Removal and Recovery of Ammonia from Liquid Manure Using Gas-Permeable Membranes

摘要

We investigated the use of gas-permeable membranes as components of a new process to capture and recover ammonia from liquid manures and other concentrated effluents. The process includes the passage of gaseous ammonia through a microporous hydrophobic membrane and capture and concentration with circulating diluted acid on the other side of the membrane. The membranes can be assembled in modules or manifolds and can be tubular or flat. The membrane manifolds are submerged in the liquid and the freeammonia is removed from the liquid matrix before it escapes into the air. The concept was successfully tested using concentrated swine manure effluents (digested and un-digested liquid manure) containing 300 to 1500 mg/L NH4-N. After ten batches, the ammonia was recovered and concentrated in a clear solution containing 53,000 mg/L NH4-N. Soluble compounds such as soluble COD did not pass through the membrane pores. The results obtained in this study show that the use of gas-permeable membrane technology could be an effective approach to recover ammonia from livestock wastewater. The final products are (1) reduced environmental emissions from livestock facilities, and (2) concentrated liquid nitrogen that can be reused in agriculture as a valued fertilizer.