Wastewater Treatment: Primary and Secondary Treatment

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CHAPTER-3 3.1 Introduction As the given situation describes, eutrophication is a result of the presence of nitrogen and phosphorus in river since no protection methods are carried out to end the release of waste into the water bodies. Such rivers are commonly known as sensitive rivers. These nutrients excite the production of algae providing food for their growth under the accurate circumstances thus causing eutrophication. Eutrophication can harm the ecosystem causing unwanted alteration in aquatic population, extreme reduction of oxygen, health issues to human-beings and animals, expensive water treatment costs and, interfering with recreational significance of water (Kuba et al., 1997). Thus the wastewater must be maintained from nitrogen and phosphorus before disposing into water bodies. The removal of such harmful nutrients must be carried out efficiently in the secondary treatment itself. Wastewater treatment includes two procedures as standard: Primary Treatment (elimination of rock-solid materials) and Secondary Treatment that uses microorganisms to eradicate organic wastes by disintegration. Tertiary treatment may also be mandatory in case of removing phosphorus and nitrogen when wastewater is discharged into sensitive rivers. The biological secondary treatment is the major type of treatment for elimination of the organic materials from wastewater (up to 90% elimination). The two usual procedures used in the treatment are: • Attached Growth Method (Fixed film system) • Suspended Growth Method (Free-film system). Each of the above types has been described within the subsequent section. 3.2 Activated Sludge Treatment (AST) – Free Film System This is the most familiar suspended devel... ... middle of paper ... ...is a simple procedure of secondary treatment where the sewage is held in a basin where the disintegration takes place by micro-organisms, air and sunrays. The steady sludge is disposed as treated seepage. This method does not required trained labourers and can be setup in a reasonable priced property. Constructed Wetland They are capable of filtering suspended solids, degrading organic matter and decompose nutrients from wastewater. Removal of ammonia by denitrification is also possible by this method. References Kuba, T.; van Loosdrecht, M.C.M; Brandse, F.A; Heijmen, J.J, (1997) Occurrence of denitrifying phosphorus removing bacteria in modified UCT type wastewater treatment plants. Water Res., 31 (4), 777 - 786 FAO Corporate Document Repository (n. d.) [online] available from [16 february 2014]
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