Challenge

Bottled water in the UK is strictly controlled by TheNatural Mineral Water, Spring Water and BottledDrinking Water Regulations (England) 20071. Theregulation specifies that bottled water should notcontain any micro-organism, parasite, property,element or substance at a concentration or valuewhich would constitute a potential danger to humanhealth.

Hydrogen sulphide (H2S) is formed when solublesulphides are hydrolysed in water and has an offensive"rotten eggs" odour and taste that are detectable evenat very low concentrations. The World HealthOrganisation (WHO) estimates the taste and odourthreshold for H2S in water to be as low as 0.05mg/litre.

Although oral toxicity data are lacking, it is unlikelythat a person could consume a harmful dose of H2S indrinking water. As a consequence, WHO has not set ahealth-based guideline value of H2S in drinking water.UK regulations do not require hydrogen sulphidemonitoring; however WHO makes it clear that H2Sshould not be detectable in drinking water by eithertaste or odour2.

In order to ensure optimal product quality andcustomer satisfaction, Britvic reviewed its HazardAnalysis and Critical Control Points (HACCP) plan andidentified the need for accurate, real-time monitoringof H2S levels in finished bottled products for the firsttime, placing the company at the vanguard of H2Sdetection in the UK beverage industry.

Britvic required reliable instrumentation that wouldenable accurate monitoring of soluble H2S levels inwater that comes directly from each of the boreholes,after processing through air scrubbers/de-gassertowers and after manganese filtration.

Analytical Technology Helps Britvic Soft Drinks Monitor Hydrogen

Sulphide in its Drinking Water Bottled Products

Introduction

Britvic Soft Drinks Ltd is one of the UK’s largest supplier of branded still soft

drinks and branded carbonates. Based in Chelmsford, Essex, the company

operates seven manufacturing sites across the UK, producing an extensive range

of recognised brands including Pepsi,Tango, Robinsons and J2O. In addition to its

manufacturing facilities, Britvic has an established infrastructure consisting of a

national distribution centre, an IT and central services department, numerous

local distribution centres and an on premise and vending division.The company

currently employs more than 3000 staff at its head office, factories and network

of depots around the country.

Britvic’s Huddersfield factory is a water bottling facility operating two boreholes,

one classified as spring water and the other as mineral water.The site houses

two high speed water bottling production lines operating 24 hours per day over

six days per week. A range of bottle sizes from 330ml to 2lt and a varied array of

packing formats form an extensive product portfolio.

According to current legislation, the quality of water produced at the

Huddersfield factory must be monitored for manganese, barium and mineral

content. Retention samples must be also taken at regular intervals to test that

micro-biological levels are within specification. Britvic recently worked with

Analytical Technology to implement effective monitoring controls for hydrogen

sulphide that would enable accurate measurement as well as compliance with

strict legislation.

Solution

The measurement of dissolved sulphide concentrationshas been traditionally performed using analysersemploying selective ion electrodes (SIE) for sensing.While providing adequate sensitivity, SIE basedsystems require frequent zero and span adjustments tomaintain measurement accuracy. As a result, most SIE-based monitoring systems are relatively expensive andrequire frequent service.

Britvic selected the A15/81 dissolved sulphide monitorfrom Analytical Technologybecause it is the only systemthat can monitor soluble H2Sin water

on a real time basis. Theinnovative system overcomesthe problems caused byconventional dissolvedsulphide monitoring systems,providing an improved methodfor measuring sulphides insolution. Rather than using anSIE sensor, the A15/81 employsa polarographic H2S gassensor that is isolated from thesample, enabling continuousoperation on many types ofwater and wastewater streamswith minimal maintenance andadjustment.

As sulphide measurements areoften taken from poor qualitysamples, analytical system fouling can be a majorconcern. For Britvic, a key advantage of the A15/81monitor is that the sensor does not come into contactwith the sample. Only the gas stream containing thestripped H2S reaches the sensor. As a consequence, thesystem continues to function regardless of the qualityof the sample. The only requirement is that largeparticulates be strained from the sample. The monitorcan easily pass particulates as large as 100 microns,thus requiring only course screening.

