Zuivering Gertjan Medema Cursus drinkwatermicrobiologie 2012
Elimination in water treatment Two principal processes: Inactivation - Natural (biological) - Forced: disinfection (chemical, physical) Removal - Sieving (ultra/nanofilters) - Attachment (sand filters, soil, ceramic filters) - Flocculation + floc removal 2
Virus structure Virus genome (RNA, ss/ds DNA) Capsid protein Spike 3
Inactivation 4
Virus inactivation in the environment Physical Heat or thermal effects Desiccation or drying Aggregation Adsorption to particles or surfaces Encapsulation or embedding Increasing inactivation at higher temperature; pasteurize Increased inactivation at lower moisture content or relative humidity; effects of RH differ between enveloped and non-enveloped viruses Clumping protects viruses from inactivating agents Adsorption protect viruses from inactivating agents; some specific chemical surfaces (heavy metals) are virucidal Viruses within membranes or larger particles are protected from inactivation Chemical Hydrogen ions; ph Viruses survive best near neutral ph and worst at ph extremes Organic matter Many viruses are stabilized and protected by dissolved, colloidal and solid organic matter, including fecal organics and natural organic matter (humic materials) Ammonia NH 3 has virucidal activity; manifest at higher ph (>ph 8) Salts and Ionic Strength Increased concentrations of salts are antiviral; some viruses are destabilized and inactivated by water lacking stabilizing salts (such as NaCl) ions such as Mg++ Enzymes Proteases and nucleases contribute to virus inactivation Biological Microbial activity Proteolytic activity Microbial predation Biofilms Biological treatment and microbial activity/metabolism in soils, sediments, water; several contributing mechanisms Proteolytic enzymes inactivate/denature virion proteins Engulfment, ingestion, etc. by protozoa, helminths, etc. Virus adsorption to biofilms can be protective or microbial activity in biofilms can cause virus inactivation and degradation 5
Principles of ozone process Ozone = strong oxidator Disruption of cell wall and reaction with nucleotides/enzymes: no reproduction At room temperature: ozone in gas Dosage of gas bubbles with diffusor Disinfection: contact time T of micro-organisms with ozone concentration C CT is design parameter (mg*l -1 min -1 ) 6
Ozone process in practice In Concrete construction C out Contact time T Ozone gas C in Inactivation versus CT 7
Inactivation kinetics: quantifying Decimal Elimination Capacity Inactivation (log) 1 0.5 Chick-Watson: 0-0.5-1 -1.5 N T k* C * T N e 10 log( N T n ) k * C T N * -2-2.5-3 0 5 10 15 CT mg*l -1 *min -1 8
Inactivation kinetics: variability Inactivation (log) 1 0.5 0 Shoulder model: delayed inactivation -0.5-1 -1.5-2 -2.5-3 Non-linear model: influence of conditions (microbial and technological aspects) 0 5 10 15 CT mg*l -1 *min -1 9
Inactivation of viruses, bacteria, bacterial spores and protozoan oocysts Inactivation (log) 1 0.5 0 Oocysts of Cryptosporidium parvum Spores of Clostridium perfingens -0.5-1 -1.5-2 -2.5 Viruses, Bacteria Environmental spores surrogate full-scale performance? -3 0 5 10 15 CT ((mg ozone /l)*min) 10
k-value of some micro-organisms k-value (log10 inactivation rate constant) 1000 100 E.coli Viruses USEPA 1991 Giardia USEPA 1991 Spores of Clostridium perfringens Oocysts of Cryptosporidium 10 1 0.1 0.01 5 10 15 20 25 Temperature 11
