BIOREMEDIATIONProcess that uses microorganisms, fungi, green plantsor their enzymes to return the natural environmentaltered by contaminants to its original condition.
TYPES OF BIOREMEDIATIONIn Situ bioremediationClean up approach that involves the direct contactb/w microorganism and contaminant.Advantages:1- Low cost.2- Minimal site disruption.3- Simultaneous treatment of contaminated water and soil.4- Minimal exposure of public and site personnel.
Disadvantages:1- Time consuming.2- Seasonal variation.3- Problematic addition of additives.
Types of In situ Bioremediation1- Intrinsic in situ bioremediation.2- Engineered in situ bioremediation.
Intrinsic BR:Bioremediation that can occur on its ownFactors effecting rate of intrinsicbioremediation:1- moisture in soil.2- pH.3- Temp4- Soil nutrients.5- presence of e acceptors (NO3 , SO4).6- Toxin conc.
Engineered In situ bioremediation:It can be spurred on via the addition of fertilizers or bymanipulating other components to increase thebioavailability within the medium (biostimulation).Recent advancements have also proven successful via theaddition of matched microbe strains to the medium toenhance the resident microbe populations ability tobreak down contaminants (bioaugmentation).
Ex Situ BioremediationEx-situ conservation means literally, "off-siteconservation“. It is removal and collection ofwaste at a place to facilitates biodegradation.Classified into1- Solid phase treatment.2- slurry phase treatment.
Solid phase treatment includes1- organic wastes.2- domestic wastes.3- industrial wastes.4- agricultural wastes.The traditional method involves the productionof compost.
CompostingIt is self heating, substrate dense, managed microbial systemsuitable for the treatment of large amount of contaminatedwaste. Hazardous compds. reported to be removed bycomposting are aromatic hydrocarbons, halogenated compds.Microbial growth is affected by1- moisture in soil.2- pH.3- Temp4- Soil nutrients.5- particle size.6- Toxin conc.
Composting can be done either1- Open land system: it is in expensive but difficult to manage.2- Closed treatment system: Expansive but manageable.
Open land system
Closed treatment system
Slurry phase systemContaminated materials, microorganism andwater are formulated into slurry within thebioreactor or fermentor.The bioreactors are designedto promote microbial degradation.
Types of slurry phase bioreactors1- Aerated lagoonsNutrients are supplied, mixers are fitted forslurry formation and surface aerators provide airfor microbial growth. Not appropriate forvolatile wastes.
2- Closed system: (low shear air lift reactors)In this bioreactor pH, temp, nutrient addition,mixing and oxygen supply can be controlled asdesired. Pretreatment involves A-fractionation of solid washing milling to reduce particle size and slurry formation.Certain surfactants like anthracene, pyrene areadded to ennhance rate of biodegradation.