Excreta Disposal Flashcards
basis for human activities
life support systems
Life support systems
energy, social, built environment and geophysical aspects
Composition of human excreta
nitrogen phosphorus potassium total NPK pathogen
*inorganic pollutants in excreta
What should be the pollutants present in excreta be?
Chemical/inorganic (nutrients in urine)
Biological (pathogens, in feces)
In constructing septic tank or pit latrine, if the site is quite right (water table is quite deep), the movement of the pollutants can only be?
3m vertically and 1m laterally
How do septic tanks limit contamination of groundwater esp in hilly and mountainous areas?
Septic tanks limit the movement of water
T or F: If the source of pollution is downstream in relation to the water source, it is more likely that the water source will be contaminated compared to a upstream source of pollution
false, converse is true
Bacterial pollutants can travel up to
11 meters
Chemical pollution can travel up to
115 meters
What is DOH standard for constructing water sources
25 m away from source of pollution
What happens if the soil is not water tight?
pollutants could leach in the soil and contaminate water source
How many years before septic tank must be dislodged to maintain its proper functioning?
every 3-5 years
Mode of transmission of excreta transmitted disease
disease individual + carriers excrete bacteria, viruses, and intestinal parasites which contaminate soil, water, hands, and arthropods such as flies and roaches which all could come in contact with food and infect susceptible individual
Where does transmission of an excreted infection depend on?
→ Excreted load → Latency persistence multiplication (How long will the organism be able to survive in the outside environment? Can it multiply in the outside environment? At what temperature do the pathogenic organisms multiply *ideal = btemp*?) → Infective dose → Susceptibility of host
category of diseases which are caused by organisms that are NON-LATENT, UNABLE to multiply in the outside environment, LOW infective dose
Category I
Viruses, protozoa, Enterobius, Hymenolepis
Transmission foci of category I and II ETD
Domestic, personal contamination
*Category II: + water and crop contamination
Mode of control for category I and II ETD
→ Improve domestic water supply
→ Health education
→ Improved housing
(Cat. 2: + effective treatment prior to discharge or reuse of excreta)
Diseases caused by organisms that are NON-LATENT, with MEDIUM TO HIGH infective dose, moderately persistent, ABLE to multiply in the outside environment
Category II
*all bacteria
Diseases caused by organisms that are LATENT, VERY PERSISTENT, no multiplication, no intermediate host, can thrive in the soil
Category III
*geohelminths: ascaris, trichuris, hookworm, strongyloides
Transmission foci for Category III
yard, field and crop contamination
Control for category III and IV
→ Avoid contamination of soil
→ Treatment before land application of excreta
→ Provision of toilets
(Cat IV: + thorough cooking and meat inspection)
Diseases caused by organisms that are LATENT persistent,NEED INTERMEDIATE HOST (pig or cow)
Category IV
→ Taenia solium, Taenia saginata
Category with transmission foci of contaminated water
Category V
Category with transmission foci of yard, field and fodder contamination
Category IV
Diseases caused by organisms that are latent, persistent, able to
multiply in the outside environment, NEED ONE OR MORE INT ACQUATIC HOSTS, can only survive in water
Category V
→ All water-based helminths: Schistosoma, Clonorchis, Fasciolopsis
Method of control for category V
→ Provision of toilets
→ Treatment before discharge
→ Control of snails
→ Thorough cooking of fish and aquatic vegetation
These are insect-related diseases which are transmitted by mosquitous
Category VI
(see health impact of sanitation improvements and complimentary inputs)
(see health impact of sanitation improvements and complimentary inputs)
General considerations in disposal of excreta
- Wastes must not contaminate any drinking water supply.
- They must not give rise to public health hazard by beingnaccessible to insects, rodents or other possible vectors which may come into contact with food or drinking water.
- They must not give rise to public health hazard by being accessible to children.
- They must not violate laws or regulations governing water pollution or sewage disposal.
