Saturday, April 8, 2017


  1. Rao M.N. and Dutta, Waste Water Treatment, Oxford and IBM Publications Ltd.
  2. Eckenfelder, WW., Industrial waste Pollution control. Me Graw Hill Book Co.
  3. C.S Rao, Environmental Pollution Control Engineering, Wiley Eastern Ltd., New Delhi.
  4. M.N. Rao, H. V.N. Rao, Air Pollution Control, Tata McGraw Hill
  5. Sincero and Sincere, Environmental Engineering, Prentice hall of India.
  6. Kelley,Environmental Engineering, McGraw Hill Publication.
  7. NPTEL video lecture by Dr. Ligy Philip
  8. Industrial waste management web notes by I W M Srinivas (GITAM university
  9. Handbook of water and wastewater treatment technologies - Nicholas P. Cheremisinoff, Butterworth-Heinemann publications
  10. Waste treatment in the process industries - edited by Lawrence K. Wang, Yung-Se Hung, Howard H. Lo, Constantine Yapijakis, CRC press
  11. Waste to resources: A waste management handbook, The Energy Resources Institute, 2014
  12. Lectures and presentations by Dr. Shrikant Jahagirdar, Head of Department (Civil Engineering) at NKOCET, Solapur, Maharashtra
  13. An introduction to stack sampling - Wallace, Saskechewan Research Council 2013
  14. Treatment of waste generated from waste generated from cement industry - Kuldeep Sharma, Ujjwal Jain, Anupam Singhal, BITS Pilani
  15. Guidelines for abatement of waste from textile industry, Rajasthan State Pollution Control Board
  16. Textile dyeing wastewater treatment - Zongping Wang, Miaomiao Xue, Kai Huang and Zizheng Liu, Huazhong University of Science and Technology, China published by InTechOpen
  17. Industrial wastewater treatment - Rein Munter
  18. "Parivesh" A newsletter from ENVIS center, CPCB
  19. Physico-chemical analysis of wastewater from cement units - D. Freeda Gnana Rani, K. Arunkumar, & S.R. Sivakumar, Jr. of Industrial Pollution Control - Enviromedia
  20. Hazardous Material (Management, Handling and Transboundary movement) Rules published by Government of India, MoEF
  21. Industrial Waste Treatment Handbook - Frank Woodard
  22. Industrial Wastewater Treatment - NG Wun Jern, Imperial College Press
  23. Industrial wastewater - UNESCO - Encyclopedia Of Life Support Systems
  24. Industrial wastewater - Abdulrzzak Alturkmani
  25. Liquid waste from industry - theories, practice and treatment - Numersorn N.L
  26. Handbook of water and wastewater treatment plant operations - Frank R. Spellman, Lewis publishers

Generalised EIA process flowchart

Tuesday, April 4, 2017

Manufacturing processes & Wastewater characteristics for Cement industry

Manufacturing processes & Wastewater characteristics for Cement industry
The major contaminant from cement industry is SPM and RSPM in the form of dust due to mining and grinding operations involved in the process. Hence, cement industries contribute to air pollution and virtually zero water pollution.
Cement is a compound madeup of
  • calcium oxide and 
  • silicon dioxide along with 
  • aluminium oxide, 
  • ferric oxide and 
  • magnesium oxide. 
 Raw materials required for the manufacture of cement are
  • lime
  • sand
  • clay
  • shale
  • iron ore and
  • blast furnace slag
In order to manufacture cement, the raw materials are passed through the following six phases:
  • Raw material extraction / Quarrying
  • Grinding, Proportioning and blending
  • Pre-heater phase
  • Kiln phase
  • Cooling and final grinding
  • Packing and shipping
Several cement plants have made a sustained effort in controlling and regulating emissions by using air pollution control devices like electrostatic precipitators and bag filters. Fugitive emissions in cement plants is still a problem

  • In cement industries, water is used only for cooling operation of manufacturing operation. Process wastewater with high pH and suspended solids may be generated in some operations. Water used for cooling is recycled and reused. Screening along with settling basin and clarifier is used for reduction of suspended solids. Treated water from wastewater treatment plant is used for development of green belt which helps in reducing noise pollution. Storm water flowing through pet-coke, coal and waste material stock piles exposed to the open air may become contaminated with high amount of sulphates, toxic metals like zinc, lead and chromium present in dust. Contaminated water from cement manufacturing industry may leach into the ground and contaminate groundwater with excessive TDS.
  • The major sources of contaminants in water due to cement industry are:
  1. Cooling water and
  2. Wet scrubbing of kiln dust that yields an effluent with a high 
    1. pH value
    2. Alkalinity
    3. Suspended and dissolved solids like sulphates and potassium
The flowchart for manufacturing process in the cement industry is shown below:

