Wastewater Generation (Domestic and Industrial):
- Domestic
Wastewater: Also known as sewage, is generated from residential,
institutional, and commercial establishments. It includes wastewater from
sinks, showers, washing machines, dishwashers, and toilets, which can
contain a wide variety of pollutants, including food scraps, oils,
detergents, and human waste.
- Industrial
Wastewater: This is produced by manufacturing and industrial processes.
The composition of industrial wastewater can vary greatly depending on the
industry but can include heavy metals, organic pollutants, heat, oils, and
chemicals.
Impacts of Wastewater:
If untreated or improperly treated, wastewater can have
significant environmental and health impacts. It can contaminate surface and
groundwater, harm aquatic life, contribute to eutrophication, and spread
disease. It also represents a loss of valuable nutrients and water resources.
Flow Diagram of a Sewage Treatment Plant:
- Preliminary
Treatment: Removes large debris, sand, and grit.
- Primary
Treatment: Settling tanks allow suspended solids to settle out as
sludge, and oil and grease are skimmed off.
- Secondary
Treatment: Biological processes degrade organic matter. Activated
sludge or trickling filter systems are commonly used.
- Tertiary
Treatment (if necessary): Additional treatment steps to remove
specific contaminants, such as nutrients or pathogens.
- Disinfection:
Usually with chlorine or UV light.
- Discharge
or Reuse: Treated water is discharged to a water body or reused for
non-potable applications (e.g., irrigation, industrial cooling).
CPCB Norms for Sewage Discharge:
The Central Pollution Control Board (CPCB) of India has set
standards for the quality of treated sewage that can be discharged into the
environment or used for irrigation. These standards specify acceptable levels
for parameters like pH, biochemical oxygen demand (BOD), chemical oxygen demand
(COD), total suspended solids (TSS), and levels of various nutrients and
pathogens.
As per the standards (as of my knowledge cutoff in September
2021), the Biochemical Oxygen Demand (BOD) should not exceed 30 mg/l, and Total
Suspended Solids (TSS) should not exceed 100 mg/l in the treated wastewater.
The standards may be stricter if the treated sewage is to be
discharged into sensitive water bodies or used for certain purposes. It's
important to regularly check the most recent CPCB guidelines or local
regulations for the most accurate information.
Note: The specific details of the treatment process
and discharge standards can vary depending on the nature of the wastewater,
local regulations, and the specific design of the treatment system. The above
information should be used as a general guide. For a specific case, you should
consult with a local wastewater treatment professional or relevant regulatory
body.