Application of ion exchange and Air Stripping Methods to remove ammonium in recirculation fish culture system effluents

Abstract

Increase in water pH in recirculation fish culture systems turns ammonium into ammonia which can kill fish even in low concentrations. The purpose of this study was to apply ion exchange and air stripping methods to remove ammonium in effluents of recirculation fish culture systems. Ion exchange method was done using Graded Zeolite Clinoptilolite from Semnan Province to remove ammonium and air stripping was applied to zap ammonium from Zeolite. Regeneration tests were conducted in which known weights of ammonium saturated Clinoptilolite were contacted with 1 normal concentration of CINa solution. Different concentrations of ammonium were selected and the effects of temperature and pH in releasing ammonia were also investigated. Results show that the cation exchange capacities in continuous systems were 7.61 to 11.22 (in breakthrough point) and 16.31 to 19.5mg ammonium per gram of ion exchanger as total capacity. The results of regeneration experiments by NaCI (1 normal) solution proved the efficiency of chemical regeneration of zeolite column to be as high as 94.9% to 99.1%. The efficiency of regeneration by air stripping was determined to be 92% in 16 hours. The efficiency of acid absorption of released ammonia in stripping process was determined as 55% where the surplus was rejected to the atmosphere. It is concluded that the method may be regarded as a completing process for water treatment in closed fish tanks.