Sunday, July 23, 2017

Secondary Treatment in Domestic Wastewater

Secondary Treatment İn Domestic Wastewater
It is a treatment method based on the principle that organic pollutants in wastes are
removed from wastewater by being used as food and energy source by microorganisms. Along
with the biochemical processes, the decomposable organic substances are oxidized by giving
electrons and become the final products, CO
2
and H
2
O. As a result, some of the biodegradable
organic matter is transformed into biomass, and the other part is transformed into energy.
Biological treatment systems basically work as two different systems. These systems are
"suspended growth" and "attached growth". Microorganisms in attached growth processes are
attached to a material such as stone, gravel or plastic.
Secondary Treatment İn Domestic Wastewater
It is a treatment method based on the principle that organic pollutants in wastes are
removed from wastewater by being used as food and energy source by microorganisms. Along
with the biochemical processes, the decomposable organic substances are oxidized by giving
electrons and become the final products, CO
2
and H
2
O. As a result, some of the biodegradable
organic matter is transformed into biomass, and the other part is transformed into energy.
Biological treatment systems basically work as two different systems. These systems are
"suspended growth" and "attached growth". Microorganisms in attached growth processes are
attached to a material such as stone, gravel or plastic.
Secondary Treatment İn Domestic Wastewater
It is a treatment method based on the principle that organic pollutants in wastes are
removed from wastewater by being used as food and energy source by microorganisms. Along
with the biochemical processes, the decomposable organic substances are oxidized by giving
electrons and become the final products, CO
2
and H
2
O. As a result, some of the biodegradable
organic matter is transformed into biomass, and the other part is transformed into energy.
Biological treatment systems basically work as two different systems. These systems are
"suspended growth" and "attached growth". Microorganisms in attached growth processes are
attached to a material such as stone, gravel or plastic.
It is a treatment method based on the principle that organic pollutants in wastes areremoved from wastewater by being used as food and energy source by microorganisms. Alongwith the biochemical processes, the decomposable organic substances are oxidized by givingelectrons and become the final products, CO2 and H2O. As a result, some of the biodegradableorganic matter is transformed into biomass, and the other part is transformed into energy.

Biological treatment systems basically work as two different systems. These systems are"suspended growth" and "attached growth". Microorganisms in attached growth processes areattached to a material such as stone, gravel or plastic.

Examples are trickling filters and rotatingbiological contactors (RBC). Trickling filters are asystem in which the wastewater is supplied in theform of drops with the help of pipes. It is moreconvenient to operate the system anaerobicallybecause it is more efficient than the aerobic system.

Rotating biological contactors are systems inwhich plastic discs attached to a shaft are used. Thesurface area of the discs has been enlarged toaccommodate more microorganisms.

An example of suspended growth systems is the activated sludge system. Activated sludgesystems are the most common method of secondary treatment. The activated sludge systembasically consists of two parts. These are the aeration tank and the settling tank. The aerationtank contains a sludge which is a microbial culture to be best defined. This sludge containsmicroorganisms such as bacteria, protozoa, fungi and algae in dense quantities. The aeration tank is continuously ventilated with blowers and diffusers so that the oxygen concentrationdoes not fall below 2 mg / L.

Depending on discharge standards, activated sludge systems arealso suitable for nitrification, denitrification and biological phosphorus removal together withorganic matter removal. Depending on the process conditions, the activated sludge reactor canbe operated under aerobic, anoxic and anaerobic conditions. In the final settling tank, theamount of biomass required is ensured by recycling to the activated sludge basin. The excesssludge formed in the system is sent to the sludge processing units.

The term “activated “sludge is used, because by the time the sludge is returned to theaeration tank, the microorganisms have been in an environment depleted of “food” for sometime, and are in a “hungry”, or activated condition, eager to get busy biodegrading some morewastes. (Handbook of Water and Wastewater Treatment Technologies, Page 239) Since theamount of microorganisms, or biomass, increases as a result of this process, some must beremoved on a regular basis for further treatment and disposal, adding to the solids produced inprimary treatment. (Handbook of Water and Wastewater Treatment Technologies, Page 239)

REFERENCES
Hasar, Halil; Water and Wastewater Treatment, Page 34-35
Cheremisinoff, Nicholas P; Handbook of Water and Wastewater Treatment Technologies,
Page 239)
REFERENCES
Hasar, Halil; Water and Wastewater Treatment, Page 34-35
Cheremisinoff, Nicholas P; Handbook of Water and Wastewater Treatment Technologies,
Page 239)
REFERENCES
1) Hasar, Halil; Water and Wastewater Treatment, Page 34-35Cheremisinoff,  
2) Nicholas P;  Handbook  of  Water   and   Wastewater  Treatment  Technologies,Page 239)
3) www.aykosan.com.tr/en/