Manufacturing processes & Wastewater characteristics for Distilleries

Manufacturing processes & Wastewater characteristics for Distilleries

Manufacturing processes & Wastewater characteristics for Sugar industries

Manufacturing processes & Wastewater characteristics for Sugar industries
The process of manufacturing sugar involves the following processes:
  1. Growing and harvesting cane
  2. Cane preparation for milling
  3. Milling
  4. Clarification
  5. Evaporation
  6. Crystallization
  7. Centrifugation
  8. Drying
  9. Refining
Beet sugar processing is similar except that it is done in one continuous process. Sugar beets are washed, sliced and soaked in hot water to separate the sugar containing juice from the beet fiber. The sugar laden juice is then purified, filtered, concentrated and dried in a series of steps similar to cane sugar processing. The process flowcharts are shown below:

Manufacturing processes & Wastewater characteristics for Fertilizer industry

Manufacturing processes & Wastewater characteristics for Fertilizer industry

Manufacturing processes & Wastewater characteristics for Thermal power plants

Manufacturing processes & Wastewater characteristics for Thermal power plants

Manufacturing processes & Wastewater characteristics for Steel plants

Manufacturing processes & Wastewater characteristics for Steel plants

Manufacturing processes & Wastewater characteristics for Textile industry

Manufacturing processes & Wastewater characteristics for Textile industry
Two types of wastes are generated in textile industries.
1. Process chemicals and
2. Process wastes
The nature of the waste generated depends on:
1. Type of textile facility
2. Processes and technologies and
3. Types of fibers and chemicals

Little or no wastewater is generated during the process of fiber preparation and yarn spinning
During slashing and sizing operations, the wastewater generated contains BOD, COD, metals, cleaning waste and size.
During weaving, knitting and tufting processes little or no wastewater is generated
Wastewater from desizing operations contains BOD from water soluble sizes, synthetic size, lubricants, biocides and anti-static compounds.
Wastewater from scouring operations contains disinfectants and insecticide residues, NaOH, detergents, fats, oils, pectin, wax, knitting lubricants, spin finishes and spent solvents
Bleaching process wastewater mainly contains hydrogen peroxide, sodium silicate and organic stabilizer and has a high pH
Singeing process yields little or no wastewater.
Mercerizing process in textile mills yields wastewater containing high pH and NaOH.
Little or no wastewater is generated during heatsetting processes
The dyeing process generates wastewater containing metals, salts, surfactants, toxics, organic processing assistants, cationic materials, colour, BOD, COD, sulphide, acidity, alkalinity and spent solvents
Printing process in textile industry produces wastewater containing suspended solids, urea, solvents, colour, metals, BOD, heat and foam
Finishing process in textile industry contains BOD, COD, suspended solids, toxics and spent solvents.
Finally, product fabrication produces little or no wastewater

Wastewater from the textile industry is classified into:
1. Dispersible wastes
Such wastes are highly dispersed and mixed with other wastes
2. Hard to treat wastes
Such wastes resist treatment and contain non biodegradable or inorganic substances that cannot be removed by conventional biological treatment methods
3. High volume wastes
Such wastes mainly contain wash water, alkaline waste and warp sizes
4. Hazardous or toxic wastes
Such wastes are a sub-group of hard-to-treat wastes. They contain metals, chlorinated solvents and non-degradable surfactants.

Acute toxicity of textile dyes leads to skin irritation, vomiting and diarrhea. Reactive dyes cause respiratory and skin problems.
The BOD/COD ratio of composite wastewater is around 0.25 implying that the wastewater contains a large amount of non-biodegradable organic matter.

