Greener Waste Technology has been working with a utility company to combat the effects of flooding on a filter bed works. The works in question is low lying and next to a river which recently burst its embankment and flooded the filter beds entirely. The flood distributed large volumes of silt and mud onto the filters blocking the beds and starving the indigenous bacteria population of oxygen which prevented the filter beds from operating efficiently.
The utility needed a fast and efficient solution to remove the inhibiting silt and sludge accumulation in order to return the works to full treatment capacity so that they could conform to their discharge permit as quickly as possible.
Straight flushing and rinsing was not an option as the river mud and silt had bound with the existing biomass within the filter beds to form a resilient glutinous mass which was quickly turning anaerobic. The traditional cleaning method of removing the media and mechanically washing was also not an option due to the length of time required to close down the filters during the cleaning process, the additional potential damage to infrastructure during the cleaning process, the difficulty of access for heavy equipment on site and the associated need for temporary treatment to support the site during filter bed down time.
Greener Waste Technology has developed an innovative and non-intrusive method of cleaning filter beds and was therefore able to assist the utility with their requirements.
Using a combination of the smart filter bed cleaning process and BioCube dosing system GWT flushed silt and mud from the media matrix to remove the septic sludge which had built up on the beds from the flooding. The flushing process was combined with a spreading programme using a blended carbonaceous bacteria product to re-seed the beds and suppress the moss growth on the filter bed surface.
Once the flood subsided the site performance was unfortunately still being affected by high water levels within the filter beds during high tide which regularly kept water sat in the lower 500mm of the filter. Ammonia was luckily not of concern at this site but the high water level was impacting on BOD removal given the smaller treatment area available during these times within the filters.
The BioCube dosing unit was added to the site to dose a blended carbonaceous bacteria product to the PST using screened sewage as the feed stock for the BioCube breeder unit. This unit helped to reduce the load from the primary tanks and improve settlement to aid with the BOD removal in the limited treatment capacity of the site and also enabled the fast recovery of the filters as the water level continued to fluctuate.
Until such time as a capital scheme can be decided upon to combat the flooding the dosing unit continues to support the treatment on site and has since enabled a fast recovery after a second flooding incident over the Christmas period.