Ammonia Recovery Enhancement Using a Tubular Gas-Permeable Membrane System in Laboratory and Field-Scale Studies

摘要

Ammonia (NH_3) gas from liquid manure (LM) can be diffused into a tubular gas-permeable membrane (GPM) and recovered by capturing it in an acidic recipient solution circulating in the GPM system. The objective of this study was to assess the impact ofincreased rate of recipient solution circulation (flow rate) on NH3 diffusion and recovery using a GPM system under laboratory and field conditions. A laboratory setup consisting of LM chambers, a recipient solution of diluted sulfuric acid (H2S04), andtwo GPM systems was used to separately recover NH3 from LM (submerged GPM system) and the headspace (suspended GPM system) of the chambers. The pH value of the recipient solution was controlled between 2 and 6 by using an acid dosing and pH controllingdevice. In the field, a setup similar to the laboratory study was used but with only one GPM system, with a larger surface area of the membrane, submerged in LM at a dairy lagoon. In the laboratory experiments, the results showed that increasing the flowrate of recipient solution in the GPM from 5.6 to 36 mL min~(-1) (more than 6 fold) increased NH_3 diffusion into the membrane and enhanced overall NH_3 recovery in the recipient solution by more than 30%. The results of the field experiments showed that increasing the flow rate of recipient solution in the GPM from 40 to 280 mL min~(-1) (7 fold) enhanced the NH_3 concentration of the recipient solution by 16.5%. Additionally, the rate of NH_3 recovery (concentration per unit time) in the field, with higher recipient solution flow rates than in the laboratory experiments, was greater than in the laboratory experiments.