1. Sewage flow
Sewage flow has a great impact on the treatment results. When the dissolved air flotation machine is working, it must be ensured that the water distribution in each flotation tank is uniform. Changes in flow mean changes in the amount of pollutants, and the amount of additives needs to be changed immediately to achieve the desired results. Desirable results.
When the sewage flow rate is too large, the horizontal flow rate of the air flotation tank will be accelerated and the residence time will be reduced, which is not conducive to the floating separation of flocs; too fast flow rate will cause too much turbulence of the water flow in the separation zone, causing the flocculation combination to crack. When the water flow is too large, the position of the outlet weir should be adjusted immediately to prevent sewage from entering the scum system.
2. Dissolved gas water volume, reflux ratio and dissolved gas tank pressure
The turbidity of the dissolved gas water source should be small. The cleaner the water source, the more fully the gas will be dissolved. The reflux ratio of the dissolved gas water volume will be determined according to the specific situation.
The greater the pressure of the dissolved air water, the more fully the oxygen will be dissolved. The optimal pressure range is 4.0-5.0kg/cm2. The pressure in the container tank is controlled by the air flotation dissolved air water outlet valve. The pressure increases after closing and decreases after releasing. . If the raw water floc increases, the reflux ratio can be appropriately increased, but the pressure of the dissolved gas water must be taken into consideration; at the same time, the normal working condition of the reflux pump must be ensured.
3. The intervention of flocculant and pH value on air flotation
The higher the COD concentration of raw water, the more chemicals need to be added; the higher the concentration of suspended solids in raw water, the more chemicals need to be added. For the occurrence of flocculation, there is a proportional dosage. If it is exceeded, the flocculation effect will decline. If it exceeds a certain upper limit, it will have contradictory effects. In addition, attention should be paid to the order in which the additives are added and the appropriate ratio.
Coagulants (such as PAC) can break hydrophobic groups during the hydrolysis process, causing suspended solids and grease to flocculate with each other, and at the same time, partially dissolved proteins can be discharged as small particles.
The flocculant PAM has a large molecule size and has the functions of adsorption, bridging, connection, and sweeping. It allows the small particles initially formed under the action of the coagulant to adsorb and connect with each other, thereby forming large flocs that are quickly separated from the water. , so that under the joint action of PAC and PAM, larger flocs are formed. The wastewater needs to be added with PAC in advance and then PAM.
Most of the currently used flocculants, PAM, are acidic flocculants with a certain proportion of pH. When the pH value of the sewage exceeds the proportion, it will cause the flocculation to break, seriously affecting the working results of the dissolved air flotation machine. Therefore, during operation, the pH value of the incoming water should be monitored and controlled.
4. Frequency of mud scraping
The frequency of the mud scraper affects the amount of slag on the air flotation surface. The more slag and the lower the moisture content, which will reduce the fluidity of the sludge and block the sewage pipes. It will also make the sludge concentration in the pool too high and the viscosity too high, making it difficult to lift. Excessive scum will cause the average density to be too high, making it difficult to separate mud and water and reducing the water quality after treatment. Therefore, the scraping frequency should be adjusted according to the amount of filtered slag.
5. Cleaning of air flotation system
Since most industrial wastewater and other sewage contain excess Ca2+ and SO42-, and appropriate flotation additives are added during the air flotation process, after the dissolved air flotation machine system works for a period of time, the flotation wheel and bearings will produce a layer of Dirt will reduce the efficiency of the air flotation system. Therefore, the air flotation ramp and releaser should be regularly maintained and cleaned. Also check the condition of the release regularly to see if it is aging, and whether the pipeline is leaking or blocked.
