4. Conclusion

Two pilot filters, with and without biological activity, were designed for continuous mechanisms to follow. It has been shown that mechanisms of volatilization, sorption, and biodegradation operate simultaneously during the biofiltration process. For, column 1, in which bacterial activity was inhibited by mercuric chloride addition, a removal efficiency of 33.33– 40.1% was obtained at steady state for all the phenolic compounds except phenol and chlorophenol for which 40.2–83.33% of initial concentrations was removed. On the other hand, 41.1% of phenol and chlorophenol initial concentrations were found in the collected gas. Thus, in this column, both physicochemical retention and volatilization are responsible for phenolic compounds removal. At the saturation of the media on the 135th day, a maximum of volatilization was obtained and reached 41.1% for more volatile compounds.

Good treatment efficiency was obtained in the biofilter (column 2). Note that 97–98.2% of COD and BOD removal were observed, respectively. Excellent performances were achieved and reached 99.9% of initial concentrations removal for all the phenolic compounds. Volatilization did not exceed 5–7% at the steady state for the more volatile compounds in this column simulating the real biofilter operation.

Woodwaste leachate was treated with an excellent efficiency by biofiltration process on the mixed media peat: perlite, although a slight problem with color due probably to peat. This is why the authors recommend improving aspect effluent quality by a final treatment if necessary. Toxicity evaluation confirmed that effluent was not toxic for algae and daphnia. It was confirmed also that algae were stimulated in the presence of diluted effluent.
