In shell side mode, PDMS was more efficient and no wetting phenomenon was 23 observed with this contactor. The differences have been explained, taking into account 24 2 the material properties (porosity, material resistance …) of the membrane and structure 25 (packing density, fibre diameter …) of the modules. Methane removal efficiencies of up 26 to 98% could be achieved, showing the viability of methane removal/recovery using this 27 technology. Simultaneous degassing of CO 2 was also monitored in both modules, 28 showing that the removal efficiency of this gas was considerably lower than for 29 methane. In general terms, the removal of dissolved CO 2 followed a quite similar 30 behaviour from that described for methane. Experimental overall mass transfer 31 coefficients were also obtained. 32
Keywords 33Anaerobic reactor; degassing; greenhouse gas emissions; membrane contactors; 34 methane recovery 35 36 3
11The performance, fouling and feasibility of a polydimethylsiloxane hollow fibre 12 membrane module for in situ methane degasification from the effluent of an Expanded
Three laboratory-scale peat biofilters were operated at 90 s empty bed residence time (EBRT) for over a year. Biodegradation of ethyl acetate, toluene, or a 1:1 mixture were investigated. In first stage, inlet concentration was progressively increased from 0.4 to 4.5 g/m(3). The maximum elimination capacity (EC) found for ethyl acetate was 190 gC/m(3).h, and it was not affected by toluene. The maximum EC found for toluene as a sole contaminant was 150 gC/m(3).h, but the presence of ethyl acetate decreased the toluene maximum EC to 80 gC/m(3).h. From respirometry monitoring, values of 3.19 g CO(2)/gC and 3.06 g CO(2)/gC for pure ethyl acetate and pure toluene, respectively, were found, with overall yield coefficients of 0.13 g dry biomass produced per gram ethyl acetate consumed and 0.28 g dry biomass produced per gram toluene consumed. CO(2) production in the 1:1 mixture was successfully simulated. Dynamics of living and dead cells were monitored in four sections of the biofilters. Concentrations ranged between 2.6 x 10(9) and 3.0 x 10(10) cells per gram-dry peat for total bacteria, and 2.4 x 10(9)-1.9 x 10(10) cells per gram-dry peat for living bacteria. At high loads loss of bacterial density in the inlet zones, and increase in the dead cells percentages up to 60% was observed. In second stage, long-term performance at an inlet concentration of 1.5 g/m(3) was evaluated to show the process feasibility. Good agreement with previous data was obtained in terms of EC and CO(2) production. Restoration of living cells proportion was also observed.
The performance and feasibility of a pilot unit of biotrickling filter (BTF) for the treatment of industrial emissions polluted by styrene was investigated for one year at a fiber reinforced plastic industrial site. The pilot unit was packed with a structured material with a volume of 0.6 m 3. Monitoring results have shown successful treatment of the industrial styrene emissions working at empty bed residence times (EBRT) between 31 and 66 s. The best performance was obtained after 300 days when a more stable biofilm had been developed, obtaining the highest elimination capacity of 18.8 g m-3 h-1 (removal efficiency of 75.6%) working at 31 s of EBRT. In addition, a photocatalytic reactor was evaluated as pretreatment of the biological process, but results have shown very low capacity for improving the BTF performance due to catalyst deactivation. The economic feasibility of the BTF was evaluated. The total direct cost, excluding capital recovery, of the biotrickling filter technology was estimated in 0.71 € year-1 per Nm 3 h-1 of treated air whereas 2.27 € year-1 per Nm 3 h-1 was obtained for the regenerative catalytic oxidizer equipped with a zeolite pre-concentrator. Results show that this technology is economically and environmentally competitive in comparison with thermal treatment.
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