The A15/81 measures sulphide ions selectively byconversion to hydrogen sulphide. Monitoring sulphidesin solution using the gas stripping technique providesextremely high measurement sensitivity allowing formeasurement of samples down to 5 parts-per-billionlevels. Because the gas sensor is very stable, monthly

zero and span checks are all that is needed. A separateport is provided to feed distilled water or sulphidestandards when required, without disrupting normalsample inlet flow.

It was also imperative for Britvic that the chosendissolved sulphide monitor be easy to operate andmaintain. Acid usage for pH adjustment in thechemistry module of the A15/81 is inexpensive andconsumption is limited to one gallon every 40 days. The

peristaltic pumps used for thesample and acid have a long-lifetubing capability that requiresreplacement every 6 months whilethe pump heads are designed foreasy tube changes, requiringapproximately 10 minutes to replaceboth tubes. In addition, the sulphidegas sensor requires no maintenanceother than an occasional visualinspection to ensure that nodeposits have collected on thesensing membrane.

Analytical Technology first fitted atrial unit in less than a week afterthe first meeting. This trial proved sosuccessful that the tender movedfrom an initial four units to a total ofsix units. The monitors wereinstalled at Britvic’s Huddersfieldfactory; three on each borehole linebeing fitted in a central location.Sample points had to be installed in

six different sections of the process and connected tothe H2S monitors. The installation of the sample pointswas undertaken internally by Britvic personnel whereasthe fitting of the monitors was carried out by AnalyticalTechnology staff. Due to the nature of the work that hadto be done by Britvic staff, involving breaking intostainless steel pipe-work and fitting stainless steelsample taps, the installation was completed incontrolled phases. The two boreholes were treated astwo different projects. Once Britvic had completed theirpart of the installation process, Analytical Technologyfitted and commissioned the monitors.

Following installation, Analytical Technology providedfull operational training to Britvic on a one-to-one basis.

Benefits

Since implementing the monitors, Britvic hasbeen able to ensure that its bottled products areaccurately and continuously monitored forhydrogen sulphide. The company has achievedthis goal while also ensuring that costs andmaintenance are kept to a minimum and reliableresults are generated in real time.

“Our customer services expectations includeRight First Time, flexible installation due to thenature of FMCG processes as well as a rapidresponse to queries and quick resolution of anyissues as and when they are identified. It is alsoimportant that contractors work within our sitestandards for health and safety and that riskassessments and method statements are suppliedto cover all scoped works, as well as wasteproduct and packaging being removed bycontractors. Analytical Technology performsexcellently against all these expectations,” explainedJason Gledhill, Continuous Improvement Co-ordinator,Britvic. “The company takes a very flexible andprofessional approach to system implementation andtechnical support that really differentiates thecompany. When requested, support is usually deliveredwithin a 24 hour period. In addition, the cost of theunits was minimal compared to the scope of theproject that the install was incorporated into.”

Conclusion

Hydrogen sulphide can be found naturally in drinkingwater systems, causing taste and odour problems.Although the levels of H2S in drinking water do notnormally constitute a cause of concern for humanhealth, WHO has made it clear that the chemicalcompound should not be detectable in drinking waterby either taste or odour. In order to comply with thisrequirement, Britvic needed a dependable dissolvedsulphide monitor for its Huddersfield water bottlingfacility. By implementing the A15/81 dissolved sulphidemonitor from Analytical Technology, the company hasbeen able to monitor soluble H2S in water on a realtime basis and assure optimal product quality.

References

1. Office of Public Sector Information, The Natural MineralWater, Spring Water and Bottled Drinking Water (England)Regulations 2007,http://www.opsi.gov.uk/si/si2007/uksi_20072785_en_1

2. World Health Organisation, Hydrogen Sulfide inDrinking-water, Background document for development ofWHO Guidelines for Drinking-water Quality,http://www.who.int/water_sanitation_health/dwq/chemicals/en/hydrogensulfide.pdf

For more information about the benefitsoffered by Analytical Technology’s complete range of analytical instruments, please call +44 1457 832800, e-mail info@analyticaltechnology.com or visit www.analyticaltechnology.com