10 Environment Biotechnology

Dr Hardeep Kaur and Dr. Sunil Mittal

1.Introduction

In modern era of technology, man is harnessing natural resources to fulfill his requirements. Nature provides nutrients, habitat, energy, water, air, and oxygen. In return, anthropogenic activities like agriculture, transport, manufacture etc. are contaminating the quality of air, water and soil. The production processes designed by human beings are not that much efficient in energy usage and utilization of raw materials. Most of the products obtained by these processes are non-biodegradable. Moreover, these processes also result in the generation of by-products and release of effluents. These products when released into the environment cause serious consequences. Environmental deterioration due to chemical contamination didn’t occur overnight. It has a long history. Chemical contamination of water is caused by nitrates and chemical effluents present in industrial waste. Moreover, wildlife biodiversity has been affected severely by heavy metals such as mercury, lead, cadmium, and chemical pesticides. However, this does not happen when natural production systems are used. Scientists are trying to reduce the pollution level as generated by manmade activities by developing some technologies that can be clean up the pollutants. Here comes the term environmental biotechnology.

Environmental Biotechnology is the approach that has been applied for managing the environmental problems.

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The term that has been applied for restoration and protection of environmental quality is known as environmental biotechnology.

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The technology that is used for the detection, prevention and remediation of environmental pollutants is called as environmental biotechnology.

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Environmental Biotechnology is a discipline that studies the employment of biological processes and systems for waste management.

2.Historical Background of Environmental Biotechnology

Industrial revolution increased the demand of consumer goods and resulted in an expansion in resource mining, agricultural and industrial production. The term “Environmental Biotechnology” is not a new one. The most familiar examples of environmental biotechnology are wastewater treatment and composting. The first episode of chemical pollution came into light in 1962 when the deleterious effect of dichlorodiphenyl trichloroethane (DDT) residues was observed on bird’s population. The same pesticide was reported to be carcinogenic for living beings. In late 1960s, another disastrous case became highlighted when several cases of paralysis and sensory loss were reported along Minamata Bay in Japan due to mercury poisoning. In the same era, another episode of cooking oil contamination with polychlorinated biphenyls (PCBs) was reported in Japan and Taiwan. The contamination resulted in severe health effects especially on females facing miscarriages and giving birth to defective children. After these episodes, the public became aware about the ill consequences of chemical contaminants. Due to raising health concerns throughout the world, two conferences i.e. United Nation Conference of Human Environment, and Earth Summit were held at Stockholm and Rio De Janerio in 1972 and 1992, respectively. But the present situation is totally different. The developed countries have legal provisions for toxic waste management. A list of at least 126 priority pollutants has been prepared by United States Environmental Protection Agency (USEPA) and European community. Therefore, innovations in biotechnological techniques have been explored for the elimination of hazardous compounds from the environment.

3.Issues related to Environmental Biotechnology

3.1 International Issues

International issues related to environmental biotechnology include marine pollution, air pollution, climate change and global warming, oil spill and energy crisis.

3.1.1 Marine pollution

Worldwide increase in ocean temperature is attributing towards the rising incidences of coral bleaching. The process of coral bleaching occurs in response to stress conditions such as high temperature. Increased temperature displaces algal growth inside the reefs. As a result, reefs turn white and the main source of energy i.e. algae gets eliminated. Most of the mass bleaching processes occurred after 1989. A well-known example of mass bleaching was reported in 1997-1998 when ten reef provinces of were severely affected. However in some cases, mass bleaching event led to mortality. For example, over an area of thousands of square kilometers, death of 90% corals was reported. In addition to increased temperature, coral bleaching also depends on the release of toxicants into ocean due to fishing activities.

Aquatic flora and fauna in coastal regions are threatened greatly by toxic algal bloom, eutrophication and sedimentation. Methane emission has also been reported both in coastal habitat as well as floor of ocean.

3.1.2 Air pollution

Three major areas that are responsible for adding air pollution into atmosphere are vehicular emissions, deforestation and industrialization. The most important gases that should be taken into consideration for their reduction to acceptable limits include volatile organic compounds (VOCs), oxides of sulphur and nitrogen, and greenhouse gases.

