Clinoptilolite and multipurpose filters for upgrading effluent ammonia quality under peak loads

Peak loads of ammonia can not always be handled with success in the biological process of nitrification and compliance with standards may be a problem. Ion exchange with clinoptilolite may be used as a second stage unit to polish the effluent and to assure compliance. Within this context, the use of clinoptilolite in an ion exchange unit or alternatively in filters together with filter material, without a significant loss of capacity, may be possible, providing substantial reductions in terms of land requirement for the upgrade. Results from units of clinoptilolite only, and in combination with (i) burned clay and (ii) sand filters have revealed that all configurations are successful as upgrades for dampening ammonia peaks. Among the configurations investigated, the combined scheme where clinoptilolite is added to a filter unit which is aerated to enhance biological activity, has given the best results, provided that enough time is allowed for the adaptation of the nitrifiers. (C) 1998 IAWQ. Published by Elsevier Science Ltd