Biological Treatment Systems

INTRODUCTION:

Water is the most important natural gift for human being and aquatic life. Due to continuous technological growth and industrialization, the water has been fully polluted and categorized as water pollution. The outlet water of industries and human which accedes the limit of organic and inorganic components in the water is called wastewater (polluted water).

SOURCES OF WASTEWATER:

–    Industrial
–    Municipal
–    Commercial

CHARECTERISTICS OF WASTERWATER:

–    Physical Characteristics
–    Chemical Characteristics
–    Biological Characteristics

Some of them appear in dissolved form, some of suspended form and  some of colloidal form are known as suspended impurities, colloidal impurities and dissolved impurities respectively. To maintain the  quality of water, its need the treatment of wastewater. The basic treatments of wastewater are:

–    Physical Treatment
–    Chemical Treatment
–    Biological Treatment / Secondary Treatment
–    Advanced treatment / Tertiary Treatment

BIOLOGICAL TREATMENT:

Main objectives of biological treatment to remove or reduce the  concentration of organic, inorganic compounds nutrients specially nitrogen and phosphorus. Also denitrification of common terminology used for biological treatment process.


METABOLIC FUNCTION

DEFINITION
Aerobic (oxic) ProcessBiological treatment that occur in the
presence of oxygen. 

  • Suspended growth: Activated Sludge
    Process, Aerated Lagoons and Aerobic Digestion
  • Attached growth: Trickling
    Filters, Rotating Biological Contractor
  • Combined: Trickling Filter +
    Activated Sludge Process.
Anaerobic ProcessBiological treatment that occur in the
absence of oxygen 

  • Suspended growth: A. Digestion
  • Attached growth: Fluidized Bed
  • Sludge Blanket: up flow anaerobic sludge blanket
  • Hybrid: up flow sludge blanket / attached growth
Anoxic ProcessThe process in which nitrate nitrogen is
converted biologically to nitrogen gas in the absence of oxygen.
The process is also called denitrification 

  • Suspended growth: Denitrification,
  • Attached growth: Denitrification
Facultative ProcessBiological treatment process in which the
organisms can function in the presence or absence molecular
oxygen
Combined aerobic and anaerobic ProcessVarious combination of aerobic anoxic and
anaerobic process group together to achieve special treatment
objectives.
  • Suspended growth: Activated Sludge
    Process, Aerated Lagoons and Aerobic Digestion
  • Attached growth: Trickling
    Filters, Rotating Biological Contractor
  • Combined: Trickling Filter +
    Activated Sludge Process.

Anaerobic ProcessBiological treatment that occur in the
absence of oxygen

  • Suspended growth: A. Digestion
  • Attached growth: Fluidized Bed
  • Sludge Blanket: up flow anaerobic sludge blanket
  • Hybrid: up flow sludge blanket / attached growth

Anoxic ProcessThe process in which nitrate nitrogen is
converted biologically to nitrogen gas in the absence of oxygen.
The process is also called denitrification

  • Suspended growth: Denitrification,
  • Attached growth: Denitrification

Facultative ProcessBiological treatment process in which the
organisms can function in the presence or absence molecular
oxygenCombined aerobic and anaerobic ProcessVarious combination of aerobic anoxic and
anaerobic process group together to achieve special treatment
objectives.

SLUDGE PROCESS:

Suspended growth biological treatment process in which the microorganisms responsible for  the conversion  of the organic matter or other constituents in the wastewater to gases and cell tissue are maintained in suspension  within the liquid. Suspended growth is mainly two types.

TURBIN AERATION SYSTEM FLOATING SYSTEM:

 Attached growth biological treatment process in which the microorganisms responsible for the conversion of the organic matter or other constituents in wastewater to gases and cell tissue are attached to same inert medium, such as rocks, slag etc. attached growth treatment process is also called fixes growth system.

TRICKLING FILTER: 

 Combined process biological treatment process in which suspended growth and attached growth are combined.

Anaerobic digestion is a process in which  microorganisms break down  biodegradable material in the absence of oxygen. The process is widely used to treat wastewater sludge and  organic wastes because it provides volume and mass reduction of the input material. As part of an integrated  waste management  system, anaerobic digestion reduces the emission of  landfill gas  into the atmosphere. Anaerobic digestion is a  renewable energy   source because the process produces a methane and carbon dioxide rich biogas suitable for energy production helping replace fossil fuels. Also, the nutrient-rich solids left after digestion can be used as fertiliser.

The digestion process begins with bacterial hydrolysis of the input materials in order to break down insoluble organic polymers such as carbohydrates and make them available for other bacteria.

Acidogenic bacteria then convert the sugars and amino acids  into carbon dioxide, hydrogen, ammonia,  and  organic acids. Acetogenic bacteria then convert these resulting organic acids into acetic acid, along with additional ammonia, hydrogen, and carbon dioxide. Methanogenic bacteria finally are able to convert these products to methane and carbon dioxide.

The technical expertise required to maintain anaerobic digesters  coupled with high capital costs  and lower process efficiencies have so far limited the level of its industrial application as a waste treatment technology. Anaerobic digestion facilities have, however, been recognized by the United Nations Development Programme as one of the most useful decentralized sources of energy supply, as they are less capital intensive than large power plants.

Careful control of the digestion temperature, pH, and loading rates is  crucial to obtaining efficient breakdown of the material, and disturbances to a digest can lead to process failure. Ensuring that the quality of input materials to the digesters is maintained and that the process effectively monitored is essential for ensuring that a digester’s performance is reliable.

ANAEROBIC DIGESTION PROCESS:

AES ARABIA LTD systems are an advanced evolution of the latest  Biological treatment methods including aerobic and anaerobic

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