Sanitation Systems for Rural Areas Flashcards
1
Q
Initial considerations for sanitation systems:
A
- if people don’t have access to a good sanitation facility, their health will be at risk
- the effective management of human excreta to protect peoples’ health, requires that it is collected and stored safely, completely serperated from human contact
- population density in rural areas is usually low
- on-site treatment is usually possible in rural areas
2
Q
Routes for faeco-oral transmission:
A
Routes from faeces to new host:
- fluids
- fields
- food
- flies
- fingers
3
Q
Characteristics of an arborloo:
A
- A shallow pit latrine which is used for 6-12 months
- often most suitable ystem in dispersed rural areas
- After each time the latrine is used, soil, ash or leaves are added to the pit
- When the pit is full to within ~20cm of ground surface, the latrine superstructure is placed over a new pit
- the full pit is covered with soil and a tree planted in it
4
Q
Characteristics of a single-pit ventilated improved pit (VIP) latrine
A
- the superstructure is slightly off-set from the pit to permit the installation of a vertical vent pipe which is fitted with a fly screen at its top
- the vent pipe has two functions: odour control and fly control
- the wind blowing across the top of the vent pipe sucks air out of the vent pipe and out of the superstructure
- the faeces slowly decompose in the pit and the urine and any water infiltrate into the surrounding soil
- designed for a effective life of 10 years
- typically 1-1.5 m diameter, 3 m depth, 100-150 mm vent pipe diameter
- the cover slab is raised 300 mm above ground level if the groundwater table is within 300 mm of ground level, either permanently or seasonally
5
Q
Advantages of single-pit ventilated improved pit (VIP) latrine
A
- low cost
- can be built by householder
- needs no water
- easily understood
- control of flies
- absence of smell in latrines
6
Q
Disadvantages of single-pit ventilated improved pit (VIP) latrines
A
- does not control mosquito
- extra cost of providing vent pipe
- need to keep interior dark
7
Q
Characteristics of single-pit pour-flush (PF) toilets
A
- squat-pans or pedestal-seat units with an integral water seal are used, depending on user’s preference
- the water seal prevents insects and odours from the leach pit entering the superstructure
- the excreta are manually flushed with 2-3 L of water into an underneath or adjacent leach pit
- the leach pit is always lined to prevent soil erosion
- normally designed for an effective life of 10 years
- must be designed for both solids storage and for the infiltration of the latrine flush-water
- infiltration rate depends on the soil type
8
Q
Advantages of a single-pit pour-flush (PF) toilets:
A
- low cost
- control of flies and mosquitos
- absence of smell in latrine
- contents of pit not visible
- gives user the convenience of a WC
- latrine can be in house
- can be upgraded by connection to sewer
9
Q
Disadvantages of a single-pit pour-flush (PF) toilet
A
- a reliable water supply must be available
- unsuitable to dispose of solid anal cleansing material if used
10
Q
Characteristics of eThekwini latrines
A
- developed in SA
- urine diverting alternating twin-vault ventilated improved vault latrines
- above ground and comprise two seperately ventilated vaults which receive only faces and anal cleansing materials
- the urine, diverted in a specially designed toilet bowl or squat plat is discharged into a small adjacent soakway
- operation follows a sequence of alternaing vaut usage with each vault being used for 12 months
11
Q
Advantages of eThekwini latrines
A
- urine seperation keeps the vault contents from becoming too wet, so they can dehydrate easily
- treated excreta can be used as a fertiliser
- easier to empty compared to the VIP latrines
- a valuable humus is produced
12
Q
Anaerobic digestion:
A
a collection of process by which microorganisms breakdown biodegradable material.
13
Q
Disadvantages of eThekwini toilets
A
- careful operation is essential
- urine has to be collected separately
- regular addition of ash or vegetable matter may be needed.
14
Q
Characteristics of alternating twin-pit PF toilets:
A
- two leach pits are operated in the same alternating sequence as the twin vault in the eThekwini latrines
- the excreta are flushed into the leach pit in use via a flow-diversion box
- each leach pit normally used for two years to ensure that all pathogens, with the exception of a few Ascaris eggs, are dead so permitting safe manual emptying
- possible because the infiltrative capacity of the sidewall restores while each pit is not in use.
15
Q
Characteristics of a biogas toilet
A
- excreta are discharged into a small anaerobic digestor from which the biogas is collected and used for cooking and/or lighting
- to increase biogas yield, animal excreta are also often added to the digester
- at intervals of 1-2 years the digester is desludged
