Removal of ammonia using Ca-P (calcium polymer) from wastewaters produced in the recycling of disposable diapers

An innovative system has been developed by Fukuoka University for the recycling of adult disposable diapers, and a pilot plant is currently being tested. The recycling process results in production of wastewater. The “Johkasou” wastewater treatment facility is highly effective in reducing BOD and COD, although specific focus should be placed on the removal of ammonia. For this purpose, the Authors investigated the performance of Calcium polymer (Ca-P), the sodium polyacrylate dehydrated with CaCl2, which displayed promising features in removing ammonia–nitrogen. The aim of the study described in the present paper was to clarify the removal mechanism and to identify optimal operating conditions. From batch type tests and semi-continuous column tests, it resulted that by exploiting Ca-P it is possible to remove ammonia–nitrogen from wastewater through ion exchange mechanism. Calcium ions are released by Ca-P and replaced by ammonia ions. Total ion exchange capacity was calculated as 0.12 mgNH4/gCa-P.