Combined biological and advance oxidation processes for paper and pulp effluent treatment

Abstract

During recent years, the socio political pressure to develop suitable technologies capable of treating wastewater from the paper and pulp industry has increased due to strict environmental regulations. System closure could potentially lead to substantial operating and discharge cost savings. This study evaluates the potential of combining an aerobic moving bed biofilm reactor (MBBR) (biological) and a Fenton-like system (advanced oxidation processes) for treating recycle mill effluent (RME). The performance of the moving bed biofilm reactor (MBBR) was evaluated at three different hydraulic residence times (HRT). The HRT used were 24, 16 and 5 h and the corresponding total chemical oxygen demand (COD) removals were 55, 49 and 43% respectively. The volatile organic acids (VOA) removals were 63.5, 58.7 and 53% respectively. The Kincannon-Stover model was used to describe the kinetic behaviour of the MBBR. The calculated KB and Umax parameters for the COD were 26.37 g.L−1.d−1 and 15.06 g.L−1.d−1 respectively. For the VOA, the KB and Umax parameters were 11.81 g.L−1.d−1 and 8.87 g.L−1.d−1. The Fenton-like experiments were carried out in batch runs. The first experiments were carried out to determine the optimal reaction parameters. Maximum COD removals were found to be at a pH of 3.33, Fe3+ dosage of 1,000 mg/L and H2O2 of 14.55 mM. Pseudo-first order reaction kinetics was used to describe the kinetic characteristics of the Fenton-like treatment system. The calculated kinetic parameters ηmax (%) and kCOD (min−1) were 53.8% and 0.112 min−1 respectively at a pH of 3.24, Fe3+ dosage of 250 mg/L and a H2O2 dosage of 77 mM.