Water Pollution and Wastewater Treatment Overview

Water Pollution

Contamination of water bodies from human activities.

Water Bodies

Includes lakes, rivers, aquifers, and groundwater.

Contaminants

Substances introduced into water in excess concentrations.

Physical Characteristics

Includes solids, temperature, color, odor, turbidity.

Chemical Characteristics

Includes organics, inorganics, and gases in water.

BOD

Biochemical Oxygen Demand; measures organic matter in water.

COD

Chemical Oxygen Demand; measures total oxygen required.

TOC

Total Organic Carbon; measures organic compounds in water.

Point Source Pollution

Single large source of water pollution.

Non-point Source Pollution

Diffuse pollution without a specific identifiable source.

Organics in Water

Includes proteins, carbohydrates, lipids, and pesticides.

Inorganics in Water

Includes pH, chlorides, nitrogen, phosphorus, heavy metals.

Gases in Water

Includes oxygen, hydrogen sulfide, and methane.

Biological Characteristics

Includes pathogens, indicators, viruses, and invertebrates.

Emerging Organics

Newly recognized organic pollutants in water.

Alkalinity

Water's ability to neutralize acids.

Heavy Metals

Toxic metals like lead, mercury in water.

Turbidity

Cloudiness or haziness of water due to particles.

Pathogens

Microorganisms causing diseases in water.

Water Cycle

Natural process of water movement through environment.

Runoff

General movement of sediments into water bodies.

Pesticide Spraying

Application of chemicals to control pests.

Fertilisers

Nutrients from farms that can pollute water.

Point Sources

Identifiable sources of water pollution.

Non-Point Sources

Diffuse sources contributing to water pollution.

Biodegradable Organic Matter

Decomposable waste by bacteria in water.

Suspended Solids

Particles floating in water affecting clarity.

Colloidal Solids

Tiny particles that remain suspended in water.

Dissolved Solids

Substances dissolved in water affecting quality.

Nutrients

Essential elements like nitrogen and phosphorus.

Acidic Species

Substances lowering water's pH level.

Basic Species

Substances raising water's pH level.

Ionic Species

Charged particles affecting water chemistry.

Soaps and Detergents

Surfactants causing pollution in water bodies.

Volatile Organics

Organic compounds that evaporate easily.

Recalcitrant Organics

Chemicals resistant to degradation in water.

Thermal Pollution

Increase in water temperature affecting ecosystems.

Radioactive Material

Substances emitting radiation contaminating water.

Fund Pollutants

Pollutants with some environmental absorptive capacity.

Degradable Pollutants

Organic waste broken down by bacteria.

Eutrophic Conditions

Excessive nutrients causing overgrowth of plants.

Persistent Pollutants

Chemicals not easily broken down by nature.

Stock Pollutants

Pollutants with little to no absorptive capacity.

Dissolved Oxygen (DO)

Measure of oxygen available in water.

DO Maximum

10 mg/L at 16°C for dissolved oxygen.

Oxygen Sources in Water

Diffusion, aeration, and photosynthesis introduce oxygen.

DO Stress Level

Below 5 mg/L, aquatic life is stressed.

Water Quality Ratings

Good (8-9), Slightly Polluted (6.7-8), etc.

Total Organic Carbon (TOC)

Measure of organic compounds in water.

Chemical Oxygen Demand (COD)

Amount of oxygen required to oxidize pollutants.

Biochemical Oxygen Demand (BOD)

Oxygen needed by bacteria to decompose organic matter.

Physio-Chemical Characteristics

Physical and chemical properties of water quality.

Physical Properties

Characteristics like temperature, colour, and odour.

Turbidity

Cloudiness or haziness in water due to particles.

Conductivity

Measure of water's ability to conduct electricity.

Sampling Methods

Techniques include grab, composite, and flow weighted.

ThOD

Total oxygen needed to oxidize a compound.

Stoichiometric Principles

Calculations based on the ratios of reactants.

C6H12O6

Chemical formula for glucose, a simple sugar.

Molecular Weight

Mass of a molecule, e.g., C6H12O6 is 180.

Oxygen Demand Ratio

1.067 g O2 per g of glucose.

Chemical Oxygen Demand (COD)

Measures pollution potential of organic matter.

Biochemical Oxygen Demand (BOD)

Indicates organic matter concentration in wastewater.

Potassium Dichromate

Oxidant used in COD testing.

Oxidation Reaction

Organic matter reacts with oxidant to produce CO2.

FAS Titration

Used to determine remaining potassium dichromate.

COD Calculation Formula

COD = (Blank-Test)M8*1000/Volume of sample.

Titration

Process to determine concentration of a substance.

Ferrous Ammonium Sulphate (FAS)

Used in titration for COD measurement.

Incubation Conditions

Sample held in dark at 20°C for BOD.

BOD5

BOD test over a five-day period.

Dissolved Oxygen (DO)

Oxygen available in water for organisms.

Sewage Sample Volume

Example used was 35 ml for COD calculation.

Blank Sample

Control sample used for comparison in titration.

Turbidity Measurement

Indicates water clarity and potential pollutants.

Organic Matter

Substances containing carbon, significant in water quality.

Environmental Engineering

Field focused on improving environmental quality.

Biochemical Oxygen Demand (BOD)

Oxygen needed by microorganisms for organic matter decomposition.

BOD5

BOD test over 5 days at 20°C.

BOD3

BOD test over 3 days at 20°C.

Exponential decay curve

Describes the rapid oxidation of BOD substances.

Dilution Factor (D)

Ratio of sample bottle volume to sample volume.

BODt

BOD at time t, measured in mg/L.

DOi

Initial dissolved oxygen in sample, mg/L.

DOf

Final dissolved oxygen in sample, mg/L.

Ultimate BOD (UBOD)

Maximum biochemical oxygen demand of a sample.

BOD rate constant (k)

Rate of BOD decay at specific temperature, day-1.

Temperature

Affects microbial activity and BOD measurements.

Time

Duration for BOD tests, influencing results.

Light

Environmental factor affecting microbial activity.

Sodium Thiosulfate

Used for titration in BOD testing.

Starch indicator

Used to indicate endpoint in titration.

BODt formula

BODt = UBOD (1-e^(-kt)).

BOD calculation

BODt = (DOi - DOf) * D.

Sample volume (Vs)

Volume of wastewater sample in mL.

Sample bottle volume (Vb)

Typically 300 mL for BOD tests.

BOD at 30°C

Calculated using temperature correction factor.

θ (theta)

Temperature correction factor, typically 1.047.

BOD test procedure

Involves titration and incubation of samples.

BOD significance

Indicates organic pollution level in water.