3.1.3 Climate change and Global warming

Global warming is a direct result of climatic change and both of these have been recognized as global problems. Atmospheric concentrations of some gases such as carbon dioxide, nitrous oxide and methane are increasing rapidly. As a result, earth’s climate is changing so that the balance between incoming and outgoing radiations is restored. Rise in sea level is the major result of global warming. International Panel on Climate Change (IPCC 2001) concluded that ecosystems get affected by climate changes. Climate change can lead to disappearance and changes in species composition of some ecosystems. Deforestation, energy consumption and methane emission from paddy fields are the major reasons of global warming.

3.1.4 Oil spill

Marine ecosystem is the main ecosystem that is threatened by oil spills. Oil spills in coastal soils and oceans are responsible for the decline in mangrove forests of West Asian countries. Sometimes oil is released accidentally into the ocean during its extraction and transport. Recent case of oil spilling was reported on 28th January, 2017 in Ennore coast of Chennai. Two cargo ships collided and resulted in the spilling of oil into the sea. Oil spill also polluted the beaches of Chennai city.

4.National Issues

There are certain national issues that need attention so that they can be sort out. These issues include solid waste problems, nitrogen deposition in plains, and erosion of top most soil, and land degradation. The listed environmental issues require the development of some strategies.

4.1 Solid wastes

Incineration and land filling activities are responsible for disposal of solid waste. This results in unpleasant smell, groundwater contamination and air pollution. Unplanned disposal of hazardous and non-degradable waste causes negative impacts on environment and pose severe health problems to people staying in urban areas.

4.2 Nitrogen deposition

The major reason of environmental degradation is nitrogen deposition. In the last few years, nitrogen deposition has increased substantially due to deforestation, fossil fuel burning and greater use of fertilizers. If nitrogen is present in higher quantity in soil and water, then the possible consequences will be variation in the distribution of plant communities and species loss. The most sensitive ecosystem is aquatic ecosystem due to surface run off and discharge of effluents. The notable consequence of nitrogen deposition is eutrophication. Nitrogen deposition also creates problems in hilly areas. Soil of high altitudes becomes deficient in nitrogen as it gets washed from hills to plains because of deforestation. This results in reduced plant growth and regeneration capacity. Moreover, rate of seedling establishment is also hampered in these areas. On the other side, higher levels of nitrogen in plains attract weeds and invasive species like grasses.

4.3 Soil erosion

The phenomenon of soil erosion is linked with other degradation processes happening in the environment. Category of degradation processes other than soil erosion includes eutrophication, siltation of reservoirs, and decline in productivity of arable land and forest regeneration. Soil erosion also affects the buffering and filtration ability of soil. There are some positive forces such as deforestation, overuse of vegetation and industrial activities, overgrazing, that are responsible for erosion of fertile soil.

4.4 Land degradation

The land degradation processes include acidification, compaction, erosion, weed invasion, and depletion of soil fertility. In addition to these processes, another factor responsible for decline in land productivity is poor agricultural practices. Excess use of fertilizers and pesticides come under the division of poor agricultural practices. Fertilizers and pesticides are polluting agents and also affect the soil micro-flora. Other activities responsible for land degradation include industrialization, mining, effluent discharge and weed intrusion. Cultivable land of coastal areas is also damaged due to water logging, inundation of sea water and salinity.

5.Outlook of environmental biotechnology

5.1. Biotechnology for environmental safety: The present day technologies need to be modified in order to minimize the rate of environment degradation as caused by agricultural practices and industrial processes. Researchers are getting motivated to develop sometechnologies that can utilize living organisms. The aim of such technologies is the production of those products that do not cause harm to the existing natural resources and environment. Environmental biotechnology is the branch of science that deals with environmental purification and protection from pollutants and contaminants.

List of ecofriendly processes include:

1. Waste water treatment and reduction of waste water generation.
2. Enhanced rate of pesticides degradation.
3. Prevention of eutrophication by the removal of nutrients from surface water
4. Decomposition of organic pollutants present in solid wastes and waste water.
5. Degradation of solid wastes via composting technology.
6. Bioremediation of heavy metals.
7. Development of ecofriendly bio-pesticides for the replacement of synthetic pesticides.

a) Decomposition of Organic pollutants: Industrial waste water contains different types of organic pollutants. The organic wastes such as carbohydrates (lignin, polysaccharides, hemicelluloses, starch), lipids (oils, wax, fats), organic acids and hydrocarbons, present in wastewater. These substrates are hydrolyzed by several enzymes such as cellulases, amylases, lipases, and large amount of energy is released. This energy is used by microbes for their growth. In the similar way, degradation of aliphatic and aromatic compounds is carried out by several microbial processes. The organic wastes are also used as substrate for commercial production of aldehydes, alcohols, biogas, ketones and organic acids. Microbes are also used in combination for the metabolism of slowly degrading organic molecules. The combination mechanism forms the basis of environmental biotechnology which is used for rapid conversion of organic waste. Some molecules present in the organic waste require special environmental conditions. The persistence of such molecules can be overcome by the reductive attack of anaerobic microbes. For example, reductive dehalogenation of halogenated compounds using anaerobic bacteria is a unique finding.

