[greensagar]

The classification given is based entirely on site specific bio-remediation and use of only microbes but on the contrary there are two main types of the bio-remediation - 1.Phytoremediation and 2.Microbial bio-remediation.
bio-remediation is a process of degradation of organic waste while it is assimalation of heavy metals if present at the site by introducing bacteria, fungi and plants.
1)Phyto-remediation:-
use of green plants and associated microbes to render a harmless environment contaminents. it was first installed by Germany nearly 300 yrs ago for treating municipal sewage.
In plants remediation occurs due to the following:-
a)accumulating organics in tissues
b) translocation of organics to leaf and their volatilization from its surface.
c) metabolized by the plant itself.
d) active plant-associated microbes may degrade organics.
e)Remediation of heavy metals is due to their accumulation in tissues.

Roots of the plants absorb organics in direct proportions to their relative lipophilicity.It has been obtained for certain pesticides, trichloroethylene, and petroleum hydrocarbons for eg, carrots are used to absorb DDT.
The rate of and quantity of degradation is rather slow.

application of phyto-remediation is:-
a)cheap
b)can be easily monitored

limitations:-
a)contaminants should be present at the root zone
b)larger site requirement for easy cultivation
c)time consuming

2) microbial Remediation:-
Bio-remediation of organics is primarily based on the fact whether the microbes are naturally present at the site or lab developed microbial inoculants are introduced in the site.

Microbes are used not only for organics certain species of bacteria, fungi and algae are capable of accumulating some toxic inorganic contaminants but the drawback is that there is no cost effective method to remove these microbes.
Microbes were employed by the US Environment Protection Agency and Exxon company to clean up Alaskan beaches contaminated by Valdez oil spill.
In India , a consortium of bacterial species has been developed to combat oil spills and oily sludge and is called 'Oil-zapper'

Hope this will help .