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.
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.
Examples are trickling filters and rotating biological contactors (RBC). Trickling filters are a system in which the wastewater is supplied in the form of drops with the help of pipes. It is more convenient to operate the system anaerobically because it is more efficient than the aerobic system.
Rotating biological contactors are systems in which plastic discs attached to a shaft are used. The surface area of the discs has been enlarged to accommodate more microorganisms.
An example of suspended growth systems is the activated sludge system. Activated sludge systems are the most common method of secondary treatment. The activated sludge system basically consists of two parts. These are the aeration tank and the settling tank. The aeration tank contains a sludge which is a microbial culture to be best defined. This sludge contain microorganisms such as bacteria, protozoa, fungi and algae in dense quantities. The aeration tank is continuously ventilated with blowers and diffusers so that the oxygen concentration does not fall below 2 mg / L.
Depending on discharge standards, activated sludge systems are also suitable for nitrification, denitrification and biological phosphorus removal together with organic matter removal. Depending on the process conditions, the activated sludge reactor canbe operated under aerobic, anoxic and anaerobic conditions. In the final settling tank, the amount of biomass required is ensured by recycling to the activated sludge basin. The excess sludge 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 the aeration tank, the microorganisms have been in an environment depleted of “food” for some time, and are in a “hungry”, or activated condition, eager to get busy biodegrading some more wastes. (Handbook of Water and Wastewater Treatment Technologies, Page 239) Since the amount of microorganisms, or biomass, increases as a result of this process, some must be removed on a regular basis for further treatment and disposal, adding to the solids produced in primary 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)
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
