Environmental Biotechnology Lecture Notes PDF

ENVIRONMENTAL BIOTECHNOLOGY Dr. Rania Farouk Ahmed 1 DEFINITION  Environmental Biotechnology ‘the use of organisms or their components in industrial or commercial processes, which can be aided by the techniques of genetic manipulation in developing e.g. novel plants...

ENVIRONMENTAL BIOTECHNOLOGY Dr. Rania Farouk Ahmed 1 DEFINITION  Environmental Biotechnology ‘the use of organisms or their components in industrial or commercial processes, which can be aided by the techniques of genetic manipulation in developing e.g. novel plants for agriculture or industry.  Environmental Biotechnology - the development, use and regulation of biological systems for remediation of contaminated environments (land, air, water), and for environment-friendly processes.  The utilization of microorganisms to improve environmental quality (protect the environment by controlling pollution). 2 BRANCHES OF BIOTECHNOLOGY Red biotechnology is biotechnology applied to medical processes. Some examples are the designing of organisms to produce antibiotics, vitamins and insulin. White biotechnology (or Grey biotechnology) is biotechnology applied to industrial processes. An example is the designing of an organism to produce a useful chemical. White biotechnology tends to consume less in resources than traditional processes when used to produce industrial goods. 3 Green biotechnology is biotechnology applied to agricultural processes. e.g. designing of transgenic plants to grow under specific environmental conditions. Blue biotechnology has been used to describe the marine and aquatic applications of biotechnology, but its use is relatively rare. 4  The primary role of environmental biotechnology: 1) Cleaning up contamination and dealing rationally with wastes. 2) Alternative and more environmental friendly processes and products.  Bioremediation: is a technique waste management means the use of biological organisms for cleaning polluted soil and water.  Bioremediation: the use of microorganisms to solve or remedy environmental problems 5 Applying Genetically Engineered Strains to Clean Up the Environment  Petroleum eating bacteria  Heavy metals (bioaccumulation) Bacteria sequester heavy and radioactive metals  Biosensors lux genes  bioremediation is used depends on 1) what is contaminated? (ecosystem or locations). 2) on the types of chemicals that need to be cleaned up (contaminants chemical structure) 3) the concentration of the contaminants (amount and duration). 7  Bioremediation is a triple-corners process: Solid Inorganic Organic Liquid Pollutants Gas Environments Organisms Soil Microorganisms Water Plants Air  Removal of a material from an environment takes one of two routes: it is either degraded or immobilized  1- Immobilisation can be achieved by A. chemicals excreted by an organism or B. by chemicals in the neighboring environment which trap or chelate a molecule thus making it insoluble.  all biological processes require the substrate to be dissolved in water, chelation renders the substance unavailable.  In some instances this is a desirable end result and may be viewed as a form of remediation, since it stabilizes the 9 contaminant.  2- Degradation : is achieved by metabolic pathways operating within an organism or combination of organisms.  Certain microorganisms using contaminants as a source of food (as carbon and nitrogen) and energy  Such activity operates through metabolic pathways functioning  within the cell,  or by enzymes either excreted by the cell or, isolated and applied in a purified form. 10 FACTORS INFLUENCES THE BIOREMEDIATION OF SOILS POLLUTION  bioremediation of soils are abiotic (physical and chemical) and biotic factors. 11 ENVIRONMENTAL CONDITIONS FOR BIOREMEDIATION A complete biodegradation :- results in detoxification by mineralizing pollutants to carbon dioxide, water and harmless inorganic salts. (Aerobic – where oxygen in some form is added to the treatment environment).  Incomplete biodegradation will yield breakdown products which may or may not be less toxic than the original pollutant. Such as degradation of tri- or tetrachloroethylene for instance can yield vinylchloride, which is more toxic and carcinogenic than the original compounds. (Anaerobic – where nitrate, iron, or other electron acceptor is added to the treatment environment).  TYPES OF BIOREMEDIATION: (2 TYPES) 1- Biostimulation  involves the modification of the environment to stimulate existing bacteria capable of bioremediation. ***This can be done by:- * addition of various forms of limiting nutrients and electron acceptors, such as phosphorus, nitrogen, oxygen, or carbon. * optimizing conditions such as aeration, pH and temperature control.  BIOVENTING: increase the concentration of oxygen (air extraction or injection) and stimulate biodegradation.  