They are several method of sewage collection
- Pit toilets: these method of sewage disposal is called the conservatory method in which water is flushed and the sewage send to a pit cantine of many meter deep. The pit toilet should be at least 3m deep and have a cover or a lid and cover is necessary to prevent the entring offlies and the escape of bad odours
- Drop latrines: here the feaces are drops into water or steam such latrines should be avoided as it lead to water borne disease and eutrophication.
SEWAGE TREATMENT IN A MODERN SEWAGE WALL
Sewage is a liquid wast from hores, industry which consist of feaces, urine, water and dissolve material.
In big towns and city the are 3 method use in treating sewage; the biological filter method and tricking filter system and attracted study method. Both treatment involves 3 stages.
STAGE 1:
This treatment first involve the removal of large material like hard paper, bottles, floating , solid etc are remove by screening or sedimentation. The crude of raw sewage flow via is grid screen with bars of about 19m apart in which large material are health to prevent blockage. It then passes slowly open chands whereby where small particles of stone and sand settle. The screening sewage then passes through a sedimentation over several weeks. The solid material(feaces) settle at the bottom as sludge.
Alum is added to speed up the settling process by occulaty that is causing to form tiny clumps or masses and causing to form tiny clumps or masses and which is the liquid part called offleert which remain on top. The sludge is then pump into digestion tank were bacterial decomposition act on it.
STAGE 2: BIOLOGICAL FILTER METHOD
In this method, the influent from sedimentation tank is part to a biological filter and this filter consist of a big stones are placed progressively below the smaller one. The stones become lower in the filter of algea protozoan and aerobic bacteria. The effect is sprinkle on the filter by rotating pipe. The aerobic bacteria and protozoans digest the liquid sewage.Additional oxygen is needed by this organism come from the photosynthesis off the algea.
The digested liquid is collected in an out flow-chanle and it lead to sedimentation tanks. It is then disinfected with chlorine and then return to the river. Before release into the river a test is conducted to ensure it purity.
STAGE 3: ACTIVATED SYSTEM METHOD
This method is quicker than the ASM the effluent is part into an aeratom tank where compressed air is force through the liquid and this supply sufficient oxygen from many aerobic bacteria require to decomposed the sewage, after of about 6 hours the affluent is passed to a humurs( sludge town werer some of the sludge is pump back to the aeration tank to supply bacteria within coming affluent. The remaining sludge is disposte of a biological filter method
