TSS/NTU Converter
Our air water pollution calculator computes tssntuconverter accurately. Enter measurements for results with formulas and error analysis.
Formula
TSS = a x NTU + b (linear correlation)
TSS and NTU are related through a site-specific linear regression where a is the slope and b is the intercept.
Worked Examples
Example 1: Stream Monitoring
Problem: NTU=50, slope=1.5, intercept=2.0, 1000 mL.
Solution: TSS = 1.5 x 50 + 2 = 77 mg/L Mass = 77 x 1000/1000 = 77 mg
Result: TSS = 77 mg/L
Example 2: Treatment Plant
Problem: NTU=5, slope=1.2, intercept=0.5, 500 mL.
Solution: TSS = 1.2 x 5 + 0.5 = 6.5 mg/L Mass = 6.5 x 500/1000 = 3.25 mg
Result: TSS = 6.5 mg/L
Frequently Asked Questions
What is the difference between TSS and NTU?
TSS (Total Suspended Solids) is a gravimetric measurement of particle mass in water obtained by filtering and weighing the residue. NTU (Nephelometric Turbidity Units) measures how much light is scattered by suspended particles using an optical instrument. TSS gives actual mass concentration while NTU is an optical proxy that can be measured in real-time.
Why convert between TSS and NTU?
NTU can be measured instantly with portable turbidimeters in the field while TSS requires laboratory analysis taking hours to days. Converting NTU to TSS allows real-time estimation of solids loading for treatment plant operations and discharge monitoring. The relationship must be calibrated for each specific water source because particle characteristics affect light scattering differently.
What affects the TSS-NTU correlation?
Particle size, shape, color, and composition all influence how much light is scattered per unit mass of suspended solids. Clay particles scatter more light per milligram than sand grains due to their smaller size and larger surface area. Algae and organic particles may scatter differently than mineral sediments requiring separate calibration curves for different water types.
What is a typical TSS-NTU ratio?
For many surface waters the TSS-to-NTU ratio falls between 1.0 and 2.5 meaning 1 NTU corresponds to 1-2.5 mg/L TSS. Clean waters with fine clay may show ratios near 1.0 while waters with coarser sediments show higher ratios. Wastewater effluent typically has different ratios than natural streams requiring separate site-specific calibrations.
What are regulatory limits for TSS?
The US Clean Water Act sets technology-based TSS limits for wastewater discharges typically at 30 mg/L monthly average for secondary treatment. Stormwater permits may require TSS below 80-100 mg/L at construction site discharge points. Drinking water treatment plants must reduce turbidity below 1 NTU and often achieve below 0.1 NTU.
What instruments measure NTU?
Nephelometric turbidimeters measure the intensity of light scattered at 90 degrees from the incident beam by suspended particles. Benchtop instruments like the Hach 2100AN provide laboratory-grade accuracy for compliance monitoring. Portable field turbidimeters allow rapid on-site measurements for construction site monitoring and treatment plant operations.