https://youtu.be/BTY-0z1hO64?feature=shared
https://youtu.be/g1tz-99eAqk?feature=shared
https://youtu.be/3DOh_rzSV7U?feature=shared
https://youtu.be/U38ahszIsQI?feature=shared
*** 04 -** Water-borne pathogens.
https://youtu.be/7fDbKDuoI8I?feature=shared
*** 06 -** What is HWTS ?
https://youtu.be/ixxEqU_UeZM?feature=shared
https://youtu.be/hwaaRgG7IUk?feature=shared
https://youtu.be/cCezUus_mZk?feature=shared
*** 08 -** WHO : UNICEF International Network on HWTS.
https://youtu.be/lfmrN-3L3uU?feature=shared
https://youtu.be/VdXCLJ9xxBY?feature=shared
*** 11 -** Sedimentation.
https://youtu.be/9-pe5UkGeBY?feature=shared
*** 12 -** Filtration : Synthetic membranes.