Issues and Scopes in Environmental Biotechnology

BT 324- Environmental BiotechnologyLecture 1

ISSUES FOR ENVIRONMENTAL BIOTECHNOLOGY

I. International issues

• Involves problems like:– Climate changes– Global warming– Marine pollution– Oil spill– Air pollution– Energy crisis

a)Climate change and Global warming

• A threat to biodiversity, ecosystems and present day environment

• Examples evident from irregularities in rains, droughts due to warm ocean currents, decline of forests, lower ground water level

• Causes: increased energy consumption, deforestation, methane emission from rice fields and swamps and other kinds of pollutions

b)Marine pollution

• Global increase in ocean temperature ad release of toxicants into ocean causing coral bleaching.

• In Indian ocean 90% corals died over thousands of kms.

• Nutrient loaded freshwater from the land causing changes in density and diversity of life forms in the coastal oceans.

• Eutrophication (toxic algal blooms and sedimentation) is the major threat to flora and fauna of the ocean

c)Air pollution

• Industrialization, vehicular emission and deforestation are the major causes.

• Some minor effects are also there because of waste deposition and soil erosion

• Gases to be concerned about: oxides of nitrogen and sulfur, carbon compounds and greenhouse gases.

d)Energy crisis

• Conventional energy sources are depleting fast and also causing most of the environmental concerns.

• Need of the hour : to reduce energy consumption and generate as much energy as possible from non-conventional resources

• Environmental friendly technology needs to be developed

e)Oil spills

• Threat to marine ecosystem and world environment

• Loss of mangrove forests in West Asia attributed to oil spills in coastal soil and oceans.

• Accidents during exploration, extraction and transport needs to be checked.

f)Decline and loss of species

• Global biodiversity changing due to human population explosion, unsustainable pattern of energy consumption, increasing production of wastes and pollution, urbanization

• Extinction, endangered, threatened species- all rates are up and increasing

II. National Issues

• It includes issues like:– Land degradation– Erosion of top soil– Siltation of reservoirs– Deforestation – Formation of degraded soil– Nitrogen deposition in plains– Solid waste in urban areas

• Requires national government involvement and development of strategies to cope with the problems

a)Land degradation

• Cause of reduction in the productive capacity of arable land

• Factors leading to land degradation are: poor agricultural practices, erosion, compaction, acidification, weeds, biological degradation, fertilizer overuse (banned fertilizers still on rampant use, subsidies leading to overuse), mining, industrialization, water logging, sea water inundation etc.

b)Soil erosion• Effects

– increased siltation of reservoirs and irrigation projects– Eutrophication of surface waters– Reduction in forest regeneration– Depletion of productivity of arable land– Severe effects on soil function (eg. Decrease in soil’s ability to filter

pollutants and act as buffer, its role in hydrological cycle and nitrogen cycle)

• Types: water erosion, physical degradation, chemical degradation• Major causes:

– Overgrazing, deforestation, agricultural activities, overexploitation of vegetation and industrial activities

c)Water pollution

• Menace all over the world• Degradation of wetlands, depletion of species, reduction in

secondary productivity, eutrophication, shrinking water bodies, are some of the direct effects

• Sources of pollution:– Untreated sewage, chemical discharges, petroleum leaks and spills,

agricultural chemicals• Poisoning the surrounding ecosystem and threatening the

health and livelihood of the people depending on the water source

• Human activities, agriculture, industries, urbanization are the major causes

d)Nitrogen deposition

• Increased nitrogen in soil and water can lead to:– a loss of species– aquatic systems are most vulnerable due to surface run

offs and domestic and industrial effluents discharge– Eutrophication– Nitrogen washed from hilltops causes deficiency at high

altitudes leading to slow growth of plants and excess in the plains leading to weeds and unwanted plants. Productivity is reduced in both.

• Causes: deforestation, burning of fossil fuels, fertilizers

e)Solid wastes

• Population and urbanization-main causes• Collection, treatment, disposal of solid wastes

needs attention and development of organized systems

• Incineration and land filling methods of waste disposal causes air pollution, water contamination, unpleasant odors and sights

• Non biodegradable and hazardous wastes need special disposal methods or else can be damaging and hazardous to health

III. Regional Issues

• Local problems- industrial processes, water logging, weed infestation, increasing salinity; due to overuse of resources

• Nitrogen deposition, weed management methods, excess use of irrigation water, poor drainage – are some more factors.

• Regional climate changes have affected biological systems, excessive water scarcity, irregular climate regime, declined agricultural production

SCOPE OF ENVIRONMENTAL BIOTECHNOLOGY

I. Biotechnology for a safer environment

• Environment is damaged- need to modify technologies to minimize the extent of the damage caused.

• Technologies utilizing biological organisms are attractive as bioresources because they don’t cause environmental damage.

• Environmental biotechnology thus aims at protection of environment and its purification from toxins and contaminants and prevents degradation of natural resources.

a) Degradation of pesticides• Organosynthetic pesticides and insecticides accumulate

and cause hazards and negative environmental effects.• Techniques for concentrations, accumulation rate etc.

of these pollutants developed.• Effects of pesticides on non-target species can be

determined by concentration and persistence of chemicals.

• Bacteria isolated for degradation of chemicals can be used to reclaim pesticide affected soil.

• Pesticide degrading enzymes studied and cultured in bioreactors (eg. Phosphotriesterase, carboxylesterase)

• GMOs developed for accelerated degradation.

b) Degradation of Organic Pollutants

• Wastewater from industries and households has carbohydrates(starch, lignin), lipids, proteins, hydrocarbons etc. organic pollutants.

• Microbes can degrade these and use the energy produced.

