| Title | Solid liquid two phase partitioning bioreactors for enhanced biodegradation of xenobiotic compounds from industrial wastewater. Case study: removal of phenolic compounds |
| Abstract | Two phase partitioning bioreactors (TPPBs) have proven to be an effective technology in reducing toxicity arising from high xenobiotic concentrations in biodegradation processes. The selective partitioning of target molecules is the rationale behind the design and operation of TPPBs, which are characterized by a cell-containing aqueous phase, and a second immiscible phase (organic solvent or solid polymer) that acts to selectively sequester toxic molecules, and to deliver these substrates to the biocatalyst based on microbial demand. In the bioremediation of contaminated water, where mixed cultures are necessarily utilized, the use of polymers as the sequestering phase is extremely advantageous as polymers are completely biocompatible and inert with respect to the biomass. This feature avoids possible parallel solvent biodegradation that could decrease the removal efficiency in liquid-liquid TPPBs. An additional advantage of polymers is their low cost in comparison to organic solvents. A new opportunity for this technology is to recycle waste materials as the partitioning phase. Recent experiments have demonstrated the feasibility of this strategy for the bioremediation of hydrocarbons and substituted phenols employing used automobile tires.
In this paper a review of the results obtained for the removal of substituted phenols as single compounds and in mixture is presented. We investigated the biodegradation kinetics of 4-nitrophenol (4NP), 2,4-dimethylphenol(2,4DMP) and 2,4-dichlorophenol(2,4DCP), in a two phase sequencing batch partitioning bioreactor (TPPB-SBR) utilizing both commercial polymers (Hytrel-DuPont and Tone-Dow Chemical) as well as used automobile tires. With polymers, the detoxification of the inhibitory substrate, in single compounds tests, occurs rapidly within the feed and in the early part of the reaction phase of the bioreactor, and leads to significantly enhanced (up to 100%) specific rates of substrate consumption. Individual polymers have varying affinities for different target molecules leading to selective uptake of substrates and, as demonstrated in our studies, an overall enhancement of the process performance arising from the preferred uptake of the more recalcitrant molecule (2,4 DMP or 2,4 DCP in mixture with 4NP). The use of polymers through many (> 60) cycles with minimal accumulation of substrates demonstrates their robustness in this application.
Waste tires were applied in the same manner for the biodegradation of 2,4DCP showing a significant detoxification effect: 65% removal efficiency was achieved in a TPPB SBR operated with tires while the conventional single phase system showed a very low removal efficiency (~17%) under the same operating conditions.
Current work is aimed at the use of mixed substrate feeds, the use of waste rubber/plastics as the sequestering phase, as well as modelling of these systems to predict suitable conditions and operating regions in the treatment of recalcitrant substrates.
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| Source | SIDISA 2012 Simposio Internazionale di Ingegneria Sanitaria Ambientale 9a Edizione, Milano, 26/06/2012 |
| Keywords | Phenolic compounds; TPPBs; kinetics |
| Year | 2012 |
| Type | Contributo in atti di convegno |
| Authors | Tomei M.C., Annesini M.C., Daugulis A.J. |
| Text | 343366 2012 Phenolic compounds; TPPBs; kinetics Solid liquid two phase partitioning bioreactors for enhanced biodegradation of xenobiotic compounds from industrial wastewater. Case study removal of phenolic compounds Tomei M.C., Annesini M.C., Daugulis A.J. Universita La Sapienza, Roma Italia Queen s University Kingston Ontario, Canada Two phase partitioning bioreactors TPPBs have proven to be an effective technology in reducing toxicity arising from high xenobiotic concentrations in biodegradation processes. The selective partitioning of target molecules is the rationale behind the design and operation of TPPBs, which are characterized by a cell containing aqueous phase, and a second immiscible phase organic solvent or solid polymer that acts to selectively sequester toxic molecules, and to deliver these substrates to the biocatalyst based on microbial demand. In the bioremediation of contaminated water, where mixed cultures are necessarily utilized, the use of polymers as the sequestering phase is extremely advantageous as polymers are completely biocompatible and inert with respect to the biomass. This feature avoids possible parallel solvent biodegradation that could decrease the removal efficiency in liquid liquid TPPBs. An additional advantage of polymers is their low cost in comparison to organic solvents. A new opportunity for this technology is to recycle waste materials as the partitioning phase. Recent experiments have demonstrated the feasibility of this strategy for the bioremediation of hydrocarbons and substituted phenols employing used automobile tires. In this paper a review of the results obtained for the removal of substituted phenols as single compounds and in mixture is presented. We investigated the biodegradation kinetics of 4 nitrophenol 4NP , 2,4 dimethylphenol 2,4DMP and 2,4 dichlorophenol 2,4DCP , in a two phase sequencing batch partitioning bioreactor TPPB SBR utilizing both commercial polymers Hytrel DuPont and Tone Dow Chemical as well as used automobile tires. With polymers, the detoxification of the inhibitory substrate, in single compounds tests, occurs rapidly within the feed and in the early part of the reaction phase of the bioreactor, and leads to significantly enhanced up to 100% specific rates of substrate consumption. Individual polymers have varying affinities for different target molecules leading to selective uptake of substrates and, as demonstrated in our studies, an overall enhancement of the process performance arising from the preferred uptake of the more recalcitrant molecule 2,4 DMP or 2,4 DCP in mixture with 4NP . The use of polymers through many > 60 cycles with minimal accumulation of substrates demonstrates their robustness in this application. Waste tires were applied in the same manner for the biodegradation of 2,4DCP showing a significant detoxification effect 65% removal efficiency was achieved in a TPPB SBR operated with tires while the conventional single phase system showed a very low removal efficiency 17% under the same operating conditions. Current work is aimed at the use of mixed substrate feeds, the use of waste rubber/plastics as the sequestering phase, as well as modelling of these systems to predict suitable conditions and operating regions in the treatment of recalcitrant substrates. Published version SIDISA 2012 Simposio Internazionale di Ingegneria Sanitaria Ambientale 9a Edizione Milano 26/06/2012 Internazionale Contributo Contributo in atti di convegno mariaconcetta.tomei TOMEI MARIA CONCETTA TA.P07.002.005 Rimozione di composti xenobiotici da acque di scarico |
