An Innovative Nanofiltration Concentrate Treatment Solution: High-Efficiency Catalytic and Oxidation Technologies Explained
Nanofiltration membrane technology is widely used in many fields, including the purification of drinking and industrial water, wastewater purification, and the concentration of valuable components in process fluids. Most nanofiltration membranes are derivatives of reverse osmosis membranes, such as cellulose acetate membranes, cellulose triacetate membranes, aromatic polyamide composite membranes and sulfonated polyethersulfone membranes. Compared with reverse osmosis, this technology operates at a significantly lower pressure and is therefore often called "low-pressure reverse osmosis" or "loose RO".
At pressures above the osmotic pressure, water molecules and a small amount of dissolved salts can pass through the selective semi-permeable membrane, while other dissolved substances, colloids, organics, bacteria and microorganisms are retained with the concentrate. This concentrate, however, carries a high pollution load and must be properly treated to meet discharge standards before being discharged.
To address the challenge of treating high-concentration nanofiltration concentrate, SINOKLE relies on its independently developed core technologies and its proprietary heterogeneous catalysts, using a combined catalytic process to significantly shorten reaction time and achieve efficient degradation of chemical oxygen demand.
CDOF (swirl ozone dissolved-air flotation) unit is the company's patented technology, integrating three technologies—multiple catalytic ozone oxidation, hydrodynamic cavitation and swirl flotation. It is the first of its kind in China and an internationally advanced integrated oxidation-flotation device. The unit can rapidly and effectively remove petroleum substances, suspended solids, colloids, COD, bacteria and other pollutants from wastewater. The system mainly consists of an oxygen generation unit, an ozone generation unit, an efficient ozone dosing unit, a multiple catalytic reaction unit and a swirl dissolved-air flotation unit.
CDOFTechnical principles
Key technical innovations of the catalyst:
(1) Uses multiple transition metal oxides (including precious metals) as catalytic components. Through extensive experiments and engineering verification, the material ratios are adjusted so that the catalyst has excellent adaptability to different wastewaters while providing high catalytic activity;
(2) Adopts multi-stage precise temperature-controlled sintering, which effectively reduces production energy consumption and the loss rate of the catalyst during use while preserving the active components, preventing secondary pollution;
(3) Uses high-activity component materials as the catalyst carrier, with a porous structure providing a high specific surface area, doped with catalytic components that are not easily lost, improving catalyst stability. The carrier has high mechanical strength and long service life.
(4) The catalyst can effectively lower the reaction activation energy, achieving deep oxidation and maximizing the removal of organic pollutants.
(5) It can accelerate the self-decomposition of ozone in water and increase the concentration of •OH generated in the water, thereby improving the ozone oxidation effect—oxidation efficiency is 2-5 times higher than ozone oxidation alone.
(6) Atomic layer deposition is used to modify the catalyst; the catalyst carrier is super hydrophilic, so the catalyst is not easily polluted, scaled or clogged and can operate over long cycles.
Selected catalyst indicators:
Laboratory test on a landfill leachate sample
Conclusion
SINOKLE's new catalyst combination can greatly degrade wastewater indicators. After ozone catalytic oxidation of the concentrate with CDOF the ozone catalytic oxidation unit, the water quality improved significantly, with a clear before-and-after comparison of water samples. The COD degradation effect is the most obvious: after combined catalytic oxidation with the new catalyst, COD can be reduced rapidly and substantially.
