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 1465–2097mgNH4+–NL−1 were treated using submerged membranes (0.13cm2cm−3), low-rate aeration (120mL airL-manure−1min−1) and nitrification inhibitor (22mgL−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 5days of operation with 96–98% recovery efficiency. In contrast, without aeration it took 25days 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%.
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