October 20 2019
Very recently another OST site have been commissioned, and the whole plant start working. OST, Oil Sludge Treatment plant is mainly used for recovering the oil and water from oily sludge coming from drilling site, refinery waste and other industrial oily sludge. It is more like a plant of covering asses, to fix the problems we did not take care of, the contamination we caused before. After the treatment, the recovered oil can be used as fuel or selling to get profit, recovered water and cleaned solids will have very small content of oil, which would be easily treated by further process.
GN main process is separate the liquid and solid, as we always do, and then separate the oil from water. So the main procedure as below:
1. Pre-mixing module --- the pre-mixing module is used to collect the oil sludge. Oil sludge coming from different sources is with different solid content. This will brings challenge in sludge treatment. The solid content of sludge feeding to GN separation system need to be less than 20 percentages. Thus in the mixing tank, operator need to add water to dilute the sludge, in the meanwhile, chemicals can be added here to oil de-mulsification process. 
2. Coarse solid separation module --- a shaker unit is installed in this module to remove the coarse solids in the sludge to make the solid content reduced. It will greatly reduce the working load of subsequent decanter centrifuge.
3. Two-phase separation module --- the decanter centrifuge in this module is used to remove the fine solids. But it is still a 2-phase separation for liquid (water oil mixture) and solids. The separated sludge can be sent back to mixing tank for washing again, liquid will be sent to next procedure for further treatment.
4. Three-phase separation module --- the disc stack separator is used to separate oil water and ultrafine solids. In this procedure, the sludge feeding should be solid content less than 3 percentages and solid size less than 400 microns. 
5. For transferring of the oil sludge, GN recommend the solid vacuum pump that is 100% pneumatic driving suitable for hazardous area application. GN also provide the containerized chemical dosing unit for adding chemicals into the oil sludge treatment plant.
And we do have many modular design, which based on our experiences, yet we are still open to customise, as we know all sites are different, in some way.