ES covers mathematical foundations, chemistry and microbiology, water and wastewater, air and noise, solid and hazardous waste, wider environmental issues and sustainable management.

Environmental Science and Engineering is tested within a 100-mark paper. The paper also includes General Aptitude. The sections below show the complete subject syllabus.

GATE ES Syllabus and Marks Distribution

There is no optional subject block in this paper. All listed sections are part of the syllabus.

Environmental Science and Engineering Unit-wise Syllabus

Mathematics Foundation

• Linear Algebra: Determinants and matrices, Systems of linear equations, Eigenvalues and eigenvectors.
• Calculus: Functions, Limit, Continuity, Differentiability, Local maxima and minima, Taylor series, Tests for convergence, Definite and indefinite integrals, Application of definite integral to obtain area and volume, Partial and total derivatives, Linear and non-linear first order ordinary differential equations (ODE).
• Numerical Methods: Approximation, errors, accuracy and precision in numerical methods; Numerical solutions (roots) of linear and non -linear algebraic equations; Interpolation and curve fitting - Least square approximation, Newton’s and Lagrange polynomials; Numerical differentiation and integration - trapezoidal and Simpson’s rule; Numerical solution of ordinary differential equations - single and multi-step methods.
• Probability and Statistics: Descriptive statistics, Measurement of central tendency, Dispersion, Skewness and kurtosis, Probability concepts, Conditional probability, Bayes theorem, Risk and reliability, Probability distributions, Correlation, Single and multiple regression models, Hypothesis testing (t-test, F-test, chi-square test).

Environmental Chemistry

• Fundamentals of Environmental Chemistry: Covalent and ionic bonding; Chemical equations, concentration and activity; Structure and chemistry of organic molecules; Chemical equilibria; Thermodynamics and kinetics of chemical reactions.
• Principles of Water Chemistry: Water quality parameters and their measurement; Acid -base equilibria; Buffer solution; Carbonate equilibrium; Solubility of gases in water; Complexation, precipitation, and redox reactions; Inorganic and organic contaminants.
• Soil Chemistry: Organic matter, nitrogen, phosphorous, potassium, cation exchange capacity, base saturation, and sodium absorption ratio.
• Atmospheric Chemistry: Composition of the atmosphere; Reactivity of trace substances in the atmosphere; Chemistry of ozone formation.

Environmental Microbiology

• Prokaryotic and Eukaryotic Microorganisms: Characteristics of diverse groups of microorganisms; Classification of microorganisms; Microbial diversity; Role of microorganisms in wastewater treatment, bioremediation and biogeochemical cycling.
• Cell Chemistry and Cell Biology: Structure of proteins, nucleic acid (DNA & RNA), lipids and polysaccharides; Structure of cell; Structure and function of cytoplasmic membrane, cell wall, outer membrane, glycocalyx; antimicrobial resistance, quorum sensing.
• Microbial Metabolism: Anabolism and catabolism; Phosphorylation; Glycolysis; TCA cycle; Electron transport chain; Fermentation; Anaerobic respiration; Energy balances; Enzymes and Enzyme kinetics.
• Growth and Control of Microorganisms: Bacterial nutrition and growth; Specific growth rate and doubling time; Monod’s model; Types of culture media; Batch and continuous culture; Effects of environmental factors on growth; Control of microbes using physical and chemical methods.
• Microbiology and Health: Pathogens and modes of transmission; Indicator organisms; Quantification of coliforms using MPN and membrane filtration techniques.

Water Resources and Environmental Hydraulics

• Global Water Resources: Structure, properties and distribution of water; Threats to water resources; Water conservation.
• Surface Water Resources: Hydrological cycle and water balance - precipitation, infiltration, evapotranspiration, runoff; Flow hydrographs; Unit hydrographs; Stage -discharge relationship; Reservoir capacity; Surface water management; Rain water harvesting and storage.
• Groundwater Resources: Geologic formations as aquifers; Vadose and saturated zones; Confined and unconfined aquifers and their parameters - porosity, permeability, transmissivity and storage coefficient; Darcy’s law and applications; Steady state well hydraulics.
• Environmental Hydraulics: Concepts of mechanics; Properties of fluids; Pressure measurement; Hydrostatic force on surfaces; Buoyancy and flotation; Laminar and turbulent flow; Flow through pipes; Pipe networks; Forces on immersed bodies; Flow measurement in channels and pipes; Kinematics of flow; Continuity, momentum and energy equations; Channel hydraulics - specific energy, critical flow, hydraulic jump, rapid and gradually varied flow; Design of lined channels.