In the primary treatment, the following sequence of operations is carried-out:
1. Screening
2. Sedimentation
3. Equalization
4. Neutralization
5. Chemical coagulation and
6. Mechanical flocculation
Screening and sedimentation helps remove organic color, suspended solids along with primary reduction of BOD and COD.
The conventional treatment is a physico-chemical treatment followed by a biological treatment system.
Sedimentation is sometimes combined with the equalization process.
Textile effluents are highly variable in terms of pH and extent of impurities
Individual process effluents affect the secondary treatment process due to the extreme variation in chemical characteristics from effluents from other processes. Hence, they are collected in a big tank and stirred continuously by rotating agitators or blowing compressed air from below. The tank has a conical bottom for enhancing the settling procces. Dilute sulphuric acid and boiler flue gas which is rich in carbondioxide is commonly used for neutralisation of alkaline effluents from neutralization. Chemical coagulation and mechanical flocculation are used to remove finely divided suspended solids and colloidal particles that cannot be removed by simple sedimentation by gravity.
Secondary treatment consists of aerated lagoon, trickling filter, activated sludge process and an oxidation pond. In this process, the dissolved and residual organic matter is removed in the aerobic or anaerobic mode. This is achieved by the digestive action of bacteria under suitable conditions. This helps to reduce the COD, BOD and toxicity.
Sometimes, an activated adsorption system along with an ozonation unit is used instead of biological treatment process.
The tertiary treatment process involves the following techniques:
Electrolytic precipitation and foam fractionation
Membrane technologies
Electrochemical processes
Ion exchange
Photocatalytic degradation
Adsorption and
Thermal evaporation

Adsorption is the most commonly used method for dye removal. It can also be used to remove toxic chemicals such as pesticides, phenols, cyanides and organic dyes.
It is an expensive process and the adsorbent should be re-activated resulting in 10 – 15 % loss of sorbent.
Other techniques used are:
1. Ion exchange
2. Membrane filtration
1. Activated carbon filter
2. Micron filter
3. Reverse osmosis
4. Post carbon filter
5. Ultraviolet light
Advanced oxidation processes
Ozonation / UV radiation
Hydrogen peroxide / UV radiation

Hydrogen peroxide and ozone

Environmental legislation related to industrial effluents and hazardous wastes

Environmental legislation related to industrial effluents and hazardous wastes
The Hazardous Wastes (Management and Handling) Rules, 1989 came into effect on 28th July, 1989. These rules shall apply to hazardous wastes as specified in schedule and exclude waste water and exhaust gases as covered under the provisions of the Water act of 1974 and Air act of 1981. It also excludes wastes arising out of the operation from ships beyond five kilometres and  radio-active wastes. The following are the salient features under this act:

  1. The occupier generating hazardous wastes specified in the Schedule in quantities equal to or exceeding the limits mentioned, shall take all practical steps to ensure that such wastes are properly handled and disposed of without any adverse effects which may result from such wastes and the occupier shall also be responsible for proper collection, reception, treatment, storage and disposal of these wastes either himself or through the operator of a facility.
  2.  The occupier or any other person acting on his behalf who intends to get his hazardous waste treated shall give to the operator of a facility, such information as may be specified by the State Pollution Control Board.
  3. The State Pollution Control Board may cancel an authorisation issued under these rules or suspend it if the authorised person has failed to comply with any of the conditions after giving the authorised person an opportunity to show cause and after recording reasons thereof.
  4. Packaging, labelling and transport of hazardous wastes shall be in accordance with the provisions of the rules issued by the Central Government from time to time.
  5.  The State Government shall undertake a continuing programme to identify the sites and compile and publish periodically an inventory of disposal sites within the State for the disposal of hazardous wastes.
  6. The State Government shall undertake a continuing programme to compile and publish an inventory of sites within the State at which hazardous wastes have at any time been stored or disposed of and such inventory
    1. The occupier generating hazardous waste and operator of a facility for collection, reception, treatment, transport, storage and disposal of hazardous waste shall maintain records of such operations in forms specified
    2. The occupier and operator of a facility shall send annual returns to the State Pollution Control Board in forms specified
    3. Where an accident occurs at the facility or on a hazardous waste site or during transportation of hazardous wastes, the occupier or operator of a facility shall report immediately to the State Pollution Control Board about the accident in forms specified.
    4. The CPCB also sets guidelines regarding import of hazardous wastes.
    Under the Air (prevention and control of air pollution) Act, 1981, 
    1. State boards may lay down standards for emissions of air pollutants from industrial units
    2. State boards should examine manufacturing process and pollution control equipment to verify if they meet standards prescribed
    3. State board can advise the state government to declare heavily polluted areas as pollution control areas
    4. Operation of Industrial unit is prohibited in heavily polluted areas without the consent of the central board.
    5. Violation of this law is punishable with imprisonment a term which may extend to three months or fine upto Rs. 10,000 or both.
    Water act came into effect in 1974 to prevent pollution of water by industrial, agricultural and household water.
    Under the Water (prevention and control of air pollution) Act, 1984,
    1. The water act is designed to assess pollution levels and punish polluter
    2. The central government and state governments have set-up pollution control boards to monitor water pollution.
    3. Central and state boards have been created under this act for preventing water pollution The act empowers the board to take:           -  water samples for analysis, govern discharge of sewage, trade effluents, study or inspect appeals, revision of policies, set minimum and maximum penalties, publication of names of offenders, offences by companies or government departments, establish or recognize water testing laboratories and standard testing procedures. Prevention and control of water pollution is achieved through a 'permit' or a 'consent administration' procedure
    In addition to the above, the government has also enacted the water pollution cess act in 1977 requiring industrial consumers to pay cess depending on the type of use as listed below:
    1. Industries using water for industrial cooling, spraying in mine pits or as boiler feed
    2. Domestic purposes
    3. Processing (pollutants are biodegradable. Eg: water from slaughter houses)
    4. Processing (pollutants are not biodegradable and are toxic. Eg: water from tannery waste, industrial wastewater from electroplating industries)
    Industries that have a treatment plant installed for treating their effluents can get a rebate of 70% on the cess payable.

