List 6 reasons “WHY” we treat wastewater focused on the different types of contaminants in municipal wastewater. Solution Due the fact that waste water is generated with different types contaminents which are composed of salts,ammonia,pathogenic material,pesticides,chemicals such as nitrates,posphorus etc..................... Most conventional waste water plants are through rivers,lakes and streams all these plants have (National POllutant Discharges Elimination System) NPDES Different types of pollutants are present in waste water are 1) BOD (Bio Chemical Oxygen Demand) 2) Ph value 3) Total suspended values 4) coliform bacteria 5) metals 6) Total dissolved solids 7) pesticides 8) Pharacetimals The Different reasons why we treat waste water treatment focused on contaminents are 1) Clean water is critical to plants and animals that live in water and drink water This is important for fishing industries,animal lifes and plants 2) All the water that is diposed into lakes and rivers used in villages for drinking so we should treat the water for removing pollutants 3) Sewage or waste water can be recycled and used for any purpose of usage of water 4) As if we dont properly treat waste water it carries so many harmful bacteria and viruses which may cause danger to health as we play and stay with water for long time (example : oceans,rivers ) 5) The chemicals and toxic acids present in water may cause various side effects to species (any species) 6) If water is not teated all the water is sent into oceans and rivers which pollute them and cause effect to aquatic and wild life 7) If the waste water is sent into lakes or ponds all the ground water in that area is polluted So we should treate waste water depending on the contaminents present in water .