Tuesday, 31 July 2012

Home Cooler Hygiene

Increasing use of coolers in the home and sale of coolers without a service agreement are creating a market for do-it-yourself cleaning and hygiene.

New products are appearing on the market aimed at satisfying this need and already in the USA the opportunities are great, with ever increasing numbers of home coolers. There is, however, a need to educate the user about the necessity for cooler hygiene.

Often a cooler left to its own devices will rapidly accumulate bacteria, resulting in bad tastes and odours and  the danger of making someone ill. Many models enable self-sanitisation by various means, such as UV irradiation and generation of ozone, but many do not have this facility.

There is need for a simple kit that will serve the purpose without difficult procedures or use of dangerous chemicals. A simple system could comprise a disinfectant spray for tap treatment and a small bottle of disinfectant for addition to the reservoir. Food-handling gloves would be useful and a single-use wipe for the exterior.  A set of user instructions would complete the pack. 

The only item missing is a descaler, although there could be a problem with including incompatible chemicals in the same box. However, using a citric acid powder should be safe enough. 

This is an interesting development and one that will create a new type of market. Issues still under debate are pricing and marketing. 

Tuesday, 17 July 2012

Descaling Water Coolers

I am often asked about descaling watercoolers and recommending the best chemical to use. To a certain extent this depends on the amount and type of scaling but, in general, three types of chemical are used. These  are: citric acid, sulfamic acid and phosphoric acid. 

The strengths of the acids, on a weight for weight basis, increase in the order given and, as a consequence, so does the danger of handling. The speed of descaling increases as the strength increases. On the contrary, the costs of the acids decrease in the ratio 17:14:1.

 So, if you have hundreds of coolers to descale, I would go for the phosphoric acid. However, there remains the question of safe handling.

The dosing device in the picture enables you to mix water and the acid in the correct proportions without having to handle the concentrated acid. The petrol-pump like configuration means that you can treat several coolers in rapid succession.

No electric supply is necessary, just a water line. This enables you to use a strong acid with maximum operator safety.

Thursday, 12 July 2012

Detecting Residual Peracetic Acid

After using peracetic acid (PAA) as a terminal disinfectant in the bottling plant or elsewhere, it is important to ensure that no traces of peracetic acid remain on surfaces which will contact food or water.

The easiest way to do this is by using test strips which show different degrees of colour at each concentration level.  However, the lowest measurable level detected by most PAA-specific strips is 5mg/l (ppm).  So, there is no information about residual PAA in the range 0-5ppm.

There is a way around this if you consider the composition of peracetic acid.  It is not a single substance, but a mixture of hydrogen peroxide, peracetic acid and acetic acid in equilibrium.  The equilibrium can shift under the influence of temperature, rate of degradation and water content, plus other factors.

                                                PAA Composition (1)

The peroxide concentration (by volume) is approximately 3.5 times that of acetic acid and approximately 6 times that of the peracetic acid initially formed.  Therefore, a peroxide type residual test strip may be used to safely estimate residual peracetic levels because they will always be lower than that of the peroxide.

Peroxide test strips are available in the range 0.0 - 0.2 - 2.0 - 5.0 ppm.

(1) Vern Taaffe - Reprocessing Products Corp - January 5, 2004


Wednesday, 11 July 2012

Preventing Flying Insects in the Bottling Plant

I have written about electric fly killers previously, where I described the importance of not locating the unit near to the filling head in order to avoid insect debris ending up in the water.

Electric fly killers are often forgotten once installed and reliance is totally on the company servicing the unit. However, it is important to realise that not all UV tubes maintain adequate performance throughout the year and their efficiency cannot be guaranteed to be at optimum levels all year round.

To maintain a satisfactory level of protection, bulbs may need to be changed more than once a year, particularly where species’ populations peak in the late season, also, traps may be under-specified or poorly sited, for example, a lot of ambient UV reduces effectiveness considerably.

The risk of contamination by flying insects can continue into autumn, and beyond, and protection in the bottling plant or cooler servicing room is critical. So, apart from correct location (at least 2m high and away from windows) it is necessary to check the effectiveness of the electric unit periodically.

Fortunately, there is an easy-to-use monitor that can provide a rapid indication of the condition of UV tubes in any electric fly trap. The UVA meter, indicated in the photo, measures tube condition quickly with no calculations necessary. This enables plant supervisors, or indeed, auditors, to record output using a simple 1- 10 scale. There is a moving bar of LED lights which also changes colour according to the condition of the tube. The unit is permanently calibrated and the batteries are user-replaceable with a typical battery life of two years.
Ideally, the bottling plant should be sealed off from the surroundings with close fitting doors and small hatches on conveyors. A door of transparent plastic strips is not always effective and the light from the electric fly killer can actually attract insects into the bottling plant if it is not well sealed.

As a final point, it is interesting to note that an ozone atmosphere generated around the filler is a natural deterrent for insects. This atmosphere will also kill bacteria, although long exposure is harmful to humans.

