Davide Mattioli

Wastewater treatment in a submerged anaerobic membrane bioreactor

Although most membrane bioreactors are used under aerobic conditions, over the last few years there has been increased interest in their application for anaerobic processes. This paper presents the results obtained when a bench-scale submerged anaerobic membrane bioreactor was used for the treatment of wastewaters generated in the agro-food industry. The reactor was fed with synthetic wastewater consisting of cheese whey and sucrose, and volumetric organic loading rates (OLRs) ranging from 1.5 to 13 kgCOD/(m3*d) were applied. Under the operating conditions studied, the maximum applicable OLR was between 6 and 10 gCOD/(g*L), which fell within the ranges of the high-rate anaerobic wastewater treatment systems, while high concentrations of volatile fatty acids were produced at higher OLR rates. With an OLR of 1.5–10 gCOD/(g*L), the reactor showed 94% COD removal, whereas this value dropped to 33% with the highest applied OLR of 13 gCOD/(g*L). The study therefore confirms that membrane bioreactors can be used for anaerobic wastewater treatment.

Effect of selected textile effluents on activated sludge nitrification process

In this study, a recently developed methodology for the assessment of the inhibitory effect on nitrifying biomass was applied to several textile effluents from productive processes. Effluents are classified according to the degree of inhibition as EC50 (concentration producing 50% nitrification inhibition); the investigated textile effluents showed a wide range of EC50 ranging from 20 ml gVSS− 1 (83 ml l− 1) to values above 100 ml gVSS− 1 (300 ml l− 1) for effluents produced by rinsing phases. Taking into account biodegradability and toxicity evaluations, most of the effluents showed a good treatability in conventional biological wastewater treatment plant. On the other hand three textile effluents showed significant toxic effects towards nitrifying biomass. In any case, the proposed procedure represents an efficient tool to prevent treatment failures due to toxic discharges.

Textile wastewater treatment in a bench-scale anaerobic-biofilm anoxic-aerobic membrane bioreactor combined with nanofiltration

This study evaluated the treatability of textile wastewaters in a bench-scale experimental system, comprising an anaerobic biofilter, an anoxic reactor and an aerobic membrane bioreactor (MBR). The MBR effluent was thereafter treated by a nanofiltration (NF) membrane. The proposed system was demonstrated to be effective in the treatment of the textile wastewater under the operating conditions applied in the study. The MBR system achieved a good COD (90–95%) removal; due to the presence of the anaerobic biofilter, also effective color removal was obtained (70%). The addition of the NF membrane allowed the further improvement in COD (50–80%), color (70–90%) and salt removal (60–70% as conductivity). In particular the NF treatment allowed the almost complete removal of the residual color and a reduction of the conductivity such as to achieve water quality suitable for reuse.