The future of water testing

The National Laboratory Service (NLS) recently announced its largest set of commercial contracts to date after having been appointed by UK water operators to assist in the preparation for the adoption of the latest EU water legislation. Ian Rippin describes how the programme will work in the new regulatory landscape.

The UK Water Chemical Investigations Programme (CIP) is a massive scale environmental testing programme facilitated by the UK Water Industry Research organisation and the Environment Agency. It is an investigation into the management and control of ‘priority substances’ and other pollutants. In this context, priority substances are defined in the Priority Substances Daughter Directive (PSDD), which supports the EU Water Framework Directive (WFD).

At the heart of the WFD and its daughter directives exists the establishment of Environmental Quality Standards (EQSs); values determined for all EU water bodies, which define if concentrations of chemical contaminants are considered of ‘good chemical status’.

Although water companies are not solely responsible for taking measures to meet these EQSs they are required to assess the contribution their actions have on contaminant loads present in receiving waters. The CIP was launched to aid this by gathering data that will provide for a much clearer understanding of the frequency, concentration and behaviour of priority substances throughout the wastewater treatment cycle. With the data captured, the measures to be implemented into the next cycle of the WFD – from 2014 onwards – can be more tailored to the cause.

The collaboration between water companies for the delivery of the CIP was essential to providing a cost effective method of collecting test data. The CIP for each individual water company varies depending on the extent and complexity of their regional networks, however, it is expected that over 20,000 samples will be taken over the duration of the programme, breaking down into 6,000 sewage effluents, 8,000 catchment samples, 5,000 wastewater treatment work process samples and 1,000 sludge samples. Having started in 2010, the CIP is now in delivery with the majority of data expected before the middle of 2012.

Before the main programme commenced the NLS conducted substance stability trials in final effluent samples, with the aim of determining how stable the compounds of interest were in wastewater treatment work discharges. The results from the trials, which were completed in May 2010, helped to determine the best testing regime. 

Stability trials were designed to establish any changes in substance concentrations after one, three and five day intervals, following a prescribed ‘trend analysis’ approach that was performed in triplicate. In some cases, the NLS continued testing after the prescribed five days to further confirm analytical results. For example, for glyphosate – the world’s biggest selling herbicide – stability testing proceeded for a total of nine days due to an expectation at the outset that this compound would prove to be unstable. Glyphosate is widely understood to be harmless to the environment, as current data suggests it breaks down quickly following its use.

It was assumed from the beginning that the substances of interest to the trials were relatively unstable or those for which no feasible or proven methods of chemical preservation are known. It was therefore surprising to discover that the majority of the substances included in the trials were found to be relatively stable under specific conditions. These conditions were designed to maintain the integrity of each sample taken, from its source to eventual analysis.

The net result is a definition for the CIP’s sample preservation, storage and maximum holding times between sample collection and analysis in the receiving laboratory. The findings suggest that to maintain sample integrity, chilling samples after collection to approximately 4°C and subsequently transporting and storing them at the same temperature is required. Samples must also be analysed or otherwise stabilised within three to five days of their collection.

The main areas of stability testing to date have focused on the following substances:
DEHP – a general purpose plasticiser used to make PVC plastic soft and flexible. DEHP was thought to be relatively unstable and is on the Priority Substance list. 
TBT – an aggressive biocide that is used as a fungicide in agriculture and as an anti-fouling agent in ship paints. TBT is classed as a Priority Hazardous Substance (PHS) and of key concern because of its prescribed low EQS.
Pharmaceuticals and PSDD (Annex 3) substances – both of these groups were included in the trials on the basis that their determination on effluent and sewage process samples is not yet well established.

Reactive aluminium – as the name suggests, a substance that is likely to be subject to change.

Total mercury – included on the basis that mercury stability and contamination has long been shown to be an issue.

Bentazone and Mecoprop – man-made chemicals that are used as herbicides. Bentazone is known to be harmful to fish and Mecoprop – widely used as an ingredient in household weed killers – to wildlife in general. Both substances were found to be more stable than previous data suggests.

Important to the success of the CIP and any large sampling programme are the sample management protocols deployed. Perhaps of most significance to any design is to ensure that samples taken are representative of the prevailing conditions in the environment being tested, therefore the identification of the appropriate sampling points is critical.

In the first element of the programme known as C1, screening of wastewater treatment works final effluents helps to confirm the concentrations and loads of substances being released to receiving waters. The majority of this screening work is now currently complete. 

During the second element of the programme, C2, investigations to assess treatment options for chemicals are proposed, with sampling concentrated at a few treatment works for each water company.

The final element, C3, tackles catchment monitoring and modelling investigations to assess pollution sources. These surveys will investigate locations identified by individual water companies that represent potential sources of contamination. These include locations where consented traders are likely to be discharging, domestic wastewater from new and old housing estates, surface water draining systems and town centre effluents from sources such as bars, restaurants and offices.

The exact requirements for both C2 and C3 investigations will depend on the results of the C1 investigations. The CIP makes a provision for the modification of the sampling programme to focus efforts on key areas of interest. This will be particularly significant if concentrations of certain substances are found to be consistently below the level of detection at specific locations.

In all cases, sample management controls have been prescribed to ensure samples can be clearly identified from their source through to final data reporting and that they are handled and stored in line with the findings from the stability trials.

The potential for sample contamination or substance loss has also been taken into consideration as the priority substances are usually only detectable at microgram or even nanogram per litre levels in wastewaters. This is particularly important for ubiquitous substances such as DEHP, aluminium, copper and zinc. Sample contamination can be avoided by using the appropriate sampling equipment; for organic substances glass sample bottles must be used and for metals testing plastic apparatus is used to avoid metal contamination. The CIP follows standard practice in deploying field based blank samples into each batch of samples collected. Analysing the blanks alongside the real samples ensures that the sampling process and the associated equipment is free from contamination.

Many of the substances identified in the CIP are not ones that are typically part of most laboratories routine suites of analysis. Given the original timescales assigned to the CIP, it was a challenge to develop methods of identification that met the EQSs, in such a short timeframe.

The production of robust performance test data is critical to proving that the developed methods are fit for purpose. The CIP demands the delivery of performance test data on a minimum of 11 batches of duplicate analyses of blanks in effluent and raw sewage.

In addition to the routine laboratory based Quality Control (QC) measures, the CIP also requires laboratories to participate in an external, independently-run Proficiency Scheme. As a comparison of laboratory generated results, the scheme helps give validity and credibility to the programme results. 

The target put in place by the Directive that all waters, surface waters and groundwaters must achieve a ‘good status’ by 2015, has created a sense of urgency for measures to progress for the WFD.

Through the deployment of the CIP, UK water companies are playing their part and will ensure that the UK stays at the forefront of how to manage priority substances in wastewaters.