E. coli concentration (CFP/l) Lab is not practice: ozone example Ozonation CT 2 mg.min/l Expected E. coli inactivation: >>5 logs Full scale E. coli data: 1000 E. coli present in 4% of samples after ozone Removal 2.7 log 100 10 1 0.1 Ozone in Ozone out 0.01 Dec-02 Mar-03 Jun-03 Oct-03 Jan-04 Apr-04 Aug-04 Nov-04 12
Oxidation HOCl, O 3, OH et al Inactivation Concentration Time Temperature ph Organic compounds Inorganic compounds Virus type Virus protection 13
UV UV UV intensity Time Reactor Lamp type UV absorption Virus type Virus protection 14
Principles UV disinfection 15
UV sensitivity organisms: determined under well-defined batch conditions Collimated beam apparatus Inactivation Inactivation kinetics First order process inactivation rate constant k Tailing Shoulder UV-dose (mj/cm 2 ) 10 log( N t ) k * N Fluence 16
Inactivation (log) UV sensitivity of viruses: examples 8 7 Poliovirus 7 studies 8 7 Adenovirus 5 studies, type 2,15,40,41 6 6 5 5 4 4 3 3 2 2 1 1 0 0 50 100 150 200 0 0 100 200 300 400 UV-fluence (mj/cm 2 ) 2 UV-fluence (mj/cm) 17
Log inactivation UV sensitivity of viruses (in collimated beam experiments) 10 9 8 7 6 5 4 3 2 1 0 0 25 50 75 100 UV dose (mj/cm2) Poliovirus 1 (ssrna) Rotavirus SA11 (ssdna) Hepatitis A (ssrna) Coxsackie B5 (ssrna) Calicivirus bovine (ssrna) Adenovirus 40 (dsdna) 18
K-values of pathogenic micro-organisms Campylobacter jejuni Vibrio cholerae Shigella dysenteriae Yersinia enterolitica Campylobacter jejuni E. coli O157 Salmonella typhi Legionella pneumophila Giardia muris Cryptosporidium parvum Hepatitis A Calicivirus Poliovirus Coxsackie virus Rotavirus Adenovirus k-value (cm 2 /mj) Bacteria Susceptible Protozoa, viruses Less susceptible 0 0.5 1 1.5 2 19
Validation No legal requirement for validation of UV (or other) treatment systems in municipal water supply Water utility determines need for and strictness of validation Review by Inspectorate 20
Example 1: UV/H 2 O 2 PWN UV/H 2 O 2 system for disinfection and oxidation of micropollutants / NOM Fluence for oxidation 560 mj/cm 2 Fluence required for disinfection 120 mj/cm 2 System design: even at extremely low UVT (80%, 1 cm) and maximum flow at end of lamp life (80%) >120 mj/cm 2 Photo: PWN 21
Example 1: UV/H 2 O 2 Validation of disinfection PWN Experiments to determine inactivation of: Cryptosporidium (CB and pilot scale, collaboration of PWN, University of Alberta): > 4.8 log inactivation at 120 mj/cm 2 Giardia (CB, collaboration of PWN, University of Alberta) > 3.4 log inactivation at 120 mj/cm 2 Campylobacter (CB, see previous): >> 7.6 log inactivation at 120 mj/cm 2 Photo: PWN MS2 (CB, pilot scale, PWN): 4.2 log at 120 mj/cm 2 22
REF (mj/cm 2 ) Example 1: UV/H 2 O 2 Validation of reactor and fluence PWN Biodosimetry data of 2 10L30 systems in series show very good results 90 80 70 REF avg = 0.983 * dosimeter dose + 0.85 60 4 16L30 reactors in series are expected to give superior performance 50 40 30 20 REF 95CL = 0.982* dosimeter dose - 3.2928 10 0 0 10 20 30 40 50 60 70 80 90 Dosimeter fluence (mj/cm 2 ) Data: Evides, PWN, Trojan, KWR 23
Example 2: UV as primary disinfection New reactor system Required fluence: 70 mj/cm 2 Biodosimetry at full scale Test unit constructed at water utility Local test water (with/without UVT reducer) 24
Bioassay setup Challenge vessel By-pass pump Dosing pump microbes Dosing pump coffee By-pass of feed water Vd Veer, Evides 25
REF (mj/cm 2 ) REF (mj/cm 2 ) Example 2: UV as primary disinfection 90 80 70 60 140 120 REF mean = 1.023 * dosimeter + 3.17 100 50 80 40 60 30 20 10 0 40 20 0 REF 95%CL = 1.0215 * dosimeter - 1.2889 UVT 88 UVT 82 UVT 75 0 20 40 60 80 100 120 140 0 10 20Ca lcula 30te d flue 40nce, sce 50 na rio 60 2 (mj/cm 70 2 ) 80 90 Dosimeter fluence (mj/cm 2 ) Medema & Beerendonk, 2005, in collaboration with Kruithof, van der Veer, Martijn, Dekker, Nugteren, Lem, van Loon (Evides, PWN, Trojan, Aqualab) Small scatter, slope > 1 and intercept > 0; 95%CL = ideal line: safe dosing without overdosing 26
