WET News

20 WET NEWS JULY 2015 As the emphasis on reducing turbidity in potable water increases and customers become less tolerant of discolouration, water companies are seeking effective methods to address water quality as a priority. The challenge: Eliminating water discolouration INSIGHT SAmpLing & monitoring the release of biofilm and entrapped inorganic material, such as iron and manganese being released from pipe walls, are causes for discolouration T he UK water industry has been targeted over the quality of drinking water supplied to the public, with 27 measures, including turbidity, put into place to improve water quality. Ofwat has applied high financial penalties to water companies who fail to keep complaints of discolouration to a set limit – a fine of up to £1,000 per complaint if targets are exceeded. Based on the number of complaints water companies received last year, this could see expected fines reaching between £2-3M if they do not meet their targets. Under the new rules, although fines can be applied to water companies who 'fail' to hit their target, they can also be rewarded for an improvement to the quality of the water provided. For this reason, water companies are looking at how they can reduce the number of complaints from the public. The main causes of discolouration is the release of biofilm and entrapped inorganic material, such as iron and manganese being released from pipe walls, typically by changes in the flow and / or pressure in the system and air trapped in the network. This gives a 'cloudy' appearance. Discolouration can be caused in many ways: sudden changes in pressure A solution: Effective monitoring Following four years of r&D, Ati's portable nephnet is providing an accurate account on turbidity. N ephNet is a battery pow- ered, portable turbidity monitor that gives the same measurement performance as the more traditional fixed monitor, with no compromise on measurement. It was created to assist the UK water industry with measuring continuous low level turbidity; to help to control the movement of water; provide a better understanding of the networks; improve the quality of data; and prove the effectiveness of flushing DMA (District Meter- ing Area) in the network. The innovation behind this technology is to maintain the accuracy of the turbidity sensor, whilst reducing the demand for power. The NephNet offers a string of benefits to help control network discolouration, includ- ing continuous remote monitor- ing of turbidity; better accuracy at lower levels; fast connection to water mains via hydrants; and wireless communications and alarms. The benefits of continuous, accurate data has 'opened the eyes' of many water companies, who have previously struggled to understand the overall condition of their networks. As only spot checks were available, there was a lack of information on why water quality differs so much within an area. Now that changes in water quality can be identified and tracked via the NephNet, the supply can be diverted where possible, and crucially, warnings can be sent out to customers to prevent complaints filtering through. Mains flushing NephNet can be used to control and monitor tactical responsive flushing and strategic opera- tional maintenance. The latter can only be carried out if the nephnet can be used to control and monitor tactical responsive flushing and strategic operational maintenance when the fire brigade connects to a hydrant; council staff with high pressure cleaning; valve operations when dealing with 'dead-legs' in the network; and leaks that can affect sudden changes in pressure. This alters the level of sheer stress, hence releasing bio-film. Once the bio-film reaches the consumer, a complaint is made and logged. To help create a solution for this, ATi has spent the past four years working closely with the water industry, in conjunction with PODDS Group at the University of Sheffield, to develop a monitor that would offer a sustainable solution to safeguarding water quality for consumers in this pioneering, pro-active area of distribution management. The UK water industry detailed the pros and cons of the existing technology that was available at the time. It became apparent that the information generated was not sufficient or accurate enough for what was needed. The main challenges were to produce a low powered, continuous sensor that was as accurate as the fixed system. It needed to be a safe source of power that was small enough to fit down a hydrant chamber, whilst also providing an informative GSM that could offer alarms via text and / or email for events. • Continuous remote monitoring of turbidity (every second) • the nephnet sensor eliminates zero drift (it has a self-zero function that deals with contamination build up on the lens) • nephnet uses very little power so can run for months without needing to re charge. • the nephnet has many of the fixed turbidity features (including continuous reading) without the need to reduce accuracy • maintenance is simple, cost free and quick 1 Discolouration can be caused in sudden changes of pressure 2 network monitoring alarm if / when an event occurs, warning the utility company and end users of potential events 3 readings can prove how effective a flushing exercise has been 4 it is the only portable turbidity monitor that can be used when adopting the poDDS model 5 Boundary box installations prove / disprove a discolouration problem at a household / DmA 6 medium-term use of a nephnet will save water companies substantial amounts of money on reducing the need to use manpower Need to kNow "these advances in robust, high-precision and reliable network monitors are revolutionising water quality management in water distribution systems. Detecting variations in turbidity from remote locations in response to immediate changes in flow, using a portable instrument like the nephnet, has shown discolouration risk can be controlled simply and at low cost. Understanding network behaviour using these monitors, therefore allows operators to condition mains for resilience purposes, or long term maintenance to reduce customer complaints and safeguard against water quality failures." Dr Stewart Husband, head of the poDDS group at the University of Sheffield the Verdict: the coNcePt measurement is continuous, accurate and reliable at low lev- els. Mains flushing can be costly and ultimately ineffective if there is no pre- and post-data to support the work. However, the NephNet can be used to prove how effective a flush has been, by continuously monitoring pre-, during and post-flush. Other benefits consist of location of dead legs; effectiveness of a valve operation; boundary box installations for complaints; locating unused water pipes; reducing the risk of injury to personnel who would previously take spot tests near busy roads / motorways; collecting risk data from proposed work and proving/ disproving discolouration from other sources. The overall accuracy and reliability of the turbidity sensor used in the NephNet allows for better data acquisition. This data is being used to check the conditions of the mains pipework and allows for better forecasting. In many cases, proposed work on the network with flushing and relining is being reassessed, delayed or cancelled due to the level of accurate information. Extensive field testing and evaluation has also demon- strated how the use of the Neph- Net allows huge savings when planning or carrying out flush- ing. One water company in the South had identified a discol- ouration risk trunk main that it believed needed major refur- bishment and possible relining. However, the NephNet identi- fied that this was not actually needed and, instead, the main was gradually cleaned by changing the flow, using turbid- ity as the control. This saved the water company a deferred cost of more than £2M, and has resulted in a long-term sustain- able maintenance strategy. Dr Mike Strahand, general manager, Europe at ATi, says; "ATi continues to work in partnership with the water companies and the PODDS Group to tweak and adjust the NephNet where possible to make the water industry that little more slicker in operations. The demand for water quality will always have new set benchmarks. It is up to us, the manufacturers, to listen and innovate where and when necessary. "The development of the NephNet has been a fantastic opportunity for ATi to work in partnership with water companies and leading researchers to develop a monitor that provides a solution for our customers for an ongoing and costly problem."

• Cover