In the world of industrial processing, thickening is a crucial step in the dewatering process. It involves the removal of liquid from a liquid-solids slurry to yield a dewatered solids product. The process can be carried out by either centrifugation or gravity settling, and it utilizes a nonfilter device known as a thickener.
During the thickening process, the slurry enters the thickener tank, where it is settled by gravity, or agitated by a rotating impeller. The rate of the thickening process is dependent on several factors, including the concentration of solids in the slurry, the type of solids, and the initial viscosity of the liquid.
The liquid thickener is a concentrate that is added to the slurry to increase its viscosity, which in turn enhances the rate of thickening. The concentrate functions by bonding solid particles together, ultimately settling them and separating liquid from solids. The liquid thickener acts as a flocculant, creating larger and denser particles that quickly settle out.
The primary purpose of thickening is to improve the efficiency of subsequent dewatering processes, which are vital in minimizing the volume of waste and reducing the cost of disposal. The dewatering process utilizes mechanical equipment such as centrifuges, screw presses, and filter presses to remove the final traces of liquid from the dewatered solids.
Centrifugation and gravity settling offer distinct advantages in the thickening process. Gravity settling is simple, cost-effective, and reliable, but its rate of thickening can be somewhat slower than that offered by centrifugation. Centrifugation provides higher rates of concentration and de-sludging, making it ideal for sludges with high solids content. Both processes, however, require careful attention to fine-tuning for optimal efficiency.
Regardless of the thickening process used, effective dewatering is dependent on the selection of the appropriate liquid thickener. Several types of liquid thickeners are available, including natural and synthetic polymers. The choice of thickener depends on the type of solids in the slurry, the liquid viscosity, and the desired rate of thickening.
In conclusion, thickening is an essential step in the dewatering process in industrial wastewater treatment. The process results in a significant reduction in the volume of waste to be disposed of, reducing overall waste management costs. The selection of the appropriate liquid thickener plays a crucial role in the success of the dewatering process. By utilizing chemical flocculants, manufacturers can improve the rate of thickening while minimizing the volume of waste.