Water/Wastewater

  • Innovative Foam & Filament Removal System

Innovative Foam & Filament Removal System

Jan 07 2009 Read 3154 Times

Foaming problems on activated sludge plants are well known. A common cause in domestic wastewater treatment is the presence of excessive foam-causing filaments such as Microthrix parvicella and “nocardioforms”. These filaments are relatively easy to recognise, but their cause is often more elusive. Very often they are associated with high FOGs (fats, oils and greases), in the influent stream, a lack of inadequate primary treatment, septicity and / or biological nutrient removal (BNR) processes.

Once foam-causing filaments become established, they can be difficult to eradicate. The foam that they create is stable and provides an ideal environment and a readily available foodsource, including FOGs, dead cell material and septic conditions. In addition, the foam continually reseeds the plant, giving these filaments a further selective advantage. Foam trapping – to prevent high suspended solids (SS) carryover in the final effluent – exacerbates these problems.

To break this vicious cycle, the foam clearly needs to be removed. Various methods have been tried over the years with varying degrees of success. These include those listed below:

Chlorination, or use of another oxidising agent, especially in the form of surface sprays

Dosing of Aluminium salts

Use of selectors

Use of scum traps of various designs

These methods vary in their level of effectiveness, and very often good results are synonymous with high costs and / or a high level of operator input. For these reasons, effective foam control in a problematic plant is seldom sustained.

Although not widely marketed, a highly effective foam removal device has been in use on the Continent for well over 10 years. Not only does this innovative piece of equipment remove up to 80m³ or more foam per day and dewater it to 3-6% dry solids, but it can do so continuously and at very low operating cost. Such is its ingenuity and effectiveness, that it was awarded the coveted Ernst-Kuntz prize in 1998.

Introduced by Corgin to the UK in 2007, the Foam Skimmer has understandably generated significant interest, both from industry and from all of the UK wastewater companies. Units are now in operation in England, Scotland, Wales and the Channel Islands.

By removing surface foam on a continual basis, the Foam Skimmer tackles much of the root cause of foam-causing filaments. This includes removing their foodsource (surface FOGs, dead cell material and septicity), their preferred environment and their ability to reseed.
Visual improvements often show within days, followed by profound effects on plant performance. Improvements vary from plant to plant, but benefits such as increased aeration efficiency, improved settlement / lower SVI`s reduced sludge wastage, reduced SS in final effluent, and overall plant performance improvements have all been experienced.

Corgin provide information packs on the Foam Skimmer, a filament identification service, site assessments, and work-or-return trial rentals to allow you to witness its performance first-hand.

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