Chang Zhihui: How To Deal With Tannery Wastewater Treatment

China is a big tanning country, and China's leather production ranks first in the world.

At the same time, China's tanning industry has also brought serious pollution to the environment and has a negative impact on people's lives.

With the further strictness of environmental regulations and the enhancement of people's awareness of environmental protection, the environment of leather making industry is reduced.

To strengthen the treatment of tannery wastewater has become a top priority.

Tannery wastewater contains a lot of harmful substances such as protein, dye, grease, sulphide, chromate and wool residue. [1] it is difficult to control and is a kind of industrial wastewater which is difficult to handle.

The oxidation of potassium ferrate in six valence iron is very strong, and the decomposition product iron hydroxide colloid is highly effective adsorption flocculant. In the process of dealing with drinking water source and waste water, it does not produce any carcinogenic carcinogenic substance. It has high safety [2], is known as "environment-friendly oxidant" [3].

In our previous work, we found that the effect of Potassium Ferrate on wastewater treatment was not very satisfactory when used less (4).

However, due to the high cost of potassium ferrate and increasing the input of potassium ferrate, the cost of wastewater treatment will be greatly increased. For this reason, we have studied the application of potassium ferrate / poly ferric sulfate combined technology in the treatment of tannery wastewater, so as to explore the way to achieve the discharge standard of waste water at the least cost.

The effect of potassium ferrate / polyferric sulfate combined technology on tannery comprehensive wastewater treatment was studied. Beaker coagulation experiment was used in the experiment.

First, tannery wastewater was adjusted to pH to 3 to 5. The potassium ferrate was added to the beaker containing tannery wastewater, stirring for 3 min, then adjusting the wastewater pH to 7 to 8, adding 50 mg/L (effective component was iron), polymerizing ferric sulfate, stirring 5 min, settling 2 h.

Using the pipette to remove the liquid accurately, the sulfide, COD, turbidity, chroma and Cr3+ content were measured respectively.

Potassium ferrate processing

When comprehensive wastewater is used, first of all, the six price iron is strong.

The oxidizing wastewater can be oxidized, and then the reduced product Fe3+ produces flocculation Fe (OH) 3 during the process of adjusting pH. The new Fe (OH) 3 has better polyphasic flocculation function and further purify the wastewater (5).

However, the production cost of potassium ferrate is relatively high, and the excessive use of wastewater will increase the cost burden for wastewater treatment. Considering the cost, we take the relatively inexpensive poly ferric sulfate as an auxiliary wastewater treatment agent.

In the process of experiment, we used potassium ferrate / poly ferric sulfate combined technology. First of all, in pH weak acid wastewater, potassium ferrate exerts strong oxidation, then adjusted the pH of waste water and added polyferric sulfate to make the newly generated Fe3+ and Polyferric sulphate simultaneously flocculating, thus removing pollutants.