a combined reed bed and freezing bed filter for...
TRANSCRIPT
A COMBINED REED BED AND FREEZING BED
FILTER FOR SEPTAGE TREATMENT AND
REUSE IN COLD CLIMATE CONDITIONS
C. Kinsley, K. Kennedy, A. Crolla
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Introduction
• Septage - accumulated sludge in septic tanks
• ~1.2x106 septic systems in Ontario (860 000
m3/yr) • 60% applied directly to agricultural land
• 40% co-treatment at WWTP
• Ontario Ministry of Environment is committed to
phasing out the land application of untreated
septage
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Reed Beds• Variation on drying bed
design
• Sludge is dewatered and composted in one step
• Plants provide many benefits: • roots create drainage pathways
• plant movement and growth breaks sludge cake
• plants absorb water from sludge
• oxygen transfer to the plant roots assist in the stabilization and mineralization of the sludge.
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Combined Reed Bed-Freezing Bed Field Study
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Reed Bed Filters Unplanted Filter
Experimental Variables• Solids Loading Rate (42-144 kg TS/year)
• Hydraulic Loading Rate (1.9-5.9 m/year)
• Planted vs unplanted
• Season (T, Precip)
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Treated Effluent Irrigation
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Plant Development
Experiment 1: Effect of SLR on Drainage
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Experiment 1: Effect of SLR on Drainage
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Experiment 2: Effect of Plant Growth on Drainage
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Design Loading Rate
• Subtract ponded water from May-Nov from hydraulic
loading.
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Year Design Hydraulic Loading Rate (mm/d)
SF RB1 RB2
2007 8.4 8.5 9.5
2008 8.4 8.2 8.8
2009 10.8 7.1 8.1
Avg. ± SD 9.2±1.4 7.9±0.7 8.8±0.7
Design Hydraulic Loading Rate = 8.6±0.7 mm/d or 2.9 m/y or 75 kg/m2/y
Experiment 3: Effect of Hydraulic Load on Drainage
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Filtrate Quality
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Significant effect of Period for COD, TSS, TN and TP was observed
(P<0.05), while no effect for Year (P>0.05) was observed.
Dewatered Sludge Quality
• Similar nutrient and solids content to solid dairy manure
• Metals and E.coli meet biosolids standards
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Acknowledgements
• Ontario Ministry of Environment
• Canadian Water Network
• René Goulet Septic Tank Pumping
• Canada Mortgage and Housing Corporation
• Eastern Ontario Water Resources Committee
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Thank you!www.orwc.uoguelph.ca