Customer Case Study

United Utilities Promotes Effective Control of Water Quality

BackgroundUnited Utilities is the UK's largest operator of wastewater systems and also owns and operates the water network in North West England. The company supplies 2,000 million litres of water every day to around 2.9 million households and business premises in the North West via a network of around 40,000 kilometres of water mains, 1,444 kilometres of aqueduct and over 100 water treatment works. United Utilities uses technology and the natural water cycle to ensure that homes and businesses throughout the region receive clean, safe drinking water on tap.

United Utilities PLC was created from the merger of North West Water and Norweb in November 1995. As well as operating its water, wastewater and electricity networks in the North West, the group also uses its core utility skills to manage other infrastructure assets, through its United Utilities Utility Solutions business. The business is also a provider of water and wastewater services to over 400 industrial and commercial enterprises.

In order to uphold its commitment to supply clean and safe drinking water, United Utilities follows a strict regime of testing to ensure it complies with the standards set by the Government and requires a range of instrumentation

in order to test water for a variety of substances. United Utilities works with several manufacturers to develop process instrumentation across a range of categories including flow measurement, chlorine, pH, colour, turbidity, level measurement, dissolved oxygen, mixed liquor suspended solids (MLSS) and ammonia.

Following a lengthy decision-making process, United Utilities appointed Analytical Technology, Inc. to supply its Q45H chlorine monitor in 2006. The Q45H from Analytical Technology is capable of measuring both chlorine and pH simultaneously, and has helped United Utilities to improve water quality while complying with the strict regulations governing the UK water industry.

United Utilities treats 2,200 million litres of wastewater every day via a network of around 39,000 kilometres of sewers. The company maintains this network of sewers and its 600 wastewater treatment works to collect and treat wastewater from homes and businesses, before returning it safely to the rivers and the sea. This network covers a population approaching seven million people in 2.9 million households and business premises. United Utilities manages the catchment areas to collect and store water

in reservoirs before treating it and delivering it to homes and industry across the region. In the North West, United Utilities maintains and operates:

184 reservoirs •455 service reservoirs and water towers •40,000 km of water mains •1,444 km of aqueduct •113 water treatment works •626 pumping stations •

Water Quality:The quality of drinking water in England and Wales is the subject of legally enforceable standards derived from the European Directive and UK legislation. The drinking water supplied to customers must meet legal quality standards.

The Government’s Department of Environment, Food and Rural Affairs (DEFRA) deals with all aspects of water policy in England, including water supply and resources and the regulatory systems for the water environment and the water industry. These include drinking water quality; the quality of water in rivers, lakes and estuaries, coastal and marine waters; sewage treatment; and reservoir safety.

By Dr. Michael Strahand, General Manager Europe, Analytical Technology

DEFRA works closely with the Environment Agency, which manages water resources and enforces water quality standards, as well as the Drinking Water Inspectorate, which regulates the quality of drinking water, and the Office of Water Services, which is responsible for economic regulation of the water industry.

The Drinking Water Inspectorate (DWI) operates as an independent body and monitors the quality of drinking water. The DWI ensures that the water companies operating in England and Wales supply water that is safe to drink and meets the standards set in the Water Supply (Water Quality) Regulations 2000 (“Water Quality Regulations”). The assessment of water quality is based on information received regularly from the water companies. This information includes the results of the millions of tests carried out each year to see if the water meets the standards set by the government in the Water Quality Regulations.

The UK government has set legal standards for drinking water in the Water Quality Regulations. Most of these standards come directly from European law and are based on World Health Organisation (WHO) guidelines. The UK has additional standards to safeguard the already high quality of water in England and Wales.

Chlorine MonitoringChlorine is used throughout the water industry as the primary method of water disinfection but the levels of chlorine are strictly regulated. In order to demonstrate regulatory compliance, United Utilities carries out thousands of tests on water each day. United Utilities monitors the quality of water as it leaves the water treatment works and service reservoirs to make sure that standards are being met, and also measures the quality of drinking water as it reaches customers. Water samples are taken from addresses selected at random within certain zones in order to monitor water quality in the zone as a whole. These samples are tested at United Utilities’ own laboratories, and the results are compared with the required quality standards. All the test results are then recorded on the Drinking Water Register.

Chlorine is the most commonly used disinfectant for the treatment of drinking and cooling water systems. Chlorine is a disinfectant added at water treatment plants to destroy contaminants, disinfect the drinking water and minimise microbial growth in the distribution network. Monitoring the level of chlorine in drinking water is of high priority to United Utilities as proof of disinfection and controlling chlorine levels in the water supply. Chlorine residual monitoring is required in drinking water systems as well as in hygienic use systems and measurements must be conducted on-site. Additionally, chlorine is highly toxic to fish and invertebrates and can cause significant damage to river habitats, and so chlorine levels in water must be carefully monitored.

