-
-
indicating fecal
contamination
-
Direct tests for pathogens
-
• Involve selective cultivation to large
- numbers
- personnel
- • Molecular tests
-
Bacterial-indicator organisms
COLIFORM GROUP
STREPTOCOCCI
SPORE FORMERS
-
-
total coliforms
- –fecal coliforms
- –Escherichia coli
-
-
–fecal streptococci
–enterococci
-
-
-
-
the
- removal of large objects -
- screening and
- sedimentation
- • Resulting effluents have
- a high BOD values
-
Secondary treatment - anaerobic
-
Anoxic digester:
- Removal of high
- molecular weight
- material; industrial
- wastewater
- • Low production of
- biomass; most C is
- converted to CO2 and
- CH4
-
-
a bed of rocks
- (10-15 cm in diameter) at a 2
- m depth. The thick biofilm that
- forms on the rocks oxidizes
- organic matte
-
-
5 -10 hours
- retention; flocs consisting of
- bacteria (Zoogloea ramigera -
- Fig. 28.7) embedded in EPS
- (slime) and eukaryotic
- microbes
-
-
Removal of inorganic nutrients
- • Most treatment facilities carry out only
- primary and secondary treatment
- • Release of nitrate and phosphate -
- eutrophication of receiving water bodies
- • Physical chemical processes:
- precipitation, filtration, chlorination
-
-
water safe for human
- consumption
- – Pathogens removed
- – Turbidity (suspended particles) decrease
- – Taste improved and odors removed
- – Nuisance chemicals removed
-
-
Large
- particles and objects removed
- • Coagulation basin (clarifier) -
- Raw water mixed with anionic
- polymers, alum, chlorine; floc
- formation by coagulation and
- flocculation; settling of large
- flocs
-
-
remaining
- suspended matter including
- microbes removed
-
-
Chlorine kills
- most microbes in 30 min but
- Protozoa (e.g.,
- Cryptosporidium) may survive
-
-
Descriptions of epidemics on the Indian
- subcontinent in the 1400s but it did not spread to
- Europe and the Americas until 1800s
-
Cholera - Vibrio cholerae
- Transmitted through raw water and food that is
- contaminated by water (vegetables, shellfish)
- Diagnosis- presence of curved rod in water stool
- • Treatment - hydration with electrolytes
-
Giardia lamblia and Cryptosporidium parvum are
-
-
-
ingested and trophozoite develop, attach
- to intestine wall leading to diarrhea, foul smell, stomach
- cramps
-
-
Tiny protozoan (2-5 μm) with highly chlorine
- tolerant cysts; mild diarrhea but groups at
- risk.
- • Transmission from animal carriers via water
- distribution systems
-
Legionellosis
(Legionnaire’s disease)
-
a waterborne pathogen transmitted via aerosols
- – Found in water and soil but grows to high numbers in warm
- waters (air conditioning cooling systems, hot pools)
-
alveolar macrophage and
monocytes
-
Pontiac fever - mild headaches, sore throat, fever, that
- disappears after a few days
- – Pneumonia that follows flu-like symptoms in the elderly; 10%
- death
- • Treated with erythromycin
-
Typhoid fever-Salmonella typhi
-
Diarrhea
- – Transmitted by contaminated food, direct contact,
- and drinking water
-
-
polio and hepatitis A
- – Maintaining of 0.6 μg/ml residual chlorine assures
- elimination
- • Both diseases are transmitted from infected
- individuals and in the developed world are
- associated with the breakdown of water
- treatment practices
-
-
a free-living ameba
- • Transmission from recreational waters (warm
- soil contaminated hot springs, rivers and
- ponds)
- • Through nose and subsequent passage to
- the brain where propagation occurs
- • Hemorrhage and brain damage and death
-
-
readily transmitted via water;
causes inflammation and necrosis of liver
-
-
cause acute
gastroenteritis
-
-
causes acute gastroenteritis,
especially in children
-
-
many types can infect both the
intestines and the upper respiratory tract
-
-
infect the intestines and upper
- respiratory tract (usually without disease
- symptoms)
-
Methods used to detect viruses
-
Electron microscopy
- • Immunoassays
- • Cell culture
- • Reverse transcriptase-polymerase chain
- reaction (RT-PCR)
-
-
Reverse transcriptase (RT) uses RNA as a
- template to make a DNA copy
- • Polymerase chain reaction (PCR)
- enzymatically amplifies specific DNA
- sequences
-
-
Size separation of PCR products
- –charged DNA molecules migrate through a gel
- in an electric field
- –small molecules migrate more rapidly than
- larger molecules
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