Toluene biodegradation in a two phase partitioning system—Use of a biodegradable solvent

Abstract

A biodegradable solvent was used in a two-phase aqueous-organic system for hydrophobic VOC (volatile organic compounds) elimination by activated sludge. Unlike usual two-phase aqueous-organic systems where the organic phase is chosen nonbiodegradable in view of its recycling, in this study the solvent was assimilated by micro-organisms simultaneously with the VOC. The chosen solvent and VOC were hexadecane and toluene. Experiments showed in a first step that activated sludge were able to assimilate part of hexadecane at different phase ratios (5 and 10% v/v) and a higher biomass growth was obtained for the lower ratio. Toluene was removed simultaneously with organic solvent elimination; cells were readily able to completely consume the toluene available at low and even at high concentrations within 48 h (0.2 and 4.3 g L 21 in the organic phase), even if they were not previously preadapted to these substrates. Consequently, a two-phase partitioning bioreactor conception with a biodegradable solvent can be envisaged.

Absorption and biodegradation of toluene: Optimization of its initial concentration and the biodegradable non-aqueous phase liquid volume fraction

“…The extract was then analyzed by gas chromatography coupled with a flame ionization detector from Perkin Elmer. The analytical conditions are reported in Table 1 and were selected according to the related literature (Chikh et al, 2011;de Moura Carrara et al, 2011). The toluene partition coefficient in each of the different phases was measured by the static method, by introducing a known amount of toluene in 22 ml vials sealed, having introduced the organic solvent or the emulsion in advance.…”

“…For growth and conservation, the activated sludge was cultivated under oxygen flow on the following mineral medium (2 g/day): Peptone, 0.64 g; K2HPO4, 0.11 g; NH4Cl, 15.2 g; CH3COONa, 140 g and some drops per month of Viandox (as an additional carbon source). Before use, activated sludge was washed several times with distillated water and diluted in a mineral salts medium containing (Chikh et al, 2011): KH2PO4: 3.4 g l -1 ; Na2HPO4: 3.09 g l -1 ; NH4Cl: 5 g l -1 ; MgSO4: 0.12 g l -1 ; CaCl2: 0.05 g l -1 ; ZnSO4: 0.01 g l -1 ; MnSO4: 0.01 g l -1 ; CuSO4: 0.003 g l -1 ; (NH4)2Fe(SO4)2: 0.1 g l -1 . The pH was adjusted to 7 ± 0.2.…”

Removal of a Mixture of Seven Volatile Organic Compounds (VOCs) Using an Industrial Pilot-Scale Process Combining Absorption in Silicone Oil and Biological Regeneration in a Two-Phase Partitioning Bioreactor (TPPB)

“…To improve the performance of the biofiltration process, the introduction of a non-apolar phase, named non-aqueous phase (NAP), can be used to absorb hydrophobic VOCs before their degradation. This kind of biological reactor is called a Two-Phase Partitioning Bioreactor (TPPB) [1,3,4]. The selection of a NAP must satisfy several criteria [5].…”