The water industry has historically relied on open cell amperometric monitors or a variation on open cell amperometric technology with buffer delivery systems for examining the levels of chlorine in the disinfection process. It is estimated that the cost to the UK water industry of operating an amperometric monitor with buffer could exceed £20 million per year. Whilst effective, many amperometric monitor designs are based on engineering technology which dates back 40 years or more and there are a number of associated problems, including excessive cost in use, maintenance requirements, high rates of component failure, envi-ronmental and health and safety issues associated with the storage, handling and disposal of buffering reagents.

Many water companies such as United Utilities are now looking for methods of measuring free chlorine residuals without the need for chemical buffering traditionally associated with such measurements. Acetate and phosphate buffers are expensive and environmentally unfriendly. Buffer delivery systems are maintenance intensive and have fairly costly con-sumables.

SolutionUnited Utilities required chlorine monitors for chlorine measurement in potable water, for monitoring and control applications, to be used at varying stages during the water treat-ment process and at various storage service reservoirs. The company devised a framework agreement extending for 5 years in total and, after a lengthy decision-making process, appointed Analytical Technology as the preferred supplier of chlorine monitors at around 100 sites at United Utilities. The contract had been put out to competitive tender and Analytical Technology scored the highest number of points against a list of criteria which covered commercial, support, and technical requirements.

Unlike on-line colorimetric and most amperometric monitors, the Q45H utilizes a membrane-covered polarographic sensor with an enhanced response at high pH that does not require the addition of costly chemical reagents. The membrane also protects the measuring

electrodes and eliminates the need for electrode cleaning systems.

The Q45H monitor from Analytical Technology is available in two ver-sions: a free chlorine monitor for drinking and cooling water systems and a combined chlorine monitor ide-ally suited for chloraminated drinking water. The combined chlorine sys-tem can also be used in wastewater effluents where sufficient ammonia is present prior to chlorination to result in a predominantly monochloramine residual.

The monitors and service pro-vided by Analytical Technology have surpassed the high expec-tations of United Utilities, and in 2007 Analytical Technology was presented with a ‘Best Instrument Supplier’ award from the water com-pany. This recognition followed an in-depth evaluation of all suppliers by United Utilities, and demonstrates Analytical Technology’s outstand-ing performance across a range of key areas including project design, delivery and quality. United Utilities’ operational equipment suppliers are monitored each quarter for quality and performance. Scoring highly in each area, Analytical Technology was recognised for its promptness of design approval, quotation reply and programme delivery.

As a company, Analytical Technology offers enhanced customer service and this is valued by companies such as United Utilities which rely on Analytical Technology’s expertise. During this installation, training of key United Utilities staff was arranged and provided by Analytical Technology, not at the request of the customer, but self initiated and managed by Analytical Technology.Lorraine J Morton, Framework Manager and John Davis, UU Engineering at United Utilities affirm, “Analytical Technology’s products have demonstrated an ability to monitor chlorine levels extremely effectively, with little maintenance intervention, under a wide range of process conditions. United Utilities has high customer service expectations from suppliers, from good levels of support to our teams to fast response times. Analytical Technology has provided an excellent level of service, and we look forward to continuing to work with the company.”

ConclusionUnited Utilities has a legal and moral duty to maintain the high standards of water quality expected of a nationally acclaimed water company. The company works extremely hard to ensure that compliance with government water quality standards is second nature and that the standards are exceeded whenever possible. The ability of United Utilities to supply fresh, clean and safe drinking water to homes in the North West demands that stringent monitoring and testing of the water takes place at every stage of the water treatment pro-cess. The development of new, efficient, and cost effective technologies by companies like Analytical Technology is crucial in this process.

Disinfection of the water delivered across the North West is essential but requires constant analysis to maintain the delicate balance between taste, safety and water quality. Analytical Technology’s new chlorine monitor, Q45H, has enabled United Utilities to enhance its repu-tation for providing drinking water of the highest quality due to its decision to only work with the best suppliers and instrumentation available.

Q45H MonitorAnalytical Technology’s range of Q45H monitors provides chlorine measure-ments that are as stable and active as traditionally buffered monitors, whilst removing the need for costly chemical reagents. The sensor contained in the Analytical Technology Q45H Residual Chlorine Monitor has a response time of up to 10 times higher than that of conventional sensors. This enables the monitor to provide reagent-free chlorine measurements for most water pH val-ues found in the UK food industry. For applications with variable pH values, the Analytical Technology monitor has an optional pH compensation feature to eliminate free chlorine error caused by process pH drift. When the correct sensor is used, there is an extended response to chlorine at high pH levels, allowing pH correction to be employed over a much wider range.

For more information about the benefits offered by Analytical Technology’s com-plete range of analytical instruments, please call 01457 832800, email us at info@analyticaltechnology.com, or visit www.analyticaltechnology.com