Unit water supply, responsibilities and the 6 principles of water purification Flashcards
What are the formation Staff’s Responsibilities?
Scales of use for personnel, vehicles and animals
Notify units of WP locations and routes of waterpoint and opening times
General distribution policy including transportation and policing
Water for fire fighting.
What are the EH Responsibilities?
Advise on suitability of water for drinking and methods of treatment
Initial and routine, bacterial and chemical testing of sources and supply
Training of CHA and CHD personnel
Advise of scale of issue in particular for climatic conditions.
What are the Royal Engineers Responsibilities?
Recce, initial field testing and development of water point
Collection of water, treatment and storage of water including protection from CBRN contamination
Construction, operation and maintenance of bulk water supply equipment
Advising formation staff on locations, availability and policy of water supply.
What are the RLC’s Responsibilities?
Transport of bulk supplies
Provision of equipment and chemicals.
What are the 6 principles of water purification?
- selection of source
- clarification
- disinfection
- contact period
- test
- de-taste
What different sources of surface water are there?
Lakes
Ponds
Reservoirs
Rivers
Streams
Canals
What are the vulnerabilities of surface water?
Surface water can be deliberately or accidentally contaminated.
What considerations are considered when looking at a potential source of surface water?
Quality
Yield
Seasonal variation
Development required (cutting back vegetation, fencing, bank/damn integrity ect.)
What different sources of ground water are there?
Artesian wells
Artesian springs (deep springs)
Land springs
Deep wells or boreholes
Shallow wells or boreholes.
What are other notable sources of water?
Source Water (Local Water Treatment Facilities)
Bottled Water
Sea Water
What are the characteristics of an ideal source?
Fast flowing large river
Oxygenated
Mountain filtered
Greater yield
Easy access
Why can flooding affect certain surface water sources?
Creates access issues to water points.
Surface runoff can cause contamination to the water source.
Damage to equipment.
What are the 2 main sources of pollution and give examples of each?
Dissolved:
Poisons
Detergents
Salts
Heavy metals
War agents
Suspended:
Leaves/twigs
Sand
Sewage, refuse
Worms
Disease causing organisms.
Why would we carry out multiple recce’s prior to identifying a water source?
Identify all potential sources in operating area
Establish suitability of potential sources
Identify sources of contamination & Identify already contaminated sources
Establish tactical/logistical suitability
Identify requirements for source development and treatment.
What are the 3 stages of carrying out a water recce?
Stage 1: Planning (Information gathering)
Stage 2: Conducting the recce
Stage 3: Testing
What is clarification?
The physical removal of suspended contaminants through filtration, settling (often aided by some form of chemical addition) or biological removal of micro-organisms.
What are the two principle methods of water clarification?
Sedimentation
Filtration
What is sedimentation?
The removal of suspended matter by gravitational action or the use of a coagulant, flocculant (flocculation) Aluminium sulphate (Alum)
What is filtration and an example?
Passing water through a filtering membrane or substance.
Millbank Bags
Stelmet Filters
Improvised Filters
What chemical can we add to increase the speed of the sedimentation process?
What does this chemical do?
Commonly Aluminium Sulphate (Alum)
Particles destabilize, aggregate and form ‘flocs’
Flocs reach a critical mass and sink to the bottom of the settler
What are the two types of sand filtration and what distinguishes them?
Slow sand filtration:
Biological process, gravity fed.
Top Schmutzdecke Layer
Fine sand
Couse sand
Gravel
Rapid sand filtration: Physical process, pressure forced
Activated charcoal
Fine sand
Gravel
What method of disinfection do we adopt and using what chemical?
Fixed Dose Chlorination: Adding a known quantity of disinfectant, to a known quantity of water, to produce a known residual content on testing after a contact period.
Calcium Hypochlorite.
What ratio do we fixed dose chlorinate?
4 grams per 50 gallons or 225 litres
What is the aimed initial dose in ppm and the ideal residual test figure in ppm?
8 initial, 5 residual.
What are the 2 contact periods and what circumstances would determine the time value to be extended?
In the military, circumstances may dictate that the contact period should be extended from 15 mins to 30 mins
30 Mins for:
Cold water (>0oC <4oC)
Suspected schistosomiases present
No check kit available.
What do we use to test the chlorination level of disinfected water?
Lovibond checkit
What do we do if the result is below 5 ppm? what could cause this?
If the result of the test indicates that there is less than 5ppm of chlorine present:
Add half the original dose
Wait a further contact period.
Test again
What could be causing the failure?
Calcium hypochlorite – out of date / incorrectly stored
Dirty water treatment equipment
What do we do if the test value is above 5 ppm?
Dilute with clarified water, wait the contact period and re-test.
When and why do we de-taste disinfected water and what do we use?
To neutralise remaining chlorine prior to consumption.
Remove unpleasant taste of chlorine.
Sodium thiosulphate pentahydrate crystals
Why do we de-taste as close to consumption as possible?
to ensure sufficient levels of chlorine are present to protect the integrity of the water from further contamination.
Like the addition of calcium hypochlorite we add the de-taste (de-chlorination) as a fixed dose, what is the ratio?
2 grams of sodium thiosulphate pentahydrate crystals per 225 litres/50 gallons of water.