Water & Wastewater Treatment and Management

• Water and wastewater quality parameters; Eutrophication and thermal stratification in lakes; River pollution - Oxygen sag curve.
• Water treatment methods — screening, sedimentation with and without coagulation, filtration, desalination, disinfection; Water distribution and storage.
• Point and non -point sources of wastewater; Population forecasting methods; Design of sewer and storm water sewers; Sewer appurtenances; Preliminary, primary, secondary and tertiary sewage treatment; Sludge generation, processing and disposal methods; Sewage farming.
• Sources and characteristics of industrial effluents; Concept of Common Effluent Treatment Plants (CETP); Wastewater recycling and zero liquid discharge.
• Kinetics and reactor design: Mass and energy balance, Order and rate of reactions, Batch reactors, Completely mixed flow reactors, Plug flow reactors.

Air and Noise Pollution

• Structure and composition of the atmosphere; sources (natural and anthropogenic); Atmospheric processes (emission, transformation, transport, removal); Indoor air pollution; Effects on health and environment; Air pollution: gases and particulate matter; Air quality standards; Primary and secondary pollutants; Criteria pollutants; primary and secondary pollutants; ambient and emission standards; air quality indices; visibility and radiative effects.
• Particulate Pollutants: Measurement and control methods; Control of particulate air pollutants using gravitational settling chambers, cyclone separators, wet scrubbers, fabric filters (Baghouse filter), electrostatic precipitators (ESP).
• Gaseous Pollutants: Measurement and control methods; Control of gaseous contaminants: absorption, adsorption, condensation and combustion; Control of sulphur oxides, nitrogen oxides, carbon monoxide, and hydrocarbons; Diffusion, Fick’s law and interfacial mass transfer. Vehicular emission control systems, including diesel particulate filters (DPFs), catalytic converters, and fuel standards.
• Air Quality Management: Point, line and area sources; Inventory; Meteorology and dispersion; atmospheric stability and inversion, mixing height, wind rose diagrams, Gaussian plume dispersion modelling, and topographic influences.
• Noise Pollution: Sources; Health effects; Standards; Measurement parameters (sound pressure level, equivalent continuous sound level Leq, day-night level Ldn); frequency analysis; and control and mitigation methods.

Solid and Hazardous Waste Management

• Integrated solid waste management; Waste hierarchy; Rules and regulations for solid waste management in India.
• Municipal solid waste management: Sources, generation, characteristics, collection, segregation, and transportation, waste processing and disposal (including reuse options, biological methods, energy recovery processes and landfilling), waste-to-energy technologies, circular economy principles, life-cycle energy analysis, decentralized renewable systems, and urban metabolism.
• Hazardous waste management: Characteristics, generation, fate of materials in the environment, treatment and disposal. Soil contamination and leaching of contaminants into groundwater.
• Management of biomedical waste, plastic waste, waste from energy sector (solar/wind/batteries etc), C&D waste and E-waste: Sources, generation and characteristics; Waste management practices including storage, collection and transfer.

Global and Regional Environmental Issues

• Global effects of air pollution: Greenhouse gases, radiative forcing and global warming potential (GWP), climate change, urban heat islands, acid rain, ozone hole. Ecology and various ecosystems; Biodiversity; Factors influencing increase in population, energy consumption, and environmental degradation.

Environmental Management and Sustainable Development

• Environmental Management Systems; ISO14000 series; Environmental Auditing: Environmental Impact Assessment; Life cycle assessment; Human health risk assessment; Occupational Health and Hygiene, Physical & Chemical Hazards.
• Environmental Law and Policy: Objectives; Polluter pays principle, Precautionary principle; The Water and Air Acts with amendments; The Environment (Protection) Act (EPA) 1986; National Green Tribunal Act, 2010; National Environment Policy; Principles of International Law and International treaties.
• Energy and Environment: Energy Sources: Overview of resources and reserves; Renewable and non-renewable energy sources; Energy-Environment nexus.
• Sustainable Development: Definition and concepts of sustainable development; Sustainable development goals; Hurdles to sustainability; Environment and economics; carbon pricing, emission trading, Environmental, Social, and Governance (ESG) frameworks.

General Aptitude Syllabus

General Aptitude contributes 15 marks within the 100-mark paper. It is not an additional paper that can be left out when choosing the technical sections.

Chapter-wise Weightage and Important Topics

Only the section-wise marks are fixed. IIT Madras has not assigned a guaranteed number of marks to each chapter of Environmental Science and Engineering. A topic may appear in one year and receive fewer questions in another; a past-paper count is not an official 2027 weightage.

For a chapter-weightage comparison, record the year, paper code, session, question number and marks of each matching question. Keep a combined question under one main topic or label the overlap explicitly; counting it twice inflates the total. GATE previous-year question papers can be used for this topic-by-topic practice.

Question Types and Negative Marking

The paper uses one-mark and two-mark questions. The number of MCQ, MSQ and NAT questions is not a fixed chapter-wise quota. In an MSQ, selecting one correct option is not enough when the correct answer contains two options.