Water deodorization method

Summary of deodorization methods in actual water treatment system

1. Deodorization method

Deodorization method has gone through a development process, from the initial water washing method to the microbial deodorization method with better effect. Common methods include activated carbon adsorption, biological deodorization, plant liquid deodorization, high-energy ion deodorization and so on.

1. 1 activated carbon adsorption method

Activated carbon adsorption technology has been used for refining and decoloring in Chinese medicine, chemical industry and food industry for many years. Since 1970s, it has been used to treat industrial wastewater. Activated carbon adsorption has gradually become one of the main methods of odor treatment.

Activated carbon is a very fine carbon particle with a large surface area, and there are even smaller pores-capillaries in the carbon particle. This kind of capillary tube has a strong adsorption capacity, and because of the large surface area of carbon particles, it can fully contact with gas (impurities). When these gases (impurities) contact the capillary, they are adsorbed and play a purification role.

Adsorption is a slow process in which one substance adheres to the surface of another. Adsorption is an interface phenomenon, which is related to the change of surface tension and surface energy. The specific surface area and pore structure of activated carbon directly affect its adsorption capacity. When selecting activated carbon, it should be determined by experiments according to the nature of waste gas. In addition, ash also has an impact. The smaller the ash content, the better the adsorption performance. The closer the size of adsorbate molecules is to the pore size of carbon, the easier it is to be adsorbed. The concentration of adsorbate also affects the adsorption capacity of activated carbon. In a certain concentration range, the adsorption capacity increases with the increase of adsorbate concentration. In addition, temperature and pH value also have influence. The adsorption capacity decreases with the increase of temperature and increases with the decrease of pH value. Therefore, low temperature and low pH value are beneficial to the adsorption of activated carbon.

In order to deodorize effectively, activated carbon with different properties is usually used. Activated carbon for adsorbing acidic substances, activated carbon for adsorbing alkaline substances and activated carbon for adsorbing neutral substances are arranged in the adsorption tower, and the odor is discharged from the adsorption tower after contacting with various activated carbons.

Characteristics of activated carbon deodorization:

1) reaction is complete, and volatile organic compounds in waste gas can be almost completely removed;

2) The corresponding adsorbent can be selected according to the type of waste gas. At present, the commonly used adsorbents are activated carbon, activated carbon fiber, silica gel, diatomite, activated alumina, synthetic zeolite and so on.

3) For waste gas components with small gas volume and difficult treatment, such as polychlorinated biphenyls, impregnated adsorbents, such as potassium permanganate impregnated carbon, can be used to achieve the purpose of thorough purification;

4) The activated carbon adsorption regeneration cycle is short;

5) Small floor space;

1.2 biological filtration deodorization

Biological filtration deodorization system uses microbial membrane attached to the surface of fiber filler or porous filler to absorb and degrade odor molecules and convert them into nontoxic, harmless and tasteless simple molecules. Firstly, the odor is collected and transported to the humidification and heat preservation system, and then passes through the biofilter rich in microorganisms, and the treated fresh gas is discharged into the atmosphere after adsorption and degradation.

The process of biological deodorization is mainly divided into the following stages:

(1) gas-liquid diffusion stage: the chemical substances in the odor first transfer from the gas phase to the liquid phase through the gas-liquid interface of the filler;

(2) liquid-solid diffusion stage: malodorous chemicals in waste gas diffuse from liquid phase to biofilm of biological filler;

(3) Biological oxidation stage: microorganisms in the biofilm formed on the surface of the biological filler oxidize malodorous gas molecules, and at the same time, the biofilm will cause the diffusion and absorption of nutrients such as nitrogen, phosphorus and oxygen.

Through the above three stages, biological filtration converts pollutants in waste gas into carbon dioxide, water, inorganic salts and minerals, thus achieving the purpose of purifying odor.

Process characteristics:

1) has wide application range and high removal rate.

2) Convenient operation and management, less maintenance.

3) No harmful chemicals are needed, and there is no secondary pollution after treatment.

4) Low operating cost and long service life.

1.3 Deodorization with plant liquid

Deodorization of plant liquid is to extract juice from natural plants to make working liquid, and spray the atomized plant liquid in regional spaces such as sedimentation tanks and biological tanks through atomizing nozzles arranged at the edge of the tank body (or tank wall). These tiny droplets scattered in space have large specific surface area and surface energy. The liquid surface can effectively adsorb odorous molecules, change the structure of odorous molecules, weaken the chemical bonds in odorous molecules, increase their reactivity, and easily react with other molecules to generate non-toxic and odorless organic salts. For example, H2S can generate SO42- and H2O, while NH3 can generate N2 and H2O. Decompose and eliminate these volatile odors before they are emitted to the surrounding environment.

After being diluted by the automatic proportional diluter, the plant liquid is transported to the nozzles arranged in the odor control area through the atomization control equipment and pipeline system, and atomized into fine mist with the particle size of 10~40 microns, which is uniformly dispersed in the control area. After the fine mist of plant liquid comes into contact with odor molecules in the air, the odor is removed through a series of reactions such as adsorption, nucleophilic addition, catalytic oxidation and chemical combination.

technical characteristics

1) low power consumption, low energy consumption.

2) The complete set of equipment has small floor space, small pipeline diameter and flexible pipeline layout, which will not affect the operation of other facilities on site.

3) It can be applied to open or closed, semi-closed and other areas.

4) High degree of automation, fully automatic operation, no need for special personnel to be on duty.

1.4 high energy ion deodorization

Principle: The energy generated by ion tube discharge is absorbed by oxygen molecules in the air to generate "enhanced active oxygen", forming gaseous oxide mixtures such as oxygen free radicals, hydrogen free radicals, positive and negative oxygen ions (bipolar ions) and ozone. The oxide mixture has very high chemical reaction ability and is easy to combine with oxidizable substances because it absorbs high electric energy and load, and can convert pollutants such as hydrocarbons and alcohols into odorless components such as CO2 and H2O. At the same time, reactive oxygen species can also destroy the internal cell structure of microorganisms (virus, mold, yeast, bacteria) and achieve the purpose of inactivation.

Process characteristics:

1) is easy to maintain, can handle pollutants, and has the function of microbial inactivation;

2) The polluted air is not in direct contact with the oxygen ion generator, which avoids the danger of fire or even explosion caused by the contact between flammable and explosive components in the polluted air and the spark generated by the high-voltage ionization element, and objectively ensures the long service life of the oxygen ion tube, a key component in the oxygen ion generator;

3) The special design of the mixed reaction zone of waste gas and ion air makes the high-energy oxygen ion air react evenly with the polluted air, and achieves the stable and optimal treatment effect.

1.5 Several deodorization methods are as follows:

Comparison project activated carbon deodorization biological filter deodorization plant liquid deodorization high energy ion deodorization

Big investment, small investment, small investment

Operating costs are getting higher and lower.

System noise is high-high-low

The odor concentration is low-medium low-medium low-high.

Secondary pollution is getting less and less.

Small area, large area and small area

Maintenance rate is low, high and low.

Installation and debugging are simple, complex, simple and simple.

Simple operation, simple, simple, simple.

The first medium in water treatment industry