ARM World First for Drinking Water Sludge Management

ferric drinking water sludge showing evidence of dewatering producing a sludge residue of up to 60% dry solids content

ARM were appointed by Essex and Suffolk Water, part of the Northumbrian Water Group to design a trial sludge reed bed system to provide treatment of  ferric sludges produced from drinking water treatment processes at the Hanningfield treatment works. ARM teamed up with Danish company Orbicon to devise a world first - reed beds designed specifically to treat drinking water sludges. Denmark has been using reed beds to treat sewage sludges for 20 years. Sludges comprising approximately 2% dry solids are intermittently dosed onto the reed bed allowing for resting periods for the sludge to dewater, leaving behind a sludge residue on the surface of the bed while the filtrate percolates through the system. The sludge residue undergoes mineralization reducing by up to 200 times its original volume. Reaching capacity, after 10-15 years, Denmark has found reed beds make a sustainable long-term solution to treat 80% of all its sewage sludge. Applying this technology to the drinking water side of water treatment will work in a similar manner. A pilot test carried out at Essex and Suffolk Water's Hanningfield Reservoir to test how well reed beds treat drinking water sludges, produced a final sludge residue of up to 60% dry solids content. The trial has proven that the technology works on ferric sludges and ARM is currently running a trial on alum sludges in conjunction with Northumbrian Water and Orbicon at Lumley near Durham. Reed beds have low energy requirements, reduce the need for transportation and use no chemicals for dewatering. They have lower capital and operating costs when compared against traditional mechanical options. Plans are now in place for a full scale design of over four hectares.  The reed beds will replace Hanningfield's sludge lagoon system.