Ammonia nitrogen stripping tower for waste water treatment

1. gas liquid balance and mass transfer speed theory 2. material: stainless steel, carbon steel 3. Ammonia nitrogen stripping

Ammonia nitrogen stripping tower for waste water treatment

 

I.Overview

High concentrations of ammonia nitrogen wastewater widely and emissions source. Such as chemical fertilizers, coking, petrochemical industry, pharmacy, food, landfill are produced a great number of high concentration of ammonia nitrogen wastewater. The large amount of ammonia nitrogen wastewater into caused not only water eutrophication, cause water black smelly, and will increase the difficulty of the water treatment and cost, even for people, and biological produce poisonous effect.

Ammonia nitrogen wastewater of the impact on the environment has caused environmental protection areas and the attention of the world, nearly 20 years, of ammonia nitrogen wastewater treatment at home and abroad for more research. The research involved in biological method, chemical method of processing technology, such as biological methods have nitration and algae breeding. The physical methods have reverse osmosis, distillation, soil irrigatio. Chemical method have ion exchange method, remove ammonia, chemical precipitation, fold point chlorination and electrochemical treatment, catalytic cracking, etc. New technologies appear constantly, in the treatment of ammonia nitrogen wastewater applications of show a tempting prospects.

This manual is specially focused on the removed method which our company is widely used.

II.Technical Description

To remove the basic principle of the method is will air ventilation with waste water, wastewater and the volatile gases dissolved in the liquid to solute gas phase, make the waste water treatment process called get blown off. Be to remove material in liquid and gas phase difference is the concentrations of the liquid into the gas phase by driving force. To remove the basic principle of the method is gas liquid balance and mass transfer speed theory.

Used to remove ammonia nitrogen removal from the water, is the gas into the water, contentious mutual fully contact with liquid, make the water dissolved free ammonia gas and liquid through the interface, to gas phase transfer, so as to achieve the purpose of removing ammonia nitrogen.   

The water of ammonia nitrogen, mostly with ammonium ion (NH4 +) and free ammonia (NH3) the state of balance and exist. The balance equation is as follows

NH4++OH-NH3+H2O (1)

Ammonia and ammonium ion of distribution between rate is calculated under the available type

Ka=Kw /Kb=(CNH3·CH+)/CNH4+ (2)

In equation  Ka——Ammonium ion of ionization constants

       Kw——Water ionization constants

        Kb——Ammonia water ionization constants

        C——Matter concentration.

Equation(1)is influenced by PH value, when high pH value, the balance to the right move, free ammonia larger proportion, when pH value for about 11, free ammonia roughly 90%.

By equation (2) can see, pH value is the effect of free ammonia water percentage in one of the major factors. In addition, the temperature can also affect reactive (1) balance, temperature, balance to move right. Table 1 lists the different conditions of ammonia nitrogen the calculated value of the dissociation rate. The data show that, when pH value is more than 10, dissociation rate at 80% or more, when the pH value of 11, dissociation rate is as high as 98% and subject to the influence of the temperature of little.

Different pH, temperature of ammonia nitrogen dissociation rate %, see the table below

pH	20°C	30°C	35°C
9.0	25	50	58
9.5	60	80	83
10.0	80	90	93
11.0	98	98	98

Ammonia nitrogen stripping tower for waste water treatment