TERTIARY TREATMENT METHODS Aya Sezer 21425149 Tertiary Treatment

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TERTIARY TREATMENT METHODS Ayça Sezer 21425149

TERTIARY TREATMENT METHODS Ayça Sezer 21425149

Tertiary Treatment • Tertiary treatment process is used to improve the quality of the

Tertiary Treatment • Tertiary treatment process is used to improve the quality of the effluent which has resulted from primary and secondary treatment processes. • The water can be safely discharged into the environment (water bodies like rivers and lakes etc. ). • Used for agricultural, industrial and, in many cases, domestic purposes.

Need Of Tertiary Treatment • To remove total suspended solids and organic matter those

Need Of Tertiary Treatment • To remove total suspended solids and organic matter those are present in effluents after secondary treatment. • To remove specific organic and inorganic constituents from industrial effluent to make it suitable for reuse. • To remove pathogens from the secondary treated effluents. • To reduce total dissolved solids (TDS) from the secondary treated effluent to meet reuse quality standards.

Chemical Precipitation • Chemical precipitation is the method of addition of chemicals to the

Chemical Precipitation • Chemical precipitation is the method of addition of chemicals to the wastewater, converting undesired soluble substances into an insoluble precipitate which can be removed easily and rapidly. • Phosphate ions can be precipitated by adding ions which form insoluble compounds with the heavy metal or phosphate ions.

Chemical Precipitation of Phosphorus • One of the consequences of high phosphate concentration is

Chemical Precipitation of Phosphorus • One of the consequences of high phosphate concentration is increased algal growth. These algaes are that can cause eutrophication in surface waters. • The wastewater treatment plants therefore use chemically suitable sedimentation materials and targeted perform phosphorus removal.

The chemicals added to the wastewater enter the reaction with the substances in the

The chemicals added to the wastewater enter the reaction with the substances in the medium. The chemicals: • Alum • Fe. Cl 3 • Fe(III) Sulfate • Lime

 • Use of Ferric chloride; Fe. Cl 3 + HPO 4 -2 <==>

• Use of Ferric chloride; Fe. Cl 3 + HPO 4 -2 <==> Fe. PO 4 ↓ + H+ + 3 Cl • Use of Alum; Al 2(SO 4)3 + 2 HPO 4 -2 < == > 2 Al. PO 4 ↓ + 2 H+ + 3 SO 4 -2 • Use of Lime; 5 Ca(OH)2 + 3 HPO 4 -2 < == > Ca 5(PO 4)3 OH ↓ + 3 H 2 O + 6 OH-

Design Strategies • Chemical Material Selection: The main chemicals used for phosphorus precipitation are

Design Strategies • Chemical Material Selection: The main chemicals used for phosphorus precipitation are alum and iron chloride. Alum and ferric chloride corrosive substances. Therefore, they can cause significant problems during transportation and storage. Due to the numerous side reactions that take place, the actual alum or iron chloride required to achieve high removal efficiencies exceeds the desired stoichiometric dose. Polymer addition may be performed to facilitate precipitation.

 • Pre-settlement: It is the precipitation of phosphorus by chemical addition before the

• Pre-settlement: It is the precipitation of phosphorus by chemical addition before the first precipitation pool. At the entrance of the pre -sedimentation, chemical substances are mixed with wastewater. The pre-sedimentation pool serves both as a reaction pool and as a sedimentation basin. • Co-precipitation: In the last settling tank, the chemical substances to be precipitated together with the biological sludge. The chemical substance can be added to the pre-settling outlet, the recycle line or the biological treatment outlet before the last settling tank.

 • After Precipitation: It is the addition of the chemical substance after the

• After Precipitation: It is the addition of the chemical substance after the last sedimentation tank. This process requires a separate mixing unit and a filtration. • Sludge Formation: The chemical precipitation of phosphorus will significantly increase the sludge production of the plant.

