EKG Remediation of Embankment

Forest of Dean slope stabilisation

Low Impact Benefits

Highway Embankment Stabilisation

Sewage Sludge

Mine Tailings

Railway Embankment Stabilisation

Reinforced Soil

Lagoon Consolidation

Consolidation of Soft Soil

 

Conventional treatment, 19% dry solids content

EKG enhanced treatment - 31% dry solids yielding 39% volume reduction and improved stacking

Dewatering of Sewage Sludge

Treatment of raw sewage produces sludge with solids content in the range 1-3%. The requirement to dewater and re-use or dispose of these materials is a fundamental issue and persistent and complex problem for all water companies in any country.

Conventional dewatering of sewage sludge involves the use of belt filter presses or centrifuges to reduce the water content to permit disposal.

Disposal is best effected if the sludge material has a dry solids content greater than 25-30%. In general terms conventional belt press treatment systems produce a sludge cake with a dry solids contents significantly below this level.

A step change in belt press dewatering performance has been achieved by combining conventional belt press technology with EKG. This breakthrough adds the dewatering effect of electroosmosis to that of conventional hydraulic dewatering.

The form of the EKG is an Electrokinetic patented enhancement of standard filtration belts.
An example of using EKG technology in sewage dewatering by Thames Water Company (London) is shown below left.

This shows that, at a dry solids content of 19%, the material is still in a semi-liquid form and difficult to transport, this can require mixing with straw to provide mechanical stability. If disposal is by incineration then fuel oil has to be added to increase the thermal content of the sludge.

At the 31% dry solids content produced by the EKG treatment, the sludge is now a solid and can be handled without the addition of bulking material and that the volume of material to be disposed of is reduced by 39%.

In addition, at 30+% dry solids many sludge cakes are auto-thermic and can be used as a fuel.

The economics and cost savings of using EKG technology to dewater sewage sludge has been identified by McLoughlin (2005) as tabulated below.

    Conventional belt press EKG belt press
  Loading Kg, dry solids per hour 540 540
  Operating hours 8,000 8,000
  Cake %age dry solids 19 31
  Disposal cost £s per m³ 15 15
  Disposal cost £s per year 340,500 208,500
  EKG saving £s per year per machine
(Six machines on site)
  £132,000 ($230,000)

 

Disposal cost comparison (after McLoughlin 2005)

Based on typical sewage treatment site with six dewatering machines, this will give a potential cost saving of c£800,000 per annum

 

 

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