Effect of coniferyl alcohol addition on removal of lignin from paper mill effluent by laccase

Laccase is a kind of powerful enzyme that is promising in pulping and papermaking industry, because it can catalyze and oxidize lignin. It has been proved that soluble lignin and its derivatives were able to be degraded, or polymerized, and removed by complete oxidation through treatment with laccase followed by coagulation. Utilizing laccase to treat wastewater of papermaking has high efficiency. Its merit includes mild reaction condition and simple equipment and so on. In this paper, a novel wastewater treatment system which consists of coniferyl alcohol and a laccase catalyzer was developed. When coniferyl alcohol was added, it was found to polymerize with water soluble lignin. Thus the system produced high molecule hydrophobic lignin polymers. The experiment showed that the addition of coniferyl alcohol could remove soluble lignin and its derivatives in the wastewater effectively under the existence of laccase. The result showed that the optimal treatment conditions were as follows: coniferyl alcohol dosage 0.0788 g/L; laccase consumption 14.72 IU/L; temperature 25 degrees C; reaction time 1h. The removal ratio for lignin reached 80%, for CODCr 51.9%, and for chroma 84.8%.