bioremediation

Question 1

Treating sewage

Answer 1

• Nitrification: autotrophic bacteria (nitrosomas, nitrobacter) converts ammonium into nitrites, and then nitrates
  
  • Denitrification: heterotrophic bacteria (agrobacterium, pseudomonas) use BOD and the oxygen from nitrate (when DO isn’t present)

Question 2

How to improve bio-remediation

Answer 2

• Nutrient enrichment (fertilization): add fertilizer to contaminated environment to stimulate growth of indigenous microorganisms that can degrade pollutants

Bio-augmentation (seeding): bacteria are added to the contaminated environment to support indigenous microbes with bio-degradative processes

Question 3

Mechanism of bioremediation

Answer 3

• Micro-organism destroy organic contaminants in the course of using the chemicals for their own growth and reproduction
  
  • Cells catalyze oxidation of organic chemicals causing transfer of electrons from organic chemicals to some electron acceptor
  • Electron receptors:
    ○ Aerobic: oxygen
    Anaerobic: nitrate, manganese, iron, sulfate (not as effective as oxygen)

Question 4

Types of bio-remediation

Answer 4

1. In situ: ‘on site’, cleaning at the site of contamination, cheap and efficient
   Limitation: cannot effectively deal with metal contaminants mixed with organic compounds
   
   2. Ex situ: ‘off site’, contaminated land is taken out of area to be cleaned up by organisms
      Limitation: expensive and damaging to the area

Question 5

Types of contaminants

Answer 5

Pollutants
- Naturally occurring compounds in the environment that are present in unnaturally high concentrations
○ Crude oil, phosphates, heavy metals

Xenobiotics
- Chemically synthesized compounds that have never occurred in nature
Pesticides, herbicides and plastics