Adjust the water PH to 10.5~12, and temperature to 35~45℃, then  membrane contactor can used for deammonia, product water ammonia content can be decreased to 0.5mg/L.

membrane contactor is a kind of special hydrophobic hollow fiber array made of polymer material. Then the array is spiral-wounded onto a water distribution tube, and then the tube is installed into a housing (at the same time, a baffler is formulated inside the housing).

Hollow fiber → Knitted fiber (under microscope) → Knitted fiber (naked eyes) → End surface

Structure of  membrane contactor:

Features of  membrane contactor:

1) Hollow fibers are knitted into an array, so that a certain space can be kept between these fibers. In this way, thousands of fibers are connected as a whole array which can resist strong water flow and will not break. Besides, the mass transfer efficiency can be improved in the array structure.

2) High fiber density makes it possible of ultimate gas removal from water;

3) Central tube water distribution + Middle baffler structure, change the water flow direction to flush vertically towards hollow fibers, which can improve the mass transfer efficiency between shell side and lumen side.

Working principle of deammonium membrane

NH4+ has the following equilibrium in water:

NH4++OH- ←→ NH3+H2O

In typical operation, wastewater flows in the shell side of membrane, while acid adsorption solution flows in the lumen side of membrane.

With the increase of temperature and PH in water, the equilibrium favors the formation of free NH3 gas. NH3 gas can permeate through the micro pores from shell side to lumen side, then act with acid:

2NH3 + H2SO4 → (NH4)2SO4

Keep the water PH above 10, and temperature above 35℃ (below 45℃), then the NH4+ in the shell side will be changed to NH3 constantly and permeate to the lumen side, then be reacted to NH4+. By these reactions, NH4+ content in wastewater can be decreased to the satisfied level. At the same time, pure (NH4)2SO4 is generated in the lumen side, which can be recycled.

Typical working process of   ETN membrane

Remarks: the equipment in dotted line is replaced by membrane contactor

membrane contactor deammonia system has the following advantages compared with traditional ammoniua removal technology:

1) High removal efficiency of ammonia nitrate, NH₄⁺-N can be decreased to below 1ppm. And the removal efficiency can be accurately fixed based on practical condition;

2) NH₄⁺-N stripping and adsorption in one step, to get a smaller footprint, less than 1/3 of tradition process;

3) Modular design, easy for transportation and capacity extension;

4) It offers a closed operation environment, which can ensure no NH₃ leakage and cleaning production.

Specifications of   ETN membrane