that stimulates the natural in situ biodegradation of any 13 biodegradable compound by providing oxygen aerobic microorganisms existing in soil.  The primary advantage of biostimulation is: bioremediation will be started by already present native microorganisms that are well-suited to the subsurface environment, and are well distributed spatially within the subsurface.  the disadvantage of biostimulation is: Addition of nutrients might also promote the growth of heterotrophic microorganisms which are not mainly degraders a waste thereby creating a competition between the resident micro flora. 14 2- BIOAUGMENTATION  Definition: The addition of microorganisms to the reaction chamber whether in situ or above ground.  Considerations before bioaugmenting: 1) Ability to survive 2) Ability to function 3) Assurances that they are nonpathogenic to higher life forms 4) Successful bioaugmentation treatments depend on the use of inocula consisting of microbial strains or microbial consortia that have been well adapted to the site to be decontaminated.  FACTORS AFFECTING BIOREMEDIATION 1-Site characteristics: Soil structure controls the effective delivery of air, water, and nutrients. To improve soil structure, materials such as gypsum or organic matter can be applied. Low soil permeability can impede movement of water, nutrients, and oxygen; hence, soils with low permeability may not be appropriate for in situ clean-up techniques 2- Redox Potential and oxygen content: typify oxidizing or reducing conditions. Redox potential is influenced by the presence of electron acceptors such as nitrate, 16 manganese oxides, iron oxides and sulfate. 3- Nutrients: - nutrients are the basic building blocks of life and allow microbes to create the necessary enzymes to break down the contaminants. - nutrients can be added in a useable form or via an organic substrate amendment ,which also serves as an electron donor, to stimulate bioremediation. 4- Moisture content: Microbial growth requires an optimum presence of water in the environmental matrix. For optimum growth and proliferation, microorganisms require 12% to 25% of moisture. 5- Temperature: Directly affects the rate of microbial metabolism and consequently microbial activity in the environment. The biodegradation rate, to an extent rises with increasing temperature and slows with decreasing 17 temperature. 6- Contaminant concentrations: Directly influence microbial activity. When concentrations are too high, the contaminants may have toxic effects on the present bacteria. In contrast, low contaminant concentration may prevent induction of bacterial degradation enzymes. 7- Contaminant bioavailability: Depends on the degree to which: * they adsorb to solids or are impound by molecules in contaminated media, * are diffused in macropores of soil or sediment, and ** other factors such as whether contaminants are present in Non-Aqueous Phase Liquid (NAPL) form. Bioavailability for microbial reactions is lower for contaminants that are more 18 strongly adsorbed to solids. TO BE CONTINUED 19  POLLUTION AND POLLUTION CONTROL Dr. Rania Farouk Ahmed 20 POLLUTION OF THE ENVIRONMENT DEFINITION  ’ means pollution of the environment due to the release (into any environmental medium) from any process of substances which are capable of causing harm to man or any other living organisms supported by the environment. 21 CLASSIFYING POLLUTION  May be made on the basis of:- - the chemical or physical nature of the substance, - its source, - the environmental pathway used, - the target organism affected or - simply its gross effect. 22 THE POLLUTANT′S PROPERTIES, INCLUDE FACTORS SUCH AS: 1) toxicity 2) persistence 3) mobility 4) ease of control 5) bioaccumulation 6) chemistry 23  1- TOXICITY  Toxicity represents the potential damage to life and can be both short and long term.  It is related to the concentration of pollutant and the time of exposure to it.  Intrinsically highly toxic substances can kill in a short time, while less toxic ones require a longer period of exposure to do damage. However, some pollutants which may kill swiftly in high concentrations, may also have an effect on an organism’s behaviour or its susceptibility to environmental stress over its lifetime, in the case of low concentration exposure. 24 2- PERSISTENCE  This is the duration of effect. It is often linked to mobility and bioaccumulation.  Highly toxic chemicals which are environmentally unstable and break down rapidly are less harmful than persistent substances. 25 3- MOBILITY  The tendency of a pollutant to disperse or dilute since this affects concentration.  Some pollutants are not readily mobile and tend to remain in ‘hot-spots’ near to their point of origin. Others spread readily and can cause widespread contamination. 26 5- EASE OF CONTROL  Factors affecting ease of control  the mobility of the pollutant  the nature duration of the pollution event  local site-specific considerations. 