bioremediation is a process of removal or degrade pollutant by using microorganisms. there are two types of bioremediation that is biostimulation and bioaugmentation.
biostimulation is process when we adding nutrients, electron acceptor, electron donor and etc to stimulate the growth and activities of indigenous microbes.
bioaugmentation is a process that we add exogenous microbes or modified microbes to treat pollutants.
phytoremediation is also part of the bioremediation but we using plant (phyto) to remove or clean up the pollutants. there are several types of phytoremediation that are:
1. phytoextraction- the pollutants are extract and translocate from contaminated soil into plant tissues. the plant then were recycle or incinerate. to apply this method, the amount of ash must less than 10% from the pollutant that we will dug up from soil.
the species of plants that we can use are sunflower, indian mustard and dandelion.
2. rhizofiltration- the pollutant were absorbed by root (rhizo) of the plants. the plant were removed after it were saturated. this kind of method was used to clean the radioactive waste in chernobyl.
3. phytodegradation- process when the pollutants were degrade by plants enzyme and the products were used for plants growth. this method cant be used for highly hydrophobic pollutants.
4. hydraulic control- used grass or tree to prevent off-site migration and decrease downward migration of contaminants by pumps the water from soils and aquifer.
5. phytovolatilisation- is the uptake and transpiration of a contaminant by a plant, with release of the contaminant or a modified form of the contaminant from the plant to the atmosphere.
6. rhizoremediation- this method not used plant to remove pollutants but microbes surrounding root of plants.
7. phytostabilisation- is the use of certain plant species to immobilize contaminants in the soil and groundwater.
the requirements for microbes to do bioremediation are:
1. Existence of organism(s) with required degradation potential
2)Presence of specific degrader(s) in the contaminated zone
3)Accessibility of Target Pollutants to the Microorganisms
4)Induction of Appropriate Degradative Enzymes
5)Availability of Electron Acceptors/Electron donors
6)Availability of Nutrients
7) Adequate pH and buffering capacity
8) Adequate temperature
9)Absence of Toxic or Inhibitory Substances
the most recalcitrant pollutans is xenobiotics. xenobiotic is a chemical which is not produced or expected to be present but could be found in an organism e.g. antibiotics are xenobiotics in humans. Natural compounds can become xenobiotics if they are taken up by another organisms e.g. uptake of human hormones by fish found downstream of sewage treatment plant outfalls.
examples of xenobiotic are Halogenated compounds, DDT (dichlorodiphenyltrichloroethane), PCBs (polychlorinated biphenyls),Nitro-group, Tertiary carbon, Plastics, synthetic polymers.