- They must not pollute or contaminate the waters of any bathing beach, shell-fish breeding ground, or stream used for public or domestic water-supply purposes, or for recreational purposes.
- They must not give rise to a nuisance due to odor or unsightly appearance.
Facilities in excreta disposal
Pit Latrine Conventional Pit Latrine Overhung Latrine Ventilated Improved Pit Latrine Pour-Flush toilets Septic Tank
Cheapest and most basic form of improved sanitation available wherein a huge pit is excavated on the ground
Pit latrine
- no privacy
- groundwater in the area should be deep, so it won’t get contaminated by the wastewater
a common toilet facility in remote rural areas wherein structure is made up of coconut leaves
Conventional pit latrine
pit + squatting plate + foundation + structure
What happens to waste in conventional pit latrines?
undergo decompositions, release methane gas
Disadvantages of conventional pit latrine
- smells bad and breeding area for insects
- children are afraid of falling into the pit
- excreta must be contained to avoid insect contact
Waste is being directly discharged into bodies of water
Overhung latrine
*spread of schistosomiasis
This has a vent pipe that is higher than the roof so the gasses formed inside could come out.
→ Every time you open the door, fresh air would come in.
• Also appropriate in areas where water is a problem
Ventilated improved pit latrine
Important actions in the ventilated improved pit latrine
→ Liquid portion of excreta seeps into the soil
→ Solids are broken to simpler compounds by biological digestion
→ Water is used only for hand washing or cleaning floor
What are the advantages of having a pour-flush toilet?
→ Inexpensive → Long-term solution → Use low volume water → Can be upgraded to connect to sewer → Minimum odor, insect and fly breeding → In-house location → Need small amount of water
Feature of pour-flush toilets which prevent entry of gas and insects
water seal
*tissues should not be flush becaused it clogs narrow pipes
Where are septic tanks usually seen?
areas not connected to sewers
What regulates the pressure in septic tank?
vent pipe
*pressure is generated every time the waste is flushed
What happens when the pressure in the septic tank is greater than the ambient pressure?
waste will be expelled back to the toilet
These are composed of minute particles found in bowel and are difficult to settle in septic tanks
scum
T or F: septic tanks are very efficient in removing pathogens and microorganisms
false, solids (almost 95-99%)
*Microbes can still be found in suspended solids and water output
It applies to the act of getting rid of sewage by any method
sewage disposal
*may be done with or without previous treatment of sewage
What collects all the wastewater to undergo treatment in the treatment facility?
sewer system
Type of sewerage system with interceptor tank per house and with regular emptying of vault
Settled sewerage system
Function of settled sewerage system
transport of liquid fraction of sewage through small-bore pipes: 3 to 4” laid in gardens or sidewalks
T or F: settled sewerage system have shallow excavation
true
*simple inspection units??
Advantages of a settled sewerage system
see diagram
- Being smaller in size, sewers will be economical
- No risk of stream pollution
- Quantity of sewage to be transported is small less cost.
- Cheaper since smaller pipes will be used
type of sewerage system which conveys black and gray water with 4” small-bore pipes laid in gardens or sidewalks and a self-cleaning flow
simplified sewerage system
Where are simplified sewerage system usually used?
dense areas
T or F: simplified sewerage system have deep excavation
false, NO deep excavation
Other features of simplified sewerage system
- Small or no pumping stations
* Small decentralized treatment plants
Type of sewerage system which transports gray and black water where pipes follow roads/streets wc also serves as protection against heavy traffic
Conventional Sewerage System
Other features present in Conventional Sewerage System
- Deep excavation
- Manholes give entrance to pipes
- Pumping stations
- Sewage treatment plants
What are the disadvantages of a conventional system
• Bigger sewers involve large excavation
• Dry weather flow being a small amount would result to silting up due to low velocity of flow
→ This can result to corrosion of pipes by the gas because the
wastewater is not moving
• Cost of pumping and treatment would increase due to large quantity of sewage
• Overflowing under worst condition may endanger public health
