What is the necessity of following coagulation theory in the water purification of turbid water?

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Dear friends, we are lifting water from open surface for our drinking water purpose. During the rainy season, the turbidity levels of water often exceeds 55 NTU's. Experts says the reason could be the soil erosion. We are suggested to opt for several purification treatment methods by them. I want to know which is the best method to treat the turbid water? Also I want to know what is the necessity of following coagulation theory in the water purification of turbid water and how does it helps in removing the turbidity? Your views are very much appreciated. Best. 

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12 Answers

  1. You should apply Azud disc filter (200 micron) + coagulation + sand filter + disinfection dosage. If you consider ultraviolete for disinfection you have to install cartridge filters (5 micron) before UV equipment. I advice you using PACS(polyaluminiumchloridehdroxylsulphide) for coagulatant. It does not effected high temperature in summer season and also it is so effective for dirty species under 1 microns. If you want to get more information please send me msg.

  4. It's to reduce the time necessary to precipitate the particles. Make the particles gathering and they become more heavy and the gravitational force acting on them is more important, so there precipitation velocity more important...

  5. it is important to "coagulate" or agglomerate smaller particles into larger ones so that they can settle under gravity quickly (settling rate in the clarifier) and be removed as sludge. This causes the clear water devoid of most of the suspended particles to flow through to the next step of purification. the coagulation is done effectively with inorganic coagulants like alum or ferric chloride or one can also use organic coagulants manufactured and sold by specialty chemical companies. Generally the organic coagulants have many advantages over the inorganic ones.

  6. Coagulation

    I am not sure if I understood your question but mostof the water treatment systems need coagulation which is a very important step. When you have turbid waters you should investigate the origin of this turbidity and many times it is also associated with colors problems and again in this case coagulation plays an important role in the treatment. In your case if turbidity is only due to sediments or silt a pre sedimentation can be useful but I do not believe that it will avoid coagulation step. Besides that normally coagulation is followed by other unit operations.

  7. Dear Hussein, I have researched coagulation processes and I think this document would be of help to you: http://ocw.tudelft.nl/fileadmin/ocw/courses/DrinkingWaterTreatment1/res00061/embedded/!434620436f6167756c6174696f6e2d666c6f6363756c6174696f6e.pdf

  8. U HAVE HAD ENOUGH FEED BACK Briefly when water has silt very fine particles of soil it chokes the pores of filtering media, takes longer spells to settle. coagulant increases the conglomerates size, that settles down is decanted first and can be easily filtered also. Fresh water sources rivers canals, strom water drains have this problem and it may be easier to dig a bore hole near by and pump soil filtered water.ygds

  9. handling turbidity and sediments during monsoon periods

    This is often a problem of handling turbidity and sediments during monsoon periods. Basically one should know the required volume of turbid water to be treated for use.  Several field trials are available and one should note the time required for removing turbidity with the use of conventional alum (aluminium sulphate), ferric coagulants with lime etc., however the use of those are limited in the recent times due to sludge handling and health implications. Of course coagulation method is not the only method, but relatively easier, efficient and cost effective. For household level, to be cheap,  one can adopt simple lime solution, then with bleaching & cloth filtration, eventually the settled residue to be removed . One can exercise simple options out of  their own repeated trials and be satisfied with the quality of clarified water.

  10. Hi Hussein, this is a recurring issue for surface water drawn in times of heavy rain where all manner of materials wash into the water body and increased stream levels (height & velocity) erode soft banks and introduce macrophytes. In general the best approach is to optimize the coagulant/flocculant dosing using jar testing. Apply the dose rates and simultaneously reduce the throughput/draw by half (doubling the retention time). Once you have achieved a satisfactory Turbidity result, incrementally increase the throughput over a couple of days to determine the optimum draw rate until the turbidity in the stream returns to normal. Best of luck, Ray

  11. We have found excellent results from the addition of small amounts of household strength bleach. You will have to experiment with dosage and dwell time. Another option is Moringa powder which is often locally available at little or no cost. It is a bactericide as well as a coagulant.

  12. This is the standard problem face by people who directly lift water from surface sources. What about try using poly aluminum chloride (PAC) in the place alum. Other option is to try a combination of alum and permitted coagulant/flocculants aids. the turbidity level you mention is quite high.