    Issues related to rehabilitation and resettlement of displaced communities

    Issues related to rehabilitation and resettlement of displaced communities

    Preparation of EIAs of road project, industry and dam

    Preparation of EIAs of road project, industry and dam

    EIA for road project
    As per the EIA notification of 14th September 2006 and its amendment dated 1st December 2009,

    highway projects are divided into two categories as mentioned below :

    1. Highways New National Highways & Expansion of National Highways greater than 30 km,involving additional right of way greater than 20m involving land acquisition and passing through more than one State come under category A.
    2. All state highway projects State highway expansion projects in hilly terrain (above 1,000 m AMSL) and or ecologically sensitive areas come under category B.
    Any project or activity specified in category B will be treated as category A, if located in whole or in part within 10 km from the boundary of:
    • Protected area identified by wildlife act
    • Critically polluted areas as identified by CPCB
    • Eco-sensitive areas identified by Environment (Protection) Act
    The environmental clearance process for all projects will comprise a maximum of four stages. These four stages in sequential order are:
    1. Screening that entails the scrutiny of an application seeking prior environmental clearance to determine whether or not the project or activity requires further environmental studies for preparation of an Environmental Impact Assessment (EIA) for its appraisal prior to the grant of environmental clearance depending upon the nature and location specificity of the project.
    2. Scoping’ refers to detailed and comprehensive TOR addressing all relevant  environmental concerns for the preparation of an EIA report.
    3. “Public consultation” refers to the process by which the concerns of local affected persons and others. After completion of the public consultation, the applicant shall address all the material environmental concerns expressed during this process, and make appropriate changes in the draft EIA and EMP.
    4. Appraisal involves detailed scrutiny of the application and other document like the Final EIA report, outcome of the public consultations including public hearing proceedings, submitted by the applicant to the regulatory authority concerned for grant of Environmental Clearance (EC).
    In terms of the EIA notification of the MOEF dated 14th September 2006, the structure of the EIA document shall be as listed below:
    • Introduction
    • Project Description
    • Analysis of Alternatives (Technology and Site)
    • Description of the Environment
    • Anticipated Environmental Impact & Mitigation Measures
    • Environmental Monitoring Program
    • Additional Studies
    • Project Benefits
    • Environmental Cost Benefit Analysis
    • Environmental Management Plan
    • Summary & Conclusion
    • Disclosure of Consultants engaged
    EIA for building industry
    The EIA Notification, 2006 is to set procedures of environmental clearance before establishment of identified nature and size. The suitability of site for a proposed development is one of the main concerns in awarding an environmental clearance to a project.
    A project is considered B category if the built-up area is between 20,000 and 150,000 sq. m. or a township area greater than 50 ha or built-up area greater than 150,000 sq. m.
    Any project or activity specified in category B will be treated as category A, if located in whole or in part within 10 km from the boundary of:
    Protected area identified by wildlife act
    Critically polluted areas as identified by CPCB
    Eco-sensitive areas identified by Environment (Protection) Act

