Viltra DMT Partnership placed an IWOX sewage treatment system in a domestic dwelling in Craigavon County Armagh in Northern Ireland. The new house was built for 6 people.

As the site had its discharge to a small stream, it was granted under the condition that the sewage treatment had to meet the strictest effluent standards of 5 mg/l biological oxygen demand (BOD) and 5 mg/l suspended solids (or 97.5% BOD removal). To meet these standards the builder choose the Dutch-Irish IWOX small scale sewage treatment plant. It was the 1.000th IWOX to be installed.

Northern Irish-Dutch partnership
Since 2006, Irish firm Viltra have been working in partnership with Dutch water technology firm DMT to provide advanced solutions for wastewater treatment problems across Ireland and wider Europe.

The partnership began with the development of the IWOX-system that has now been delivered across Ireland and into Scotland, England, Greece and France.

Only one mechanical part
Many STP systems have increased effluent quality of 15 mg/l BOD and 30 mg/l suspended solids. With the development of packed media and rotating disks, discharges of 10/13 are claimed. However this design greatly complicates the system and increases the chance of failures and still has minimal nitrification and no nitrogen removal.

Viltra/DMT has entered the market with a STP which has been engineered based on down scaling WWTP technology. The only one mechanical part used is a robust blower. A sophisticated circulation system equalizes influent flow fluctuations and prevents sludge build up as well as SS wash out in a compact two stage settlement tank.

Three step process
The Viltra/DMT IWOX 5/5 process contains three steps:
- the influent flows into the pre-settlement tank, where large solids settle
- the wastewater flows into the denitrification and oxidation tank, where COD, BOD and nitrogen is removed
- activated sludge flows into the first clarifier compartment where the activated sludge is recirculated to the denitrification compartment

Designed recirculation and denitrification prevent sludge floatation and ensures the clean effluent of 5 mg/l O2 BOD and 5 mg/l SS. The second stage in the clarifier tank acts as a backup system. The oxidation, as well as the recirculation, are achieved by use of the same blower, reducing the amount of needed energy and mechanical parts.

The original news release was published on the website of DMT.


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