1. Introduction

The industry of paper is one of the principal economic sectors in Quebec. In 2011, 56.4% of total canadian production of paper was achieved by Québec and was evaluated at 14.9% of total world exportations [1]. In this year, approximately 373 million cubic meters were generated as water process and were discharged in the environment after only basic physicochemical treatment.

In 2006, the value of shipments of paper was 10.7 billion or 7.5% of the value of shipments of all Quebec's manufacturing industry. The value of exports in 2005 was estimated at 7.3 billion or 9.7% of all exports of Quebec and contributes to 46.1% of total newspaper production in Canada and 9% of global paper production.

© The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

distribution, and eproduction in any medium, provided the original work is properly cited.

Thus, considerable quantities of wood residue are generated, which produce large volumes of leachate by percolation of water and following industrial processes. Woodwaste leachate contains lignin and phenolic compounds at important concentrations and must be treated before its discharge in the environment.

Phenolic compounds are toxic to humans and ecosystem, persistent, and endocrine disruptor molecules. They are found in woodwaste leachate and pulp and paper industrial effluents. It is necessary to develop new and innovative technologies adapted for these toxic effluents' treatment and phenolic compounds' removal. Several processes were studied for phenol removal such as membrane processes, ozonation [2], advanced oxidation [3], and activated carbon [4]. Ozonation was proven to be effective but it requires energy, and produces gases and causes the formation of not yet identified by-products with an important risk to human health [5–8]. As phenolic compounds are persistent, it might be suitable to combine ozonation with biological treatment [9].

Biological methods are efficient, innovative, and economic. Biological treatment of organic pollutants was investigated in conventional activated sludge treatment plants (CAS) and in membrane bioreactors (MBR). Mailler et al. [10] compared emerging pollutants removal by both biofiltration and conventional activated sludge plants. This classical biological unit (CAS) has already been well documented and compared with membrane bioreactor [11–18]. No significant difference was observed between CAS and MBR when a critical solids retention time (SRT) necessary for nitrification (SRT > 10 days at 10°C) was exceeded and the suspended solids concentration in the effluent was low for CAS plants [19].

Biofiltration process has various advantages compared to CAS and MBR technologies [20, 21]. It is an economical, simple, and innovative solution for water and air pollution control [20, 22, 23].

Figure 1. Possible mechanisms in operation during biofiltration process.

Phenolic compounds removal by biofiltration was investigated by [9, 24] but the involved mechanisms of this removal were not described before.

This work aims to study phenolic compounds removal in woodwaste leachate using a trickling biofilter and, second, to describe the mechanisms responsible for their transformation and removal. In otherwise, we aim to answer the following questions: Are phenolic compounds eliminated by volatilization, biodegradation, sorption, and biosorption or by all of these processes, and what is the contribution of each mechanism?

This study supposes that the mechanisms of volatilization, sorption, and biodegradation operate simultaneously during biofiltration process. We aim at confirming these assumptions and determine the contribution of each mechanism to the overall phenols removal efficiency (Figure 1).
