ENVIRONMENTAL BIOTECHNOLOGY

Submitted by:Mehak Parashar, Aditi

MiglaniProject Guide:

Dr. Tanuja NautiyalDepartment of Chemistry

Northern India Engineering College

New Delhi

INTRODUCTION Environmental biotechnology is biotechnology that is applied to and used to study the natural environment. Environmental biotechnology could also imply that one try to harness biological process for commercial uses and exploitation. The International Society for Environmental Biotechnology defines environmental biotechnology as "the development, use and regulation of biological systems for remediation of contaminated environments (land, air, water), and for environment-friendly processes (green manufacturing technologies and sustainable development).

BIOACCUMULATION

BIODEGRADATION

BIOREMEDIATION BIOLEACHINGBIOMETHANATION

BIOACCUMULATION Bioaccumulation refers to the accumulation of substances, such as

pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. Thus, the longer the biological half-life of the substance the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high. Bioaccumulation, for example in fish, can be predicted by models.Biotransformation can

strongly modify bioaccumulation of chemicals in an organism.BIOACCUMULATION is result of three

processes:1)uptake2)storage3)elimination

BIOCONCENTRATION & BIOMAGNIFICATIONBioconcentration is a related but more specific term,

referring to uptake and accumulation of a substance from water alone. By contrast, bioaccumulation refers to uptake from all sources combined (e.g. water, food, air, etc.)

Biomagnification, also known as bioamplification or biological magnification, is the increase in concentration of a substance that occurs in a food chain as a consequence of:

Persistence (can't be broken down by environmental processes)

Food chain energeticLow (or nonexistent) rate of internal degradation/excretion

of the substance (often due to water-insolubility)

CASE STUDYLONG ISLAND ESTUARY

BIODEGRADATIONBiodegradation is the chemical dissolution of materials by

bacteria or other biological means. Although often conflated, biodegradable is distinct in meaning from compostable. While biodegradable simply means to be consumed by microorganisms and return to compounds found in nature, "compostable" makes the specific demand that the object break down in a compost pile. The term is often used in relation to ecology, waste management, biomedicine, and the natural environment (bioremediation) and is now commonly associated with environmentally friendly products that are capable of decomposing back into natural elements. Organic material can be degraded aerobically with oxygen, or anaerobically, without oxygen. Biosurfactant, an extracellular surfactant secreted by microorganisms, enhances the biodegradation process.

Co-metabolismCo-metabolism is defined as the simultaneous

degradation of two compounds, in which the degradation of the second compound (the secondary substrate) depends on the presence of the first compound (the primary substrate). For example, in the process of metabolizing methane, propane or simple sugars, some bacteria, such as Pseudomonas stutzeri OX1, can degrade hazardous chlorinated solvents, such as tetrachloroethylene and trichloroethylene, that they would otherwise be unable to attack. They do this by producing the methane monooxygenase, enzyme which is known to degrade some pollutants, such as chlorinated solvents, via co-metabolism. Co-metabolism is thus used as an approach to biological degradation of hazardous solvents.

BIOREMEDIATIONBioremediation is the use of micro-organism metabolism to remove pollutants. Technologies can be generally classified as in situ or ex situ. In situ bioremediation involves treating the contaminated material at the site, while ex situ involves the removal of the contaminated material to be treated elsewhere. Some examples of bioremediation related technologies are phytoremediation, bioventing, bioleaching, landfarming, bioreactor, composting, bioaugmentation, rhizofiltration, and biostimulation.

CASE STUDYTERI(Tata Energy Research Institute)

BIOLEACHING

Bioleaching is the extraction of metals from their ores through the use of living organisms. This is much cleaner than the traditional hea leaching using cyanide. Bioleaching is one of several applications within biohydrometallurgy and several methods are used to recover copper, zinc, lead, arsenic, antimony, nickel, molybdenum, gold, silver, and cobalt.

Process Of BioleachingBioleaching can involve numerous ferrous iron and sulfur

oxidizing bacteria, including Acidithiobacillus ferrooxidans and Acidithiobacillus (formerly known as Thiobacillus). As a general principle, Fe3+ ions are used to oxidize the ore. This step is entirely independent of microbes. The role of the bacteria is the further oxidation of the ore, but also the regeneration of the chemical oxidant Fe3+ from Fe2+. For example, bacteria catalyse the breakdown of the mineral pyrite (FeS2) by oxidising the sulfur and metal (in this case ferrous iron, (Fe2+)) using oxygen . This yields soluble products that can be further purified and refined to yield the desired metal.

Pyrite leaching (FeS2): In the first step, disulfide is spontaneously oxidized to thiosulfate by ferric ion (Fe3+), which in turn is reduced to give ferrous ion (Fe2+):

Process Of Bioleaching(1)      spontaneous The ferrous ion is then oxidized by bacteria using oxygen:(2)      (iron oxidizers) Thiosulfate is also oxidized by bacteria to give sulfate:(3)      (sulfur oxidizers) The ferric ion produced in reaction (2) oxidized more

sulfide as in reaction (1), closing the cycle and given the net reaction:(4)   The net products of the reaction are soluble ferrous sulfate and sulfuric

acid. The microbial oxidation process occurs at the cell membraneof the

bacteria. The electrons pass into the cells and are used in biochemical processes to produce energy for the bacteria while reducing oxygen to water The critical reaction is the oxidation of sulfide by ferric iron. The main role of the bacterial step is the regeneration of this reactant.

The process for copper is very similar, but the efficiency and kinetics depend on the copper mineralogy. The most efficient minerals are supergene minerals such as chalcocite Cu2S and covellite,CuS. The main copper mineral chalcopyrite CuFeS2) is not leached very efficiently, which is why the dominant copper-producing technology remains flotation, followed by smelting and refining. The leaching of CuFeS2 follows the two stages of being dissolved and then further oxidised, with Cu2+ ions being left in solution.

BIOMETHANATIONBiomethanation is the formation of

methane by microbes known as methanogens. Organisms capable of producing methane have been identified only from the domain Archaea, a group phylogenetically distinct from both eukaryotes and bacteria, although many live in close association with anaerobic bacteria. The production of methane is an important and widespread form of microbial metabolism. In most environments, it is the final step in the decomposition of biomass.

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