Wastewater Definition
Wastewater is water whose characteristic is not suitable to domestic , commercial or industrial purpose/use. It contains substance or pollutants in higher concentration than desire for domestic, commercial or industrial use.
Requirement of Wastewater Treatment
•If wastewater not treated properly may harmful to environment and living organisms including human.
•Decaying pollutants in water deplete dissolve oxygen in water may harm aquatic life.
•Toxic/hazardous substance in wastewater in crease concentration of same in receiving water body, which pollute water body and water unsuitable for various purposes.
•Pathogens in wastewater pollute receiving water body and make water unsuitable for drinking or domestic purpose
So it is very important to give proper treatment before final disposal of wastewater
Types of Wastewater
•Wastewater generally classified in two types
Domestic Wastewater
Industrial Wastewater
Commercial Wastewater
Domestic Wastewater (Definition)
Domestic wastewater is wastewater generated by from use of water in domestic activity like bathing , cooking, cleaning etc.
Industrial Wastewater (Definition)
Industrial wastewater is wastewater generated from use of water in industrial activity like cooling, boiler, reactor cleaning etc.
Commercial Wastewater (Definition)
Wastewater generated from commercial activity like water parks, resorts , etc falls in this category.
Parameters Use for characterization of Wastewater
•Parameters use for characterisation wastewater are as follows
–pH
–Suspended Solid (S.S) measure in mg/l or ppm
–Dissolved Solid (D.S) measure in mg/l or ppm
–Chemical Oxygen Demand (COD) measure in mg/l or ppm
–Biological Oxygen Demand (BOD) measure in mg/l or ppm
–Total Nitrogen TM measure in mg/l or ppm
–Ammonical Nitrogen in mg/l ppm
–Phosphorus in mg/l or ppm
Wastewater Treatment Stages
•Wastewater treatment categorized in following stages
–Preliminary Treatment
–Primary Treatment
–Advance Primary Treatment
–Secondary treatment
–Secondary with nutrition removal (Advance Secondary Treatment)
–Tertiary Treatment
–Advanced Treatment
Preliminary Treatment
Purpose
Preliminary treatment provide to remove floating material, oils, heavy and large substance.
Units
•Oil and Grease Traps- removes light density substance like oil grease.
•Grit chamber- removes heavy and large dense substance
•Screens – removes large size floating materials
•Neutralizing tank – adjust pH of wastewater
Secondary Treatment
Secondary treatments mainly consists of biological treatments and secondary settling Tank or clarifier
Purpose
Removal of biodegradable organic substance which dissolved in wastewater. like carbon, nitrogen and phosphorous.
Classification
Biological treatments further classified as aerobic treatment and anaerobic treatment.
Aerobic Treatment are those treatment which require oxygen to complete thee treatment or treatment carried out in presence of air/oxygen
Anaerobic treatments are those which carried out in absence of oxygen/air.
Facultative Treatments
facultative treatments are those which carried out in presence or absence of oxygen.
Secondary treatment further classified on basis of growth of microorganisms.
Suspended Growth Process
In this type of process mass of microorganisms or colonies remains suspended in wastewater.
Attached Growth Process
In this type of process microorganisms mass or colony allowed to grow on surface of inert medium.
Aerobic Treatments
Suspended Growth
Activated Sludge Process (Aeration Tank)
Aerated Lagoon
Aerobic Digester
Attached Growth
Trickling Filter
Rotating Biological Contactor
Anaerobic Treatments
Suspended Growth
Anaerobic contact process
Anaerobic Digestion
Attached Growth
Anaerobic fluidized bed
Advance Secondary Treatment
Purpose
Advance secondary treatment use to remove specific nutrient or pollutants from wastewater like carbon , Nitrogen, phosphorus.
Units
•Nitrification –denitrification process
•Phosphorous Removal Process
•Biological Removal of heavy metals
Tertiary Treatments
Purpose
Tertiary treatments provide removal of residue of suspended solid, dissolved pollutants, smell, colour and pathogens from wastewater. Generally disinfection and various kind of filtration process use as tertiary treatment
Units
•Chlorination
•Ozonetor
•Activated Carbon Filter
•Pressure Sand Filter