Microbiology in water and waste management — A/L Biology

What must I remember about Microbiology in water and waste management?

• Potable water must be free of pathogenic microorganisms, hazardous chemicals, and turbidity; municipal water purification follows sequential stages: Coagulation/Flocculation (adding alum), Sedimentation, Rapid Sand Filtration (removing suspended particles and cysts), and Disinfection (Chlorination, Ozonation, or UV irradiation to eradicate enteric pathogens).
• Coliform bacteria as water quality indicators: Direct pathogen detection is difficult and erratic; instead, Total Coliforms and Fecal Coliforms (specifically Escherichia coli) serve as universal index organisms indicating fecal contamination from human/animal warm-blooded intestines.
• Standard Coliform Testing: Three sequential tests — 1) Presumptive test (gas and acid production in lactose broth / MacConkey broth to estimate Most Probable Number - MPN), 2) Confirmed test (inoculation on EMB agar producing greenish metallic sheen for E. coli), 3) Completed test (Gram staining Gram-negative non-sporing bacilli and lactose fermentation re-verification).
• Wastewater / Sewage Treatment — Primary and Secondary stages: Primary treatment is mechanical physical settling removing settleable solids and floating grease; Secondary (biological) treatment uses aerobic microorganisms to consume dissolved organic matter (Activated Sludge process with aeration basins, Trickling filters) drastically reducing Biochemical Oxygen Demand (BOD).
• Tertiary Treatment and Sludge Digestion: Tertiary treatment removes residual nitrates and phosphates via denitrification and chemical precipitation to prevent eutrophication; Anaerobic sludge digestion uses methanogenic Archaea to convert settled solids into renewable Biogas (60-70% CH4, 30-40% CO2).

Test yourself (1 minute)

1. Biochemical Oxygen Demand (BOD) metric

   BOD measures the amount of dissolved O2 consumed by aerobic microorganisms to decompose organic matter in a water sample over 5 days at 20°C (BOD5); high BOD indicates severe organic pollution.

2. E. coli as ideal indicator criteria

   Consistently present in massive numbers in mammalian feces, does not proliferate naturally in clean freshwater, survives longer than bacterial pathogens, and is readily detected via simple standard selective cultures.

3. Activated Sludge biological dynamic

   High aerobic microbial flock (Zoogloea ramigera, protozoans, rotifers) kept suspended by constant air bubbling, converting dissolved organics into microbial biomass that rapidly settles as secondary sludge.

Practise Microbiology in water and waste management questions today

Source: NIE G.C.E. (A/L) Biology Syllabus & Resource Book, Unit 9

What should I study first?

What comes next?

Next in the syllabus

Where does Microbiology in water and waste management fit in the syllabus?

Year 2 · Term 3