Monday, 9 July 2012

Removing Labels from 19L Bottles

I have written about label removal previously and described two possible methods of removing residual glue from polycarbonate bottles. These involved either steam removal or solvent removal. 

The surest way is to use a steam gun. The temperature is then high enough to soften the glue and some elements in the glue which are water soluble at high temperatures will be dissolved, although it still will be necessary to use some mechanical action.

Using solvents can be hit-or-miss because there are several types of glue used and although some solvents will work on a wide range of glues there are always exceptions. There is a limitation on the type of solvent that you may use; very strong solvents can get into the polycarbonate polymer and lead to taint problems. 

The type of solvent most often recommended is denatured alcohol. Be careful, however, on the choice of product because some denaturants have a very strong taste, such as Bitrex, which is designed to make the taste of the alcohol unpleasant. Also, the higher the alcohol content, the more expensive the product becomes.

Thursday, 5 July 2012

Measuring Peracetic Acid Concentration

Peracetic acid is often used in bottling plants as a terminal disinfectant. There are several methods of measuring peracetic acid concentration and these are reviewed here: 

A titration technique involves the use of three different chemicals and relies on detecting a colour change, followed by a calculation. 

The simplest method utilises test strips which change colour on immersion in the test solution. The colour is related to the concentration in mg/L.

Conductivity measurement is not reliable and requires addition of a tracer (nitric acid) to the peracetic acid. 

A recent development has seen the emergence of peracetic acid sensitive electrodes. The test solution is made to flow through a cell where the electrodes produce a signal related to concentration. The whole system can be made automatic, so that top up occurs as the solution becomes depleted.

Wednesday, 4 July 2012

Safer Alternative to Ozonation of Water

Problems of bromate formation when ozonating water containing small amounts of bromide are well known.  Even concentrations of bromate as low as 10 millionths of a gram per litre can be considered carcinogenic.  However, ozone is very efficient in killing unwanted microorganisms in water.

Alternatives are few and far between, but some new technology has appeared on the scene which may change this.  UV has been used in the past, but still has shortcomings, particularly for destruction of spore-forming microorganisms in high solids water.  However, the synergistic effect of combining UV with ultrasound opens up new possibilities.

The ultrasonic emitter, located directly in the UV radiation chamber, causes the formation of minute super-heated steam voids in the water under low pressure. These voids form around spores, bacteria and cysts. When the voids collapse, zones of extreme temperature and pressure are created destroying microorganisms in close proximity.

At the same time, free radicals, hydrogen peroxide and other active species are generated in the process. They provide a significantly enhanced disinfection and photochemical oxidation of microorganisms compared with conventional UV treatment.  An added bonus is that the ultrasound action prevents any build up of inorganic deposits on quartz sleeves and chamber walls, thereby maintaining optimum UV intensity.

Bromates are not formed, therefore removing the dangers associated with ozonation techniques.

Tuesday, 3 July 2012

Pre-washing 19L Bottles

Many 19L bottles are returned from the customer in a poor state of cleanliness.  They may have been stored incorrectly before collection or been abused when used for other purposes.

The delivery and collection operator should refuse collection of abused bottles and the customer should be charged accordingly with the cost of replacement.  However, this rarely happens and the soiled bottles are collected and returned for washing.

Bottles which are heavily soiled or show considerable algal growth should be rejected in the checking process before washing.  However, many bottles are "borderline" and this is where the bottle checkers need to make a decision to reject or go forward with washing. Mistakes can be made and some bottles may enter the bottle washer and cause costly contamination.

It is preferable to have a pre-washing facility available for these bottles.  Semi-automatic equipment is available which makes this task much easier.  It is better to use equipment like this rather than depend on "home-made" rigs.

Cleaning by jets and brushes with a hot detergent solution will provide clean bottles, both inside and out.  To be extra safe, sanitising products may be used which give both cleaning and disinfection.  The bottle then may be added safely to the stock entering the bottle washer.


Monday, 2 July 2012

Detergent Top-up in Bottle Washers

During bottle washing, the concentration of detergent in the wash tank will decrease during the day. This is caused by the bottles taking out detergent as they pass through the wash section and is known as “drag out”. 

With some machines the drag out can be considerable, so that by lunchtime the concentration may be half of the original. In hard water situations this can lead to ineffective washing and scale build-up on heater elements. The loss of detergent should be compensated throughout the day.

There are several ways of doing this, the most basic being to top up the detergent manually. Other methods involve automatic addition via a pump. This may be through timed addition, where the pump adds detergent in increments throughout the day, or by closed loop addition where the pump is linked to a conductivity probe. The pump will activate when the conductivity (concentration) falls below a set threshold.

If you do not want to invest in additional equipment, a simple top-up chart can be provided which shows how much detergent needs to be added at different conductivity levels.  Low-cost pocket conductivity meters are available from several suppliers for measuring the conductivity at regular intervals throughout the day