Bioremediation Of Chromium Using Bacterial Biofilms

Bioremediation of Chromium using Bacterial Biofilm

Aafreen Fathima Chemical Lab

Bioremediation •

Bioremediation

can

be

defined

as

any

process

that

uses

microorganisms, fungi, green plants or their enzymes to return the natural environment altered by the contaminants to its original condition Bioremediation In-Situ

Ex-Situ

•

Heavy metals are bioremediated using Biosorption technique.

•

Biosorption is a process that involves the use of biological materials that form complexes with metal ions using their

Biofilms • Biofilms are ubiquitous in nature. • A biofilm is an aggregate of microorganisms in which cells are stuck to each other and/or to a surface • These adherent cells are frequently embedded within a selfproduced matrix of extracellular polymeric substance (EPS). • In biofilms microbial cells constitute about 15% and EPS constitute about 80%.

Exopolysaccharides(EPS) • Exopolysaccharides are high-molecular-weight polymers that are

composed

of

sugar

residues

and

are

secreted

by

microorganisms into the surrounding environment • It plays various roles in the structure and function of different biofilm communities • EPS consists of polysaccharides, proteins and uronic acids etc., • Hence it has many functional groups like carboxyl, amine, hydroxyl, phosphoric etc., • These functional groups plays a key role in biosorption by

Biofilm Development

Biofilm formation 1. Formation of conditioning layer 2. Bacterial adhesion 3. Bacterial growth 4. Biofilm expansion

Chromium • Chromium is one of the widely used metals • Chromium, a steel grey, lustrous, hard and brittle metal, occurs in nature in bound forms that constitute 0.1-0.3 mg kg-1 of the earth’s crust. • Chromium has several oxidation states, the trivalent and the hexavalent are the most stable ones. The trivalent chromium is less soluble and less mobile when compared to hexavalent chromium, so trivalent chromium is less toxic than hexavalent chromium. • The drawback of using chromium is heavy metal pollution which is a serious problem for life in general. Chromium is a mutagen and a carcinogen. • Since chromium is a pollutant and a soil contaminant, after

Aim of the Project The aim of the present study is to remove chromium from the effluent using biosorption, a technique which employs bio-films developed using chromium tolerant bacterial strains

Objective • Isolation of chrome-tolerant bacterial strain from the sludge • Adaptation

of

the

strains

with

respect

to

increasing

concentration of chromium and studying the chrome uptake capacity • Forming an immobilized bacterial layer using the adapted strains on different substrata • Applying for the bioremediation of chromium

Metal uptake studies •

To study the metal uptake potential of the bacterial strains from the effluent

•

To check the maximum absorption of the metal by the adapted bacterial strains

Methodology • Batch

experiments

were

conducted

using

different

concentrations of chromium- 25, 50, 75 and 100 ppm • Substrate- Kaolin clay • Broth- Nutrient broth • Control – Without bacteria and/or Kaolin • pH plays an important role in biosorption

• The culture and kaolin are added to the metal solution and the flasks are incubated at 37⁰c with moderate stirring • Samples of 1 ml were collected after 24, 48 and 72 hours, centrifuged and analyzed for chromium • Analysis of chromium in the sample can be done in 2 ways, 1. Atomic absorption spectrophotometer 2. Diphenyl carbazide method (DPC)

Results

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