ATP Meters

Over the past ten years or so, a great deal of emphasis has been placed on the use of bioluminescence technology in the detection of microorganisms.

The mechanism by which fireflies produce a flash of light was first analyzed and identified by William McElroy in 1947. McElroy found that central to the light emission process was a specific enzyme reaction catalyzing the consumption of adenosine triphosphate (ATP).

In microbes, ATP can only be detected when living cells are present. It has since been established that the amount of light emitted from this reaction is directly proportional to the amount of ATP present. A high reading of relative light units (RLUs) indicates that the sample contains a high number of micro-organisms, provided that the background ATP level is low.

Unlike traditional testing methods, results from a bioluminescent reaction can be obtained quickly. Light is produced within seconds and can be measured with a luminometer (ATP Meter).

The current palm-sized instruments bring together state-of-the-art photodiode technology with simple user-friendly design to produce an affordable hygiene-monitoring system. Used with  ATP swabs, levels of contamination can be determined in just 15 seconds.

Key features of luminometers include, low cost, high sensitivity, compactness, simplicity in use, self- calibration with background check. Readings may be downloaded onto a PC or, as an optional extra, analysis software will provide spreadsheet-compatible data.

Preferred Bottle Wash/Sanitiser for Polycarbonate

New products specially designed for washing polycarbonate bottles are a rarity on the market. However, one new product provides many benefits for the bottler and gives that added confidence that the bottle is clean and germ-free. The product contains a food-safe disinfectant as well as the cleaning power of other products.

Extensive testing and trials have been carried out which show low TVCs, as expected, but also a reduction in the incidence of green bottles returning to the plant. The new product may be used under adverse conditions, for example, if the heater stops working or the throughput of bottles has to be increased because of production demand. If the concentration of the product is cranked up further, it behaves like a disinfectant and will pass the requirements for EN 1276.

The product generates slightly more foam than a regular bottle wash product, but rinsing is very rapid under normal conditions and the foam is controlled, particularly at normal wash temperatures.

The foam tracer makes the wash solution easier to see and provides reassurance that all parts of the bottle are being thoroughly washed. 

Taps for 25L Containers

The ability to reduce the manual handling of chemical drums can only be beneficial from a safety point of view. Pouring dangerous chemicals from a 25L container into a measuring jug is not the safest of procedures, but many plant operators do this.

As with many things, there is a simple solution. The cap/tap assembly illustrated in the photo provides a simple way of avoiding the lifting and pouring of chemicals. The cap replaces the standard cap and by simply punching out the centerpiece of the new cap, the tap can be screwed into the cap unit. In this way the drum can be left on its side, preferably in an elevated position, and chemical dispensed into the measuring jug via the tap.

The cap/tap unit is of robust construction and resistant to chemicals normally found in the bottling plants.

Alcohol as a Disinfectant?

Surface disinfection is important in the cooler servicing room but it is essential not to leave any residual disinfectant on water-contact surfaces. Peroxide spray is excellent in this respect because breakdown products are water and oxygen. However, some brands of peroxide spray can be expensive.

Alternatives tend to leave a residue of disinfectant unless rinsed off thoroughly. This is true of the low-cost cleaner/sanitizer types of spray and those containing a quaternary disinfectant, which should not be used at all if there is a danger of the product being sprayed onto water-contact surfaces.

An alternative to consider is alcohol. This has been used for many years in the medical profession and in dentistry. Alcohol is very volatile and will quickly evaporate from a surface leaving no residue. The germ-kill effect is excellent and there are no problems of oxidising interaction with skin which leaves those white patches seen with peroxide.

From a cost point-of-view, the alcohol may be diluted with water and still maintain good efficacy. Users in the UK need to be registered  with Customs and Excise but this is a simple formality.

Using strong, lint-free dry wipes and alcohol solutions in the cooler servicing room provides an interesting alternative to peroxide and other disinfectants. 

UV Disinfection in the Bottling Plant and Water Coolers

The advantages of UV disinfection are well-known, for example, there are no by-products, the taste and smell of the water remains neutral, UV radiation is non-corrosive and very effective against parasites and protozoa.

The discovery that UV inactivates Cryptosporidium parvum oocysts has given greater emphasis to the role of UV. Its applications extend beyond potable water to municipal waste water, swimming pools, water features, industrial cooling circuits and industrial process water.

However, an important criterion is the method of generation of UV. There are two main types of UV lamp - low pressure and medium pressure. The low pressure lamp disrupts the DNA in the cell and prevents cell reproduction. Unfortunately, the other proteins and enzymes are not destroyed. The proteins and enzymes are capable of repairing the DNA, particularly in the presence of light, so that disinfection is not complete.

Medium pressure lamps, on the other hand, destroy proteins, DNA and enzymes, so that disinfection is complete. The table below gives a summary of the performance of the two types of lamp.

