Author(s)

R. F. Vieira, D. Lopes, I. R. Baptista, S. A. Figueiredo, V. F. Domingues, J. Vaz, H. Varela, R. F. Jorge, O. M. Freitas, C. Delerue-Matos

Abstract

Solid waste management is an activity associated with unpleasant odours. In this context, biofilters are often used to remove the compounds in their origin, namely ammonia, hydrogen sulphide and mercaptans.

In order to valorise natural materials from Portuguese woods for use as packing in biofilters, preliminary characterization and adsorption studies were carried out. This permitted the selection of the materials for this study: pine (Pinus pinea) bark and woodchips mixed with compost.

Kinetics and equilibrium studies at a laboratory scale were carried out to determine the adsorption capacity of ammonia. Pseudo-first order and pseudo-second order models were applied to describe the kinetic isotherm. Pseudo-second order model was the best fit for pine (Pinus pinea) bark and pseudo-first order model for woodchips/compost. Langmuir’s and Freundlich’s models were applied to describe equilibrium isotherm for both materials; the Langmuir model being the best fit. The highest maximum adsorption capacity was observed for woodchips/compost, 1.61 ± 0.54 mol NH₃/kg.

Pilot scale studies have also been developed into a real mechanical biological treatment (MBT) plant for municipal solid waste. Two biofilters were installed using woodchips mixed with compost and pinus bark.

The performance of each unit was characterized by the removal efficiency of ammonia and odours. The results obtained suggest that the wood-chip/compost mixture had higher odour removal efficiencies.

Keywords

ammonia and sulphur removal, biofiltration, natural materials, odour control