Advanced enzymatic elimination of phenolic contaminants in wastewater: a nano approach at field scale

Abstract

The removal of recalcitrant chemicals in wastewater treatment systems is an increasingly relevant issue in industrialized countries. The elimination of persistent xenobiotics such as endocrine-disrupting chemicals (EDCs) emitted by municipal and industrial sewage treatment plants remains an unsolved challenge. The existing efficacious physico-chemical methods, such as advanced oxidation processes, are resource-intensive technologies. In this work, we investigated the possibility to remove phenolic EDCs [i.e., bisphenol A (BPA)] by means of a less energy and chemical consuming technology. To that end, cheap and resistant oxidative enzymes, i.e., laccases, were immobilized onto silica nanoparticles. The resulting nanobiocatalyst produced at kilogram scale was demonstrated to possess a broad substrate spectrum regarding the degradation of recalcitrant pollutants. This nanobiocatalyst was applied in a membrane reactor at technical scale for tertiary wastewater treatment. The system efficiently removed BPA and the results of long-term field tests illustrated the potential of fumed silica nanoparticles/laccase composites for advanced biological wastewater treatment.

Degradation of a broad spectrum of trace organic contaminants by an enzymatic membrane reactor: Complementary role of membrane retention and enzymatic degradation

“…They achieved improved removal of phenol when granular activated carbon too was incorporated into the membrane structure. Conversely, various enzymes can be immobilized on membranes, thereby facilitating conversion of resistant chemicals concurrent with the retention of the insoluble metabolites (Gasser et al, 2014;Hou et al, 2014). The uniqueness of this study is that it systematically demonstrates improved degradation of a range of TrOCs by dynamically immobilized laccase on the UF membrane.…”

Laccases to take on the challenge of emerging organic contaminants in wastewater

“…The occurrence of a more polar transformation product after treatment with laccase from the Thielavia genus showed that real BPA transformation took place even at such low concentrations (Hommes et al 2012). The established immobilization method was further optimized for the production of immobilized laccase from the Thielavia genus on fsNP in kilogram scale (Gasser et al 2014). The produced biocatalysts were subsequently applied in a membrane reactor with a volume of 460 L in a pilot plant fed with real WWTP effluent.…”

“…After 43 days, enzymatic activity was 43 % of the initially applied activity, showing that the biocatalysts remained stable over the whole duration of the experiment. In accordance with this pilot-scale experiment, treatment costs were estimated to be 0.130€m −3 (excluding personnel and maintenance costs) when applying the process for tertiary wastewater treatment at the WWTP at Birsfelden (Switzerland), which treats 28,000 m 3 wastewater each day (Gasser et al 2014). Hence, the costs are slightly above but in the same range as the estimated treatment costs for PAC adsorption and ozonation (also excluding personnel and maintenance costs) for the WWTP at Au (Switzerland, treating 33,000 m 3 wastewater per day) which were estimated to be 0.114 and 0.078€m −3 , respectively (Rosenstiel and Ort 2008).…”

“…Hence, the costs are slightly above but in the same range as the estimated treatment costs for PAC adsorption and ozonation (also excluding personnel and maintenance costs) for the WWTP at Au (Switzerland, treating 33,000 m 3 wastewater per day) which were estimated to be 0.114 and 0.078€m −3 , respectively (Rosenstiel and Ort 2008). However, treatment costs by means of immobilized laccases might be reduced further by optimization of the treatment technology and decreasing biocatalyst production costs (Gasser et al 2014).…”

“…One drawback of enzymes in dissolved form is that they are inactivated in wastewater over time due to harsh conditions, i.e., unfavorable pH, high salt concentrations, chemical/ biological denaturing agents, or temperature (Majeau et al 2010;Cabana et al 2011). In order to overcome this problem, immobilization and insolubilization techniques for laccases have been investigated lately (recently reviewed by Ba et al 2013) and some techniques were shown to considerably enhance enzymatic stability in wastewater treatment processes (e.g., Gasser et al 2014). Furthermore, immobilization or insolubilization also facilitates the retention/reuse of the biocatalysts and thereby greatly improves the efficiency of the process (Brady and Jordaan 2009;Corvini and Shahgaldian 2010).…”