Drinking water quality
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Transcript of Drinking water quality
QUALITY
Guideline of drinking water quality WHO published- vol 1 1993
vol 2 1996
Acceptability aspectsAcceptability aspects Microbiological aspectsMicrobiological aspects Chemical aspectsChemical aspects Radiological aspectsRadiological aspects
Physical parameters
Turbidity- <5 NTU
Colour - upto 15 TCU
Taste & odour Temperature
Chlorides- std 200mg/l max 600mg/l
Hardness- calcium- 100-300 mg/l
Ammonia- NH3 & NH4+ upto 1.5mg/l pH - 6.5-8.5 <7 -corrosion & incrustation >8- compromise efficiency of
disinfection H2S - 0.05-0.1mg/l Fe - 0.3mg/l Na - 200mg/l
Total dissolved salts
TDS level <600mg/l [good] < 1000mg/l [acceptable]
Sulphate <250mg/l CaSO4 – 270mg/l MgSO4 – 90mg/l
Zn 3mg/l Mn 0.1mg/l
Dissolved O2 indirect effects
Cu 1mg/l
Al 0.2mg/l
Bacteriological indicators Coliforms- faecal groups -E coli Non faecal –klebsiella aerogens Faecal streptococci - recent faecal pollution Clostridium perfringes - remote infection
Virological aspects Cl2 - 0.5mg/l , 30min ,pH - 8 O3 - 0.2-0.4mg/l , 4min
Biological aspects Protozoa- E.histolytica ,giardia ,balantidium coli Helminths – Free living organisms – algae , fungi
inorganic constituents organic constituents
inorganic constituents
arsenic – 0.01mg/l dissolution of mineral ores ,industrial effluents cadmium – 0.003mg/l accumulate in kidney, long T1/2- 10-35y chromium -0.05mg/l cyanide – 0.07mg/l processed cassava ,thyroid and CNS effects fluoride – 1.5mg/l dental & skeletal flurosis production of Al ,manufacture of phosphate
fertilizers (4%)
Lead Pb – 0.01mg/l , plumbing systems
placental transfer -12th week and continues interfere with Ca2+ metabolism, renal tumors subencephalopathic neurological &behavioural
effects
Hg - 0.001mg/l ,target organ- kidney, methylHg- CNS effects
nitrate & nitrite – nitrate- 50mg/l nitrite – 3mg/l concent of nitrate + concent of nitrite
= < 1 G.value of nitrate G.value of nitrite
selenium Se- 0.01mg/l
ORGANIC CONSTITUENTS UPPER LIMIT OF CONCENT ( microgm/l )
Chlorinated alkanes
CCl4 2
dichloromethane 20
Chlorinated ethenes
Vinyl chloride 55
1.1-dichloroethene 30
1.2-dichloroethene 50
Aromatic hydrocarbons
benzene 10
toluene 700
xylene 500
Ethyl benzene 300
styrene 20
TDI- tolerable daily intake
NOAEL- no- observed –adverse- effect level
LOAEL- lowest- observed- adverse -effect level
UF - uncertainty factor
TDI = NOAEL/LOAEL UF GV =TDI x BW x P C P=Fract of TDI allocated
to drinking water C=daily drinking water
consumption BW= body wt
Somatic Hereditary
Stochastic effect - carcinogenesis Non-stochastic effect - severity Aim- prevent NSE &reduce probability of SE DW- safe limits + reasonably low Becquerel- 1 disintegration/sec
GV- gross alpha activity 0.1Bq/L gross beta activity 1Bq/L
Activities in surveillance function approval of new sources watershed protection approval-construction & operating procedures of WW
disinfection of plant & distribution
system periodic flushing programmes & cleaning
of water storage facilities certification of operators regulation of chemical substances Cross-connection control ,back flow control ,leaK detection control
Sanitary surveys Monitoring programmes
Development of codes of practice for well construction ,pump installation and plumbing
Inspection quality control in bottled water
Elements of surveillance programme SANITARY SURVEY SAMPLING BACTERIOLOGICAL SURVEILLANCE presumptive coliform test- MULTIPLE TUBE
METHOD MEMBRANE FILTER
TECHNIQUE Confirmatory tests DETECTION OF FAECAL STREP & Cl.PERFRINGES COLONY COUNT BIOLOGICAL EXAMINATION CHEMICAL SURVEILLANCE
THANK U