Excellent Ammonia Performance from Hydro's DynaOxy Filter at Wessex Water site

When investing in improved waste water discharge standards to meet stricter limits under the AMP3 guidelines, Wessex Water decided to upgrade its treatment works at Merriot, Somerset. Three DynaOxy nitrification filters from Hydro International to polish the treated water prior to release to the local water course.

Wessex Water specified Hydro International's DynaOxy nitrification filters for the treatment works at Merriot, Somerset.
"The filters are continuing to perform very satisfactorily and exceeding the specified standards," comments Steve Tomlin, Technical Manager at Wessex Water. "It is achieving less that 1.0 mg/litre of ammoniacal nitrogen on average, and the BOD and solids levels are also very good."

The DynaOxy filter comprises a media filter bed held within a hopper into which water from the humus tanks is pumped via a manifold to deep within the DynaAktiv media. Nitrifying bacteria, colonising the media surfaces, convert the ammonia content to soluble nitrate, as well as removing suspended solids and associated BOD. The water flows up through the DynaAktiv bed into the open space above the sand, and the cleansed water exits via a weir at the top of the tank before discharge.

Oxygen is added through non-clog aeration hoods within the filter bed, to maintain the dissolved oxygen level in the water to maintain the metabolism of the bacteria. The bacteria count is kept at a high level throughout the filter as the media is continually air lifted from the bottom of the hopper, washed and replaced at the top to ensure a cleansing life cycle.

Not only does this remove inactive solids and dead biomass, every grain of DynaAktiv media moves through the most favourable high ammonia zone a number of times every day. As a result, the DynaOxy os very tolerant of ammonia load surges.

The DynaOxy provides nitrification, filtration and aeration in one system, so is very economical of space, with a small footprint. The three 9.123m high filter units with associated pipework, blowers and stairway access were installed on a 12.5m by 6.6m concrete slab at Merriot STW.

If you would like any further information on or any of Hydro International's stormwater, wastewater and sewage treatment systems, please call 0800 269371.

For further information please email Hydro International Plc

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