FEATURE WATER TREATMENT
POLLUTION: AN ADAPTABLE AND AFFORDABLE SOLUTION
Dick Tett, sales and marketing director of WES, describes the development of a treatment system for Wessex Water, to help tackle the growing problem of phosphorous pollution
T
he innovative and flexible solution resulting from the joint collaboration
between WES and Wessex Water is good news for both companies, for the water industry and for the environment. Phosphorous in wastewater is a key cause of eutrophication, the over- enrichment of lakes and other surface waters with mineral and organic nutrients. It stimulates excessive growth of algae, in particular, whose subsequent death and bacterial decomposition strips the water of its oxygen and creates an unhealthy situation. The main sources of phosphorous in
water include agricultural fertiliser run-off from fields, detergents from household drains, and waste from various industries. Its level in the discharges from municipal and industrial wastewater treatment plants must be controlled to minimise eutrophication issues. These range from increased purification costs to diminished recreational and wildlife conservation value of natural waters, loss of fish and other livestock, and even lethal effects from toxic algae in drinking water.
DRIVERS & CHALLENGES Legislative demands for reduced phosphorous levels in discharged wastewater, along with pressure from environmentalists, have been key drivers for Wessex Water. In addition, there is a drive for any new water treatment approach to be cost-effective and
practical, and to consider health and safety. One effective and commonly used step
in the removal of phosphorous is to dose water with ferric chloride. Seeking increased or upgraded ferric dosing at multiple locations, Wessex Water issued a framework tender call, to which WES responded.
LIST OF REQUIREMENTS The first challenge for WES was to create a dosing system flexible enough to meet all control requirements and other product standards relating to Wessex Water, other water utilities and approved suppliers. An aspect essential to the system’s practicality was its size and weight. Every detail of the design also had to be weighed up in terms of its cost, to ensure the overall price was competitive. Time efficiency and the potential risks related to weather effects were crucial too. WES established that it was able to
answer these challenges and had the necessary equipment and capacity to manufacture, handle and transport units of each size. After presenting an outline plant design, its specialists worked closely with Wessex Water’s internal Engineering & Construction project team on developing it to meet their specific operational needs. The result was a cost-effective, compact and versatile package. Its standardised approach, with broad applicability,
Design, delivery and installation of the ferric chloride and ferric sulphate units initially ordered by Wessex Water took 9 months and was complete in summer 2018
enabled just two size variants, 5,000 and 10,000 litres, to address the differing circumstances of a large number of sites. Use of a common rather than bespoke
design contributed to the solution’s cost efficiency. Further time and expense were saved by fully constructing and testing each package in the controlled conditions of the factory, before delivery, instead of assembling them on site. Even the largest of the units could easily be handled in one lift and transported on a single, non-articulated, flatbed truck. Easy carriage and small dimensions gave them flexibility for installation on disparate sites, where space was often at a premium and the terrain could be difficult.
Use of a common rather than bespoke design contributed to the solution’s cost efficiency. Further time and expense were saved by fully constructing and testing each package in the controlled conditions of the factory, before delivery, instead of assembling them on site
REDUCED EXPOSURE TO RISK As well as reducing time and labour costs, these advantages minimised the number of personnel needed on site and the duration of their exposure to associated health and safety risks. This was especially welcome in view of the added hazards and complexities sometimes posed by adverse weather conditions. Design, delivery and installation of the
ferric chloride and ferric sulphate units initially ordered by Wessex Water took 9 months and was complete in summer 2018. At the time of writing, WES has received a total of 18 orders for supply of 5,000 and 10,000 litre systems directly to Wessex Water or via its contractors. To WES, this project is particularly
important as it has established the company’s first formal framework co- operation with Wessex Water. For the water industry, that co-operation has produced a practical, affordable and adaptable answer to the challenge of complying with legislation aimed at reducing phosphorous levels. Its positive environmental impacts should be far- reaching.
WES
www.wes.ltd.uk
32 DECEMBER/JANUARY 2019 | PROCESS & CONTROL
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