REF (mj/cm 2 ) On-line monitoring of UV system performance Components Trojan UVT monitor Picture: Trojan UV CFD based UV fluence model 90 80 70 60 REFmean = 1.023 * dosimeter + 3.17 Flow meter 50 40 UV sensor 30 REF95%CL = 1.0215 * dosimeter - 1.2889 20 10 0 0 10 20 30 40 50 60 70 80 90 Dosimeter fluence (mj/cm 2 ) Biodosimetry to calibrate UV fluence model 27
Use of biodosimetry in process control in practice: the heart of the Water Safety Plan Inputs from online readings: Flow UVT UV intensity Microprocessor / PLC Calculate Reduction Equivalent Fluence 35 msec PLC Control lamp power Photo: P. Oostdam, Evides 28
Ultra/nanofiltration Virus elimination Removal: sieving 27 nm 29
Virus elimination filters Removal: attachment Electrostatic interactions Hydrophobic interactions - Virus characteristics pi capsid composition capsid structure - Particle composition composition electric charge structure - Matrix composition organic matter bivalent cations conductivity 30
Virus elimination Removal: flocculation - - - Ca ++ - - - - - - Ca ++ - - - - Electrostatic interactions Hydrophobic interactions - Virus characteristics pi capsid composition capsid structure - Particle composition composition electric charge structure - Matrix composition organic matter bivalent cations conductivity 31
Coagulatie + snelfiltratie 32
Proefopstelling AKF locatie Berenplaat water na coagulatie/dlf Kool: Chemviron F400 Geen spoeling Filtratiesnelheid: 5 m/uur Contacttijd: 12 minuten 33
Concentratie (PFU.l Verwijdering van MS2 bacteriofagen -1 ) 10000000000 1000000000 100000000 10000000 Verse AK in Verse AK uit Beladen AK in Beladen AK uit 1000000 100000 Dosering 10000 0,1 1 10 100 Tijd (uren) 34
Concentratie (CFU/l) Verwijdering van E. coli en Clostridium-sporen E. coli SSRC 10000000 10000000 1000000 1000000 100000 100000 Verse AK in Verse AK uit Beladen AK in Beladen AK uit 10000 1000 100 10 0,1 1 10 100 10000 1000 100 10 0,1 1 10 100 Tijd (uren) 35
Concentratie (CFU/l) Verwijdering van Giardia en Cryptosporidium Cryptosporidium Giardia 1000000 100000 1000000 100000 10000 10000 1000 1000 100 100 10 10 1 1 0,1 0,1 0,01 0,01 0,1 1 10 100 0,1 1 10 100 Tijd (uren) Verse AK in Verse AK uit Beladen AK in Beladen AK uit 36
Verwijdering van micro-organismen DEC of logverwijdering van: Verse kool Beladen kool kolom 1 kolom 2 kolom 1 kolom 2 MS2 0,0 0,0 0,0 0,0 E. coli 0,0 0,1 0,3 0,3 Clostridium 0,4 0,6 0,4 0,4 Cryptosporidium 2,7 2,7 1,3 1,1 Giardia 2,1 2,0 2,1 2,2 37
Verwijdering natuurlijke indicatorbacteriën - onderzoek met grote volumes Lage concentraties indicatorbateriën in influent en effluent van het koolfilter Onderzochte volumes: 10-500 liter Concentraties bepalen met: - Hemoflow (cross flow ultrafiltratie) 38
Verwijdering gedoseerde vs. natuurlijke organismen DEC of logverwijdering van: Verse kool Beladen kool kolom 1 kolom 2 kolom 1 kolom 2 E. coli gedoseerd 0,0 0,1 0,3 0,3 E. coli natuurlijk 0,4 0,4 1,1 1,0 Sporen gedoseerd 0,4 0,6 0,4 0,4 Sporen natuurlijk 1,1 1,0 0,9 0,9 Hypothese: pre-coagulatie bevordert de verwijdering door betere hechting 39
Micro-organism elimination in water treatment NL Inactivation Ozone UV UV/peroxide Chlorine dioxide Chlorine (safety) Removal Soil passage Membrane filtration (UF/NF) Sand filtration Flocculation/floc removal/filtration Reservoirs 40