Filtration • Tertiary filters are for filtering the liquid sewages from the secondary wastewater

Filtration • Tertiary filters are for filtering the liquid sewages from the secondary wastewater treatment system. • Provides additional removal of suspended solids and further reduction of biochemical oxygen demand(BOD).

Normal Filter Cycle • Suspended particules are removed from water by flowing the water

Normal Filter Cycle • Suspended particules are removed from water by flowing the water through granular filter media at a high rate. • The solids are removed within depth of the granular material. • Filter water is removed from the filter through an underdrain system.

Backwashing Process • Cleaning the filter media is done with an upflow water wash.

Backwashing Process • Cleaning the filter media is done with an upflow water wash. • Air scour ensures thorough cleaning volume of the water above the filter bed increases to just above the edge of the waste gullet. • Dirt is flushed out of the media and captured via water overflow into the waste gullet dirty backwash water is evacuated from the filter for recovery.

Nitrification • The biological conversion of ammonium to nitrate nitrogen is called Nitrification. •

Nitrification • The biological conversion of ammonium to nitrate nitrogen is called Nitrification. • It is autotrophic process energy for bacterial growth is derived by oxidation of nitrogen compounds such as ammonia. • Nitrification is a two-step process; First step: NH 4 + + 3/2 O 2 → N 02 - + 2 H+ + H 2 O (Nitrite) Second step: N 02 - + 1/2 O 2 → N 03 - (Nitrate) Overall reaction: NH 4 + + 2 O 2 N 03 - + 2 H+ + H 2 O

Denitrification • Denitrification is accomplished under anaerobic or near anaerobic conditions by facultative heterotrophic

Denitrification • Denitrification is accomplished under anaerobic or near anaerobic conditions by facultative heterotrophic bacteria commonly found in wastewater. Nitrates are removed by two mechanisms; 1) conversion of NO 3 to N 2 gas by bacterial metabolism 2) conversion of NO 3 to nitrogen contained in cell mass which may be removed by settling. • Denitrification occurs when oxygen levels are depleted and nitrate becomes the primary electron acceptor source for microorganisms.

Denitrification Filters • The filter medium serves as an attachment surface for suspended propagation

Denitrification Filters • The filter medium serves as an attachment surface for suspended propagation denitrification organisms and denitrification takes place. • The filter is operated anaerobically. • Nitrogen gas formed by denitrification is accumulated in the filter, so it is necessary to release the nitrogen gas. This causes an increase in the load loss. • The resulting load loss can be reduced by backwashing with water with only 1 to 5 minutes. The backwash water is not retained in the system.

Membrane Filtration • Low pressure microfiltration and ultrafiltration membranes for the tertiary treatment of

Membrane Filtration • Low pressure microfiltration and ultrafiltration membranes for the tertiary treatment of wastewater in urban wastewater treatment plants. • Largest area of use, feeding of aquifers or facilitating the reverse osmosis process after the preliminary treatment of the secondary purification outlet for the purpose of drinking water.

Membrane Efficiency • High quality outlet water is obtained. • The membranes act as

Membrane Efficiency • High quality outlet water is obtained. • The membranes act as physical barriers. The removal efficiencies of conventional pollutants with these membranes depend on the fractions of these contaminants, which are dependent on the amount of suspended material.

Preliminary Treatment • Preliminary treatment is of great importance in optimizing membrane efficiency. •

Preliminary Treatment • Preliminary treatment is of great importance in optimizing membrane efficiency. • Preliminary treatment may be chemical coagulation, chlorine or chloramine addition, filtration and flow balancing. • Membrane clogging may be higher in low alum(<12 mg/L) doses than filtration without coagulants. • At higher doses(>25 mg/L), membrane yield can be significantly increased.

Clogging and Cleaning • Bio clogging results from co-occur of biofilm formation and accumulation

Clogging and Cleaning • Bio clogging results from co-occur of biofilm formation and accumulation of bio-organic matter. • Chlorine or chlorine is added to the feeding water as a standard for the prevention of biofouling.