What is Total Suspended Solid (TSS) in Wastewater & How Can It Be Reduced Effectively?

Wastewater quality monitoring plays a vital role in protecting public health, preserving aquatic ecosystems, and maintaining efficient industrial operations. Before wastewater can be discharged or reused, it must be carefully analyzed and treated to remove harmful contaminants that may pollute rivers, lakes, groundwater, and municipal water systems.

Among the many water quality parameters monitored, total suspended solids in water is one of the most critical indicators of contamination, as high TSS levels can reduce treatment efficiency, damage equipment, and harm the environment. Regular tss analysis in water helps facilities maintain compliance and optimize performance. In this blog, we will explore the definition, causes, impacts, measurement methods, and effective ways to reduce total suspended solids in wastewater.

Definition of Total Suspended Solids (TSS)

Total Suspended Solids (TSS) refer to the concentration of solid particles suspended in water that are large enough to be captured by a filter. These particles are not dissolved in the water; instead, they remain floating or dispersed within the liquid. The concentration of total suspended solids in wastewater is typically measured in milligrams per liter (mg/L).

Examples of suspended solids include:

• Soil and sediment
• Organic waste
• Food particles
• Sludge
• Algae
• Industrial debris
• Fibers and plastics
• Biological materials

TSS is considered one of the most important indicators of water pollution because excessive suspended particles can reduce water quality, interfere with treatment systems, and harm aquatic life.

Difference Between Dissolved and Suspended Contaminants (TDS vs TSS)

Water contaminants are broadly categorized into dissolved and suspended forms. Understanding total dissolved solids and total suspended solids is essential for designing effective water treatment systems.

Here are the key differences between dissolved and suspended contaminants in water:

Parameter	Total Suspended Solids (TSS)	Total Dissolved Solids (TDS)
Nature of particles	Undissolved solid particles	Fully dissolved substances (ions/molecules)
Visibility	Visible or causes turbidity	Invisible
Particle size	Larger particles (>1–2 µm)	Very fine / molecular level
State in water	Remains suspended or settles over time	Completely mixed in solution
Examples	Sediment, sludge, algae, organic debris, silt	Salts, minerals, heavy metals, nitrates, chlorides
Removal methods	Filtration, sedimentation, coagulation, flotation	Reverse osmosis, ion exchange, distillation
Treatment stage	Primary / secondary treatment	Advanced / tertiary treatment
Impact on water quality	Causes turbidity and clogging	Affects taste, salinity, and chemical balance
Effect on equipment	Clogging, abrasion, reduced flow	Scaling, corrosion, membrane fouling
Response time in treatment	Relatively fast removal possible	Requires intensive purification

Common Sources and Causes of Total Suspended Solids in Wastewater

There are multiple natural and human-made sources of total suspended solids in water. Understanding the following sources is important for selecting the right treatment approach in TSS in wastewater treatment systems.

• Municipal Wastewater: Domestic sewage is one of the major contributors to suspended solids in wastewater. It typically contains a mixture of organic and inorganic materials generated from household activities.

Common components include:

1. Food particles and kitchen waste
2. Soap and detergent residues
3. Paper fibers and sanitary waste
4. Human waste
5. Organic matter and biological sludge

• Industrial Wastewater: Industrial wastewater often contains fine particles, oils, chemical residues, and sludge, which can significantly increase total suspended solids in wastewater levels.

Industries commonly contributing to high TSS include:

1. Food and beverage processing
2. Textile manufacturing
3. Mining and mineral processing
4. Pulp and paper industries
5. Pharmaceutical production
6. Consruction and concrete operations

• Stormwater Runoff: Stormwater runoff is another major source of suspended solids, especially in urban areas. Rainwater flowing over surfaces collects and transports contaminants into drainage systems and natural water bodies.

Typical pollutants include:

1. Soil and sediment
2. Road dust and debris
3. Oil and fuel residues
4. Plastics and litter
5. Construction site particles

• Agricultural Activities: Agricultural runoff contributes suspended solids through soil erosion and surface wash-off from farmland.

Key contributors include:

1. Soil particles and silt
2. Fertilizers and manure
3. Pesticide residues
4. Crop debris and organic matter

• Biological Growth: Biological activity can also increase suspended solids in water, especially in nutrient-rich or stagnant conditions.

Common contributors include:

1. Algae growth due to excess nutrients
2. Bacterial and microbial colonies
3. Organic biofilm formation
4. Decaying organic matter

How Are Total Suspended Solids Measured?

The standard method used globally for TSS analysis in water is the gravimetric filtration technique, commonly based on procedures outlined in Standard Methods for the Examination of Water and Wastewater (APHA).

