18.Sewage Treatment

Assoonasearlypeoplesestablishedsettlementtheyhadtheproblemofgettingridofsewage——theirorganicwastesand,sometimes,thoseofdomesticanimals.Naturedisposesofsurplusorganicmaterialinfourprincipalwaysbydilution,oxidation,putrefaction,andfiltration.Earlypeoplesrel ......     (本文共 5829 字 )     [阅读本文]>>




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