Published by ADEKUNLE BROWN, CHEMIST/WATER PLANT OPERATOR at OMOTOSHO ELECTRIC ENERGY POWER PLANT(shift head)
There's a pipeline work upstream our plant and this has lead to an increase in total suspended solids of our raw water.
I am having trouble with coagulation.
I am using poly aluminum chloride as coagulant.
Raw water turbidity is 200-240 NTU.
Thanks to all the experts that contributed to this post.
Currently have been able to get the coagulation right by varying the dosing rate and the purifier inlet flow.
About jar test the company I work for have no provision for jar test. However, over the years have been able to master the characteristic of my raw water across the seasons.
The current problem may be as a result of pipeline work upstream.
Thanks.
Published by ADEKUNLE BROWN, CHEMIST/WATER PLANT OPERATOR at OMOTOSHO ELECTRIC ENERGY POWER PLANT(shift head)
I would suggest carrying out jar tests looking at different coagulants, as it could be an alternative one could be better. But also use jar tests to establish the ideal pH and coagulant dosage. Jar tests could be carried out in combination with zeta potential measurements.
Published by Dr Lisa Davies, Senior Scientist at Scottish Water
Thank you Dr Lisa.
Published by ADEKUNLE BROWN, CHEMIST/WATER PLANT OPERATOR at OMOTOSHO ELECTRIC ENERGY POWER PLANT(shift head)
Hi Brown,
I suggest you test the physicochemical properties of the water to know the coagulants that will get the job done. You can perform jar tests, for each coagulant to determine the best one and quantity to be used.
Regards
Thank you sir.
Published by ADEKUNLE BROWN, CHEMIST/WATER PLANT OPERATOR at OMOTOSHO ELECTRIC ENERGY POWER PLANT(shift head)
Try to do several jar test and see the PH. By the way your raw water turbidity is not that much high. It can happen more than 1000 NTU specially during rain season. I am advising you to do several jar tests.
Good luck
Published by Abenet Alemayehu, Senior Principal Engineer, Senior Civil Engineer, Resident Engineer at GIBB INTERNATIONAL LTD
If the work upstream has caused upsets in your process then you have to find out exactly which water analysis parameters have changed i.e is it turbidity, pH, toc? Usually, if the PAC was working well before then it should still work, only now you have to compensate for the changes in the mentioned parameters by using a polyelectrolyte to deal with the high turbidity or adjusting the pH. If the organic content of the water has significantly increased, you might need to try Ferric Chloride as your primary coag. If these strategies do not work, then you have no other choice but to redo the process of finding a new coagulant altogether by doing new jar tests with many different reagents. Good luck.
Published by Oswell Kapotsa, Regional Head - Northern Namibia at Heat Exchange Products
In agreement. pH is very important.
From where ideal coagulating activity would be between 5-&-7 pH.
Wow, thanks for this insight
Published by ADEKUNLE BROWN, CHEMIST/WATER PLANT OPERATOR at OMOTOSHO ELECTRIC ENERGY POWER PLANT(shift head)
My experience with water treatment in water with high turbidity is very good. Normally I have problems with water with high colour. Of course you have to do several jar tests to find the best coagulation dosage. pH and alkalinity are also very important factors.
I wish you good look in your trials. Best regards
Published by Ademar Cesar Ferreira, H2O Engenharia Ltda - General Director
these answers are dead on. PH is critical when you are dealing with coagulants.
Published by Tim Shrum, Pump Department Manager at Diamond Well Drilling Inc.
Whenever there is a change in raw water inflow conditions or characteristics affecting flocculation, do a batch of jar tests with different poly types and different solution, also check if pH has changed?
this should get you back on track
Published by Gary Brown, Water Practitioner at Dikubu Water
Greetings Adekunle,
What's the influent pH from this stream?
Published by Marcus Moore
@ Marcus, On the average 7.5
Published by ADEKUNLE BROWN, CHEMIST/WATER PLANT OPERATOR at OMOTOSHO ELECTRIC ENERGY POWER PLANT(shift head)
You can check a higher doses of coagulant with corelation of the optimal pH range for the coagulant and you can try to use some of floculant.
Is the high turbidity is mainly organic or inorganic mater?
Do other paramiters of raw water increased? (excepting turbidity)
Published by Bozena Mrowiec
As early, I and the other have sugested, you should test a new optimal dose of the coagulant and optimal pH value for coagulation or you should try to use another coagulant, for example aluminum sulfate, or mixture of different coagulants) and for the best flocculation you will try to use some polymer. For these necesery you should carry on laboratory tests. Good luck and good results!
Published by Bozena Mrowiec
Both organic and inorganic, the river passes through the Forrest. Only the Turbidity change.
Published by ADEKUNLE BROWN, CHEMIST/WATER PLANT OPERATOR at OMOTOSHO ELECTRIC ENERGY POWER PLANT(shift head)
Aluminium coagulant has a pH range limitation that is narrow. check ph, and do some pH correction to around 7.
Published by Julius Musiimenta, managing Director at hydraulic & Sanitation consult ltd
Maybe just pH is not right: try some Jar tests at different pHs (alkaline) and/or using different coagulants.
Published by Ing.Tiziano Zampollo, Employee at Water Engineers & Consultants - WEnCo