Challenge

Ightham Mote is a moated medieval manor house dating from the 14th century. The site has a staff of 20, is home to 26 residents, and attracts an average of 500 visitors per day. It is the National Trust’s busiest visitor centre and restaurant.

The existing system was overloaded in terms of organic loading, and at full capacity in terms of hydraulic loading. It was essentially acting as a septic tank rather than an aerated biological treatment plant. It was also housed in underground GRP tanks and was affected by ingress of groundwater into the system.

The National Trust began the process of arranging to pump the site’s effluent to the local utilities site. In the meantime, Pollution Control (UK) was commissioned to provide a rental system to cope with demand during the contract negotiations and construction of the pump station.

Solution

Pollution Control (UK) decommissioned the existing system and supplied a complete biological treatment system including primary settlement module and ECO-SAF module with an upward flow clarifier cell, utilising an existing GRP tank as the balance capacity. The 430pe plant was based on 150litre/person/day and 108g BOD/person/day.

Outcome

Consent levels for the system were:

  • Suspended solids - 40mg/litre
  • BOD - 30mg/litre.

Analysis was taken over a two-year period with average results of <17mg/litre suspended solids and <7mg/litre BOD.