Properties of wastewater
The Properties of wastewater are critical for understanding its composition, behavior, and treatment requirements.
These characteristics can be broadly categorized into physical, chemical, and biological properties. Below is a detailed
explanation of each:
Summary Table of Wastewater Characteristics
| Category | Parameter | Description
| Physical | Color | Visual appearance of wastewater.
| | Odor | Smell caused by organic decomposition or chemicals.
| | Temperature | Thermal condition affecting biological activity.
| | Turbidity | Cloudiness due to suspended solids.
| | TSS | Concentration of suspended solids.
| Chemical | pH | Acidity or alkalinity of wastewater.
| | BOD | Oxygen demand for organic matter decomposition.
| | COD | Oxygen demand for chemical oxidation of pollutants.
| | Nutrients (N, P) | Nitrogen and phosphorus causing eutrophication.
| | Heavy Metals | Toxic metals like lead, mercury, and cadmium.
| Biological | Pathogens | Disease-causing microorganisms.
| | Indicator Organisms | Microorganisms used to assess pathogen presence.
| | Biodegradable Organic Matter| Organic compounds broken down by microorganisms.
Physical Characteristics
These describe the physical properties of wastewater, which can be observed or measured without altering its chemical
composition.
a. Color
Definition: The visual appearance of wastewater, which can range from light yellow to dark brown or black.
Significance: Indicates the presence of organic matter, industrial dyes, or other contaminants.
b. Odor
Definition: The smell of wastewater, often caused by the decomposition of organic matter, hydrogen sulfide, or
ammonia.
Significance: Strong odors can indicate the presence of anaerobic conditions or high organic content.
c. Temperature
Definition: The thermal condition of wastewater, typically measured in degrees Celsius (°C).
Significance: Affects the rate of biological activity and the solubility of gases (e.g., oxygen).
d. Turbidity
Definition: The cloudiness or haziness of wastewater caused by suspended solids.
Significance: High turbidity indicates the presence of particles that may need to be removed during treatment.
e. Total Suspended Solids (TSS)
Definition: The concentration of solid particles suspended in wastewater.
Significance: High TSS levels can clog pipes, reduce treatment efficiency, and harm aquatic life.
Chemical Characteristics
These describe the chemical composition of wastewater, including organic and inorganic substances.
a. pH
Definition: A measure of the acidity or alkalinity of wastewater, ranging from 0 (acidic) to 14 (alkaline).
Significance: Extreme pH levels can harm aquatic life and interfere with treatment processes.
b. Biochemical Oxygen Demand (BOD)
Definition: The amount of oxygen required by microorganisms to decompose organic matter in wastewater.
Significance: High BOD indicates high levels of organic pollution, which can deplete oxygen in water bodies.
c. Chemical Oxygen Demand (COD)
Definition: The amount of oxygen required to chemically oxidize organic and inorganic matter in wastewater.
Significance: Provides a broader measure of pollution compared to BOD.
d. Dissolved Oxygen (DO)
Definition: The amount of oxygen dissolved in wastewater, essential for aerobic biological processes.
Significance: Low DO levels can indicate pollution and harm aquatic life.
e. Nutrients
Nitrogen (N): Present as ammonia (NH₃), nitrates (NO₃⁻), or nitrites (NO₂⁻).
Phosphorus (P): Present as phosphates (PO₄³⁻).
Significance: Excess nutrients can cause eutrophication in water bodies.
f. Heavy Metals
Definition: Toxic metals like lead (Pb), mercury (Hg), cadmium (Cd), and chromium (Cr) that may be present in
industrial wastewater.
Significance: Harmful to human health and the environment.
g. Organic Matter
Definition: Substances derived from living organisms, including proteins, fats, carbohydrates, and oils.
Significance: Decomposes in water, consuming oxygen and potentially causing odor and pollution.
Biological Characteristics
These describe the living organisms and biological activity in wastewater.
a. Pathogens
Definition: Disease-causing microorganisms, including bacteria (e.g., E. coli), viruses, and parasites.
Significance: Must be removed or inactivated to protect public health.
b. Indicator Organisms
Definition: Microorganisms (e.g., coliform bacteria) used to assess the presence of pathogens in wastewater.
Significance: Helps monitor the effectiveness of disinfection processes.
c. Biodegradable Organic Matter
Definition: Organic compounds that can be broken down by microorganisms.
Significance: Determines the BOD and COD levels in wastewater.
d. Algae and Protozoa
Definition: Microscopic organisms that may be present in wastewater.
Significance: Can contribute to biological treatment processes or cause problems in water bodies.
4. Other Characteristics
a. Toxicity
Definition: The presence of harmful substances that can adversely affect living organisms.
Significance: Requires specialized treatment to remove toxic compounds.
b. Volatile Organic Compounds (VOCs)
Definition: Organic chemicals that evaporate easily, such as benzene and toluene.
Significance: Can cause air pollution and health risks.
c. Oil and Grease
Definition: Fats, oils, and grease (FOG) that can form a layer on the surface of wastewater.
Significance: Can clog pipes and interfere with treatment processes.
