Abstract

A laboratory-scale submerged attached growth bioreactor using Luffa cylindrica as support material for the immobilization of nitrifying bacteria was applied for polishing the effluent of an UASB reactor treating domestic wastewater under the tropical conditions of northeast Brazil, in the City of Campina Grande (7^o 13’ 11” South, 35^o 52’ 31” West, 550 m above m.s.l.), Paraiba state. L. cylindrica showed a very good performance as a solid substrate for the development of the biofilm aggregating microorganisms capable of metabolizing both organic and inorganic compounds adsorbed on it, particularly those responsible for nitrification. The efficiency of nitrification varied within the range of 82 - 95% with a mean of 88%. The final effluent had an ammonia nitrogen mean concentration of 5 mg.L^-1, which is less than that recommended by the National Council for the Environment for discharges into receiving bodies in Brazil.

Key words: Nitrification, Batch reactor, Attached growth, Post-treatment, Luffa cylindrica.