Connolly & Palfrey (2011)
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© WRc plc 2011 IMPACT OF WASTE WATER TREATMENTS ON REMOVAL OF NOROVIRUSES FROM SEWAGE 17 May 2011
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Transcript of Connolly & Palfrey (2011)
© WRc plc 2011
IMPACT OF WASTE WATER TREATMENTS ON REMOVAL OF NOROVIRUSES FROM SEWAGE
17 May 2011
defra project reference WT0924
Elaine Connolly, project manager, defra
Roderick Palfrey, WRc plc, Swindon,
Wiltshire ([email protected])
Project period October 2010 May 2011
Impact of wastewater treatments on removal of noroviruses from sewage
Background to the research
Increasing industry and food safety
concerns about norovirus
Little known about norovirus in the
natural environment
Initial research to look into the scale of
the problem
© WRc plc 2011
Measurement of Norovirus gene template in crude, storm and treated sewages
Determine significance of treated effluents on total load discharged
Determine reductions in Norovirus by different treatment process trains
Investigate correlations between removal of faecal indicators, in particular coliphage, and attenuation of Norovirus by treatment processes
Objectives
© WRc plc 2010
Sampling from sewage treatment
Final / tertiary effluent sample
Secondary effluent sample
Primary effluent / storm sewage
surrogate sample
Crude / influent sample
Storm tanks
© WRc plc 2011
5 works (3 coastal)Advanced activated sludgeHigh rate activated sludgeBiological (percolating) filterChemically aided settlement (CAS) + biological aerated flooded filter (BAFF)Membrane bio-reactor
70 samples between November 2010 and February 2011
Sampling
© WRc plc 2010
Sample locations and numbers (1)
6 4 6
3
InfluentPrimary
FilterAdvanced activated sludge Effluent
InfluentHigh rate activated sludge
UV
2 4
4
4
© WRc plc 2010
Sample locations and numbers (2)
5
Primary Biological filter
3
5
Membrane bio-reactor
44
Biological aerated flooded filter (BAFF)
CAS
5525
UV
© WRc plc 2011
Measurements
NorovirusRNA genome using threshold cycle countVeroMara at Scottish Marine Institute, Dunstaffnage
Faecal indicatorsE.coli, total coliformsF+ & somatic coliphageSamples to NLS (National Lab Service)
Works operation indicatorsBOD, suspended solids
© WRc plc 2011
Hypotheses and principles
Primary settlement can model storm tank performance
Norovirus behaves as bacteriophage (F+ and somatic) in terms of physical removal
Norovirus activity cannot be measured
Membrane bioreactor (MBR) treatment likely to significantly reduce concentrations of norovirus
UV treatment is not expected to affect norovirus measurement
© WRc plc 2011
Influent sewage Secondary effluent
Final effluent
ASP advanced 6.4 6545 ND 2170 ND
ASP high rate ND 341 ND 431 ND 354
Percolating filter ND 3818 ND 382
Biological aerated filter,BAF
ND 340 ND 407 ND 384
Membranebioreactor
4 2147 ND 708
Measurements all as genome copies / ml; ND = not detected in 10 mls; sensitivity
Range of norovirusconcentrations
© WRc plc 2010
Norovirus concentrations
© WRc plc 2010
F+ phage concentrations
© WRc plc 2010
E.coli concentrations
© WRc plc 2010
Removal rates across works
© WRc plc 2010
Norovirus compared to F+ phage removal
Log10 removal
Norovirus GII F+ phageActivated sludge nutrientremoval (ASP_adv) 3.64 3.12Activated sludge high rate (ASP_hr) 2.76 2.65
Percolating Filter 1.56 0.52
Biological aerated filter 1.74 2.17
Membrane bioreactor 1.84 3.12
All from geometric mean differences, between primary and final effluent
© WRc plc 2010
Removal of indicators by individual stages
© WRc plc 2010
Correlation between faecal indicators
© WRc plc 2010
Correlation between F+ and norovirus
© WRc plc 2011
Sewage treatment reduces Norovirus loadTreatment process types may significantly affect removal of norovirus
Activated sludge processes and Membrane Bioreactors most effectiveFilter processes may have differential effects between bacterial and viral indicators
Norovirus analysis is complex individual values in this study were inconsistent with related samples
Some indication that F+ phage could be a surrogate for treatment effectiveness
Initial findings
© WRc plc 2011
Replace percolating filters with activated sludge plants or membrane bioreactors?
Build new works to accept all sewer flows?
Costs for new works (10 million population) Energy costs increase 5 10 foldNew build £1 3 billionOperating costs increaseGreenhouse gas emissions double
Final thoughts ..
© WRc plc 2011
WRc Project team: Matthew Hoblyn, Mark Harman, Tony Dee, Rob Moore
Defra project manager: Elaine Connolly
With thanks to the staff and management of the host sampling sites
And to the project management group
Thank-you
Next Steps
Final report and recommendations to be
prepared
Discussion of finding with stakeholders
Follow up research
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