Cleaner Waters

A case study of Thames Water Utilities Limited

Thames Water Utilities Limited is the largest water and wastewater management company in the UK. It supplies 2.6 billion litres of drinking water per day to nine million customers across London and the Thames valley. Further, the company recycles around 4.6 billion litres of sewage per day produced by around 15 million customers.

Thames Water is regulated under the Water Industry Act, 1991 and is owned by Kemble Water Limited, a consortium formed in late 2006 specifically for the purpose of purchasing Thames Water. As of November 2017, the largest stake in the company was held by OMERS (23.07 per cent), followed by Hermes (13.06 per cent) and the Universities Superannuation Scheme (10.94 per cent).

The treatment process

For its water supply operations, Thames Water sources raw water from various rivers and groundwater sources and pumps it into the company’s water treatment works through a network of 308 pumping stations. At  larger water treatment sites, water is stored in reservoirs, before it undergoes treatment. Currently, the company has around 26 raw water reservoirs, some of which are being used by local communities for sailing, fishing, etc. The water collected in the reservoir first undergoes a screening process whereby the branches and leaves are removed. In order to remove particulate matter from the water, the flocculation process is adopted, under which a solution is added to the water to make the particles bigger and easier to remove. For removing invisible particles, the water is passed through two types of filters – the rapid gravity filter and the slow sand filter. At a few water treatment works, additional methods like ozone, carbon and ion exchange are used for removing invisible and dissolved particles from the water. Currently, the company operates around 94 water treatment works facilities. Once the water has been treated, around 1 mg of chlorine per litre is added to it. This kills any remaining bacteria in the water and keeps it safe. Following the final treatment, the water leaves the treatment works and is stored in covered reservoirs. Currently, the company has around 235 clean water reservoirs. Finally, the water is supplied through a network of pipes and pumping stations across the country.

Thames Water also has a sewage treatment network comprising 350 sewage treatment works; 109,000 km of sewers; 4,780 sewage pumping stations and 1.2 million manholes. The wastewater goes down the drain and into a pipe, which takes it to a larger sewer pipeline under the ground. These sewers take the wastewater to a sewage treatment plant, where it is put through several cleaning processes so that it can be put back safely into the rivers. The first stage of cleaning involves removal of large objects that may block or damage the equipment, or are unsightly. Further, special equipment is used to remove the grit that gets washed into the sewer. The next stage is the primary treatment process where the organic solid matter is separated from the water by putting it into large settlement tanks, which causes the solids to sink to the bottom of the tank. These settled solids called “sludge” are used to generate renewable energy, resulting in cost savings of around £15 million per year. At the company’s sewage treatment plant in Didcot, the sludge is used to generate renewable gas, which is supplied to around 200 homes in the area. Once the visible bits of sludge are removed, the wastewater is put into rectangular tanks called “aeration lanes” to pump air into it. This stimulates the good bacteria, which break down the bugs by eating them. At the final treatment stage, the treated wastewater is passed through a final settlement tank, where the good bacteria sink to the bottom. This forms more sludge, some of which is recycled back to the “secondary treatment” stage, and the rest goes to the sludge treatment stage. Now, the clean water passes over a wall near the top of the tank. Sometimes additional treatment is needed if the river that the treated wastewater will be returned to is particularly sensitive. The treated wastewater is slowly passed through a bed of sand, which acts as a filter and catches any remaining particles. Once the wastewater has been completely cleaned, it is put back into the local rivers and streams.

Lastly, the sludge collected during the process is treated and most of it is recycled to be used as a fertiliser by farmers on agricultural land. The company also uses it to generate energy through processes like anaerobic digestion, conversion into biomethane and thermal destruction.

Focus on customer satisfaction

In order to improve customer satisfaction, the company engages in face-to-face interaction with its customers by setting up field-based management teams to help in emergency situations. It has developed a new waste one-stop shop to enhance customer experience and fast-track dispute resolution. The customers are provided with the option of receiving text message updates relating to supply issues or interruptions. The company has made its social media service operational 24×7 to ensure round-the-clock communication with the customers. Further, it has launched a new digital platform and a website, which have around 600,000 registered consumers.

Towards innovation

The company uses the latest data and analytics to monitor weather reports and river and ground  water levels. This helps deliver a proactive and preventive response to adverse weather conditions. To improve efficiency, it has started using “designer” bacteria in the wastewater treat-ment process. The use of these bacteria will help reduce the space and power requirements of the wastewater treatment process. With a smaller processing footprint, there is less pressure to build new or larger treatment works to accommodate the growing population. Further, to address the problem of algal blooms, the company is conducting trials of new algae filters at reservoirs.

The landmark Thames Tideway Tunnel project

About 15 miles long, 7 metres wide and 65 metres deep, the Thames Tideway Tunnel is the biggest infrastructure project ever undertaken by the UK water industry. Most of the engineering work is being carried out by a company called Tideway, which will complete construction by 2024. The cost of the project is £4.2 billion. In 2017-18, around £13 of the average household bill for 2017-18 will go towards the project, and this amount will eventually rise to about £25 per year.

The new super sewer will intercept at least 94 per cent of sewage entering the Thames river in a typical year. The tunnel will capture all of the “first flush” from the sewers after a heavy rain. This contains all the sediment that has built up during drier periods, which causes the most damage. As a result, instead of over 50 sewage spills a year, there will only be three to four, mostly due to surface water run-off after heavy storms. The project also offers a number of economic and environmental benefits. It protects the ecosystem of the Thames river and helps sustain commercial fishing industries. A cleaner river will enhance London’s reputation as a business centre and a tourist destination.

The way forward

As part of its Progressive Metering Program (PMP), Thames Water Utilities Limited aims to roll out smart water meters in the UK till 2030 in order to improve water management. The PMP will also provide customers online access to their accounts under the My Meter Online (MMO) initiative. MMO will empower customers by giving them greater control over water usage and billing. So far, the company has installed over 100,000 smart meters. Currently, the company’s water leakage levels stand at around 677 million litres per day (mld). To bring it down to 556 mld by 2035, it is planning to replace water mains, target leakages and improve network operations.

In light of the increasing energy and chemical costs, and the need to reduce carbon emissions, Thames Water Utilities is exploring innovative ways to minimise the resources being used for sewage treatment. To this end, low-maintenance, natural treatment processes need to be introduced at the smaller works, while the aeration process must be optimised at the company’s larger works. All these initiatives will go a long way in enhancing the company’s operational performance and improving customer satisfaction.


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