Lowering Water Turbidity

[Oson]

Hello All:
I'm a Civil Engineering from a 3rd World Country, with a lot of things to do and very few resources for doing them.
I operate a Municipal drinking water Plant for 80 thousand people, our only treatment plant has a capacity for 100 l/sec, (1600 gpm) when the water turbidity is low 15 or 20 NTU maximum. The River our main water supply during more than 6 months of the year has very high turbidity up to 3000 NTU sometimes, and our Plant turns almost useless in those periods.
I need help in building an structure to lower the River turbidity before sending the water into the Plant, I have built a sand filter lagoon covering 1800 m2 of area with a filtration rate of 0.10 m per hour, which gives me about 900 gpm, but the water is still not clear enough. May I please hear some ideas, that could be within our economical reach.
I am thinking on a brick tank and putting some Alum in it.?
could it work?
Thanks for your time.

 

[bimr]

Your best option is probably to drill a well under or near the River and allow the soil to filter the water.

Mechanical clarifiers are normally used for turbidity removal because a mechanical clarifier is more economical than a large settling basin. A large settling basin is very inefficent as far as operation.