b) Wastewater treatment: Industrial and domestic waste water contains organic These organic matters undergo total or partial degradation in environment by the action of microorganisms, yeast, fungi, and algae. However, in some cases, untreated or partially treated organic matters are released into the water. This leads to eutrophication and carbon deposition in water bodies along with the deterioration of water quality. Organic matters are degraded biologically by several processes such as denitrification and methanogenesis via anaerobic respiration, and aerobic respiration. Organic load present in the wastewater can be reduced by sewage oxidising ponds, sewage sludge, biowave generating oxidization system etc. Presence of complex polymers such as cellulose, hemicelluloses and lignin in waste water can be reduced by using the artificial cultures of anaerobic bacteria cultures like Fibrobacter sp., Ruminococcus sp., and Clostridium thermocellum. Certain processes have also been developed for the degradation of lignocellulosic material by the combined activities of fungi and bacteria (aerobic and anaerobic). In addition to organic matter, wastewaters also contain nitrogenous and phosphorus containing compounds. Therefore, it is necessary that these compounds should be removed along with organic matter during wastewater treatment. Since phosphates are sedimentary in nature, therefore they form insoluble precipitates with many metals. These precipitates can be separated either by flotation or sedimentation. In contrast, nitrogenous compounds are difficult to remove because of their easy solubility in water. Recent studies recommend the use of denitrifying bacteria for nitrogen removal from wastewater.First step of aerobic and anaerobic treatment process involves the conversion of nitrogen into ammonia. The ammonia thus produced undergoes nitrification and denitrification into nitrogen. However, such types of processes also result in the loss of valuable nutrients that can be converted into biomasses and harvested for usage as fodder, fuel or wood. In general, waste water treatment technologies are divided into three types i.e., primary, secondary and tertiary treatment.

c) Transformation and removal of heavy metals: Heavy metals are kept under control in the environment by the biological and chemical transformation of their ions. Biological transformation involves the use of higher plants and microbes. However, the ability of microorganisms and higher plants to transform toxic metals into non-toxic has not been utilized fully. Firstly, metal tolerant plant species are screened and selected before their introduction into metal contaminated areas. Plantation of such types of species can reclaim the land. Heavy metals are transformed by microorganisms either by chelation, precipitation, bio-modification, bio-sorption, volatilisation and complexation. Some bacterial species release organic acids. These charged compounds reduce the availability and toxicity of metals by forming complexes with metals. Bio-sorption technology is used to remove heavy metals from wastewater. In this process, metal ions form complexes by binding to the cell wall of the bacteria. Some bacterial species have been reported that have the 30 times more capacity to their biomass for absorption of Zn and Cu. This process can also be explored for gold recovery from diluted solutions. The growth of concerned bacterial species needs to be optimized so that the bio-sorption method can be used on commercial scale.

d) Processing of solid wastes: Present system of solid waste management involves the burning of solid wastes or dumping into open pits. The effects of such types of practices have already been realized and therefore, suggestive measures have to be taken for disposal of solid wastes. The most acceptable method for solid waste disposal is sanitary landfilling. The landfills are designed in such a way so as to ensure minimum impact on environment. However, discharge of lechates is the major environmental concern related with these landfills. Another major thing that should be taken into consideration while constructing landfills is the reduction of gases emission. Solid wastes from industry, agriculture, households and agriculture can be processed in a better way using aerobic composting procedures. Composting procedure requires the conditioning of raw materials, artificial inoculation of microbes, thermophilic microbes for degradation, and aeration for additional improvements. Composting technology involves the use of vertical and horizontal flow reactors, and rotating drum reactors, so as to increase the rate of compost production and reduce the time period for solid waste processing.

