We are planning to replace drying beds with a flexible tank for storing sludge that has a dry solids content of 4% and is to be used as agricultural fertilizer.
What are the pitfalls to avoid and the tips to ensure proper operation of this type of unit?
Be careful to store only raw liquid sludge (not polymerized), or else the sludge will harden at the bottom of the tank.
Also, plan ahead so you can adequately mix the sludge, particularly when it has to be removed from the tank.
Thanks for your answer.
Actually, the idea was to inject the polymer at tank inlet to achieve dryness of about 4%.
We have no provision for mixing, apart from the fact that there will be 4 different outlets in order to alternate pumping of the sludge.
If you are talking about geotubes:
Improper injection of polymer will result in a custard-like consistency, which is difficult to deal with when the time comes to collect the sludge for spreading purposes.
This is caused by blockage of the pores, making removal of the water contained in the sludge impossible.
You want to position the geotube in such a way as to allow for sludge removal using a mechanical shovel.
In any case we tried it once and were not pleased with the result.
Ensure you have adequate vents and that they are in good working order. One of our storage tanks exploded because of the gases released during fermentation.