Suggestions for re-treatment method for water mixed with solids and mud after coagulation and sedimentation process?

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We have a problem in a drinking water station here in Egypt for which I would appreciate suggestions about how to solve. The station treats about 70,000 cubic meter a day. After the coagulation and sedimentation processes, a lot of sludge remains in the sedimentation pool. To clean this sludge the station pumps back the sludge to a tank which is 500 meters away from  the incoming source, where about 5000 cubic meters of water is mixed with sludge every day.

We are therefore losing every day about 5000 cubic meters of water and bearing a high cost for this. I am trying to find a solution to re-treat this 5000 cubic meter water a day .

I am working with this water treatment plant and looking out for some equipment for treating water mixed with solids and mud after coagulation and sedimentation process. We need to retreat about 5000cu/m per day

Best Regards 

Mahmoud Zedan 

Answers

Comments

Dr. M.P Sukumaran  Nair
Screening to remove solids sand filtration to remove mud etc, coagulation with alum to settle colloid particles ,activated carbon to remove foul odour, and chlorination to kill micro organisms and for gaining potability.
Dr MP Sukumaran Nair
Syed Zeeshan Murtaza
Agreed with Andrew Fletcher !
Dear it seems like this system needs operational changes, however much more details and plant survey is required for a complete remedial action plan. Please find below some points and apply them if possible:
1) Increase the RAS (Return Activated Sludge) flow to aeration basin OR biological reactor (If available) to increase the age of bacteria. For example: Increase 10% flow in first step and observe for five days then 15 % to 30% gradually.
2) If any nutrient is dosed i-e DAP or UREA..check the NH4-Nitrogen and PO4 results....they should not exceed more than 1 ppm. Reduce dosing if results are higher than 1 ppm.
3) Coagulant should be dosed at outlet of aeration basin, however rapid mixing is required. If there is a degaser b/w aeration tank and secondary clarifier, dose the coagulant just before degaser for better mixing and retention time.
5) If tertiary clarification is available, dose floculant (Polymer) just before tertiary clarifier @ tertiary upstream.
6) If you have centrifuges or belt press for dewatering, conduct Sludge Volume Index SVI 30 test. Also adjust the dosing of polymer at belt press.
7) Temperature adjustment of effluent is one of the most critical points among treatment. Keep it in consideration.
I wish, if I could have the complete data.
Best regards.
Guy McGowen
There seem to be many mechanical suggestions to resolve this issue. All are practical and solid. The waste treatment facility IS the problem. Chemicals are expensive. Water is a resource. Pathogens are a reality. The waste and or sludge/slur are valuable nutrients. Your farmers are in desperate need of this . Please do not use water to make the problem worse. Do use oxygenation cycle but stop any chlorine, DO use Archaea microbes to reduce waster (organic compounds) then refit waste nutrient rich water for agricultural use. No smell, no pathogens, agricultural land or reforest. Change desert back into ag or forest. Simple solution for a hard problem. Good luck.
Andrew Fletcher
Clearly, Egypt needs to move away from aerobic treatment to anaerobic digestion where most of the solids are converted into methane gas, which could then be used to run desalination plants to convert brackish and sea water into potable water. The waste from this process would be pathogen free and contain all of the nutrients required to convert desert soil into fertile arable soil. If forests could be grown along the coastline, it is feasible that localised climate could be modified to induce additional rainfall. Egypt has planted forests and now exports timber from what was once desert, using solids and waste water for irrigation. Egypt as far as I am aware has not planted a coastal forest yet. This would need to be established along the shoreline for maximum benefits. I also believe that deserts are formed when coastal vegetation was removed by earlier civilisations, who grew grain to fuel manpower, which in turn impoverished the soils and eventually led to prolonged drought and deluge cycles.
Over the years I have corresponded with the Egyptian Embassy and other governments affected by an inherent lack of rainfall, but alas no one has taken on board these self evident truths. Andrew PS The video is a presentation I did at the House of Commons. http://youtu.be/KHhXqzk7LhE
george v
The sludge treatment is realy issue if i am not wrong. Read this apper which is sort of case study describing different ways about waste treatment fro the drinking water treatment plant WASTES FROM WATER TREATMENT PLANTS: LITERATURE REVIEW, RESULTS OF AN ILLINOIS SURVEY AND EFFECTS OF ALUM SLUDGE APPLICATION TO CROPLAND - http://www.isws.illinois.edu/pubdoc/cr/iswscr-429.pdf
Muneeb Sunna
I think the sludge pumped into the holding tank needs to be dosed with a polymer to aid its thickening, and the supernatant can be decanted and pumped back to the head of the works at 10% of the plant flow rate. The thickened sludge can be spread over drying beds and the subnatant recycled together with the supernatant as well. A jar test can be carried out to determine a suitable polymer for the thickening process. This is a common industry practice.

Hope this helps.
Good Luck
Xavier Doló Masnou
Hello, you have several options to solve the problem, no sludge turbines you move the mud with very little water, if need be can be used as fertilizer in cultivation, on the other hand, you should try to separate it from oxygenation or by decantation, or with self-cleaning filters either by gravity or by pressure, separating the solid particles depending on their size in microns, recovering the water at the end of simply add it to the main processing process, or tratala with filters in the same area, if the also add to the main process will help to dilute the sludge part, but this is all speculation, to make a good diagnosis and a good solution would need more imformation, or see the plant, we produce drinking water plants, and discard with our system this problem, because the water and produce directly without solid, but still you can help solve the problem if you give me more imformation can study the case and talk to you about some more concrete thing.

Yours truly.
Xavier Dolo
xdolo@dologroup.com
Ajmal Hussain
use morind seeds as a coagulator which will settle the mud and solid
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