Characteristics of Water

Study Notes

Physical characteristics: solids, temperature, color, odor, turbidity, oil and grease, conductivity
Chemical characteristics: organics (proteins, carbohydrates, lipids, surfactants, phenols, pesticides, emerging organics), inorganics (pH, chlorides, alkalinity, nitrogen, phosphorus, heavy metals), gases (oxygen, hydrogen sulfide, methane)
Aggregate organics: BOD, COD, TOC
Biological characteristics: pathogens, indicators, viruses, invertebrates

Point sources: single large sources
Non-point sources: diffuse source of pollution that cannot be attributed to a clearly identifiable, specific physical location or a defined discharge channel
Measurements: Amm.N., Inorg.N., Kjeldahl N., Org.N

Phosphorus: aqueous forms (orthophosphates, polyphosphate, and organic phosphates), importance as nutrient
Sulphur: aqueous form (sulphate), reduced to sulphide and further to hydrogen sulfide, formation of sulphuric acid and pipe corrosion
Metallic constituents: priority pollutants (Cd, Cr, Cu, Fe, Pb, Mn, Hg, Ni, and Zn), micronutrients/toxicants, measurable forms (dissolved, suspended, acid extractable)

Primary treatment: removes solids, physical operations (screening, sedimentation)
Secondary treatment: removes organics, biological and chemical operations
Tertiary treatment: removes nutrients, biological and chemical operations

First unit operation
Objective: removal of coarse and fine objects, which may get entangled in mechanical equipment (e.g., grit chambers, sedimentation tanks, etc.)
Examples: general runoff of sediments, pesticide spraying, fertilizers from farms

Fund pollutants: those for which the environment has some absorptive capacity
- Degradable: organic residuals broken down by bacteria
- Thermal: injection of heat into water source
- Eutrophic: excessive nutrients leading to too much aquatic plant growth
- Persistent pollutants: inorganic/synthetic chemicals partially broken down
- Bacteria, viruses, artificial hormones: from domestic and animal wastes
Stock pollutants: those for which the environment has little or no absorptive capacity
- Minerals and inorganic/organic chemicals not removed by natural processes (e.g., lead, cadmium, mercury, some agrochemicals, persistent synthetic chemicals, non-biodegradable plastics, and heavy metals)

Important measure of water quality
Oxygen is marginally soluble in water and inversely proportional to temperature
Maximum DO at water temperature of 16°C is 10 mg/L
DO analysis measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution
Oxygen gets into water by diffusion from the surrounding air, by aeration, and as a product of photosynthesis