eutrophication

A large dose… an innovative approach to eutrophication

eutrophication

Phosphorous in wastewater is a key cause of eutrophication which is the over-enrichment of lakes and other surface waters from mineral and organic nutrients. It stimulates excessive growth of microscopic algae and plankton, creating a dense algal bloom, where the subsequent death and bacterial decomposition strips the water of its oxygen and creates an unhealthy environment. Eutrophication is a huge concern as many waterways and lakes in the UK are currently failing to meet the strict standards set for nutrient levels under the nation’s Water Framework Directive.

Agricultural fertiliser run-off from fields, detergents from household drains, and waste from various industries, are the main causes of phosphorous in water. The levels in the discharges from municipal and industrial wastewater treatment plants must be controlled to minimise eutrophication issues. Such issues include increased purification costs to diminished recreational and wildlife conservation, loss of fish and other livestock, and potentially lethal effects from toxic algae in drinking water.

Drivers and challenges
Pressure from environmentalists and legislative demands in the UK to reduced phosphorous levels in discharged wastewater have been key drivers for one of WES’s key customers, Wessex Water. But how could the utility company find a new water treatment to tackle these issues, that was both cost-effective and practical, as well ensuring health and safety remained a focus?

One effective and commonly used step in the removal of phosphorous is to dose water with ferric chloride. And, so seeking increased or upgraded ferric dosing at multiple locations, Wessex Water issued a framework tender call, to which WES Ltd responded.

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. Ensuring they were resourceful and efficient with timings due to the potential risks poot weather might impact the project, were crucial considerations 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 and Construction project team on developing it to meet their specific operational needs.

A package for all sites
Their innovative approach and thinking, resulted in a cost-effective, compact and versatile package. Furthermore, its standardised approach, with broad applicability, enabled just two size variants, 5,000 and 10,000 litres, to address the differing circumstances required at a large number of sites.

The 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 at the WES factory in Basingstoke, before delivery, instead of assembling them on site.

Even the largest units could easily be handled in one lift and safely transported on a single, non-articulated, flatbed truck. Meanwhile, easy carriage and there relatively small dimensions gave them flexibility for installation on disparate sites, where space was often at a premium and the terrain could prove to be challenging.

The advantages of reducing time and labour costs meant that the number of personnel needed on site was also minimised. Moreover, the duration of their exposure to associated health and safety risks was especially welcomed, in view of the added hazards and complexities sometimes posed by adverse weather conditions.

Successful co-operation
Design, delivery and installation of the ferric chloride and ferric sulphate units initially ordered by Wessex Water took 9 months and the project was completed in summer 2018. Since then, WES Ltd has received dozens of orders for the supply of 5,000 and 10,000 litre systems by water utility companies and their contractors.

To WES, this project was particularly important as it 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.