What do you know about Coagulation theory? Can it be applied to cleanse turbid water and is it effective for Water purification in Rural areas?


Most of the rural areas in the “Developing countries” depend on surface water such as irrigation channels or open ponds for their drinking and other domestic uses. Towards the end of the cultivation season, the water supply in the irrigation channels is occluded, the water then becomes shallow and turbid, and by the end of rainy season the remaining water in the surface which collected in surface depressions (open ponds) becomes depleted by vaporization. Both water sources ultimately become turbid and contaminated, which constitutes a hazard for rural inhabitants.

This warrants upgrading water quality through purification, decreases of turbidity, and removal of pathogens .

The turbidity of surface water is increased when rain water runs across the surface of the ground, forming open pools in surface depressions. The rain water picks up many substances such as suspension materials, collided materials, minerals, salts, organic and inorganic materials. This provides a perfect medium and adsorption site for chemicals, causing organic and biological reactions which result in aesthetically undesirable tastes and odor. Also the turbid water provides a perfect medium for the growth of all type of microorganisms and pathogens which are responsible for causing the people the majority of diseases and infection.



Hussein Ibrahim
Dear All Thanks for your answers and Comments ,,,Then I think that we need primary stilling Tanks for the coagulation process by adding some chemical that accelerate the accumulation of slitting eg. and then connected this tank with Re-washable Sand Filter for more purification , we need some such means in Rural Areas ,
Hussein Ibrahim
Dear All Thanks for your answers and Comments ,,, In some of the Rural Areas the people use some natural substance and not chemical for the Coagulation more safety , this natural materials is used to be taken from trees and it is effective ,, such as Moringha Tree ,we don't know what is the mechanism , but it helps in separating and remove the turbidity
Edwin Ricarte
First is you should know about the characteristics of your turbid water( mosly pH only ) in order to know the type of flocculant that you will need(ionic or cationic flocculants). Flocculants makes all suspended solids to adhere to each other thus the coagulated solids will have a higher density than the water which will make it separate. You can separate/decant the solids by filtration or the other means. In some cases where suspended solids are minimal, a flocculant may not be necessary and an RO system can solve the issue. No chemicals needed but a physical separation only.
Michael Orbon
It is usually used to increase effectiveness of disinfection, and not separately. Without coagulation the disinfectant is much less effective.

Have you investigated slow sand for a really really low tech application? It still requires an operator with understanding of the process, but requires no special chemicals to enhance the effectiveness. I would only use it when other options were unavailable, but it can work. Combine slow sand with leaving bottles in an ultraviolet source (sunlight) in bottles that are permiable to UV and I would feel pretty good about an improvement of two or three orders of magnitude. But always test your product!
Michael Orbon
Coagulation Theory has to do with electronic charges and attraction and repulsion of particles in suspension. It works because particles, during Brownian motion, become closer than a certain radius that determines that they will be attracted to each other. The number of collisions is related to the amount of turbidity. The concentration of particles in the effluent is what determines how safe the water is. If it is too high, the particles may either carry, or indicate the presence of, or inhibit the disinfection of protozoans and other biological agents. You can ask the question about whether it is effective in some water or another but, in the end, jar testing and sampling of the effluent is what determines effectiveness. There are polymers, cationic agents and anionic agents and even bentonite clay that I have seen work to improve the surface charge or particle density of the solution. Usually you want to try out Alum or ferric chloride for cheapness and some specialty chemical polymer for efficiency.
lyseconcept jean Marius

as I do not cease repeating it on the forums the question does not arise of knowing if one can do this or will clera with such or such device.
'turbid' water thus - soiled are they always BIOLOGICAL?
All is the question there, because if they are not any more in 'biological' state, after any unspecified treatment, that they become?
if they are in 'biological' matter it there no problem to undergo a treatment of biological purification. if they are impregnated micro pollutant chemical those Ci will be present at exit of any treatment.
I am frightened that at our time the 'Biological' characteristic is forgotten at this point. After one can do everything but which will be the consequences about it.
one proposes to me to make a treatment of the liquids 'lixitiat' of one THIS of class 2 of a volume of 500m3 day. If this liquid contains micro pollutant chemical, biology can nothing make. one proposes to me to reject the effluent in the river like that is currently done. it is already in the train of pollor in a perennial way the environment and one me porpose to continue when precisely I fight so that the ground serf more dustbin.
Francis Reilly
coagulation can remove color and suspended solids, but I'm not certain it can reliably purify water to safe drinking water quality for pathogens or contaminants other than hydrophobic ones. Additionally, the flocculant will still be present at the bottom of the water body treated. So any contaminants or pathogens will not really be removed from the system, just moved to another place in the system with the ability to be remobilized. Murky water is still useful for irrigation, and other safer techniques exists for rendering water potable.
Ademar Cesar Ferreira
It seems to be a general question. Coagulation theory is a very complex issue to be answered shortly.It is normally aplied in surface waters and even in turbid waters. It is easier to deal with turbid waters, since the system has been well designed than coloured and low turbidity waters where coagulationj shall be applied correctly.
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