Water-efficient, low-energy, phosphorus reduction technology has enabled United Utilities to deliver tightened phosphorus removal consents at one of its wastewater treatment works.
Water companies in England and Wales are experiencing ongoing challenges in meeting new and expected phosphorus permits, some as low as of 0.25mg/l.
To help meet tightening permit limits, United Utilities purchased a Flocell XFM 40 modular filtration system unit comprising eight modular filters, capable of flows of up to 40l/s.
The decision follows a successful 12-week trial at one of the company’s rural wastewater treatment works (WwTW) in Appleby, Western England, which demonstrated capability to meet phosphorus concentrations less than 0.25 mg/l when combined with chemical dosing.
During the trial, the team undertook in-depth particle size distribution analysis and total suspended solids (TSS) analysis on over 1,000 individual samples.
Callum Grundy, principal innovation engineer, at United Utilities said, “Following the trial, we have established the Flocell system as one of a range of treatment options United Utilities have available for use on appropriate wastewater treatment works.
“We were looking for a filtration technology that could be deployed to help meet low phosphorus concentrations without the impacts of backwash returns. This was found in the system, which was trialled successfully over a 12-week period.
“The engagement and collaboration we had with wastewater treatment specialist WCSEE and sustainable filtration specialist Flocell was fundamental to the success of the trial. We are now looking forward to exploring its potential further and are really pleased to be supporting the local economy here in the Northwest, with the technology being manufactured in Wigan.”
Precedent setting
Flocell is a business division of Evolution Aqua Group that partnered with WCSEE to modify the Flocell XFM technology for wastewater treatment.
Originally developed for application in koi carp pond filtration, the system has been used in the aquatic sector for over two decades.
Dr Adam Guest, senior process engineer at United Utilities, who advised during the Appleby trial, said, “The simplicity and robustness of the system means it can be set up to be operational very quickly with limited commissioning requirements.
“The introduction of tertiary solids removal systems to help meet tight phosphorus drivers, can result in significant volumes of backwash water being returned to the inlet works. This can lead to hydraulic challenges on many sites, particularly on some of our smaller, rural WwTWs.
“The ability of the system to operate for extended periods without backwash, and the limited backwash volume, make it ideal. In dialysis mode there is no requirement for a complex flow control system, which also adds to the simplicity of installation.”
Gavin Haywood, director at Evolution Aqua said, “Achieving these results, while maintaining over 99.9% water use efficiency, removes the need for backwash tanks and associated infrastructure and maintains operational hydraulic loading in a small and compact footprint which requires only a level base, reducing concrete usage that can be delivered to site and brought online within a few hours of deployment.”
