CHAPTER-33.1 IntroductionAs the given situation describes, eutrophication is the result of the presence of nitrogen and phosphorus in the river since no protection method is available. is implemented to put an end to the discharge of waste into water. body. These rivers are commonly called sensitive rivers. These nutrients stimulate the production of algae, thereby providing food for their growth under specific circumstances, thereby causing eutrophication. Eutrophication can harm the ecosystem, causing undesirable alteration of the aquatic population, extreme reduction of oxygen, health problems for humans and animals, high costs of water treatment and interfering with the recreational importance of water (Kuba et al., 1997). Thus, wastewater must be preserved from nitrogen and phosphorus before being discharged into water bodies. Removal of these harmful nutrients must be done effectively during the secondary processing itself. Wastewater treatment includes two standard procedures: primary treatment (removal of solid materials like stone) and secondary treatment which uses microorganisms to eradicate organic waste through disintegration. Tertiary treatment may also be mandatory for phosphorus and nitrogen removal when wastewater is discharged into sensitive rivers. Biological secondary treatment is the main type of treatment for the removal of organic matter from wastewater (up to 90% removal). 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 in the following section. 3.2 Activated Sludge Treatment (AST) – Free Film System This is the best known suspended development...... middle of paper ...... is a simple secondary treatment procedure where wastewater is retained in a basin where disintegration takes place by micro-organisms, air and sunlight. Stable sludge is discharged in the form of treated infiltration. This method does not require skilled labor and can be installed on a property at a reasonable cost. Constructed wetlandThey are able to filter suspended matter, degrade organic matter and break down nutrients from wastewater. Removal of ammonia by denitrification is also possible by this method.ReferencesKuba, T.; van Loosdrecht, MCM; Brandse, F.A.; Heijmen, JJ, (1997) Occurrence of phosphorus-removing denitrifying bacteria in modified UCT wastewater treatment plants. Water Res., 31 (4), 777 - 786FAO Corporate Document Repository (nd) [online] available from [February 16 2014]