Following are the steps involved in the gravimetric method for measuring total suspended solids:

1. Sample Collection and Preparation: A representative water sample is collected in a clean container. The sample is thoroughly mixed to ensure uniform distribution of suspended particles before analysis.
2. Filtration Process: A measured volume of the sample is passed through a pre-weighed glass fiber filter using a vacuum filtration assembly. Suspended solids are retained on the filter surface, while dissolved substances pass through.
3. Drying of Residue: The filter containing retained solids is dried in an oven at 103–105°C until a constant weight is achieved. This step removes all moisture without decomposing the solids.
4. Cooling in Desiccator: After drying, the filter is cooled in a desiccator to prevent moisture absorption from the atmosphere, which could affect weighing accuracy.
5. Final Weighing: The dried filter is weighed using an analytical balance with high precision. The difference between the initial and final weight represents the mass of suspended solids.
6. Calculation of TSS Concentration: The concentration is calculated based on the weight of retained solids and the volume of the sample filtered, and is expressed in milligrams per liter (mg/L).

Total Suspended Solids Calculation and Formula

The standard Total Suspended Solids formula for calculating TSS is:

TSS (mg/L) = (A − B) × 1000 / V

Where:

• A = Weight of dried filter with suspended solids (mg)
• B = Weight of clean filter (mg)
• V = Volume of sample filtered (mL)

This formula helps determine the concentration of total suspended solids in wastewater in milligrams per liter (mg/L).

Step-by-Step Calculation Example

Consider the following sample data:

• Weight of clean filter (B) = 100 mg
• Weight of filter after drying (A) = 160 mg
• Volume of sample filtered (V) = 500 mL

Now applying the formula:

TSS = (160 − 100) × 1000 / 500
TSS = 60 × 1000 / 500
TSS = 120 mg/L

So, the total suspended solids in water for this sample is 120 mg/L.

Interpretation of TSS Values

TSS values help determine the level of contamination and treatment efficiency in water systems:

• Low TSS (0–50 mg/L): Indicates relatively clean water with low suspended particle content
• Moderate TSS (50–150 mg/L): Suggests presence of organic and inorganic suspended matter requiring treatment
• High TSS (150+ mg/L): Indicates heavily polluted water with significant suspended solids load

In TSS analysis in water, higher TSS values typically indicate poor water quality, increased turbidity, and higher treatment load. Lower values reflect effective treatment and better overall system performance. For total suspended solids in drinking water permissible limit, levels are expected to be very low, as drinking water standards prioritize clarity, safety, and aesthetic quality.

Proven Methods to Reduce Total Suspended Solids in Wastewater

Since suspended solids vary in size, density, and composition, multiple treatment stages are typically used to achieve efficient TSS in wastewater treatment and maintain consistent water quality.

Here are the most commonly used methods for reducing suspended solids in water:

1. Filtration Systems: Filtration is one of the most direct and widely used methods for removing suspended solids by physically separating particles as water passes through a filtration medium.

This process is commonly implemented using:

• Bag and cartridge filtration systems for removing fine suspended particles, rust, and debris
• Sand and multimedia filtration units for reducing turbidity and bulk solids in high-flow applications
• Centrifugal separators for continuous removal of heavier suspended particles using rotational force.

2. Coagulation and Flocculation Systems: Coagulation and flocculation are chemical treatment processes designed to destabilize fine suspended particles and convert them into larger, settleable flocs.

In industrial and municipal systems, this process is typically achieved using:

• Chemical dosing systems that inject coagulants to neutralize particle charges
• Polymer dosing systems that promote floc formation for improved separation
• Automated feed systems that ensure consistent chemical control and treatment efficiency

3. Sedimentation and Clarification Systems: Sedimentation is a gravity-based separation process used to remove heavier suspended solids by allowing them to settle naturally over time.

This method is commonly implemented using:

• Clarifiers designed to promote controlled settling of solids
• Sedimentation tanks that separate sludge from clarified water
• Lamella or inclined plate settlers for enhanced settling efficiency in compact systems

4. Biological Treatment Systems: Biological treatment uses controlled microbial activity to break down organic matter and reduce suspended solids in wastewater streams.

This is typically achieved through:

• Activated sludge systems that biologically degrade suspended organic particles
• Aeration systems that supply oxygen to support microbial activity
• Biofilm-based treatment reactors that enhance long-term treatment efficiency

5. Advanced Filtration and Membrane Systems: Advanced treatment systems are used as final polishing stages to achieve high-quality effluent suitable for discharge or reuse applications.

These systems include:

• Ultrafiltration (UF) systems for removal of fine suspended solids, bacteria, and colloidal particles
• Membrane filtration systems that deliver consistent low-turbidity effluent quality
• Integrated pre-treatment and polishing systems designed for water reuse applications

Achieving Cleaner Water Through Effective TSS Control

Controlling total suspended solids in wastewater is essential for maintaining efficient treatment performance, regulatory compliance, and environmental protection. Combining filtration, chemical treatment, sedimentation, and advanced processes ensures consistent solids removal and stable performance.

Regular TSS analysis in water further supports monitoring and optimization. For reliable, high-performance wastewater treatment solutions, Cannon Water Technology offers advanced systems designed to effectively reduce TSS and improve overall water treatment efficiency.