Bespoke Sludge Thickener Blends into Background and Controls Odour

A low-profile sludge thickener has been designed so that it is virtually invisible in its surrounding rural landscape. In addition, odour control has been built into the design so the many weekend visitors who come to enjoy the natural beauty of the area hardly notice it.

Sludge thickening is a universal requirement of modern foul water treatment works and there are many standard thickeners available. However, at some installations there is a need for a thickener built to a bespoke design that addresses the particular issues of the site.

A&J Fabtech has completed the installation of a bespoke sludge thickener with a low-profile outline that means it is barely visible in the landscape. The design also ensures excellent odour control and a long, reliable working life.

Commissioning the thickener was one of the last stages of a major upgrade of a water treatment works that serves a large metropolitan area in the North of England. Located beyond the urban area, the works is in a valley popular with weekend ramblers and for family outings, so all plant has been designed for minimum visual intrusion.

A&J Fabtech maintains the capabilities to design, fabricate, install and commission one-off systems, as well as having a range of standard water treatment equipment.

The requirement in this case was for a sludge thickener designed around a central drive with a static access bridge. This was to be one of the last installations in a multi-million pound, multi-year project that modernised a treatment works that serves a large population.

Mark Wright, Managing Director for A&J Fabtech gives some details. “We went for a low-profile design that would sit discreetly in the landscape, rather than a taller solution that would be visible from a distance. Also, the client wanted to take a positive approach to odour control, but requested a simple solution that would be low maintenance and reliable in the long term.”

The finalised design was based around a sludge thickener with an access platform and stairs fabricated in galvanised mild steel so that they will stand up to the rigours of many winters. A&J Fabtech’s in-house designers ensured that all loads, radial, axial, dynamic and static, generated by the thickening process are transferred to the foundations via the access platform, and that no other part of the installation is put under stress. This simplified the design and also means easier maintenance requirements throughout the expected decades-long life of the installation.

A&J also came up with a very simple solution for odour management. They put a roof over the thickener and provided a ventilation system that controls the dispersal of the odour. The roof itself is actually quite a sophisticated design, being a two-piece unit executed in a grade of glass-reinforced plastic that will not degrade under the naturally-occurring ultraviolet light.

The roof fully encloses the thickener and includes inspections points, louvre access doors and light boxes so that it is not dark beneath the roof. Due to the exposed nature of the site, A&J Fabtech also allowed for substantial wind loading as well as the static element loading. Permanent lifting eyes were designed-in so that the roof could be craned into position and easily lifted off in the future for maintenance.

Mark concludes: “As part of the commissioning and hand-over process, we had built a bespoke lifting rig for safe, drama-free lifting and have left it on site for future use.”