Articles & Case Studies


Posted: Thursday 22nd September 2011

When Holiday Inn decided to build a new hotel on the edge of the South Downs, quality and the environment were top of their agenda. The four star hotel has 141 rooms, conference facilities and a restaurant that has recently been awarded an AA Rosette for high quality food. The Winchester site is easily accessible by customers wanting a room for the night, a venue for a business meeting or a stylish place to get married, but it is the location which caused the most concern when plans were drawn up.

Sited above chalk drinking water aquifer resulted in Environment Agency consent of 5mg NH4]N. With no mains drainage within close proximity, it was imperative that the wastewater produced by the hotel be treated to a very high quality prior to discharging to ground.

The EnSo OceanProfessional MBR 500was selected for its exceptional process performance. There were a number of space constraints on site and we were asked to design a system that could be installed with a 2.4m deep inlet invert with location below the coach]parking area, which would also help the aesthetics of the hotel. To aid efficient sampling with minimum disruption to the car park, ports were cast into the tank to allow monitoring from ground level without having to lift any covers. This state of the art system can treat sewage from 500pe but with a footprint of only 10m x 7m.

The Ocean Professional MBRutilises MicroClear Membrane technology, supplied to EnSo International by Weise Water, Germany. The quality that is produced from the OceanProfessional MBRis second to none, offering a 5:5:5 mg/l (BOD;SS;NH4]N) with the option to utilise the final effluent for irrigation or for discharge to sensitive receiving waters, as with the Holiday Inn.

As there is a large restaurant on site, installation of efficient FOG management in the form of a 2]stage interceptor was important as fats, oil, grease and putrescibles from the kitchen will impact severely on the process treatment performance of the treatment works. A three stage primary settlement tank efficiently captures gross solids and is followed by a pre]aeration tank. A separate MBR tank allows fully treated effluent to be drawn through the membranes prior to discharging to the soakaway located below the car park.

As with all MBRs (Membrane Bio]Reactors), this is a high rate process therefore more time is required to operate and maintain the system which includes occasional in]situ chemical cleaning. EnSo are employed by the hotel to carry out all routine servicing and maintenance on the system.

Installation of the system was completed by Morgan Ashurst, one of the UKs largest contractors, within 2 weeks and was ready for operation in time and on budget prior to the hotel being opened. This system has been operational for over twenty months and consistently achieves its discharge consent with ammonia results of less than 1 mg/l produced on a regular basis.

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