The technology that converts waste material into valuable nutrients so that they can be used in fields is vermicomposting. This type of technology is suitable for those materials that require longer degradation time. The vermiculture technology depends upon the efficiencies of earthworm, bacteria (thermophilic and mesophilic) and fungi. The composting process is also affected by types of earthworms, size and depth of bins and microbial diversity. One another technique is anaerobic fermentation of wastes. Anaerobic degradation of waste material generates biogas as the most important product. Biogas production is affected by types of bacteria. The major factors that should be taken into consideration for achieving uninterrupted anaerobic degradation include temperature, water content, and pH and redox potential.

e) Development of bio-pesticides: Bio-pesticides have gained lot of attention because of the ill effects of synthetic pesticides. However, bio-pesticides have not gained that much popularity amongst farmers. The reason being is their expensiveness and less availability in market, and limited production on commercial scale. Development of bio-pesticides involves the exploration of bioactive agents i.e. living organisms. The development of bio-pesticides includes.

• Identification of living organisms.
• Study of their growth habitat.
• Multiplication of microbes.
• Stability of microorganisms at particular conditions such as pH, temperature etc.

f) Degradation of pesticides: Uncontrolled use of synthetic insecticides and pesticides has resulted in their bio-accumulation. Their ill effects have been studied extensively. Effect of synthetic pesticides on non-target species can be analyzed by estimating the persistence and concentration of the chemicals. Those pesticides that are having low half- life are less toxic as compared to those that are having longer half- life. Certain reports claim that the pesticidal residues in soil and water can be degraded by the use of microbes (bacteria). Some enzymes such as carboxylesterase, phosphotriase, and glutathione-S-transferase have been studied extensively, to know about their role as pesticides degrading agents and for detoxification of contaminated sites.

6.Environmental Biotechnology for Management of resources

The field of environmental biotechnology is related to:

1. Reclamation of degraded resources.
2. Biogas and biofuel production.
3. Biomining and Bioleaching

a) Reclamation of wasteland: Land degradation reduces the production capacity of land. Anthropogenic activities that are responsible for land degradation include inappropriate use of agricultural land, poor irrigation practices, and improper crop rotation. Other factors that contribute to the formation of wasteland include industrial effluents, acid mine drainage and saline water. In India, different types of soils like acidic, alkali, water logged, mine waste soils and saline soils are found. However, these types of soils are used for production of crops. Saline soils of India cannot be reclaimed because they are frequently inundated by sea water. However, biotechnology has led to the development of those crop types that are suitable for cultivation in wasteland. Microbial inoculation is also practiced in mine wastelands to reclaim the soil for plantation. In order to facilitate the leaching of metals into deeper soil layers and their immobilization, phosphate and lignocelluloses solubilizing microbes are used in combination with organic material such as saw dust, coir pith, leaf dust etc., and rock phosphate, for the reclamation of mine waste soils. Greater number of biotechnological applications can be used in future so as to reclaim more and more waste soil.

b) Biogas and biofuel production: Biogas production from solid wastes and sewage sludge can be produced successfully by anaerobic fermentation process. The fermentation process is dominated by bacteria that form major products like carbon dioxide, propionic acid, hydrogen, acetic acid, and intermediary products such as volatile fatty acids. Biogas production and quality is altered by the pressure generated by hydrogen and methane gases. Biogas production technology is an integral part of solid wastes processing in urban area. This technology requires detailed analysis of reactor designing, syntropic interaction, reaction conditions and pre-processing of the substrate.

In a similar manner, Biofuel production also involves the use of biomass (microbial, animals and plants) and microorganisms. However, the focus point is the production of bioethanol from corn, sugar, wheat as well as from waste material from food processing industries. Biofuel production is advantageous since it reduces carbon dioxide emission and makes better use of agricultural overproduction.

c) Biomining and Bioleaching: The process by which metals are extracted from their ores by using living organisms is known as bioleaching. This process has received greater attention since it can sort out some major problems as experienced by mining industries. Metals that have been extracted via bioleaching include gold, copper, uranium. Moreover, bioleaching of ores serves as an alternative energy saving source. In contrast, biomining involves the extraction of metals from their ores by using prokaryotes or fungi. This technology controls the frequent release of acids and metals.

Conclusion

Environmental biotechnology provides alternates that can either prevent pollution or remove pollutants from the environment in an easy way. The most advantageous thing is that the pollutants are removed from soil and water bodies without compromising the environmental quality. Environmental pollution has resulted in deterioration of environmental quality, and greater consumption of fossil fuel resources. Here comes the role of environmental biotechnology that aim towards the improvement of resource quality, and replacement of fossil fuels with renewable raw materials. The central themes of environmental biotechnology are minimum production of byproducts and greatest utilization of substrate.