    The prior environmental clearance granted is valid for a period of five years. The regulatory
    authority concerned may extend this validity period by a maximum period of five years provided
    an application is made to the regulatory authority by the applicant within the validity period
    The structure of the EIA document listed below:
    1. Introduction
    2. Project Description
    3. Description of the Environment
    4. Anticipated Environmental Impacts & Mitigation Measures
    5. Analysis of Alternatives (Technology and site)
    6. Environmental Monitoring Programme
    7. Additional Studies
    8. Project Benefits
    9. Environmental Management Plan
    10. Summary & Conclusion
    11. Disclosure of Consultants engaged
    EIA for dam
    An EIA for a dam project should discuss the following:

    1. Location of the project, characteristics of the dam, total land area required, catchment area above the dam site,storage capacity and total cost of the project
    2. It should clearly state  the need for the project
    3. Based on facts and the guidance manual provided by the MoEF, the project should be classified as category A or category B enabling the decision makers to opt for a Rapid EIA (REIA) or a Comprehensive EIA (CEIA)
    4. The study comprises of the following five stages
      1. Determination of baseline conditions
      2. Identification of differ

    Preparation of EMP

    Evaluation of Impacts

    Evaluation of Impacts

    Baseline data collection required for EIA

    Baseline data collection required for EIA
    Baseline data collection refers to collection collection of baseline information information on biophysical biophysical, social and economic aspects of a project area.
    Project area is defined as the area where environmental environmental effects effects and impacts impacts are felt during construction or operational stages of a project.

    Collection of baseline information serves two purposes: 

    • It provides a description of the status and trends of environmental factors (e.g., air pollutant concentrations) against which predicted changes can be compared and evaluated in terms of importance.
    • It provides a means of detecting actual change by monitoring once a project has been initiated.

    Major environmental environmental parameters parameters to be considered in field are:

    • Physical: topography, geology, soil types, surface and ground water condition, watershed condition, pollution levels etc.
    • Biological: terrestrial and aquatic ecosystems, types flora and fauna, environmentally environmentally sensitive sensitive wetlands wetlands, prime agricultural land etc
    • Socio‐economic: demography, development needs and potential, infrastructure facilities, economic activities etc.
    • Cultural: location and state of archeological, historical, religious sites

    Primary Sources: Result of the field and laboratory data collected and analyzed directly
    Secondary sources: Data collected indirectly from published records or documents such as project documents, village proFlie, maps,photos, internet sources etc

    Methods of data collection:

    1. General methods: Literature review, map interpretation, checklists (e.g. scaling and questionnaire checklists, matrices etc)
    2. Resource‐based methods: methods: Scientific Scientific instruments instruments and techniques techniques(inventory, species area curve, sampling techniques, PRA, RRA)

    Data Processing
    Raw data is converted into knowledge and information that is more easily comprehensible. Tools such as tables, graphs, maps can be used for presentation.

    1. For physical data: graphs, tables, enumeration
    2. For biological data: species numbers, volume, density, biomass can be calculated.
    3. Species diversity (No. of species/Area sampled) can also be used for processing processing biological biological data calculated calculated through through species richness of an area.
    4. Socioeconomic data: Data such as male/female male/female, skilled/semi skilled/semi skilled skilled labor force for construction and operational activities can be presented through, graphs, tables, population pyramids etc. which can be collected through sampling (random, stratified or mixed).

    Baseline studies in EIA may take a long time, hence EIA is blamed for higher costs and delays in project implementation.
    Therefore, the studies should be focused on those aspects that are likely to be affected.
    Four critical points exist project implementation

    1. Decision on Project Project Approval Approval
    2. Decision on the Location of Project
    3. Decision on the Project Design
    4. Decision on the Operation of Project

    Methods of EIA

    Methods of EIA

    Listed below are the important methodologies for assessing the impacts of any developmental activity on the environment:

    1. Adhoc method
    2. Checklist method
    3. Matrix method
    4. Network method
    5. Overlay method
    6. Environmental index using factor analysis
    7. Cost/Benefit analysis
    8. Predictive or Simulation methods

    These methods might vary from:
    Simple to Complex
    Static piece-meal approach to Dynamic nature of the environment

    The change in EIA is moving away from a simple listing of potential impacts to complex modes involving identification of feedback paths leading to higher order impacts as compared to the easily visible first order impacts involving uncertainities. This approach can be considered as an overall management technique requiring different

    kinds of data in different formats along with varying levels of expertise and technological inputs to accurately forecast the results of any planned development.

