A membrane contactor for ammonia stripping,pilot scale experience and modeling

Ammonia is even in low concentrationsproblematic to life in water environments due tothe effect as a fertiliser promoting eutroficationand is normally removed by denitrification inwaste water treatment plants. Likewise ammo-nia in animal manures poses a threat to theenvironment in various ways without carefuladministration of the manure as a fertiliser. Thisoften results in inadequate use of the animalmanures and in the case of denitrification ofMSW ammonia is sacrificed at the expense ofconsiderable energy cons umption. A better solu-tion is to strip the ammonia from these sourcesfor subsequent optimal uses. There are many conventional ways to removeammonia from water but mo st methods are depen-dent on relatively large amount of energy for theoperation. Membrane contactors offer a superiorsolution for stripping ammonia because theyprovide a large surface area that facilitates fastseparation of the ammonia from the wastewatereven at low energy input per mole ammoniaremoved. Experiments have been reported usingporous, hydrophobic hollow fibre and tubularmembrane contactors for ammonia stripping fromvarious wastewater treatment effluents followinganaerobic digestion [1–3] but so far this technol-ogy has only been reported in larger scale opera-tion in a few cases [4]. In this investigation bothlaboratory and fairly large scale pilot plant opera-tion has been in operation in order to optimise theuse of the technology.