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SAI INTERNATIONAL SCHOOL
                                                        STD-VII

                                            SUBJECT - CHEMISTRY
                                TOPIC-MANAGEMENT OF WASTE WATER
                   SUB TOPIC-ALTERNATIVE METHOD OF SEWAGE DISPERSAL

                                                           LESSON NOTE



               Alternative method of sewage disposal:-




               Septic Tank: -





                                                                         A septic tank is simply a big
                                                                         concrete or steel tank. Waste
                                                                         water flow into the tank at one
                                                                         and treated water leaves the
                                                                         tank at the other.









               Vermicomposting: -
                                                                      Vermicomposting is a method in
                                                                      which worms, usually red wigglers,
                                                                      white worms, earthworms are used
                                                                      to decompose vegetables or food
                                                                      waste other than meat, dairy
                                                                      products and fats or to and produce
                                                                      manure. Vermicast is the end
                                                                      product of breakdown of organic
                                                                      matter by worms. Vermicompost
                                                                      formed contains water soluble

                                                                      nutrients and can be used as an
                                                                      organic matter.







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