Herford - Germany
Facing up to increasingly strict regulation
The presence and development of industry in and around Herford, combined with an expanding population has caused an increase in the quantity and variety of the types of wastewater needing to be treated by municipalities.
In order to comply with German and European regulations on effluent discharge, the construction of a high performance wastewater treatment plant was required.
The aim was to improve the water quality of the River Werre, without generating odour or noise nuisances.
The area for the treatment plant being located between railway lines, a road and the river, necessitated the plant fitting into a very tight space, close to built-up areas.
Thanks to new compact technological solutions, the treatment capacity of the plant reaches 300,000 PE.
The Veolia Water Technologies technology has ensured the construction of the plant on a limited area of 7,400 m2. Very compact processes such as biofilters and lamellar settlers with ballasted flocs efficiently remove carbon, nitrogen and phosphorus containing pollution, without nuisance and respectful of stringent standards. The plant is highly reliable thanks to permanent supervision managed by sophisticated automation systems and standby equipment.
Nowadays, the River Werre is used for fishing and for supplying treatment works, dedicated to drinking water production due to the improved water quality.
Pre-treatment of wastewater
Elimination of solid matter, grease and sand :
- 20-mm screening
- wastewater lifting via pumping station
- grease and grit removal by flotation and settling
- 3-mm screening
Primary treatment :
Elimination of suspended solids and partial phosphorus removal by lamellar settling of flocs previously formed during coagulation/flocculation stage.
Secondary treatment :
Elimination of carbonaceous and nitrogenous pollution :
- By upflow biofiltration process : nitrification and denitrification biological treatment are achieved in the same cell
Elimination of suspended matter and residual phosphorus as a final polishing step :
- By high rate settling after coagulation/flocculation stage with the addition of microsand
Mixed sludge composed of primary, biological and tertiary sludge are thickened on a dewatering table with addition of polymers, resulting in a dry solid content of 6%.
Thickened sludge is then directed to the old station, which was refurbished for sludge treatment.
Primary and tertiary sludge
- flocs precipitated at the bottom of the lamellar settler, from the primary and tertiary treatment stages.
- excess biomass in Biostyr cells
- suspended matter filtered by biofilters
- flocs from biofilter wash water treatment precipitated in the lamellar settler
The wastewater and sludge treatment facilities are entirely covered. Polluted air is extracted by a ventilation system and treated in scrubbing towers using the Aquilair process.
The centralised control system provides a fully automated solution that monitors and controls the process, whilst allowing manual operator control as required.
On-line monitoring of the process, using discrete instrumentation (ammonia, COD and phosphorus analysers...) enables the plant control to respond quickly and effectively to variations in pollution load.
Optimisation of the biofilters is performed by the one-line Regul-Filtre™ management system, which regulates number of biofilters in filtration to keep the ammonia load constant.
Veolia Water Technologies' Processes
Multiflo, Biostyr, Actiflo, Aquilair,