It is very strange that China even have more strict environmental requirement on the dredging field than all over the world, on the waste solids disposal and also the fluid dump, no matter how it have been applied on field, in paper it is really advanced. So basically when the oil market is down, we get a chance there, some client in dredging field said. Just like you have done in waste management field. Also we have realised that not only china all over the world, people are taking more care on the environmental protection. For dredging, what we need is:
Recycle the cleaner fluids.
Dump and reuse as much as possible on the solids.

Not like the oil gas drilling, from the pond, or from the river, from sea, there are sands, rocks, and other things as you can imagine which have been buried in it. So the separation seems very different. Except the basic concepts.

Separate the biggest particles and other stuff other than the sands and silts. There are many ways to do this, one is dig another pit / pond, with at big screen from where dredging pump feeds, let the screen separate unreasonable parts to the pond, keep them away from the progress. Another way is gumbo box, it is quite same as the mining applications, to separate the biggest rocks from the first step, then others feeding directly to the shale shaker.

Then directly, or by another pump from the pond. The feeding goes to the double deck shaker. In GN, it is GNZS706E, which is good to separate the bigger sands and the most of the bigger solids. going through two sieves.

Catched by the pump, feeding to the cyclones, to get the silts separated.
Then in the same way, separated by the decanter centrifuge. 

Sometimes it also need help from chemicals that why a flocculent unit is there. To concentric the small particles to be bigger ones, then easier to be separated.

Kindly contact GN for a full solution.