WASTEWATER
TREATMENT
The major reason for practicing industrial wastewater treatment inclide:
- Reduction of existing stream contamination
- Industrial plant expansion or production increases
- Water reuse
- Product recovery and reuse
- Reduction in shock discharges
- Toxic and hazardous waste discharge reduction
The following waste constituents may be of concern in industrial pollution control and waste treatment, depending on the nature of the industry and its wastes.
Excessive waste acidity or alkalinity
Both low and high pH are deleterious to aquatic life; mineral acid and alkali discharge may affect natural water’s alkalinity buffering capacity.
Suspended solids
Impart turbidity, settleable matter, and nuisance conditions to waters.
If organic, it will contribute to biochemical oxygen demand (BOD) pressure on receiving streams.
Soluble organics
Typically cause depletion of dissolved oxygen in receiving waters by encouraging microbial cell growth and respiration. Often expressed as biochemical oxygen demand (BOD) or chemical oxygen demand (COD).
Trace organic contaminants
May impart objectionable taste and odors to receiving waters used for potable water supply ; may be toxic to aquatic life or water supply.
Color and turbidity
Constituents present in some industrial wastes in small concentrations can degrade a receiving water quality by light extinction and the effects on aesthetics and aquatic life.
Nitrogen and organic substances
Ammonia in water is very toxic to fish. Both nitrogen and phosphorus stimulate algae growth, which can degrade pond, lake, and impoundment water quality.
Refractory organic substances
May contribute to stream contamination by foaming, toxicity, and resistance to biodegradation.
Oil and floating matter
Can degrade aquatic life in small amount, and can cause aesthetic, taste, and odor problems in water supply sources.
Heavy metals and cyanides
Sometimes present in industrial processing effluents, representing toxicity to aquatic life and receiving water supply users.
Volatile materials
Gaseous hydrogen sulfide is toxic and other volatile gases in waste may cause air pollution.
Oxidizing or reducing materials
Chemical activity in industrial wastes can be very toxic to aquatic life.
Temperature
Water hotter or colder than the ambient temperature can harm aquatic life.