Creating a sustainable and innovative Sludge Treatment Reed Bed system
Up to 225 million litres of water a day is treated at Hanningfield water treatment works. The sludge wastes from this process have previously been pumped to adjacent sludge lagoons. As these lagoons neared the end of their serviceable life, Essex & Suffolk Water started to look for an alternative and sustainable solution.
They decided to progress with a reed bed system, as this solution could offer substantial financial and environmental advantages. It was an innovative choice. Reed beds had been used for the treatment of sewage sludge since the late eighties, but had never been used for the treatment of sludge from water works.
Essex & Suffolk Water therefore hired the partnership of Orbicon and ARM Limited to create the world’s first reed bed system specifically designed to treat drinking water sludge. A test plant was set up, and following successful test results, Orbicon designed the full-scale plant with 16 reed beds.
The traditional mechanical and chemical methods of dewatering only reduce the volume of sludge. A reed bed system, on the other hand, utilizes natural processes to reduce and treat the sludge. The benefits of this method are:
- Effective reduction of sludge residue
- Better working environment
- Cost effectiveness
- No use of chemicals
- Cleaner waste water
- Low levels of maintenance labour and power
- Water conservation
- A positive impact on local nature
- Good options for recycling, e.g. as fertilizer on agricultural land
From the water works plant, an underground pipe delivers sludge to the reed beds. The beds then naturally filter the sludge, and clear filtrate water is returned to the reservoir for re-use. On its journey back to the reservoir, the water flows into Great Prestons lagoon, where it helps sustain valuable habitat and wildlife. The Sludge Treatment Reed Bed system is a long-term solution, as solid residue is retained on the surface of each reed bed for a 15-20 year period, after which it is excavated for land application.