27 6- BIOACCUMULATION  As is widely appreciated, some pollutants, even when present in very small amounts within the environment, can be taken up by living organisms and become concentrated in their tissues over time.  Xenobiotic compounds are chemical compounds found in an organism but it are not normally produced or expected to be present in it. 28 7- CHEMISTRY  since the reaction or breakdown products of a given pollutant can sometimes be more dangerous than the original substance.  two or more substances occurring together produce a combined pollution outcome which is greater than simply the sum of their individual effects. 29 PRACTICAL TOXICITY ISSUES  Mechanisms of the toxic action of pollutants arises  There are two main mechanisms, often labelled ‘direct’ and ‘indirect’.  Direct, the effect arises by the contaminant combining with cellular constituents or enzymes and thus preventing their proper function.  indirect, the damage is done by secondary action resulting from their presence.  BIOREMEDIATION  upgraded techniques involving living organisms, specifically plants and microbes, for the removal and/or immobilization of contaminants.  Microbial bioremediation techniques: 1) Biostimulation (enhancing the activity of native microbes) 2) Bioaugmentation (increasing the viable microbial counts) 3) Bioaccumulation (storage of toxic or nontoxic elements by the microbes) 4) biosorption (removal of elements from the environment through adsorption) 31  BIOREMEDIATION  microbial bioremediation can be classified on the basis of the nature of substrate: (1) inorganic contaminants (2) organic contaminants 32  BIOREMEDIATION (1) inorganic contaminants  include toxic heavy metals  microbes in any case cannot degrade the metal ions.  able to transform metallic ions from higher to lower oxidation states to stabilize them or  able to metabolize, detoxify and accumulate metals mostly in cell wall like any other nutrient element. Microbes releasing chelating agents and acids changing physicochemical properties such as redox potential, increasing the bioavailability of metal ions (biosorption, first step in the interaction between microbial cell and 33 metal ions, then the physical adsorption, ion exchange and complexation) (2) ORGANIC CONTAMINANTS (OCS)  Biodegradation of OCs: refers to the catabolic activity of microbes transforming them into less or completely nontoxic residues.  single microbial species hardly degrades any organic substrate in isolation and works well in community.  less or completely nontoxic residues Fungi have, however, several advantages over bacterial degrading processes as the former can grow at higher concentrations of toxic organics 34 Biological Treatment Processes:  Biological treatment processes, are those that use microorganisms to coagulate and remove the non-settleable colloidal solids and to stabilize the organic matter.  The discussion of biological treatment processes has been further divided into the following two categories: A- Suspended growth processes. B- Fixed growth processes.  (1) Suspended growth processes refer to treatment systems where microorganisms and waste are contained in a reactor. Oxygen is introduced to the reactor allowing the biological activity to take place. Examples of suspended growth processes include activated sludge systems.  (2) Fixed growth processes refer to systems where a biological mass is allowed to grow on a medium (as a carrier). Wastewater is sprayed on the medium or put into contact in other manners. The biological mass stabilizes the wastewater as it passes over it. Examples of fixed growth processes include biotrickling filters and bioscrubbers ADVANTAGES OF BIOREMEDIATION  highlyspecific  Less expensive  If mineralization occurs get complete degradation and clean up  Does not transfer contaminants from one environment to another  Uses a natural process  Good public acceptance  Process is simple DISADVANTAGES TO BIOREMEDIATION  Not quickly  Often need to develop a system  Always need to test and optimize conditions empirically – not with computer models  May have inhibitors present  Compounds may not be in a biodegradable form – polymers, plastics  DEFINITIONS  Bioremediation is any process that uses organisms (microorganism, algae and plant) or their enzymes to return the polluted environment to its original condition.  Biodegradation is the use of these organisms in the degradation of different pollutants.  Co-metabolism: in this process the microorganism produces an enzyme to utilizes its nutrients, but by chance this enzyme can degrade a pollutant. PRACTICAL APPLICATIONS TO POLLUTION CONTROL  Technologies of practical applications (Fixed growth processes) are divided into three main types, biofilters, biotrickling filters and bioscrubbers. TO BE CONTINUED 41