Performance of modified hollow fiber membrane silver nanoparticles-zeolites Na-Y/PVDF composite used in membrane bioreactor for industrial wastewater treatment.

Membrane bioreactor (MBR) deteriorates due to fouling on the membrane pores, which can reduce the membrane performance. To reduce membrane fouling, the addition of inorganic filler can enhance the antifouling properties. This study investigates two different membrane preparation by thermally induced phase separation (TIPS) and dip coating methods to modify hollow fiber membrane with Silver Nanoparticles (AgNPs)-Zeolites used in MBR for industrial wastewater treatment. Performance was evaluated by analyzing the flux of water and wastewater, rejection, water content, and antifouling properties. Characterization result represented the synthesized silver nanoparticles had similar diffraction peak with commercial AgNPs, then the micrograph of AgNPs and zeolites addition membrane showed that the inorganic material had an octahedral shape representing zeolite crystal and irregular shape representing AgNPs. The addition of zeolites and AgNPs resulted in satisfying performance, increased flux, rejection, and antifouling properties.

Semi-hydrolysate of paper pulp without pretreatment enables a consolidated fermentation system with in situ product recovery for the production of butanol.

Utilization of lignocellulosic biomasses for biobutanol fermentation usually requires costly processes of pretreatment and enzymatic hydrolysis. In this study, paper pulp (93.2% glucan) was used as a starting biomass material to produce biobutanol. We conducted enzymatic semi-hydrolysis of paper pulp without pretreatment and with low enzyme loading, which produced high concentrations of cellobiose (13.9 g L-1) and glucose (21.3 g L-1). In addition, efficient fermentation of the semi-hydrolysate was achieved similar to that with the use of commercial sugars without inhibitors. Finally, we designed a novel non-isothermal simultaneous saccharification and fermentation with in situ butanol recovery, which was composed of a repeated semi-hydrolysis process and successive butanol-extractive fermentation process under the respective optimal conditions. The consolidated system improved butanol production, butanol yields, and butanol productivities and enabled repeated use of medium when compared with other integrated hydrolysis and fermentation processes.

Novel biobutanol fermentation at a large extractant volume ratio using immobilized Clostridium saccharoperbutylacetonicum N1-4.

Product inhibition by butanol and acetone is a known drawback in acetone-butanol-ethanol (ABE) fermentation. Extractive fermentation improves butanol production by several ABE-producing Clostridium spp., but only low volume ratios (<4) of extractant to broth (Ve/Vb) have been studied. Here, a novel extractive fermentation process was developed using Clostridium saccharoperbutylacetonicum N1-4 and a large Ve/Vb ratio. A mixture of oleyl alcohol-tributyrin (1:1 (v/v)) yielded high distribution coefficients for both butanol (3.14) and acetone (0.660). Although a fed-batch culture using free cells and the oleyl alcohol-tributyrin mixture at a Ve/Vb ratio of 5 had a lag phase of >24 h, it produced a higher concentration of total butanol (i.e., butanol produced in all the phases per broth volume used) of 24.2 g/L-broth after 96 h compared with 14.4 g/L-broth at a Ve/Vb ratio of 1, resulting in a low butanol concentration in the aqueous phase. The use of cells immobilized with calcium alginate beads shortened the lag phase to <12 h. Butanol production was achieved not only in a 3-phase mode (extractant, beads, and tryptone-yeast extract-acetate (TYA) medium) but also in a 2-phase mode (extractant and beads containing TYA medium, without an aqueous phase) at a Ve/Vb ratio of 5, resulting butanol concentrations of 30.9 g/L-broth and 27.7 g/L-broth, respectively. The 3-phases fed-batch extractive fermentation at a Ve/Vb ratio of 10 showed a better performance compared with published reports: a total butanol concentration of 64.6 g/L-broth and a butanol yield to consumed sugar of 0.378 C-mol/C-mol.