Advantages of Ceramic Membrane in Oil Removal in Coking Residual Ammonia Wastewater

The sewage generated in the gas purification process accounts for more than 80% of the total coking sewage. The treatment of residual ammonia water is an important process of coke oven gas purification, which contains harmful impurities such as coal tar, phenol, ammonia, hydrogen cyanide, and hydrogen sulfide, and a small number of germanium compounds. It is the main source of wastewater from the coking industry. Coking industrial wastewater needs to be pretreated before treatment, so the removal of residual ammonia is an important link.

The hazards of residual ammonia:

1. The content of tar substances is too high, and the solvent method will produce emulsion when removing phenol. The efficiency of dephenolization decreases and solvent consumption increases and steam dephenolization can block equipment. When entering the biochemical device, it will also increase the burden of the biochemical system, inhibit microbial activity, and affect the wastewater treatment effect.

2. Due to the high oil content of the remaining ammonia water, the equipment in the gas purification system will be seriously blocked. Especially the heat exchanger and ammonia distillation tower shorten the service life of the equipment, increase the production cost, and deteriorate the gas purification index.

3. The tar substances in the residual ammonia water directly enter the surface water, which will cause water eutrophication and seriously deteriorate the water environment. It also brings great harm to agriculture, fisheries, and people's health.

Ceramic membrane technology:

A ceramic membrane is a porous asymmetric membrane made of aluminum oxide, titanium oxide, zirconium oxide, and other materials through a special process. Ceramic membrane filtration is a fluid separation process in the form of "cross-flow filtration". Driven by the pressure, the raw material liquid flows in the membrane tube, small molecules permeate the membrane, and the concentrated liquid containing macromolecular components is retained by the membrane so that the fluid can achieve the purpose of separation, concentration, and purification. The filtration accuracy of ceramic membrane covers microfiltration and ultrafiltration, and the filtration pore size of the microfiltration membrane ranges from 0.05μm to 1.4μm. The filtration accuracy of ultrafiltration membranes can range from 10KDa to 50KDa. The membranes with different pore diameters can be selected according to the viscosity of the material and the content of suspended matter to achieve the purpose of clarification and separation.

The inorganic ceramic membrane has the characteristics of high-temperature resistance, chemical corrosion resistance, high mechanical strength, strong antimicrobial ability, large penetration, strong cleanability, narrow pore size distribution, good separation performance, and long service life. Currently, it has been successfully applied in the separation process of chemical and petrochemical, food, biology, and medicine.

The ceramic membrane has strong oleophobicity, and the oil penetration concentration is very low. Therefore, ceramic membranes have outstanding advantages in oily wastewater, which are manifested in high membrane flux, long service life, and relatively loose requirements for membrane pore size. The remaining ammonia water is very corrosive, but the ceramic membrane has good corrosion properties.

Principle of ceramic membrane filtration:

The remaining ammonia water is pumped into the heat exchanger and then into the ceramic membrane filter. The upper part of the filter is a light oil, the middle part is the filtered ammonia water, and the lower part is equipped with tar and backwash water outlets. Steam and clean water are used for the backwashing of the ceramic membrane filter and the regeneration rinse is discharged into the clarifier.

Advantages of ceramic membrane technology:

1. The oil removal effect of ceramic membrane filter is obvious.

2. The remaining ammonia water is highly corrosive, but the ceramic membrane filter shows good corrosion resistance during the experiment.

3. The oil-water separation process is simple. The ceramic membrane filter combines the traditional filter tank and tank into a complete filter device, which is easy to operate and maintain.

4. Good backwashing effect, short consumption time, and easy control.

5. The ceramic membrane filtration equipment has a simple structure, small floor space, less supporting equipment, convenient installation, easy to insert into the existing production process system, expansion, and increase of component capacity without worrying about the technical difficulties caused by this.

6. The ceramic membrane filter has a long service life.