1. Engineering Measurements of Particles Volumetric measure
Units: mL/L
Settleable solids
30 minutes settling in Imhoff cone
Large particles

2. Gravimetric measures Total solids
mass concentration = mass per volume of suspension
mg/L = ppm by mass (approx)
Total solids
Mass of everything except the water
Evaporate the water off; weigh the residual

3. Total suspended solids (TSS) Filter sample
0.45 to 1 m glass fiber filter
Dry at 105C
Tchobanoglous and Schroeder, Water Quality

4. Tchobanoglous and Schroeder, Water Quality

5. Total dissolved solids (TDS)
What gets through the filter
TS = TSS + TDS
Not truly dissolved -- includes colloids
TSS caught on filter
TDS passes through

6. Light scattering Turbidity Color Turbidity
Light scattering at 90 degree angle
Nephelometric turbidity units (NTU)
Color
Turbidity
Photocell

7. Secchi disk clarity Assesses light penetration in water
Drop a standard disk into water until it disappears
Reported as “feet”
(e.g., Lake Tahoe exhibits about 65 ft of clarity)

8. Many constituent-specific methods
Chemical Measures
Units for dissolved constituents
Molar concentration = moles per unit volume
Mass concentrations = mg/L or g/L
Units for particles
Mass concentrations = mg/L
Many constituent-specific methods
Standard Methods for the Examination of Water and Wastewater
EPA Methods

9. Inorganic vs. Organic Volatile Solids (VS) Burn off organics at 550C
VS = TS - FS
Volatile Suspended Solids (VSS)
Same thing except we burn the filter
VSS = TSS – FSS
Organics burn off (volatilize)
Fixed (inorganic) solids remain

10. Total Organic Carbon (TOC)
Chemically oxidize organics to CO2
Infrared detector reads the CO2
Works for:
Dissolved
Small particles
CO2 detector
Sample
Oxidizers (ozone, UV light, hydrogen peroxide, etc.

11. Electroconductivity
Conductivity of solution is proportional to the number of ions
Correlates with TDS EC
TDS