Recently, KWI, the subsidiary of SafBon, took a 100,000 t/d advanced phosphorus removal upgrading project for sewage treatment plant in Xinjiang Province. This is the first large-scale advanced dephosphorization project for sewage treatment plant which applied dissolved air flotation (DAF) technology in China after KWI acquired by SafBon. It is laying a solid foundation for the promotion and application of KWI DAF in the municipal industry. At present, the project is under construction and is expected moving to operation stage in February next year.

The project applied four KWI-patented "U"-type MCH-100 DAF devices, which are equipped with KWI's third-generation patented high-efficiency dissolved gas reactor (ADR). A single DAF device is designed has 1,000m3/h processing capacity, its designed hydraulic load is 30m3/m2h, and the designed hydraulic retention time is <15min. The DAF is able to treat influent with 0.5-1mg/L total phosphorus while the effluent quality is designed with the total phosphorus ≤0.3mg/L and the suspended solids (SS) ≤10mg/L. The DAF and the ADR are made of SS316L stainless steel. The size of a single device ia: 12m (L) × 5m (W) × 3.5m (H). The entire project footprint is 35m × 15m. This project shows strong advantages of the KWI DAF, especially the small footprint and high efficiency.

The "U"-type MCH-100 DAF devices is KWI's newly developed rectangular air flotation equipment, which adopts the unique patented "U-shaped board" design concept. The principle is as shown in the figure. The raw water enters from the bottom of the DAF. Due to the special structure of “U-shaped plate” arranged horizontally, the water flows up along the outer side of the “U-shaped plate” and flows along the inside of the “U-shaped plate” to the clear water outlet. During this up and down flow, the contact time between the bubbles and the suspended particles is increased invisibly, and the coagulation flocculation effect of the particles is enhanced, and the microbubbles in the dissolved gas can quickly adhere to the suspended particles. Surface and drag it to the surface of the air bearing area. With such special design, the MCH-100 DAF devices obtains a high hydraulic load of 30 m/h, which greatly reduces the footprint of the floatation tank.

"U-Shaped Board" Design Conceptual Diagram

MCH DAF Devices

The Patented ADR

Main advantages:

1. Up to 99% dissolved gas efficiency;

2. Stable micro-bubble particle size, which is not easy to be broken during the decompression release process, and at the same time can ensure a high rising flow rate;

3. The pressured gas is released directly through the pressure relief valve, does not require any auxiliary microporous release and dissolved gas release device. There is no clogging caused by corrosion and scaling, which will result in a decrease of the dissolved gas efficiency.

The Effects of KWI DAF

Because of the patent features of KWI DAF, its application is not limited to the traditional solid-liquid separation field. In addition to the application of deep dephosphorization in wastewater, KWI DAF is still used in the following applications with unique advantages:

1. For seawater desalination pretreatment and tap water: algae removal, removal rate 99%;

2. Residual biochemical sludge concentration: The concentration of concentrated sludge is up to 5%;

3. Clarification of filter backwash: the suspended solids of the effluent <10mg/L. Effectively tapping the processing capacity of existing sewage plants;

4. Oil Removal from oily sewage: oil content of effluent ≤ 5mg/L;

5. Fiber recycling in paper industry: Recycling of papermaking fibers without adding drugs;

6. Advanced sewage dephosphorization: Reducing total phosphorus from 0.5mg/L to <0.1mg/L

7. Concentration and clarification of sludge water in the water plant: suspended solids content of effluent <30mg/L, concentration of concentrated sludge >3%.

KWI DAF Series Devices

Based on the applications mentioned above, we have reason to believe that SafBon-KWI DAF will break people's limited understanding of traditional DAF with its unique advantages, and achieve international leading in the field of solid-liquid separation in various industries in China.