Enhancing recovery of ammonia from swine manure anaerobic digester effluent using gas-permeable membrane technology

Abstract

Gas-permeable membrane technology is useful to recover ammonia from manure. In this study, the technology was enhanced using aeration instead of alkali chemicals to increase pH and the ammonium (NH4(+)) recovery rate. Digested effluents from covered anaerobic swine lagoons containing 1465-2097 mg NH4(+)-N L(-1) were treated using submerged membranes (0.13 cm(2) cm(-3)), low-rate aeration (120 mL air L-manure(-1) min(-1)) and nitrification inhibitor (22 mg L(-1)) to prevent nitrification. The experiment included a control without aeration. The pH of the manure with aeration rose from 8.6 to 9.2 while the manure without aeration decreased from 8.6 to 8.1. With aeration, 97-99% of the NH4(+) was removed in about 5 days of operation with 96-98% recovery efficiency. In contrast, without aeration it took 25 days to treat the NH4(+). Therefore, the recovery of NH4(+) was five times faster with the low-rate aeration treatment. This enhancement could reduce costs by 70%.

Characterizing the Performance of Gas-Permeable Membranes as an Ammonia Recovery Strategy from Anaerobically Digested Dairy Manure

“…Several areas for further study were identified:Determining ways to avoid transfer of water vapour when GPM is used at high temperature.Evaluating the benefit of NH 3 removal using the GPM system on methane gas production in a pilot-scale biodigester.Evaluating options to increase the NH 3 capture rate, e.g., more concentrated acid, acid with more available donor protons, higher flowrate of trapping solution.Evaluating the fertilizer value of the trapped nitrogen solution.Longer duration trials with digestate or RM.Evaluating clogging of the GPM with time.Use aeration to increase pH and recovery rate, such as done by Dube et al [14]. …”

“…If successful, GPMs could be implemented into the anaerobic digester cycle, whether within or prior, to reduce the ammonia inhibition of methanogenesis. Research has shown success in the use of GPM for ammonia recovery of anaerobically digested swine manure, but there is a lack of research using dairy manure digestate [14]. It is hypothesized that with higher pH, temperature, and initial TAN concentration, there will be more capture due to more gaseous ammonia present, and that the conditions within an AD will increase ammonia capture compared to raw manure.…”

Recovery of Ammonia in Raw and Co-digested Swine Manure Using Gas-Permeable Membrane Technology

“…Some technologies have been used to reduce the excess N content in livestock wastewater, promoting its recovery in the mineral form (NH + 4 ) and allowing its reuse as agricultural fertilizer in areas far from the livestock concentration with greater needs for the N nutrient. Dube et al (2016) and Garcia-Gonzalez et al (2016) used a new process utilizing gas-permeable membranes (GPM) in low pressure systems to capture the N present in the digestate from the anaerobic mono-digestion of SM and store it in a concentrated form in an acid solution of 0.5 M H 2 SO 4 .…”

“…The aeration effect is double, on the one hand, it promotes the increase in pH values and, on the other hand, promotes the increase in the concentration of the free ammonium which favors the passage of NH 3(g) through the membrane (Vanotti et al, 2017). In the studies conducted by Dube et al (2016), the GPM system with low-rate aeration promoted removals of 97-99% of the initial NH + 4 contents in the digestate in 5 days of operation, obtaining an accumulation of 11,900 mg of NH + 4 -N L −1 in the acid solution. In the studies conducted by Daguerre-Martini et al (2018), the GPM system with low-rate aeration removed 65-85% of the initial NH + 4 contents in swine manure in 4 days of operation, obtaining concentration of NH + 4 -N in the acid tank of 37,400 mg L −1 .…”

“…Successful N recovery using GPM has already been performed on different organic wastes such as poultry litter (Rothrock et al, 2010(Rothrock et al, , 2013, swine manure (Garcia-Gonzalez and García-González et al, 2015) and digestate from mono-digestion of swine manure (Dube et al, 2016;Garcia-Gonzalez et al, 2016;Vanotti et al, 2017) with NH + 4 recovery above 90% of the total content of this form of the nutrient in the residues. However, recovery of N in the digestate from systems operating in ACoD has not yet been performed.…”