Industrial Process Of Printing And Dyeing Wastewater

The conventional treatment of printing and dyeing wastewater is generally divided into biochemical + physicochemical and physicochemical + biochemical two types of treatment process?

But because of the lack of hydrolytic acidizing units?

Is there not enough aerobic biochemical unit reaction in the actual operation?

The problem that leads to the high cost of subsequent physicochemical treatment.

A "hydrolytic + aerobic" tandem process to add hydrolytic acidification in front of a traditional aerobic biological treatment unit?

Can make printing and dyeing wastewater difficult to degrade the organic matter hydrolysis?

To produce more biodegradable substances?

Improving the biodegradability of wastewater?

Thus improve the COD removal rate of the traditional process.

Many new printing and dyeing wastewater treatment equipment (including domestic sewage and dyeing wastewater treatment) are developed by the process of "hydrolysis and aerobic" biological treatment process?

Significant environmental and economic benefits have been achieved.

The four processes of printing and dyeing process have wastewater discharge, ferrous sulfate pretreatment stage (including singeing, desizing, refining, bleaching, mercerizing and other processes) from the desizing wastewater, refining wastewater, bleaching wastewater, mercerizing wastewater;

Dyeing wastewater from the dyeing process;

Printing wastewater and soap wastewater from printing process;

The finishing wastewater from the finishing process.

Printing and dyeing wastewater is the mixed wastewater of the above-mentioned types of wastewater, or in addition to bleaching wastewater comprehensive wastewater.

The anaerobic hydrolysis

Dye is a kind of difficult to degrade synthetic organic matter, its molecular structure mainly contains difficult to biodegrade electron attractor group - azo group and so on.

If the attractor electron substituents on the molecular structure can be removed, and the electron double chain can be broken, the subsequent biodegradation will be easy, and the dye molecules also lose the hair color group.

Hydrolysis acidification degrades organic matter of dyes and decolorization mechanism lies in the use of hydrolysis acidification microorganisms enzymatic action to break the azo group electron double chain.

This biodegradation process requires the participation of multiple enzymes.

In the process of hydrolysis, the bacteria of Pseudomonas, Aeromonas and Helicobacter have better decolorization ability.

The decolorization ability of the mixed bacteria was higher than that of the individual bacteria, and the mixed bacteria depended on the synergistic effect, which made the degradation of dyes more complete and decolorization more thorough.

Hydrolysis acidification process was used in the buffer, to reduce the pH of raw sewage, to increase the proportion of soluble COD in wastewater, so as to improve the COD removal efficiency of subsequent aerobic treatment, at the same time can also buffer, adjust the possibility of impact load effect, the prevention and overcoming the follow-up activated sludge process may occur in the process of handling or filamentous sludge bulking bacterium excessive growth, enhance treatment system running stability and reliability.

Coagulation air floatation

Dyeing wastewater biodegradability is poor, only rely on biochemical treatment generally difficult to meet the discharge requirements.

In order to ensure that the final effluent is stable and discharged to the standard, and to prevent the occurrence of accidents in the biochemical system, a physicochemical process is added after the biochemical system.

By adding coagulants or decolorizers, the residual chromaticity in the wastewater can be removed. In addition, the colloidal substance can be converted to suspended matter and separated from the water along with the remaining smaller and lighter suspended matter in the wastewater.

In addition, the metabolites of some bacteria can be removed to ensure the best treatment effect.

There are two kinds of separation after adding coagulant, namely precipitation and gas floatation, in which the pressurized dissolved gas floatation has a better decolorization effect for the treatment of dyeing wastewater.

In addition, as the separation capacity of air floating is about 4-5 times of that of precipitation, the area of separation zone can be greatly reduced, a large amount of investment can be saved, and the separation effect is stable and not affected by the external environment, so the pressure dissolved air floating method is chosen as the physicochemical treatment measure.