    1. Ad hoc methods

    Ad hoc methods indicate broad areas of possible impacts by listing composite environmental parameters (Ex: flora and fauna) likely to be affected by the proposed activity.
    These methods involve assembling a team of specialists who identify impacts in their area of expertise. Here, each parameter is considered separately and the nature of impacts (long term or short term, reversible or irreversible) are considered.
    These methods give a rough assessment of total impact while giving the broad areas and the general nature of possible impacts. In this method, the assessor relies on an intuitive approach and makes a broad-based qualitative assessment. This method serves as a preliminary assessment and helps in identification of important areas like:

    • Wildlife
    • Endangered species
    • Natural vegetation
    • Exotic vegetation
    • Grazing
    • Social characteristics
    • Natural drainage
    • Groundwater
    • Noise
    • Air quality
    • Visual description and services
    • Open space
    • Recreation
    • Health and safety
    • Economic values and
    • Public facilities

    Types of Ad hoc method are:

    • Opinion poll
    • Expert opinion and
    • Delphi methods

    This method is very simple and can be performed without any training. It does not involve any relative weighting  or any cause-effect relationship.
    It provides minimal guidance for impact analysis while suggesting broad areas for possible impacts. Moreover, it does not even state the actual impacts on specific parameters that will be affected.
    The drawbacks of this method are listed below:

    1. It gives no assurance that a comprehensive set of all relevant impacts have been studied
    2. Analysis using this method lacks consistency as it different criteria are selectively evaluated by different groups
    3. It is blatantly inefficient as it requires a considerable effort to identify and assemble a panel for each assessment.
    2. Checklist method
    In this method, environmental factors are listed in a structured format by giving importance weightings for factors and application of scaling techniques for impacts of each alternative.
    Checklists are strong indicators of impact identification. They effectively garner the attention and awareness of their audience. Impact identification is a fundamental function of an EIA. Checklists may be:
    1. Simple
    2. Descriptive
    3. Scaling or
    4. weighting type
    Simple checklists are a list of parameters without guidelines regarding either interpretation or measurement of environmental parameters or specific data needs or impact prediction and assessment.

    Descriptive checklists  include list of environmental factors along with information on measurement, impact prediction and assessment.

    Scaling and weighting checklists facilitate decision making. Such checklists are strong in impact identification. While including the function of impact identification, they include a certain degree of interpretation and evaluation. The aforementined factors make these methods attractive to decision-making analysis.
    However, the scaling and weighting methods are subjective and hence pose the danger of imparting equal importance to every impact. Another defect observed by critics is that numerical values assigned to impacts can be derived on the basis of expert knowledge and judgement alone.
    Scaling and weighting checklist techniques quantify impacts reasonably well although they use subjective extimates. However, they make no provision for assessing dynamic probabilistic trends or mitigation, enhancement and monitoring programmes. These methods cannot identify higher order effects, impacts and interactions.

    Simple and descriptive checklists simply identify the possible potential impacts without any rating regarding their relative magnitudes.

    Scaling and weighting checklists remove decision making from the hands of decision makers while they impart a single number to various inherently different impacts and this aspect prevents the decision maker to consider the possibility of trade-offs.

    In checklist method, the impacts are tabulated in the form of cells with information either in the descriptive form that gives information regarding possibility or potential existence of an impact whereas in the scaling or weighing methods the magnitude or importance of impact is given. Sample checklists or weighing methods used in EIA are shown below:
    The advantages of this method are:

    1. It is simple to understand and use
    2. It is good for site selection and priority setting
    Disadvantages of this method are:
    1. It does not distinguish between direct and indirect impacts
    2. It does not link action and impact
    3. It is cumbersome at times

    3. Matrix Method
    This methodology provides a framework of interaction of different activities of a project with potential environmental impacts caused by them. A simple interaction matrix is formed when project actions are listed on one axis (usually vertical) and environmental impacts are listed along the other axis. This technique was pioneered by Leopold et al in 1971. It lists about 100 project actions and about 88 environmental charateristics and conditions. An example of this matrix is shown below:
    Similarly, a sectoral matrix is shown below:

    • The advantage of the matrix method is that it links action to impact
    • This is a very good method for displaying EIA results

    The disadvantages of this method are listed below:

    • It is difficult to distinguish between direct and indirect impacts using this method
    • There is potential for double-counting of impacts
    • It is qualitative in nature and does not refer to quantity of impact
    4. Network method:

