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Using Liqui-Cel™ to recover Ammonia from Industrial Wastewater

Using Liqui-Cel™ to recover Ammonia from Industrial Wastewater

The Problem

Ammonia is both a problem and a blessing. In industrial waste, ammonia requires treatment before discharge. Yet it is a valuable nitrogen fertilizer in the form of ammonium sulfate.

The Solution

Liqui-Cel™ membrane contactors are a clean, safe, and effective means to convert dilute waste ammonia into concentrated fertilizer stock.

The Chemistry

Understand Ammonia/ammonium chemistry as follows:

At low pH, ammonia exists as the ammonium ion (NH4+), making it water-soluble. The addition of a base, such as NaOH, transforms it into dissolved ammonia gas (NH3) with a finite vapor pressure. NH3 can permeate through Liqui-Cel™ pores. When the receiving liquid is sulfuric acid (H2SO4), the ammonia undergoes conversion into clean, marketable ammonium sulfate. The pKa of NH3/NH4+ is approximately pH 9.5:

NH3 (gas) + H2O (liq) ⇌ NH4+ (aq) + OH- (aq)

The Process

TMCS is an advanced process for removing ammonia using Liqui-Cel™ membrane contactors. Liqui-Cel™ developed and optimized TMCS (Trans Membrane Chemi-Sorption) contactors specifically for efficient chemical transfer.

In this TMCS membrane process, operators adjust the incoming wastewater feed to a pH of 11–12—above ammonia’s pKa—to drive ammonia into the gas phase. The fluid is filtered to remove fine particles and prevent fouling, then flows through the shell side of the TMCS contactor. Meanwhile, sulfuric acid, diluted to a pH of 1–2, circulates through the hollow fibers. Inside the fibers, ammonia converts to ammonium ion and reacts with the acid to form ammonium sulfate crystals. This process becomes economically viable when ammonia concentrations exceed 200 ppm. The higher the ammonia level the better.

The company then recovers the ammonium sulfate solids and sells it wholesale as fertilizer stock.

To ensure successful operation, it’s critical to:

  1. Remove particulates and oxidants to protect membrane surfaces
  2. Maintain proper pH levels in both wastewater and acid streams
  3. Safely handle sodium hydroxide (NaOH) and sulfuric acid (H₂SO₄)

SnowPure and Solventum provide technical expertise to support your process development.

More can be found by speaking with an expert at SnowPure. We also link to a paper written by scientists at Liqui-Cel™.