Phycoremediation by High-Rate Algal Ponds (HRAPs) - Biotechnological Applications of Microalgae - page 183

Domestic water supply, Domestic and
industrial wastes, soil erosion, inflow-
infiltration.

Decomposing wastes
water, industrial wastes.

Domestic and industrial
wastes, natural decay of
organic materials.

Odor

Solids

Color

Domestic and industrial
wastes.

Physical
properties

Te mperature

Organic:
Carbohydrate - Domestic, commercial and industrial wastes.
Fats, oil & grease - Domestic, commercial and industrial
wastes.
Pesticide - Agriculture wastes, Phenols - Industrial wastes
Protein - Domestic & industrial wastes
Surfactants - Domestic & industrial wastes,
Others - Natural decay organic materials.

Inorganic:
Alkalinity - Domestic waste & water supply,
groundwater filtration.
Chlorides - Domestic waste & water supply,
groundwater, filtration, water softeners.
Heavy metals & pH - Industrial wastes.
Phosphorus - Domestic & industrial waste,
natural runoff.
Sulfur - Domestic water supply,
Domestic & industrial waste.
Toxic compounds - Industrial wastes.

Chemical
constituents

Wa stewater Characteristics and their
resources

Gases:

Hydrogen sulfide & Methane -
Decomposition of domestic wastes.
Oxygen - Domestic water supply, surface -
water infiltration. Open watercourses, treatment

plants.

Biological
constituents

Animals Viruses

Open watercourses, treatment
plants.

Plants

Domestic wastes

Protista

Domestic wastes, treatment
plants.

FIGURE 12.2 The physical, chemical, and biological characteristics of wastewater.
( Source : From Rawat et al., 2011.)

1. Color: The physical appearance, qualitative significant color of wastewater
depends on holding times in tanks, and varies from a light brown to light
gray color. The color is known to turn dark gray or black in the event of
wastewater going stale. A color change of wastewater is due to fermenta-
tion of the various chemical compounds produced, in particular hydrogen
sulfide and ferrous sulfide. Color can be measured by comparisons using
standard methods.

2. Odor: The offensive odor in wastewater is mainly due to dissolved impuri-
ties and a number of odor compounds produced by living enriched microbes
and decaying aquatic organisms when under anaerobic conditions. The
principal odor-producing compound is hydrogen sulfide, produced as gas
by bacterial decomposition under anaerobic conditions.