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Connolly & Palfrey (2011)

Connolly & Palfrey (2011)






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    Connolly & Palfrey (2011) Connolly & Palfrey (2011) Presentation Transcript

    • Impact of wastewater treatments onremoval 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
    • Background to the research Increasing industry and food safetyconcerns about norovirusLittle known about norovirus in thenatural environmentInitial research to look into the scale ofthe problem
    • 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
    • Sampling from sew age treatment Storm tanksCrude / Secondary Final / tertiary Primary effluent /influent effluent effluent storm sewagesample sample sample surrogate sample © WRc plc 2010
    • 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
    • Sample locations andnumbers (1) 6 4 6 3Influent Primary Advanced Filter Effluent activated sludge 4 2 4 4Influent High rate UV activated sludge © WRc plc 2010
    • Sample locations andnumbers (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
    • 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
    • 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
    • Range of norovirusconcentrations 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
    • 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+ 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
    • Removal of indicators byindividual stages © WRc plc 2010
    • Correlation between faecalindicators © WRc plc 2010
    • Correlation between F+ andnorovirus © WRc plc 2010
    • 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
    • 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
    • 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
    • Next Steps Final report and recommendations to be prepared Discussion of finding with stakeholders Follow up research
    • 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.