Engineering Measurements of Particles Volumetric measure Units: mL/L Settleable solids

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

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

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

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. 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. Organics burn off (volatilize) Fixed (inorganic) solids remain • 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

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

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