NFC system(New Freeze/Thaw Concentration System) is an energy saving and environmentally friendly treatment system using an ammonia absorption refrigerator whose energy source is waste heat from co-generation gas system.
The NFC system achieves high dewatering and filtration velocity just using a third of electricity for dewatering treatment.
Mechanism
Ice crystals are formed from water molecules only, so all other molecules including floc particles are rejected to get frozen by the growing ice crystal in freezing treatment. This forces the floc particles to become consolidated at the boundaries between ice crystals. After freezing is complete, the sludge is no longer a suspension of fine floc particles but a matrix of ice crystals and solid particles become the size of fine sand. When the ice cristals thaw, the particles remain consolidated and do no dissolve. The particles are large enough to easily separate solids from liquids.
The Main Feature of NFC system
NFC system uses an ammonia absorption refrigerator whose energy source is waste heat from co-generation gas system in purification plant. This refregerator uses only a quater of electlicity compared to the traditional electric compression refregerator.
The NFC system finely separates into liquid and solid at high dewatering and filtration velocity and it significantly reduces electlicity consumption for dewatering treatment.
The filter cake of freeze / thaw sludge can be efficiently utilized as soil conditioner for grounds soil as well as gardening soil.
Flow diagram
(Click this picture to enlarge)
The property of freeze/thaw sludge
The dewatering and filtration velocity of freeze/thaw sludge is approx. eight times higher than that of untreated sludge.
The dewatering and filtration velocity reaches approx. three times higher than that of untreated sludge when it is mixed with 25% of freeze/thaw sludge in summer and 50% in winter.
This photo is untreated and freeze/thaw sludge after 30 minutes settlement. It shows the good solid-liquid separation.
