Working with Southern Water at Whitewall Creek WwTW

Southern Water’s Whitewall Creek WwTW serves a population of 85,000 in the catchment area of Rochester, Kent. Operational fatigue, high levels of grit and H2S corrosion due to the Works proximity to the coast meant that long-standing screening equipment had reached the end of its serviceable life.

Southern Water looked to replace the existing equipment with the latest in Screens and Screenings Handling technology and invited framework partner M&N to look at options. In 2015 M&N completed an upgrade to the Inlet Works which involved the supply and installation of 2 escalator screens, 2 wash presses, an overhead launder complete with grit trap and a new MCC to control the equipment.

Whitewall Creek Screens and Screening Handling Set Up

Objectives

• Provide a complete package of Screens and Screenings Handling solutions by working with M&N's manufacturing partners.

• Design a layout that would ensure ease of maintenance & servicing going forward.

• Overcome natural hydraulic challenges on site.

Implementation

Following a review of the relevant information and discussions with Southern Water operations, engineering and procurement M&N brought together manufacturing partners FSM Frankenberger GmbH & Co, Kuhn GmbH and in-house design teams to put together a packaged solution best suited to the site’s operational requirements and budget.

With the issue of the site being hydraulically challenged M&N design engineers used specialised software to assess the hydraulics and ensure the final screening solution was designed to ensure no issues occurred downstream of the proposed new screening equipment.

A package of 2 FSM Frankenberger 1200mm FRS III Escalator Screens and 2 Kuhn HD 300/1200 Wash Presses were selected to comprise the Screens and 4.5m³/hr Screenings Handling requirements of the new design.

In preparing layout options to ensure ease of future equipment maintenance & servicing, it was also necessary to take into account the potential impact of grit and stone capture in the launder flow.

An M&N Inline Grit Trap was incorporated into the design package to capture as much of the grit and stone as possible. This was also factored in to maximise the brush life of the Kuhn Wash Press. The launder arrangement, including the FSM Escalator Screen interfaces with the launder and grit trap was modelled using M&N’s 3D CAD software to ensure there would be no issues at key interface points, optimising installation time of the final package on site.

M&N’s specialist Controls & Automation division fabricated a bespoke MMC to serve the new equipment, incorporating dedicated PLC software and telemetry.

All aspects of the mechanical and electrical installation were undertaken by M&N personnel and completed over a 4 week period.

Whitewall Creek FSM Escalator Screens

Whitewall Creek Kuhn Wash Presses

Results

In 2018 M&N engineers undertook an inspection of the performance of the plant at Whitewall Creek.

Despite the naturally high levels of grit in the channels feeding the screens, since the 2015 installation Southern Water have not required any spares for the Inlet Screens. Screens and Screenings Handling performance had been maintained over the period, with the following run hours recorded for the equipment:

FSM FRS III Escalator Screens - 3800 hours run

Kuhn KWP Wash Presses - 420 hours run

Project Summary

M&N’s collaborative approach, exclusive relationships with key manufacturing partners, extensive in-house resources and expertise provided Southern Water with a complete Inlet Works Screening and Screenings Handling package that:

- Maximises operational performance

- Delivers significant OPEX and projected TOTEX savings* 

* Unique control philosophy (nudge & weight) significantly reduces OPEX and TOTEX costs.

Equipment Profile

FSM FRS III Escalator Screens (x2)

Kuhn KWP Wash Presses (x2)

M&N Grit Trap

Bespoke MCC

Both Kuhn and FSM Frankenberger are Internationally recognised as manufacturers of high performance Screens and Screenings Handling equipment.

Independent testing at Chester Le Street saw the FSM FRS III Escalator Screen achieve average screenings capture ratios of 85.33%.

Operational Suitability:

• Fabricated in Grade 316 stainless steel to offset coastal location and H2S impact

• Capable of handling maximum flow of 378 litres/sec 

• Installed to overcome hydraulic challenges

• Robust, hardwearing construction 

Escalator Screen Design Benefits:

• Unique Brush Positioning offering optimum cleaning

• Self adjusting brush

• Choice of perforation sizes

• Screen frame, covers, chains, sprockets, filter panels, shafts & discharge chute all manufactured from Stainless Steel

• Screenings lifters fitted to every 10th panel (as standard)

• Rag lifters on screen prevent build up in front of screens

• Easy to retrofit

• 100+ UK installations

Wash Press Design Benefits:

• Highest score for STF in the market

• Capacity of up to 24m³/h

• Low wash water requirements

• Offers up to 87% reduction in volume, weight & disposal costs of screenings output

Whitewall Creek Screenings Output

 Download Whitewall Creek case study PDF [407 KB]