Suspended Solids vs Settleable Solids vs Sludge Concentration Malaysia
Suspended Solids vs Settleable Solids vs Sludge Concentration Malaysia
Suspended solids, settleable solids and sludge concentration all describe material present in wastewater, but they are not the same measurement.
They may use different instruments, procedures and units.
Understanding the difference helps wastewater operators and Malaysian factories avoid purchasing the wrong meter.
Quick Comparison
ParameterWhat It IndicatesCommon UnitTypical MethodSuspended solidsInsoluble particles carried in watermg/LPortable meter or laboratory methodSettleable solidsVolume of solids settling during a defined periodmL/LSettling coneSludge concentrationSolids concentration in sludge or mixed liquormg/L or g/LLaboratory or suitable sludge meterTurbidityWater cloudiness caused by particlesNTU or FNUTurbidity meterTDSDissolved substances in waterppm or mg/LTDS/conductivity meter
Results from these tests should not be used interchangeably.
What Are Suspended Solids?
Suspended solids are insoluble particles carried within a water sample.
They may include:
Fine sediment
Organic matter
Biological solids
Food-processing residue
Industrial particles
Treatment-process solids
Results are normally expressed in milligrams per litre (mg/L).
The Qiwei SS-500B Portable Suspended Solids Meter measures from 0 to 500 mg/L.
What Are Settleable Solids?
Settleable solids are particles that settle under defined test conditions.
The result is commonly expressed as the volume of settled material per litre of sample, such as mL/L.
A settling cone may be used to observe how much material settles during the required test period.
This measurement provides different information from suspended-solids concentration.
Why Are mg/L and mL/L Different?
Suspended-solids results describe particle mass relative to water volume.
Settleable-solids results describe the volume occupied by material that settles.
Two samples can have:
Similar suspended-solids concentration
Different settling behaviour
Different settled volume
Different particle density
Therefore, mg/L should not be converted directly into mL/L using a general formula.
What Is Sludge Concentration?
Sludge concentration describes the amount of solids in sludge, mixed liquor or another high-solids process sample.
Depending on the application, it may be reported in:
mg/L
g/L
Percentage solids
Another process-specific unit
Sludge samples may contain much higher concentrations than treated wastewater.
Can the SS-500B Measure Sludge Concentration?
The SS-500B has a published range of 0–500 mg/L.
Many sludge or mixed-liquor samples may exceed this range significantly.
Before offering the SS-500B for sludge measurement, confirm:
Expected concentration
Sample type
Required unit
Required measurement method
Whether dilution is allowed
Whether a dedicated sludge-concentration meter is required
Do not assume that an instrument for 0–500 mg/L wastewater can measure every sludge sample.
When Should You Measure Suspended Solids?
Suspended-solids measurement is useful for:
Influent and effluent comparison
Factory wastewater screening
Sedimentation checks
Filter-performance monitoring
Treated-water checks
Environmental field measurements
Construction-runoff screening
Aquaculture-water monitoring
A portable meter allows operators to compare several sampling locations quickly.
When Should You Measure Settleable Solids?
Settleable-solids testing may be useful when the operator needs to evaluate:
Material settling behaviour
Sedimentation performance
Sludge settling
Clarifier conditions
Volume of settled particles
Changes in wastewater characteristics
The correct test duration and procedure should follow the applicable method.
When Should You Measure Sludge Concentration?
Sludge-concentration measurement may support:
Activated-sludge process control
Mixed-liquor monitoring
Sludge-return checks
Sludge-thickening operations
Dewatering processes
Solids inventory
Treatment optimisation
These applications may require a wider-range or dedicated instrument.
Suspended Solids vs Turbidity
Turbidity indicates how cloudy water appears and is normally reported in NTU or FNU.
Suspended solids are reported in mg/L.
Fine particles may create high turbidity even when their total mass is relatively low. Large particles may add more mass but settle quickly.
There is no universal NTU-to-mg/L conversion.
Suspended Solids vs TDS
TDS represents dissolved substances.
A basic TDS meter estimates dissolved content through conductivity and does not directly measure suspended sediment or sludge particles.
If the customer asks for suspended solids, do not automatically recommend a TDS meter.
Questions to Ask the Customer
Before selecting an instrument, ask:
What sample is being tested?
Is it clear water, wastewater or sludge?
What unit is required?
What is the expected concentration?
Is the customer checking particle mass or settled volume?
Is the result for process monitoring or official reporting?
Is a portable or online instrument required?
Does the sample contain strong colour, oil or foam?
Is laboratory comparison available?
Is an approved test method specified?
The required unit often reveals which measurement the customer actually needs.
Practical Instrument Selection
Choose a portable suspended-solids meter when the customer needs operational readings in mg/L within the instrument’s range.
Choose a settling cone and appropriate procedure when the required result is settled volume in mL/L.
Choose a suitable sludge-concentration instrument or laboratory method when testing high-solids sludge or mixed liquor.
Choose a turbidity meter when the customer requires NTU or FNU.
Choose a TDS or conductivity meter when the customer requires information about dissolved substances.
About the Qiwei SS-500B
The SS-500B provides:
Measurement range: 0–500 mg/L
Displayed resolution: 1 mg/L
AC adaptor or AA-battery operation
Two measuring bottles
Portable field and indoor use
It is suitable for routine suspended-solids screening where the expected concentration is within its range.
Contact MTM Precision
For the Qiwei SS-500B Portable Suspended Solids Meter, settleable-solids and wastewater instrument selection, technical consultation or quotation, contact:
MTM Precision Sdn. Bhd.
Professional Test & Measurement Solutions Partner in Malaysia
Website: www.mtmpre.com.my
Email: mtmpre@yahoo.com
WhatsApp: +6016-660 7346
Showroom & Service Centre
No. 29-1 & 29-2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.
Malaysia Coverage:
Selangor, Kuala Lumpur, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Perlis, Terengganu, Sabah and Sarawak.
15 Sep 2026
