Kinetics And Characteristics Of Organic Pollutants In Ozonation Of Printing And Dyeing Wastewater

The effect of ozone contact oxidation time on the removal efficiency of organic pollutants in printing and dyeing wastewater was studied experimentally.

The results showed that the removal efficiency of ozone to CODCr was not directly proportional to the contact time, and the reaction process could be divided into three stages, all of which belonged to first order reaction.

Also shows that single use

The degradation of organic matter in printing and dyeing wastewater is not economical and reasonable.

Printing and dyeing wastewater is one of the main sources of water pollution. It has the characteristics of high concentration, high chromaticity, complex components and poor biodegradability. It contains refractory organic matter, and the fluctuation of water quality and quantity of drainage is also fluctuating.

To achieve the effective removal of organic pollutants in such wastewater, we must make an in-depth analysis of the degradation characteristics of organic pollutants in water, grasp the distribution characteristics of water in the water, and choose the appropriate treatment technology.

Ozone is a strong oxidant that pforms complex organic matter into simple organic matter, which changes the polarity, biodegradability and toxicity of pollutants.

Under ideal conditions, most of the compounds and compounds in the wastewater can be oxidized to the highest state. Ozone treatment as a powerful, effective and economical oxidation method has been steadily increasing in the chemical oxidation process of purifying sewage.

Due to the limitation of the organic degradation process, the CODCr degradation curve fluctuated in a short time. Therefore, the kinetics of ozonation was investigated by prolonging the contact reaction time.

In the experiment, the ozone distribution was not uniform at the beginning, and the other time was regarded as saturated addition and ozone concentration was a certain value.

Therefore, according to the above formula, when reaction speed constant KM and [O3] are certain, lnctco and reaction time t should be linear.

In the first stage, the substances participating in the reaction are mainly substances that are easily oxidized by ozone. These substances have a high KM value, and ozone rapidly enters the reaction tower and reacts with them.

Completely oxidized to H2O and CO2, so the concentration of organic matter in water decreased rapidly.

In the second stage, the reaction material at this stage is mainly the products that did not react with ozone in the previous stage, and the products that were not completely oxidized by ozone at the last stage. They had lower reaction rate with ozone and smaller KM value.

Because the ozone flow rate in the reaction tower is constant, the decline of ozone consumption rate means the increase of [O3] in the reactor, so that the oxidation-reduction potential (ORP) in water also rises to a higher value. It is difficult to oxidize in water. The organic matter with high ORP value also starts to react with ozone in this new environment.

At this stage, the KM value is small and [O3] is larger, but the slope -KM[O3] is still significantly lower than that in the first stage, and the decline rate of organic matter concentration in water decreases and the duration is longer.

In the third stage, the residual organic matter in water is relatively difficult to be oxidized by ozone. The reaction rate between them is very low, and the KM value is very low. Although this time is very large, it can be regarded as saturated, but the slope -KM[O3] is still very small, nearly 0..

Ozone pair

Organic compounds are removed in a certain way, but mainly in unsaturated organic compounds. Ozone oxidizing organic matter in printing and dyeing wastewater can be divided into three stages. The indicators of residual organic pollutants in printing and dyeing wastewater are represented by CODCr. The three stages are 0~30min, 30~75min and >75min respectively, and all stages belong to first order reaction.

The kinetic equation of ozone oxidation for printing and dyeing wastewater was obtained.

The experimental results show that simply increasing the ozone contact time is not economical for removing organic matter in water. In practical application, ozone and biochemical methods should be combined with water treatment units. Ozone oxidation is used as a pretreatment to control the reaction in the first stage, improve the biodegradability of wastewater, and give full play to the advantages of each treatment unit, so as to achieve the energy saving and high efficiency of sewage treatment.