekly, monthly and annually. This schedule should be a live document and be amended in light of any information that comes from your own regular internal audits and external audits which the customer may undertake through the year.

Many mills use separate schedules for rodent control and insect control and a third schedule for general cleaning duties in and around the mill. This is mainly because different personnel have responsibilities for different areas. The second miller, where there are sufficient funds to have one, invariably has the majority of the mill cleaning as his re- sponsibility, the silo operatives will look after silo cleaning, and generally each operative will look after the area in which they work. Many believe in handing internal silo cleaning out to third parties, thus absolving themselves of liability. But some millers may choose to carry out this function with their own personnel. Silo manufacturers are now making allowances for this by increasing the number and size of personnel doors to gain access to silos, and many provide clean air supplies adjacent to the doorways so that a breathing apparatus can easily be used.

Once your cleaning schedule is established, it needs to be monitored to ensure it remains effective and relevant. To this end you need to carry out audits, and obviously the person carrying out the audits should be someone different from the person who carries out the cleaning.

Many millers choose to make the quality assurance function embrace hygiene, and this works well in most cases. However, it is vitally important that the person carrying out the internal audit knows what he or she is doing, and an element of training will be required for people who are new to the job. Courses in basic food hygiene are readily available, and the more employees who attend these, the better. Indeed these are now available on the Internet and employees can undergo a course of training without having to leave site, thus minimizing the cost.

Having mastered the art of general housekeeping and established good inspection regimes, you also must evaluate whether or not your facilities require structural changes. Most frequently required are bird proofing to the eaves of buildings, fly screens over window openings and door closers to prevent rodents from entering. It is also useful to install doors made of metal — at least the bottom half — or a strip along the base where rodents would normally chew wood to gain access.

Rodents and certain avian pests are attracted by food spilled around the yard and at intake points. It is important that these spillages are cleaned up immediately.

Many millers choose to use a specialist for pest control and call one in to bait the premises for rodents and occasionally for insects. Again, a schedule is drawn up, agreed to and then implemented. Some customers do not like to see baits in production areas, so it is important to agree to a schedule and protocol with the customer’s views in mind.

The choice of rodent bait is also important and customers will also have distinct views on this. There may also be legislation in place that dictates what can and cannot be used. With insects, baiting can only really be in the form of pheromone traps which will indicate when the level of insect activity is rising. Those who follow the seasons will know that insects become active just before they breed, and they breed when the temperature is right for them.

Pheromone traps have been criticized by some as being an agent that invites insects into the mill. When the males smell the pheromone, they head toward it, giving perhaps an inflated view of numbers of insects that are active. However, you can use such traps for what they are worth and you can use your own observations from your daily inspection of the premises. All information is useful when it comes to choosing a time for mill fumigation.

Millers are restricted in the types of fumigation they can use, and the number of choices is gradually dwindling. Some millers choose not to fumigate annually but carry out very specific treatments in various areas of the mill continuously throughout the year. This requires diligent inspection of the premises, before and after treatment, but it can be a very successful way of controlling stored-product insects. You cannot beat good housekeeping when it comes to keeping both insects and rodents at bay, but it is important to keep the internal workings of machinery in good order to minimize insect activity.

I have been in several mills where it becomes evident as soon as I have taken the sifter doors off that there is a stored product insect infestation since the odor of insect urine within the sifter can be clearly evident and the smell is quite unique as many an experienced miller can tell you.

Good maintenance programs and regular inspections of sifters, roller mills and purifier internal workings will all pay dividends in the fight to control insects. Good inspection of grain at the intake point is also valuable when it is possible to reject individual vehicles that are carrying badly infested grain. This is not possible when grain comes in on ocean-going vessels, as it is not practical to reject a vessel. In such cases it requires a good cleaning house to process grain before it goes into silos. Take the infestation immediately, before insects have chance to breed, and keep a close eye on stored grain, turning it over and aspirating it regularly throughout its life in storage.

Removing all sources of water is vitally important since, like all living creatures, rodents, birds and insects are unable to live and breed without a source of water. Fix the dripping taps, mend the gutters and make sure all doors to shower rooms and other places where water can be accessed are fitted with automatic door closers. Underground conveyor trenches and elevator pits are notorious for being places where water will settle and provide a ready source of water for rodents and insects. Keep them clean and dry.

Regularly mow grass around the perimeter of the building, keeping at least a meter clear between the building and any tall grass. Some millers encourage owls to nest nearby since the presence of a bird of prey will drastically reduce rodent numbers.

And finally, I cannot stress the importance of inspection. This is just as important as the cleaning itself. It is no good simply looking at the center of the floor, as it is the corners and inaccessible places where insects and rodents will go to breed. Look in all the storage areas and places where there is little human activity. Places such as maintenance stores where replacement filter sleeves are kept and storage areas for sifter cloth and sifter sleeves are the areas where infestation will develop if you are not diligent in your duties. The morning walk about will tell you all you need to know if you are organized in where you go and what you are looking for. A tidy mill is the sign of a tidy mind, and a clean and well maintained mill will produce a quality product.

Editor’s note: This is the final Milling Operations article written by Jonathan Bradshaw, who owned an operated J.B. Bradshaw Ltd, a consultant business to the milling industry and was a regular contributor to World Grain for many years. Jonathan died on Sept. 14 after a long illness. He will be greatly missed.