More Related Content Similar to Connolly & Palfrey (2011) Similar to Connolly & Palfrey (2011) (20) More from Shellfish Association More from Shellfish Association (20) 1. IMPACT OF WASTE WATER TREATMENTS ON
REMOVAL OF NOROVIRUSES FROM SEWAGE
17 May 2011
© WRc plc 2011
2. Impact of wastewater treatments on
removal of noroviruses from sewage
defra project reference WT0924
Elaine Connolly, project manager, defra
Roderick Palfrey, WRc plc, Swindon,
Wiltshire (rod.palfrey@wrcplc.co.uk)
Project period October 2010 May 2011
3. 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
4. Objectives
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 © WRc plc 2011
5. Sampling from sew age treatment
Storm tanks
Crude / Secondary Final / tertiary
Primary effluent /
influent effluent effluent
storm sewage
sample sample sample
surrogate sample
© WRc plc 2010
6. Sampling
5 works (3 coastal)
Advanced activated sludge
High rate activated sludge
Biological (percolating) filter
Chemically aided settlement (CAS) + biological
aerated flooded filter (BAFF)
Membrane bio-reactor
70 samples between November 2010 and
February 2011
© WRc plc 2011
7. Sample locations and
numbers (1)
6 4 6
3
Influent
Primary
Advanced
Filter Effluent
activated sludge
4 2 4
4
Influent
High rate UV
activated sludge
© WRc plc 2010
8. Sample locations and
numbers (2)
5 3
5
Primary Biological filter
5 2 5
5
CAS Biological aerated UV
flooded filter (BAFF)
4 4
Membrane bio-reactor © WRc plc 2010
9. Measurements
Norovirus
RNA genome using threshold cycle count
VeroMara at Scottish Marine Institute, Dunstaffnage
Faecal indicators
E.coli, total coliforms
F+ & somatic coliphage
Samples to NLS (National Lab Service)
Works operation indicators
BOD, suspended solids
© WRc plc 2011
10. 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
11. Range of norovirus
concentrations
Influent sewage Secondary Final effluent
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, ND 340 ND 407 ND 384
BAF
Membrane
4 2147 ND 708
bioreactor
Measurements all as genome copies / ml; ND = not detected in 10 mls;
sensitivity
© WRc plc 2011
16. Norovirus compared to F+
phage removal
Log10 removal
Norovirus GII F+ phage
Activated sludge nutrient
removal (ASP_adv) 3.64 3.12
Activated 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
20. Initial findings
Sewage treatment reduces Norovirus load
Treatment process types may significantly affect
removal of norovirus
Activated sludge processes and Membrane
Bioreactors most effective
Filter 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
© WRc plc 2011
21. Final thoughts ..
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 fold
New build £1 3 billion
Operating costs increase
Greenhouse gas emissions double
© WRc plc 2011
22. Thank-you
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
© WRc plc 2011
23. Next Steps
Final report and recommendations to be
prepared
Discussion of finding with stakeholders
Follow up research
24. This document was created with Win2PDF available at http://www.win2pdf.com.
The unregistered version of Win2PDF is for evaluation or non-commercial use only.
This page will not be added after purchasing Win2PDF.
