Water Microbiology

• 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

• 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• 10 – 109 /ml• Plankton = communities in water

(bacterioplankton + zooplankton + phytoplankton

•

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“

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

Wastewater Treatment Plant

Wastewater TreatmentActivated sludge tank

Trickling filter system

Aerobic Degradation of Biodegradable Organic Matter (BOM)

• aerobic microbes

• BOM 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