Sludge drying reed beds.
Sludge reduction occurs by dewatering (draining, evapotranspiration) and mineralization. Sludge from wastewater treatment plants (2,500-125,000 PE) is treated in sludge reed basin systems with 1-18 basins with loading rates of 25-2,200 tons dry matter/year for 10 years. In general, the sludge type is surplus activated sludge or a mix of mesophile digested sludge and surplus activated sludge. Dimensioning and design of reed basin systems for 10-year periods of operation depends on how the sludge is produced, rate of production (tons of dry matter/year), sludge type, quality and regional climate. Loading cycles are related to the sludge type and the age of the sludge reed systems. The period can be divided into a number of operating phases: commissioning, full operation, emptying and re-establishment of the system. Experience shows that efficiency makes special demands on the design of the systems and on the operational control in order to obtain a final dry matter content in the sludge residue of approximately 40% and the number of operating years. Sludge loadings with surplus activated sludge and surplus activated sludge mixed with anaerobically digested sludge amount to a maximum of 60 and 50 kg dry matter/m2 x year, respectively.
Nielsen
S
S
Hedeselskabet, Environmental and Energy A/S, Ringstedvej 20, DK-4000 Roskilde, Denmark. smn@hedeselskabet.dk
D001673:Biodegradation, Environmental; D003247:Conservation of Natural Resources; D017753:Ecosystem; D006109:Poaceae; D012722:Sewage / Q000737:chemistry*; D014835:Volatilization; D014865:Waste Disposal, Fluid / Q000379:methods*
D012722:Sewage