Dead end ultra-filtration of sugar beet juice expressed from cold electrically pre-treated slices: Effect of membrane polymer on fouling mechanism and permeate quality

Treatment of soy sauce wastewater with biomimetic dynamic membrane for colority removal and chemical oxygen demand lowering

Soy sauce wastewater has been produced in soy sauce production and consumption. To reuse this kind of water resource, the chemical oxygen demand (COD), colority should be removed or lowered. Biomimetic dynamic membrane (BDM), GO&Laccase@UF membrane, was prepared by filtering mixture of graphene oxide (GO) and laccase through ultrafiltration (UF) membrane. Compared to UF membrane, the prepared BDM showed great performance in removal of COD and colority, due to the higher laccase activity with existence of GO. The removal rate of colority reached ~80% by one step filtration operation. Moreover, the multiple cycle test evidenced that the value of COD and colority in the permeate after 5 consecutive cycles with the same GO&Laccase@UF membrane still meet the standard for reuse water. This work indicates the promising of BDM for wastewater from food industry.

Biomimetic dynamic membrane for aquatic dye removal

This study utilized physical adsorption and filtration of carbon nanotubes (CNTs) and laccases to fabricate biomimetic dynamic membrane (BDM) for the advanced treatment of dye wastewater. In BDM, the adsorption, enzymatic degradation and membrane separation demonstrated a synergism effect on pollutant removal. At first, the fabrication methods of BDM were investigated, and the mixed filtration for laccases and CNTs showed a better performance than the stepwise filtration. Furthermore, the operation parameters of BDM, including CNTs and laccase loading amounts, dye concentration, agitation speed and transmembrane pressure (TMP), were studied. Suitable CNTs and laccase amounts could reduce filtration resistance and increase catalysis efficiency, while moderate TMP and agitation speed were in favor of boosting the BDM structure for catalysis and permeability. Optimized operation parameters (CNT loading amount = 20 g m^-2, laccase loading amount = 74.6 g m^-2, agitation speed = 100 rpm, and TMP = 1.0 bar) sustained a high removal rate, and the flux was over 120 L m^-2 h^-1, even for 7 operation cycle' tests. BDM exhibited an excellent dye removal rate, stable flux and great antifouling capacity, on the ground that adsorption saturation and foulant may be alleviated "online and in-situ" by the enzymatic degradation. Afterwards, the bionic layer on BDM, after absorption saturation and catalyst deactivation, could be eliminated rapidly by carrying out a simple backwash cleaning operation, then a new one could be fabricated immediately. Therefore, BDM is a good candidate for functional membrane materials in future water treatment.