Abatement of binary gaseous chlorinated VOC by biotrickling filter: Performance, interactions, and microbial community.

The treatment of waste-gas containing chlorinated volatile organic compounds (CVOCs) has become a difficult issue in current air pollution control. Biotrickling filters (BTFs) have been recognized to be applicable for the treatment of CVOCs, but research on the biodegradation of binary gaseous CVOCs is rare. Herein, a BTF inoculated with Methylobacterium (M.) rhodesianum H13, Starkeya sp. T-2 and activated sludge was established to investigate the biodegradation of the gaseous dichloromethane (DCM) and 1,2-dichloroethane (1,2-DCE) and their interactions implicated. The bioaugmented BTF showed a faster startup (13 days), better removal efficiencies of DCM (80%) and 1,2-DCE (72%), and superior mineralization (65.9%) than that inoculated with activated sludge alone. The ECs of DCM and 1,2-DCE were positively related with the inlet load when the total inlet load was <50 g m-3 h-1. However, inlet loads higher than 50 g m-3 h-1 led to dramatic drop of the RE of DCM and 1,2-DCE due to the limitation of the degradation capacity of microorganisms and the toxic effect of high-concentration substrates. Besides, BTF could stand a lower shock load of 400 mg m-3, while higher shock loads would deteriorate the RE of DCM and 1,2-DCE. And BTF showed better impact resistance toward DCM than 1,2-DCE, probably because the 1,2-DCE biodegrading bacteria was more sensitive to the concentration change. For the same reason, the removal recovery of DCM after starvation was quicker than 1,2-DCE. Kinetic interactions were quantified by the EC-SKIP model, results of which revealed that DCM cast negative effect on 1,2-DCE biodegradation, while 1,2-DCE could promote DCM biodegradation. Moreover, both the results of real-time PCR and high-throughput sequencing showed M. rhodesianum H13 had stronger competitiveness and adaptability than Starkeya sp. T-2. The survived M. rhodesianum H13 and Starkeya sp. T-2 after starvation robustly demonstrated the success of bioaugmentation as well as its great potential of engineering application.

Simultaneous biodegradation of dimethyl sulfide and 1-propanethiol by Pseudomonas putida S-1 and Alcaligenes sp. SY1: "Lag" cause, reduction, and kinetics exploration.

Simultaneous biodegradation of malodorous 1-propanethiol (PT) and dimethyl sulfide (DMS) by Pseudomonas putida S-1 and Alcaligenes sp. SY1 was investigated and the interactions implicated were explored. Results showed that PT was completely degraded in 33 h, while a lag of 10 h was observed for DMS degradation alone, and the lag was even extended to 81 h in the binary mixture. Mechanism analysis found that the lag was mainly attributed to the exposure of DMS degrader (Alcaligenes sp. SY1), rather than PT metabolites and PT degrader. The exposure time and PT concentration also influenced the lag duration much. Citric acid could effectively reduce the lag. Pseudo-first-order model was proved suitable for the description of PT degradation, revealing that PT degradation could be enhanced in presence of DMS with a concentration of < 50 mg L-1. A modified Gompertz model, incorporated the lag phase, was developed for the description of DMS degradation in the mixture, revealing that DMS degradation depended on the initial PT concentration, and when the lag was not considered, PT with low-concentration could promote DMS biodegradation, while a higher concentration (> 20 mg L-1) cast negative effect.

Interaction of tetrahydrofuran and methyl tert-butyl ether in waste gas treatment by a biotrickling filter bioaugmented with Piscinibacter caeni MQ-18 and Pseudomonas oleovorans DT4.

Bioaugmented biotrickling filter (BTF) seeded with Piscinibacter caeni MQ-18, Pseudomonas oleovorans DT4, and activated sludge was established to investigate the treatment performance and biodegradation kinetics of the gaseous mixtures of tetrahydrofuran (THF) and methyl tert-butyl ether (MTBE). Experimental results showed an enhanced startup performance with a startup period of 9 d in bioaugmented BTF (25 d in control BTF seeded with activated sludge). The interaction parameter I2,1 of control (7.462) and bioaugmented BTF (3.267) obtained by the elimination capacity-sum kinetics with interaction parameter (EC-SKIP) model indicated that THF has a stronger inhibition of MTBE biodegradation in the control BTF than in the bioaugmented BTF. Similarly, the self-inhibition EC-SKIP model quantified the positive effects of MTBE on THF biodegradation, as well as the negative effects of THF on MTBE biodegradation and the self-inhibition of MTBE and THF. Metabolic intermediate analysis, real-time quantitative polymerase chain reaction, biofilm-biomass determination, and high-throughput sequencing revealed the possible mechanism of the enhanced treatment performance and biodegradation interactions of MTBE and THF.