Chapter 4 - Sewage Disposal System

types of sewage disposal system

cesspool, privy, septic tank, public sewer line

hole in the ground curbed with stones, bricks, concrete hollow blocks

allow raw contaminated sewage to leach into the soil

cesspool

concrete sealed vault with a wooden shelter constructed for the collection of raw sewage.

objectionable due to danger of contaminating the source of water supply

privy

device or receptacle used to expedite the decomposition of the elements contained in raw sewage waste

prevailing type

septic tank

public sewage system operated by the government consisting of a sewage treatment plant that conveys the raw sewage from buildings to a disposal system

prevailing type

public sewer line

public sewer line classification

combination public sewer, sanitary sewer, storm drain

oldest type, conveys both storm water and sanitary wastes.

obsolete and no longer allowed

combination public sewer

public sewer facility that carries regular sanitary waste only

terminates in modern sewage dispersal plant

rainwater is not permitted

sanitary sewer

sanitary sewer two classification:

intercepting or trunk line, tributary or contributing

sanitary sewer, conveys sanitary waste to a dispersal plant

made of concrete pipe 0.6 to 3 m diameter

min depth of 3 m

intercepting sewer

an intercepting sewer branch

made of vitrified clay or concrete pipe

installed not more than 3 meters below street grade

tributary sewer

public sewer line that carries storm water

terminates in canals, lakes, river

storm drain

man’s access for inspection, cleaning and repair

interval of 75 to 150 m

diameter” 90 to 120 cm

manhole

pump that will discharge waste in the sump and transfer it to the house drain installed overhead

sewage ejector

suspended solid of the sewage is removed to form a semi-liquid substance

accumulates at the bottom of the septic tank

sludge

parts of the solids are formed into floating _

scum

both scum and sludge are processed by anaerobic bacteria, transforming then into liquid and gases

digestion

bacteria lives in the presence of material oxygeb

aerobic

bacteria lives in the absence of free oxygen

anaerobic

bacteria functions even with or without free oxygen

facultative

process of decomposition

stabilization

decomposition caused by anaerobic bacteria, accompanied by bad odors

putrefaction

sewage that turns dark and smell unpleasant due to anaerobic decomposition is called

septic

principal component of natural gas

methane gas co4

simplest oxide of carbon

carbon dioxide co2

by-product of methane, poisonous

carbon monoxide co

evolves as a moist gas from organic waste

hydrogen h2

colorless gas with offensive odor

hydrogen sulfide h2s

colorless gas having an irritating odor

sulfur dioxide ho2

two most popular and widely used material for constructionn of septic tank are

plastered concrete hollow blocks, reinforced concrete

minimum dimensions of septic tank: wide cm x long cm x depth cm

90, 150, 120