Low pressure lamps have a high efficiency, low power consumption, are easy to apply and ideal for small flows. Medium pressure lamps are compact, powerful, with an efficiency independent of water temperature and with no possibility of photoreactivation of micro-organisms.

An indication of the UV spectral emission curves of the two types of lamp are shown in the diagrams below.

Which Dry Wipes for Cooler Servicing?

Often, regular paper towels are just not good enough for some of the tough jobs in the bottling plant or cooler servicing room. You need high strength, good absorbency, low lint and a large size for usability over larger surface areas.

The characteristics of preferred industrial dry wipes, would be high strength, both wet and dry, with a dense structure and extremely low lint. Absorption capacity should be, on average, 500% of its own weight and the wipe should be able handle water, oil and chemicals.

During servicing of coolers, no paper pieces should be generated, for example, by tears on jagged edges of the internal casing framework, or during cleaning of taps. In this case, strength of the wipe and resistance to tearing, even when wet, is very important. Normal quality paper towels are not good enough for these strict requirements.

How to Measure Bottle-Wash Cleaner Concentrations

Many customers are using conductivity to measure concentrations of bottle wash detergent. This has several advantages over titration methods, for example, the variability in results from different operators can be virtually eliminated with the conductivity technique. This is particularly true if the titration is complicated and involves more than two chemicals. Furthermore, the chemicals have to be replenished periodically and the measurement time is longer. Conductivity meters have improved considerably in design and simplicity of use, so that several types of “pocket” conductivity meters are now available at reasonable prices.

However, there are differences in quality, related to materials of construction and convenience of design. The  most sensitive part of the conductivity meter is the electrode unit. If the meter is going to fail, then this will usually occur with the electrode unit. Some pocket meters have replaceable electrodes and this is a big advantage, otherwise the meter has to be returned to the manufacturer for electrode replacement.

Robustness is another important factor and the meter should be able to survive being dropped on the plant floor. Some meters are self-sampling, in other words, by dipping the meter in the wash tank sampling drawer, a sample is collected in a small cup surrounding the electrode. All these improvements come at a premium, but at the end  of the day the extra investment is worthwhile. To effectively use the conductivity technique, a calibration graph needs to be drawn showing conductivity versus concentration. Your chemical supplier will be able to provide this for you.

Carry-over is another phenomenon easily measured using conductivity. All that is needed is to establish a baseline conductivity reading for “no carry-over”, your supplier will help you to do this.

Cleaning Schedules for the Bottling Plant

It is important to create a cleaning schedule for your bottling plant.  This may be mapped out in a simple chart, shown in the picture below.  A hygiene manual is essential.  This will have detailed cleaning and hygiene programmes for each area of the plant.  These should be easy to follow and readily understood by new operators.  Bottling plant mangers should check regularly that the schedule is being followed.  All too often, the schedule will "drift" into a shortened version.

Apart from possible hygiene problems, a "drift" of cleaning schedule can be confusing to suppliers.  I have read cleaning schedules from customers and subsequently recommended products based on the schedule.  I then have been surprised when the operators said that the products did not work.  On paying a visit to find out why, and observing the operators working, it became clear that the operators were using a different schedule which actually warranted using the product in a completely different way.

The bottled water industry is not unique in this, in a manufacturing company, the plant operators would not follow manufacturing instructions on a computer screen, they preferred to write the instructions on the wall with a felt pen, their reasoning being that computers were notoriously unreliable.

Obviously, if operators come up with new ideas that improve the cleaning schedule, then their ideas should be adopted and the cleaning schedule changed.

It goes without saying that discrepancies between written schedules and actual practice can cause problems during an audit, if the auditor happens to spot it.

Staphylococcus aureus in the Bottling Plant

S. aureus lives up your nose.  You do not need to be ill to carry this opportunist pathogen around.  However, if you have a habit of touching your nose, have a cold, cough or a fit of sneeezing you can contaminate a large area.  If another person's immune system is down, S. aureus can make that person very ill.

If you happen to sneeze in the bottling plant, this could contaminate the water at that critical stage between filling and capping.  It is essential, in preventing this, to have a positive air pressure either around the bottling machine or preferably throughout the bottling plant.

A high percentage of bacteria in the bottling plant are airborne.  They float in through open doors.  One flush of a toilet releases an aerosol of bacteria many of which remain airborne.  Enterococcus faecalis is very common in indoor environments and represents a high percentage of airborne bacteria.

Check your airflow in the plant and make sure the flow is out rather than in.  Ideally, the bottling plant should be sealed off from the rest of the building, although, for practical reasons, this is not always possible.  Another point is that bacterial aerosols can be formed by spraying the floor too vigorously during clean up.  Always use a foaming disinfectant before spraying the floor with water.