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www.GOALias.blogspot.com18.2 W18.2 WHATIS SEWAGEEWAGE?Sewage is wastewater released by homes,industries, hospitals, offices and otherusers. It also includes rainwater that hasrun down the street during a storm orheavy rain. The water that washes offroads and rooftops carries harmfulsubstances with it. Sewage is a liquid waste.Most of it is water, which has dissolvedand suspended impurities. Theseimpurities are called contaminants.Activity 18.2Locate an open drain near your home,school or on the roadside and inspectwater flowing through it.Record colour, odour and any otherobservation. Discuss with your friendsand your teacher and fill up thefollowing Table 18.1.We know that sewage is a complexmixture containing suspended solids,organic and inorganic impurities,nutrients, saprotrophic and diseasecausing bacteria and other microbes.Organic impurities –Human faeces,animal waste,oil, urea (urine),Table 18.1 Contaminant surveypesticides,herbicides, fruitand vegetablewaste, etc.Inorganic impurities – Nitrates,Phosphates,metals.Nutrients– Phosphorusand Nitrogen.Bacteria– Such as whichcause choleraand typhoid.Other microbes – Such as whichcause dysentery.18.3 WATERFRESHENSUP — ANEVENTFULJOURNEYIn a home or a public building generallyone set of pipes brings clean water andanother set of pipes takes awaywastewater. Imagine that we could seethrough the ground. We would see anetwork of big and small pipes, calledsewers, forming the sewerage. It is likea transport system that carries sewagefrom the point of being produced to thepoint of disposal, i.e. treatment plant.Manholes are located at every 50 mto 60 m in the sewerage, at the junctionS. No. Type of sewagePoint of originSubstances whichcontaminateAny otherremark1. Sullage water Kitchen2. Foul waste Toilets3. Trade waste Industrialand commercialorganisations221WASTEWATERSTORY221