High-ammonia wastewater is common in chemical, fertilizer, landfill leachate, coking, pharmaceutical, food processing and some industrial production processes. Traditional ammonia removal methods may include biological treatment, air stripping, chemical precipitation or other processes.
Membrane-based ammonia removal is another technical route. In this process, ammonia in water is transferred across a hydrophobic membrane and absorbed by an acid solution on the other side. This type of process is often based on a membrane contactor rather than pressure-driven filtration.
The main potential advantage is selective ammonia transfer under suitable conditions. The process may also allow ammonia recovery in the form of ammonium salt solution, depending on the absorbent and system design.
However, membrane ammonia removal is not suitable for every wastewater. The process is affected by pH, temperature, ammonia concentration, suspended solids, scaling components, oil content and other contaminants. Pretreatment may be needed to protect the membrane and maintain stable operation.
Project owners should also understand that ammonia removal performance cannot be promised without testing. Removal efficiency depends on wastewater characteristics, operating conditions, membrane area, circulation flow, pH control and absorbent design.
Before considering membrane-based ammonia removal, the following data should be prepared: ammonia nitrogen concentration, total nitrogen, pH, temperature, COD, TSS, hardness, oil content, salinity and target discharge or recovery requirement.
For some projects, membrane ammonia removal may be used as a standalone treatment step. For others, it may be combined with biological treatment, chemical treatment or concentration processes.
The correct approach is to evaluate the wastewater first, then decide whether membrane contactor technology is technically and economically suitable.