Aluminum Profile Wastewater Treatment Water Reuse Equipment

Aluminum profile wastewater treatment, water reuse equipment

Waste Water Features

The aluminum profile production process mainly includes the degreasing, alkali etching, pickling, oxidation, sealing and coloring of the formed aluminum profile, and the profile after the above-mentioned process needs to be cleaned with water, and this part of the profile cleaning water is discharged in the form of overflow The cleaning tank is the main source of wastewater from the aluminum profile factory. In addition to a large amount of aluminum ions, the production wastewater from aluminum profile plants also contains some metal ions such as zinc, nickel, and copper. The pH of the wastewater varies depending on the production requirements, but most of it is acidic.

Table 1 Aluminum profile wastewater quality table

Wastewater treatment process

In view of the characteristics of aluminum profile wastewater mainly containing various metal ions and suspended solids, the process of neutralization adjustment and coagulation sedimentation is adopted.

The aluminum profile production wastewater is discharged from the workshop and flows into the neutralization adjustment tank, which is equipped with air agitation to balance the water quality. After the wastewater is balanced in the water quality and volume of the regulating tank, alkali is added to adjust the pH value to 6-9, and then pumped into the sedimentation tank, and the flocculant (PAM) is added during the pumping process. After the metal ions in the wastewater react with alkali to form hydroxides, under the action of the flocculant, they form larger particles of alum, which settle quickly under the action of gravity, and the clear liquid in the upper half of the sedimentation tank can be directly discharged.

The sludge in the sedimentation tank is concentrated in the sludge tank and pumped into the plate and frame filter press for dewatering and then used for sanitary landfill or comprehensive utilization.

Process principle

1. Regulating pool
In the treatment of aluminum profile wastewater, the tank type of the regulating tank is divided into two types: intermittent and continuous. For manual adjustment, it is necessary to divide the adjustment tank into two compartments. The retention time of the wastewater in each compartment is 1～2 h, which is used in turns and intermittently to facilitate manual adjustment; automatic adjustment only needs one compartment for the adjustment tank, and the pH automatic regulator is used to control the wastewater. pH value, due to the aluminum profile wastewater contains a large amount of aluminum, and aluminum is in an amphoteric state in the solution. When pH<3, the main form of aluminum is Al(H2O)3+6; when pH=7, aluminum hydroxide becomes the main form of Al3+; when pH>8.5, most of the aluminum hydroxide is hydrolyzed into bands Negatively charged complex anion. Therefore, the pH value must be controlled in an appropriate range during engineering commissioning so that aluminum can fully precipitate in the form of aluminum hydroxide.

2. Reaction cell
The function of the reaction tank is to make the Al3+ and OH- in the aluminum profile wastewater fully react to form the insoluble Al(OH)3 precipitation. Usually vertical flow sedimentation tanks use vortex flow reactors, and advection sedimentation tanks use baffle reactors.

3.Coagulation sedimentation tank
After the metal ions in the wastewater react with alkali in the conditioning tank, insoluble hydroxides are formed. However, because the formed particles are small and are not easy to settle under the action of water flow, flocculants must be added to make these particles bond and aggregate. Into larger particles, which are removed by solid-liquid separation in the sedimentation tank. The sedimentation tank adopts advection or vertical flow, especially the latter is the most widely used. Vertical flow sedimentation tank is particularly suitable for floc settlement, and is simple to operate, easy to manage, and the supernatant can be drained directly. The retention time of the sedimentation tank is 2h, and the surface load is 1m3/(m2·h).

4. Sludge treatment
The aluminum profile sludge discharged from the sedimentation tank has a moisture content of more than 90% and needs to be dehydrated. According to the factory's production capacity and scale of sewage disposal, two methods, natural drying and mechanical dehydration, are selected to treat the sludge. Natural drying is to use a drying tank to hold the sludge and use the sun to dry it. The advantages of this method are labor-saving and economical, but it is only suitable for enterprises with a small amount of sludge, and it is very troublesome in rainy weather; mechanical dewatering includes the use of centrifuges, belt filter presses, and plate and frame filter presses. However, due to the loose structure of aluminum sludge and its corrosiveness, only the plate and frame filter press has the best effect. Therefore, in the engineering design, the sludge is discharged from the sedimentation tank to the sludge thickening tank by static pressure, and then pumped to the plate and frame filter press after being concentrated. After treatment, the moisture content of the sludge can be reduced to about 70%, and the sludge cake can be transported or comprehensively utilized.