Transient Performance of a Two-Phase Partitioning Bioscrubber Treating a Benzene-Contaminated Gas Stream

Abstract

The dynamic performance of a prototype, two-phase partitioning bioscrubber in response to fluctuating benzene waste gas feeds has been characterized through a series of spike, step, and shutdown-restart experiments. From stable operation at a nominal loading capacity of 62 +/- 6 g/(m3 h) and removal efficiencies of over 99%, the bioscrubber was subjected to influent benzene concentration step changes and spikes as high as 10- and 20-fold, respectively. The bioscrubber responded rapidly and effectively to all feed concentration spikes and steps, as well as to step changes in the feed flow rate, maintaining nearly undisturbed performance. Although benzene absorption by the two liquid phases was found to dominate the early stages of each transient, Achromobacter xylosoxidans Y234 responded quickly to prolonged disturbances, readily consuming most of the excess absorbed substrate. The results demonstrate that the two-phase partitioning bioscrubber can rapidly acclimate to and recover from fluctuations, ensuring that stable performance can be maintained both during and aftertransients. The presence of n-hexadecane promotes benzene capture in the two-phase system by increasing the absorption driving force, an important characteristic during high intermittent loadings. Rapid recovery from two different shutdown scenarios further demonstrates the practical potential of the two-phase partitioning bioscrubber as a high-performance biotechnology alternative for the treatment of toxic waste gases.

Bioprocesses for air pollution control

“…In such a case, the presence of an organic phase has shown to be favourable as it will play a buffering role and avoid or, at least, reduce inhibition. 20,141 A similar effect will also be reached if an organic phase absorber is put in front of a conventional single aqueous phase stirred tank bioreactor, instead of directly mixing both the aqueous and the organic phase in the bioreactor itself. 139 Some typical examples of performance data for two-liquid phase stirred tank bioreactors are summarized in Table 6.…”

“…20 It was observed that under given operating conditions the biomass concentration in the reactor will naturally reach and stabilize at a rather constant value. 140,141 Non-steady-state load conditions are not unusual in full-scale operation. In the case of occasional shock loads, the system may become inhibited and may need some time to recover in the case of a single aqueous phase bioreactor.…”

A strategic approach for the design and operation of two‐phase partitioning bioscrubbers for the treatment of volatile organic compounds

“…1 However, the first design of this type of system required considerable operator intervention to maintain two distinct liquid phases and to operate the system at steady state. Design improvements led to the two-phase partitioning bioscrubber (TPPB) in which aqueous and organic phases are homogenously mixed, 6 and we have demonstrated the practical application of TPPB technology to the treatment of VOCs, in particular benzene, 3,7,8 with some publications directed to the demonstration of process feasibility 3,6,7 and others toward fundamental issues, such as maintenance energy and oxygen transfer. 7,9 Recently, TPPBs have also been applied to the treatment of other pollutants such as styrene, 10 isopropylbenzene, 11 dichloromethane, 12 pentachlorophenol, 13 n-hexane, 14 and mixtures of up to 11 compounds.…”

“…2 Of the biotechnologies used for the treatment of VOCs, biofiltration has been shown to be useful because of its uncomplicated and inexpensive design which is typically coupled with long-term performance requiring only minimal maintenance and operator attention. 3 However, biofilters have great difficulty in dealing with high inlet VOC concentrations because of the potential for microorganisms to be inhibited or killed at the biofilter inlet, 4 and are also prone to clogging and channeling.…”

Adsorption Properties of Bamboo Charcoal and B-cyclodextrin on Volatile Organic Compounds

“…However, the efficiency of biological method to remove water-insoluble VOCs is very low, mainly because the mass transfer from gas phase to liquid is blocked [4]. In the traditional biological method, the hydrophobic VOCs from the gas phase through the liquid membrane to biofilm exists greater resistance in the process of mass transfer, thereby reducing the bioavailability [5], and this has become the main factors of restricting the microbial capture and degradation of VOCs.…”