Water Microbiology
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Tap (drinking) water
Surface water (freshwater)
Waste water
(Marine water)
Water borne diseases
Tap water (drinking water)
• Optimum = no microorganisms
• Microbial quality determination
• Faecal coliforms, Escherichia coli – indicator
of fresh faecal contamination (cultivation
43°C)
• Coliforms - indicator of total faecal
contamination (includes faecal coliforms) =
“total coliforms”
Tap water (drinking water)
• Enterococci – the third indicator of faecal
contamination (metabolically LAB)
• Mesophiles – temperature optimum 20-45°C,
sources: soil, faeces, plant…. (EU CFU at
36°C)
• Psychrophiles - temperature optimum <20°C,
often autochthonous water microflora;
source: soil (EU CFU at 22°C)
Tap water (drinking water)
• Clostridium perfringens – potentially
pathogenic, quality indicator for processing
from surface water
• Pseudomonas aeruginosa - potentially
pathogenic, (CR bottled water)
• Disinfection: Ag, Cl, O3, UV radiation
MICROBIOLOGICAL STANDARDS FOR DRINKING
WATER
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Total plate counts
< 200 cfu/ml at 22oC
< 100 cfu/ml at 36oC
E. coli, coliforms
Absence from 100 ml
Enterococci (faecal streptococci)
Absence from 100 ml
Nitrates (NO3-)
< 50 mg/l (adults)
< 15 mg/l (infants)
Surface water (freshwater)
• Regularly contaminated
• Number of bacteria very fluctuable
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10 – 109 /ml
• Plankton = communities in water
(bacterioplankton + zooplankton +
phytoplankton
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Surface water (freshwater)
• Saprobity = the level of surface water quality,
determined by:
• Organic matter content
• Density of microorganisms
• Character of processes (aerobic, anaerobic)
• Level of solved oxygen
• Biological oxygen demand (BOD)
Surface water (freshwater)
• Oligotrophic water:
• no organic mater,
• low (no) number of microorganisms – close
to drinking water,
• fully saturated with oxygen,
• aerobic processes,
• good water for plenty organisms
Surface water (freshwater)
• Eutrophic (polysaprobic) –
• very high level of organic mater, very high
microorganisms number , nearly no oxygen,
• anaerobic processes,
• nearly no higher organisms
• Mesotrophic (mesosaprobic)– medium level
of contamination and others factors, water
acceptable for several organisms
Biofilm formation
Marine Water – „A High Pressure
Refrigerator“
Wastewater Treatment
Wastewater Treatment Plant
Figure 11A. Generalized plan of a secondary sewage treatment plant using either (or both) an ACTIVATED SLUDGE or a TRICKLING FILTER SYSTEM. Note
the direction of flow of the various sludges and effluents. If you can draw this plan from memory and describe what each component's purpose is, you
qualify for the SEWAGE EXPERT gold star and will surely score well on the final exam.
Wastewater Treatment
Activated sludge tank
Trickling filter system
Aerobic Degradation of Biodegradable
Organic Matter (BOM)
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• BOM
aerobic microbes
CO2, nitrate,sulphate, phophate (mineralization)
Water Borne Diseases
• Cholera (Vibrio cholerae), enterotoxin,
diarrhea, oral rehydration therapy
• Salmonelosis (Salmonella enterica Enteritidis)
• Shigellosis (Shigella dysenteri)
• Traveler´s diarrhea (Escherichia coli)
• Helicobacter pylori
• Hepatitis A long incubation period
Water Borne Diseases
• Legionella pneumophila
• Pseudomonas aeruginosa
• Hepatitis A long incubation period
• Giardia lamblia, G. Intestinalis, endemic in US
• Entamoeba histolytica
• Cyclospora cayetanenis
Summary of Water Borne Diseases
• WBDs are transmitted almost entirely true
facal contaminated water
• Prevention: proper sanitation procedures
(minimizing faecal pollution, washing hands,
traetment of polluted water)
Many rural areas in Cambodia show high rates
of waterborne and water related diseases