Effects of organic matter in aquacultural waste on the ammonium exchange capacity of clinoptilolite

Abstract

Clinoptilolite, an ammonium-selective ion exchanger, is being used to control ammonia accumulation in recirculating culture systems. Studies were conducted to establish a correlation among the ammonium exchange capacity of clinoptilolite, level of organic matter in aquacultural wastewater, and regenerant solution type. A recirculating culture system of 2300-I capacity provided wastewater with a represantative organic matrix. Treatment of the wastewater led to a decrease in the performance of clinoptilolite under non-equilibrium (packed-column) and equilibrium operating conditions. The extent of the effects increased with an increase in organic level of the treatment solution. In packed-column tests, the maximum observed reductions in mean removal efficiency (3.5%), volume of wastewater treated prior to reaching breakthrough (14.9%), and operating exchange capacity (19.7%), occurred in columns regenerated with a brine of pH 7.0. Columns regenerated with a brine of pH 10.5 showed little response. Treatment of aquacultural wastewater produced a brown discoloration of the packing which was removed by treatment with 1 bed volume of a hypochlorite restorant solution (0.5% Cl 2).