Sludge drying reed beds
Sludge drying reed beds (SDRBs) or Sludge Treatment Reed Beds (STRBs) is a constructed wetland solution used for the management of sludge coming from big activated sludge treatment plants. SDRBs are able to fully substitute conventional sludge lines, leading to economic advantages in terms of sludge treatment and allowing a safe reuse in agriculture of dried sludge. SDRBs can also be used for in-situ treatment of sludge coming from septic and Imhoff tanks.
Advantages 
- no complicated mechanical equipment
- low and simple maintenance
- almost negligible energy consumption
- reduced leachate production
- more than 50% reduction of operational and maintenance costs
- no chemicals
- no hygienic issues
- high flexibility, i.e. high capability in terms of sludge accumulation
- high reduction of total solids during the mineralization phase
- good landscaping
- possibility to reuse the dried sludge in agriculture
Courtesy Steen Nielsen (Orbicon, DK)
More information
Worldwide experiences
Several sludge drying reed beds (SDRBs) were implemented in Denmark, Germany and France in last years. For insance, up to 150 are currently implemented in France, with an increase rate of 20 SDRB plants per year. More than 70% of WWTPs above 100,000 PE are nowadays equipped with SDRBs in Denmark.
Italian experience
The Water Utility Acque Spa has installed a couple of SDRB systems for small and medium size WWTPs (2,000-10,000 PE) in Tuscany Region, highlighting the advantages in terms of costs in comparison to conventional technological solutions (Giraldi et al., 2008, Ceccanti et al., 2010). IRIDRA has also designed a SDRB for the drying of sludge from a septic tank serving the winery of Casorzo (AT - Italy), which produce 30.000 qt of wine per year.
SDRB vS traditional centrifuge
SDRB examples
SDRB of Kolding (Denmark) for 125,000 PE and an extension of 3.3 ha (Source: Steen Nielsen, Orbicon)
SDRB for the sludge produced by the Casorzo winery (AT - Italy), designed by IRIDRA
References
Ceccanti B., Bianchi V., Iannelli R., Peruzzi E., Masciandaro G.(2010) “Sludge phytotreatment (Phragmites australis) for their reuse in the environment”. Atti della "12th IWA Specialized Group Conference on "Wetland Systems for Water Pollution Control", 4-8 Ottobre 2010, Venezia, Italia, 237 – 243.
Giraldi D., Masciandaro G., Peruzzi E., Bianchi V., Peruzzi P., Ceccanti B., Iannelli R. (2008) “Hydraulic and biochemical analyses on real scale sludge consolidation reed beds in Tuscany (Italy)”. Atti della "11th IWA Specialized Group Conference on "Wetland Systems for Water Pollution Control", 1-7 Novembre 2008, Indore, India, 634 – 639.