• Can be used in other industrial processes. • Bioconversion- to convert waste substances at faster

rate utilize microbial combinations for cometabolism of difficult substrates.

• Reductive attack by anaerobic microbes is used to degrade complex chemicals that require special environment conditions and special microbes

c) Treatment of wastewater• Wastewater contains oxidisable organic matter- catabolic

process of micorbes used.• Biological degradation by aerobic respiration, denitrification

under anaerobic conditions or methanogenesis.• Sewage sludge oxidising systems, ponds have been developed.• Process developed for degradation of lignocellulose by

integrating metabloic activities of fungi, aerobic and anaerobic bacteria.

• Nitrogen and phosphorus need to be removed simultaneously to prevent eutrophication- denitrifying bacteria used which convert dissolved nitrogen into ammonia and then free dinitrogen. Alternative- secondary treatment to convert it into biomass in ponds.

d) Measurements and modeling of the effects of pollutants

• Procedures to predict effects of a particular toxin have been designed. Still needed more complex bioassays, involving combination of toxic agents.

• Ecotoxicology requires selection of species or a combination thereof as test systems for toxicity analysis. Not very feasible though due to physiological differences among species.

• Artificial systems such as synthetic membranes are used to understand the transport kinetics of toxins.

e) Transformation and removal of heavy metals

• Conventional- Chemical and biological transformation of heavy metal ions.

• Screening and selecting of tolerant plant and microbial species

• Microbial transformation involves extracellular chelation, complexation and precipitation, biosorption, biomodification, volatilisation and intracellular complexation.

• release organic acids which form complex with metals reducing toxicity and bioavailability.

• Biosorption(adsorption of metals on cell surface) used for removing metals from water.

f) Processing of solid wastes

• Sanitary landfill better for environment than simple dumping in open pits or burning. Discharged leachates need attention. Better designed landfills needed.

• Aerobic composting used for organic wastes. Technique to maximise microbial activity and minimise loss of carbon and nitrogen to be improved.

• Vermicomposting(degradation with help of earthworm, fungi,etc.) upgrades the value of the waste material- can be used as nutrient for plants.

• Anaerobic fermentation- optimization of the process for specific waste leads to more economical end products.

g)Development of Biopesticides

• Biopesticides- the biologically active compounds, dead or living parts of the plants or animals, or the whole plant, animal or microbe applied to control agricultural and domestic pests.

• Biopesticides still not popular- cost, limited production.

• Exploration and analysis of the bioactive principles of biological substances and organisms is crucial. Steps- identification, growth, dose- effect study.

II. Biotechnology for management of resources

• Indiscriminate use of resources causing environment problems

• Excess withdrawal of ground water, deforestation, mining deteriorate the quality of the resources.

• Development of alternatives and technologies to harness new resources is needed.

a)Reclamation of Wasteland

• Degraded land be reclaimed to increase agricultural production.

• Some lands like saline soils in coastal India can’t be reclaimed- frequent sea water inundation. Biotechnology provides methods to generate crop types suitable to this type of soil and new plant types are also developed.

• Lignocellulolytic and phosphate solubilizing microbes applied in mine waste soils to facilitate metal leaching to deeper soil layers and to immobilize metals.

b)Biomass production

• Regeneration of biomass needed to counteract deforestation and environmental damage.

• Plant species for wood and grass for fodder-afforestation.

• Wastewater for freshwater aquaculture converts wastewater to secondary biomass(fish).

• Single cell proteins, pigments, antioxidants, amino acids can be produced by using wastewater.

c)Leaching of metals and minerals

• Ore quality is decreasing- microbial leaching helpful to extract low concentrations of metals

• Species for bioleaching-Sulfolobus,Thiobacillus• Copper and uranium extracted by bioleaching.• Solubilization of phosphate from insoluble

phosphate rocks by microbes (Burkholderia, Erwinia) used to convert glucose containing wastes gluconic acids.

• Microorganisms in situ for dislodging oil used ofr microbial enhanced oil recovery from oil wells.

d)Biogas and Biofuel production

• Anaerobic fermentation used to generate biogas from sewage sludge and organic solid wastes. Reactor designing, reaction conditions manipulations etc. need optimizations.

• Ethanol made from corn, wheat, sugar used as fuel supplement.

• Biofuels- no pollution, better environment

III.Development of environmentfriendly process

• New approach to manage urban waste. Involves sanitary landfill, aerobic and anaerobic treatment, leachate treatment, wastewater treatment etc.

• Better sustained waste management system-more economical and energy efficient

a) Integrated waste management

b)Development and designing of bioreactors

• Proper design through use of dynamic models.• Elements for modeling a biogas reactor: reactor

structure, substrate concentartions, micorbial biomass, gas collection system.

• Problems to be tackeld:– Floatation of active biomass due to gas load– Generation of effective biomass within the reactor– Development of biogas quality

• Examples- slurry bioreactors, solid state fixed bed bioreactors, solid state bioreactors with natural ventilation, solid state bioreactors with forced aeration, rotating drum dry solid bioreactors.

c)Integrated pest management

• Termed as environment friendly pest control, it involves natural, biological and if necessary, chemical control.

• Still less applications.• IPM programmes focus on single pest rather

than multiple pest interaction and also doesn’t involve ecologically sustainable control tactics.

• Biotech approaches has opened new avenues making it more biointensive.

IV. Biotechnology for conservation of biodiversity.

• GMO crops- potential biodiversity risk.• Loss and degradation of habitats is the major threat to

biodiversity mainly caused by introduction of GMOs, soil contamination, deforestation.

• Emphasis on habitat protection rather than a single species. • Steps suggested:

– Microbial manipulation of contaminated habitats– Soil specific plantation– Buffer zone by people– Afforestation– Prevention of overgrazing

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