Process Issues/Improvements Discussion

2.9.4 Viral patbogeDJ

Vi ^ruses f ^ou nd in S\vimming pools and similar environments include mo/111sapor ^VlNS, JJOpill ^oma virus. cntcro viruses and adcoo viruses. M ^o /111.sc,por virus causes M ^o l/uscum

co11tag1os11n1, an innocuous cutaneous disease limited to ^humans. II is spread by direct

person-to-person contact or indi ^rec tly through physical cooU1ct ,vith contaminated

surfaces. S\vimming pool-related cases cx:cur more frequently in children ^than in adults

Lesions are most often found on the anns. back of the legs nnd back. suggesting

transmission through physical contact ,vith the edge of the poo� benches around the pool,

S\Vimming aids carried into the pool or shared towels (Castilla ^{ct al.,} 199S). ^The only

source of Al/oll11sr:ipor virus in S\Vimming pool and similar facilities is infected bathers

(Oren & \Vcndc, ¹⁹⁹¹⁾ Public education. limiting conlllct bcrwcen infected and non

infected people, medical treatment and frequent cleaning of surfaces in facilities are all

of an accidental f ^ca cal release or vomit is to prcvenl the use of the poo ^l unlil the contaminants arc inactivaled (\VHO, 2006)

There are over 50 types of Adc ¹¹ 0 virus (Hunter, 1997), and \vhile some may cause entcric infections and arc therefore shed in re.aces. they an: also associated \vith rcspirntory and

ocular symptoms and non face.al ^l y-derived transmission Ade110 viruses type 3 and 4 cause pharyngo-conjuctivnl fever amongst bathers TI1crc llllvc been several reponed outbreaks of Ade110 viruses associated \vith pools (1-larlcy et al ., 200 I; Papapctropoulou &

Vnntarnki s, 1998. Turner cl of, 1987) Control mc:uurcs include pub ^l ic education.

policies thot exclude people with gastro enteritis from swimming. inactivating the poo ^l contaminants in case of an accidental faecal release or vomit before a ^l lo\ving patrons in

the pooL

2.9.S Criteria for indiCJ1tor organisn1s

Identifying p11thogcnio microorganisms in the ,wtcr is cxtreme.ly difficult, unreliable and not routinely undcnaken as a laboratory procedure. lnste:id the presence of other micro­

organisms (indicators), ,vhich may be associated ,vith pathogenic organisms is determined . The indicator should be absent in unpo ^l luted environments and present when

the source of pathogenic microorganisms of concern is present The indicator should not multiply in the environment and it should be present in greater numbers than the pathogenic microorganisms Indicators should respond to natural environmental conditions and water treatment processes in a manner similar to the pathogens of concern They should be ca11y ¹⁰ isolate. identify and enumerate. Tcsu to ddaminc presence of

indicators should be inc:<pensive_ thereby permitting numerous samples to be taken (if appropriate).

l\llicroorganisms tlult arc used to assess the microbi11I quality of S\vimming pool 11nd similar environments include Hetc-rotropbic r1J11c Count-1 IPC (a general measure of non specific microbial lcvc.lJI), faeca ^l indiauors (such as thcrmotolcrant coliforms, E.n:ltt'rtcltla

coll), Pst11domonas o�n1gil10JD. Sraphylococc11s a1cnus and Ugto,icl/a spp (\VHO, 2006)

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2.10 Pool water ^treatment

Pool water treatment can be classified into physical or chemical treatment Physical treatment includes filtration, circulation, coagulation and dilution Chemical treatment includes disinfection, pH correction and shock trcatmcnL

2.10.1 Filtntion

Filtrution improves the sanitary status of S\vimming pools by removing bacterial organisms from the swimming pool wnter. it also improves clarity oflhe S\vimming poo ^l

by ensuring the removal of panicles which may shield micro-organisms from direct contact ,vith the dis infcctllllt. The different filter types are discussed be ^l ow.

2.10. 1. l Types or filters

The different types of filters used for swimming pool ,vntcr filtration includes Diatomaceous Earth (DE) fi ^l ters. sand filters and cartridge ft ^l tcrs. 1n the Diatomaceous earth type of filter, o.lso called a DE liher, the ,vatcr passes into a metal or plastic tank, through n series of grids (also called filter elements) covered with fabric, and back out of the unit The grids do not actual ^l y pcrfonn the filtration process, bur instead are coated ,vith a fi ^l ter media.. diotomaceous earth. that docs the actual filtering work (Tamminen.

I 995) Diatomnccous eanh or kicsclguhr comprises the fossilized ske ^l eta ^l remains of tiny marine plant organisms known as diatoms. The particle siu of diotomaceous earth for s\vimming pool lihrution media is in the order of 15 micrometer 10 19 micrometers (ISPE.

1989). There arc bA.Sically two types of DE filter the vertical grid and the spin type.

Sand fi ^l ters consist of2 types· slow sand or biological fillers and rapid sand or mechanical filters- lo slow sand filters, water puses onto a layer of sand or unifonn grade (between

o 2 and 0.3mm in diameter) The sand is supported by a bed of line gavel, underneath which is n collection pipe system The filtration rate may be in the order ofO 2m ^J /hour/m ¹

Pool and spa sand filters can tr11p particles in the range of 30 ¹⁰ 50 microns The supema1an1 water above the sand bed, \Yhose depth varies from l 10 1.5 met.rt$, helps to overcome the resistance of the liltcr bed. thus promoting the do\vnwn.rd flo\v of ,wtcr through the sand bed II also provides a wa111ng period or some hours for the rn,v \\'liter 1o

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2.10 Pool ^{water treatment}

Pool ,vatcr treatment can be cl ^ass ified into physical or chemical treatment Physical ueatment includes !ilLration, circulation. coagulation and dilution Chemical treatment

includes disinfection, pH correc:rion and shock tn:atmcnL

2.10.l Filtmtion

Filtration improves the sanitary status of swimming pools by removing bacterial