low cost water treatment

1. Low Cost Water Treatment

2. WATER TREATMENT
The goal of every water supply system is the provision of a sufficient quantity of good
quality water. An adequate quantity and quality are essential prerequisite for public health.
Diseases : scabies and trachoma- may be prevalent in areas with insufficient Water
supply, preventing good personal hygiene,
: typhoid, Cholera and gastro enteritis may be transmitted through
Contaminated Water.
While Water supply is dependent on the local situation and is often limited by scarce natural
resources,
Water quality can be improved by appropriate Water treatment processes.
The main goal of any Water treatment process- is the removal of disease- causing organisms
(pathogens)
i.e. bacteria, viruses, protozoan cysts and worm eggs.
However, Water treatment requires special expertise in installation, design and operation,

3. Water – classification and Treatment
The origin of all sources of water is rainfall. Rainfall water, surface water, ground water.
1. Rain Water – Collected from roofs or prepared catchment for storage in small or big
reservoirs is soft, saturated with O2 and Corrosive. M.O. from air, collecting reservoirs are
liable to Contamination.
2. Surface Water
A- Natural Quiescent waters as in Lakes and ponds Uniform quality than streams,
Long storage permits sedimentation of suspended matter, bleaching of color & removal of
bacteria.
Self purification – less in smaller lakes.
If catchment is protected and unerodible, The stored Water may not require any treatment other
than disinfection.

4. b- Artificial Quiescent Waters as in Impounded
Reservoirs.
Same is as natural lakes and ponds.
Top layers- may develop algae,
Bottom layers- high turbidity, CO2, Fe, Mn
C- Flowing waters as in Rivers, other natural Courses
and Irrigation Canals.
More variable is quality and less satisfactory.
Quality depends on Watershed, geology and topoggraphy
Substantial Variations in quality – maximum flows. In
populated regions – pollution – sewage & aid wastes.
The natural and manmade pollution – Color, turbidity,
tastes & odors, hardness, bacterial & other M.O. and
hence treated properly before supply

5. D- Sea Water
3.5% salts in solution
Off shore Waters – 30,000-36,000 mg/l D.S.
Demineralising – separation of salts or Water.
Very costly. Only adopted When unavoidable.
E- Wastewater Reclamation
Sewage or other waste waters of community-
May be used for – Cooling, flushing, lawns, parks.
After necessary treatment – for fire fighting & for certain
industrial purposes.

6. Ground Water
Rain Water percolating Through ground.
Beyond the reach of Vegetation.
Chemical characteristics representative of the state it passes
Through.
In limestone formations – Very hard, deposit in pipes, and
relatively non-corrosive.
In granite formations – soft, low indissolve minerals, relatively
high in CO2 & actively corrosive.
Uniform quality but changes due to Water logging, over-draft from
areas adjoining saline Water sources and recycling of water applied
for irrigation and pollution.
Spring
Due to emergence of ground water to the surface. Shallow strate
spring – may have surface pollution. Prennial or intermittent
Discharge depends on the nature & size of catchment, recharrge
and leakage Through the sub-surface.

7. And should be avoided whenever alternative, better quality
Water sources are available.
The removal of toxic substances or the reduction of high
mineral or organic con.s generally requires advanced, costly
treatment processes which are often not feasible in rural
areas.
In such situations, the use of alternative, better quality water
source is recommended, if feasible in terms of technical and
economical factors.
Water treatment should be avoided whenever possible, if
better Water quality sources such as springs, groundwater,
or rainwater are available.

8. Alternative Water Sources
Ground Water – normally safe for Consumption provided the
installations are (i.e. spring catchment and deep or shallow wells)
properly located, Constructed and maintained
Rain Water– from roof catchments will also yield safe drinking Water.
With respect to Water quality
Surface water is the least desirable option for a water source.
Surface water is unprotected and constantly exposed to possible
contamination.
Water drawn from rivers, irrigation canals, ponds, and lakes must
normally be treated before use, especially when contaminated by
people and/or animals.
Water treatment, at least for bacteriological improvement, is generally
necessary When surface water is used as a raw water source.

9. WATER QUALITY
Drinking Water should meet the following basic Water quality requirements:
• No pathogenic organisms.
• Free of substances of acute toxicity (long orshort term).
• Offer a pleasant appearance ; taste and odor free,
• Not stain textiles or other materials,
• Not cause Corrosion or encrustation of the water supply conduits, strucyures,
installations.
Guidelines for Drinking Water Quality
Parameter Unit Highest Desirable Level Max. permissible Level
Coliform Colony/100ml - 10
E. Coli Colony/100ml - 2.5
Turbidity NTU 5 25
Color mgPt/l 5 50
Iron mg/l 0.1 1.0
Maganese mg/l 0.05 0.5

10. Treatment
Design, operation, and maintenance of rural water treatment processes are generally
the most difficult Tasks in a rural water supply system.
The most appropriate treatment process(es) must be chosen from a Variety of
methods.
The selected process should conform to the following basic requirements for rural
Water treatment:
• Installation should be simple, robust and durable.
• Treatment should be efficient and reliable.
• Use of mechanical equipment should be minimum.
• Use of chemicals should be avoided, if possible.
• Operation and maintenance of the treatment plant should be fully sustained by the
local community.
• Treatment system should require participation and approval of the users.
• Costs (especially those for operation & maintenance) should be low.
Basic requirements for rural water treatment are best met by the use of
physical and biological treatment processes. Chemical processes should be used
only if no alternative Water source or treatment process is available.

11. Upward-flow Sand Filters
Considerable experimental work has been carried out on upward-flow
sand filters. In these, raw water is introduced into a gravel layer
supporting a bed of coarse 3-4 mm sand about 30 cm deep. In its
passage upwards, coarse suspended matter is retained in the lower part
of the sand bed and finer material is progressively removed by the
upper layers. The Through-put must be restricted to prevent lifting of
the sand. With most raw water rates of 500 to 1500 l/m3 per hour
effect a significant improvement in quality and there is evidence that
some biological activity is able to take place. The action is therefore a
compromise between the mechanical action of rapid filter and the
biological and mechanical action of slow filter. The major advantages
offered by the upward-flow sand filter are, firstly simplicity of
construction, secondly, ease of cleaning. It has been found that
accumulated suspended matter may be removed by simply stopping
the input of raw water and rapidly lowering the level of water above
the bed by

17. Single pot with holes in the middle
12-15 liters capacity
3/2 Kg of bleaching powder and 3 Kg of coarse sand (in the range of 1.4 to 1.6 mm)
Of 9000-13000 liters Water content having a withdrawal rate of 900-1300 litres/day
(40-60 people/day) for a period of at least one week giving chlorine residuals in the
range of 0.2 to 0.8 ppm.
7 to 10 liters capacity. Six to eight holes of 0.6 cm diameter are made in the bottom
of the pot.
2 to 4 cm size.
A dry mixture of 1.5 Kg of bleaching powder and 3 Kg of sand is placed over the
gravel.
Addition of sodium hexametaphosphate (75 gms or 5 per cent of bleaching powder).
With community wells of 9000 to 13000 litres content and daily draw off rates of
900 to 1300 litres (40-60 people/day), one pot is enough to give required
chlorination (0.2 to 1.0 ppm).