    • This method uses the matrix approach and extends it to include both the primary as well as the secondary impacts
    • It is shown in the form of a tree called impact tree. This diagram is also called as reference or sequence diagram
    • Identification of direct, indirect along with short, long term impact is a crucial and basic step of making an impact tree
    • The impact tree is used to identify cause-effect linkages
    • The impact tree is a visual description of linkages
    • The diagram below shows the example of a network analysis:

    The advantages of the network method are:

    • It links action to impact
    • It is useful to check second order impacts in a simplified form
    • It handles direct and indirect impacts
    The disadvantages of this method are:
    • It becomes overly complex if used beyond simplified version
    • It is completely qualitative in nature
    5. Overlays
    • This method depends on a set of maps of a project area's environmental characteristics covering physical,  social, ecological and aesthetic aspects
    • It enables separate mapping of critical environmental features at the same scale as project's site plan (Ex: wetlands, steep slopes, soils, floodplains, bedrock outcrops, wildlife habitats, vegetative communities, cultural resources, etc)
    • In the old technique, environmental features were mappped on transparent plastic in different colours
    • Modern technique of the same activity is done using computer software, hardware, data and skilled people. It is called GIS (Geographic Information Systems)
    The advantages of this method are:
    • It is easy to understand and use
    • It has a good display and
    • It is good for setting site selection
    The disadvantages of this method are:
    • It addresses only direct impacts
    • It does not address impact duration or probability

    Capabilities and limitations of EIA

    Capabilities and limitations of EIA

    The capabilities of an EIA are listed below:

    • An EIA is capable of establishing baseline data (concerning social, physical and biological parameters) before starting any development activity
    • An EIA enables the government and public at large to evaluate the benefits of the project versus the environmental degradation or modification
    • An EIA also enforces regular monitoring to ensure that the project is not damaging the environment  beyond repair
    • An EIA is capable of informing the public at large regarding any development activity in an environmentally sensitive area thereby causing public outcry enabling the government to terminate any project with vested interests that damages the livelihood of people (tribes sustaining on the environment).
    • An EIA guides the project proponent to study the environment and propose the needed modifications to mitigate the adverse effects of any development activity

    EIA suffers from the following limitations
    • EIA should be undertaken at the project level but it is undertaken at the policy and planning level
    • Range of project alternatives inthe project EIA is small
    • There is no defined criteria to determine what type of projects undergo an EIA thereby requiring unnecessary expenditure and delay
    • Lack of comprehensive environment information base, limitation  of time, manpower and financial resources
    • More research and development of improved methodologies is required to overcome limitations related to uncertainities in data
    • EIA reports are extremely academic, bureaucratic and lengthy containing too many tables of collected data without data analysis, interpretation and environmental implications
    • In actual practice, EIA ends immediately after project clearance and no follow-up action is taken
    • It does not incorporate strategies of preventing environmental intervention.
    • Project EIAs are limited to the projects direct impacts and this leads to ignoring wide range of impacts including:
      • Cumulative impacts
      • Global impacts
      • Indirect, secondary or induced impacts
      • Synergistic impacts
     Finally, the issue of resource conservation, waste minimization, bye-product recovery, and improvement of efficiency of equipment need to be pursued as the explicit goal of EIA.

    Objectives of EIA

    Objectives of EIA:
    EIA is a process that envisions several objectives which are  described below:
    • EIA facilitates decision making: EIA provides a systematic systematic investigation of the environmental implications of a proposed project alongwith the suggested alternatives before a decision is taken. The decision along with documents related to the planned activity is called Environmental Impact Statement.
    • EIA helps in development: EIA provides a framework for considering location, design and environmental issues together. It helps formulate actions along with indicatons where the project can be modified to eliminate or minimize the adverse effect on the environment. By considering environmental impacts at an early stage in the development activity helps to develop an area in an environmentally sensitive manner. EIA helps improve relations between developer, the planning authority and the local communities.
    • An EIA is an instrument for sustainable development: Sustainble development mainly includes
      • Maintenance of overall quality of life (QOL)
      • Maintainance of continuing access to natural resources.
      • Avoidance of extended environmental consequences.
     An EIA can:
    • modify and improve design
    • ensure efficient resource use
    • enhance social aspects
    • identify key impacts and measures for mitigating them
    • inform decision-making and condition-setting
    • avoid serious and irreversible damage to the environment
    • protect human health and safety