disinfection ce326 principles of environmental engineering iowa state university department of...
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DISINFECTIONDISINFECTION
CE326 PRINCIPLES OF ENVIRONMENTAL ENGINEERINGCE326 PRINCIPLES OF ENVIRONMENTAL ENGINEERINGIowa State UniversityIowa State University
Department of Civil, Construction, and Environmental Engineering Department of Civil, Construction, and Environmental Engineering Tim Ellis, Associate ProfessorTim Ellis, Associate Professor
March 22, 2010March 22, 2010
AnnouncementsAnnouncements
Wednesday lab in Town classroom Wednesday lab in Town classroom – Finish water treatment plant labFinish water treatment plant lab– Exam reviewExam review
22ndnd exam scheduled for this Friday, March exam scheduled for this Friday, March 2626thth
HISTORYHISTORY
J_____ S____ and the Broad Street pump in 1854J_____ S____ and the Broad Street pump in 1854 he was able to show that 59 of the 77 c________ he was able to show that 59 of the 77 c________
victims used the pump on Broad Streetvictims used the pump on Broad Street There was a w___________ in the vicinity where There was a w___________ in the vicinity where
cholera was endemic but nobody at this cholera was endemic but nobody at this workhouse got cholera. workhouse got cholera.
This particular workhouse had its own w___. This particular workhouse had its own w___. The cause of contamination turned out to be the The cause of contamination turned out to be the
d_____ of an infected person that was within three d_____ of an infected person that was within three feet of the well.feet of the well.
ohn nowholera
orkhouse
ell
rain
Broad Broad Street Street PumpPump
ChlorinationChlorination
Disinfection of water supplies by c____________ Disinfection of water supplies by c____________ began in Chicago and New Jersey in 1908, began in Chicago and New Jersey in 1908,
within 2 years chlorination of w_____ s________ within 2 years chlorination of w_____ s________ was practiced in N.Y., Montreal, Milwaukee, was practiced in N.Y., Montreal, Milwaukee, Cleveland, Nashville, Baltimore, and Cincinnati. Cleveland, Nashville, Baltimore, and Cincinnati.
By 1918, over 1000 c_____ treating more than __ By 1918, over 1000 c_____ treating more than __ bgd were chlorinating their water supplies.bgd were chlorinating their water supplies.
By 1923 the typhoid death rate had dropped more By 1923 the typhoid death rate had dropped more than 90%than 90%
By the beginning of WWII, typhoid, cholera, By the beginning of WWII, typhoid, cholera, dysentery were practically eliminated in U.S.dysentery were practically eliminated in U.S.
http://www.americanchemistry.com/100years/timeline.html
hlorination
ater upllies
ities 3
TheoryTheory Chick’s Law: Chick’s Law:
rate, k, is a function of c___________ and t______ (i.e., CT) and type of rate, k, is a function of c___________ and t______ (i.e., CT) and type of organismorganism
Typical disinfectants:Typical disinfectants:– Chlorine:Chlorine: ClCl22 + H + H22O → HOCl + ClO → HOCl + Cl--
– ChloraminesChloramines
NHNH33 + HOCl → NH + HOCl → NH22Cl + HCl + H2200
NHNH22Cl + HOCl → NHClCl + HOCl → NHCl22 + H + H2200
NHClNHCl22 + HOCl → NCl + HOCl → NCl33 + H + H2200
dN
dtkN
oncentration ime
monochloramine
dichloramine
trichloramine
Pellet dropper Tablet feeder
ChlorinatorsChlorinators
Gas – 2,000 pound
Courtesy Smith Group Consulting, LLC
ChlorinatorsChlorinators
+-battery
Electrolytic CellNaCl + H20 + 2e- NaOCl + H2
anode cathodeNa+ + e- Na 2Cl- Cl2 + 2e-
+-
Hand held chlorine producing unit (CPU)
If the products are mixed, the result is household bleach.2 NaOH(aq) + Cl2(g) = NaCl(aq) + NaOCl(aq) + H2O
Chlorine Contact TankChlorine Contact Tank
www.wsd.dst.il.us/tour/imgbig/contact_tk_1.jpg
OzonationOzonation
strong o______, but strong o______, but no residualno residual
no THM f_________ no THM f_________ but other (non-but other (non-chlorinated) DBPs chlorinated) DBPs possiblepossible
often used as a often used as a p__________ p__________ disinfectantdisinfectant
xidant
ormed
rimary
Chlorine DioxideChlorine Dioxide
strong oxidant, but not strong oxidant, but not a powerful as o_____a powerful as o_____
dose limited to 1.0 dose limited to 1.0 mg/L due to health mg/L due to health concerns of chlorite concerns of chlorite and c_______and c_______
residual is not long residual is not long l______l______
zone
hlorate
asting
Ultraviolet (UV) LightUltraviolet (UV) Light uses thin layer of water and uses thin layer of water and
mercury vapor arc l_____ mercury vapor arc l_____ emitting UV in the range of 0.2 emitting UV in the range of 0.2 to 0.29 micronto 0.29 micron
depth of light p_________ depth of light p_________ limited to 50 - 80 mmlimited to 50 - 80 mm
powerful, but no residualpowerful, but no residual
amp
enetration
ADSORPTIONADSORPTION takes advantage of physical/chemical bond of takes advantage of physical/chemical bond of
pollutant with adsorbent (typically g_______ pollutant with adsorbent (typically g_______ activated carbon or p_________ activated carbon)activated carbon or p_________ activated carbon)
one ounce of GAC has a surface area of ____ one ounce of GAC has a surface area of ____ acresacres
good process for removal of good process for removal of – THMsTHMs– DBPsDBPs– SOCsSOCs– VOCsVOCs
ranularowdered
5-10
ADSORPTIONADSORPTION PAC dose is typically _____ mg/L can be as PAC dose is typically _____ mg/L can be as
high as ___mg/Lhigh as ___mg/L GAC can be used instead of a_______ in GAC can be used instead of a_______ in
dual media filters, dual media filters, – called filter adsorbers called filter adsorbers – must replace GAC every ____ yearsmust replace GAC every ____ years
separate stage adsorption unit (contactor separate stage adsorption unit (contactor unit) unit) – GAC must be replaced or regenerated every __ GAC must be replaced or regenerated every __
to __ monthsto __ months
5-1050
nthracite
1-3
34
Particle Size vs. Treatment AlternativesParticle Size vs. Treatment Alternatives
Macromolecules Smaller ParticlesLarge
Suspended Particles
MF UF NF RO
Divalent salts
Monovalent salts
Water
Micro filtration (MF) - bacteria, algae, clay, large MW humic acids Ultra filtration (UF) - humic acids, viruses, proteinNanofiltration (NF) – viruses, divalent saltsReverse Osmosis (RO) – monovalent salts
Membrane TreatmentMembrane Treatment
Reverse OsmosisReverse Osmosis