ASABE Technical Library - Abstract

Abstract.

We are presenting a new and effective way of recovering ammonia from liquid manures. The recovery of nutrients from wastes for re-use as concentrated plant fertilizers is a new paradigm in manure management. In the work presented in this paper a new process using gas-permeable membranes at low pressure was applied to raw swine manure containing high-ammonia (2,390 mg NH₄⁺-N/L) to recover the nitrogen. The process was refined further. To increase the ammonium (NH₄⁺) recovery rate (that is normally carried out using an alkali), in this study we used low aeration and nitrification inhibition. The aeration reacted with the natural alkalinity, which released OH^- and increased the manure pH above 8.5. This pH increase promoted gaseous NH₃ release from the manure and rapid permeation through the submerged membrane with excellent (98%) recovery of the N. Ammonia emissions losses were less than 1.5%. The new approach substituted for large amounts of alkali chemical that were needed to obtain the same effect and reduced the operational costs of NH₄⁺ recovery by 57%.