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• An innovative two-stage bioreactor was applied for anoxic H 2 S removal. • Dilution of the treated gas stream was avoided. • Clogging issues were avoided. • High H 2 S removal performance was observed even with changing bacterial community. A two-stage bioreactor operated under anoxic denitrifying conditions was evaluated for desulfurization of synthetic biogas laden with H 2 S concentrations between 2500 and 10,000 ppm v. H 2 S removal efficiencies higher than 95% were achieved for H 2 S loads ranging from 16.2 to 51.9 gS m liquid −3h−1. Average H 2 S oxidation performance (fraction of S-SO 4 2− produced per gram of S-H 2 S absorbed) ranged between 8.2 ± 1.2 and 18.7 ± 5.3% under continuous liquid operation. Nitrogen mass balance showed that only 2–6% of the N-NO 3 − consumed was directed to biomass growth and the rest was directed to denitrification. Significant changes in the bacterial community composition did not hinder the H 2 S removal efficiency. The bioreactor configuration proposed avoided clogging issues due to elemental sulfur accumulation as commonly occurs in packed bed bioreactors devoted to H 2 S-rich biogas desulfurization. [ABSTRACT FROM AUTHOR]

A two-stage biological waste gas treatment system consisting of a first stage biotrickling filter (BTF) and second stage biofilter (BF) was tested for the removal of a gas-phase methanol (M), hydrogen sulphide (HS) and α-pinene (P) mixture. The bioreactors were tested with two types of shock loads, i.e. , long-term (66 h) low to medium concentration loads, and short-term (12 h) low to high concentration loads. M and HS were removed in the BTF, reaching maximum elimination capacities (EC max ) of 684 and 33 gm −3 h −1 , respectively. P was removed better in the second stage BF with an EC max of 130 gm −3 h −1 . The performance was modelled using two multi-layer perceptrons (MLPs) that employed the error backpropagation with momentum algorithm, in order to predict the removal efficiencies (RE, %) of methanol (RE M ), hydrogen sulphide (RE HS ) and α-pinene (RE P ), respectively. It was observed that, a MLP with the topology 3-4-2 was able to predict RE M and RE HS in the BTF, while a topology of 3-3-1 was able to approximate RE P in the BF. The results show that artificial neural network (ANN) based models can effectively be used to model the transient-state performance of bioprocesses treating gas-phase pollutants. [ABSTRACT FROM AUTHOR]

With an increasing demand for efficacious, safe, and affordable vaccines for human and animal use, process intensification in cell culture-based viral vaccine production demands advanced process strategies to overcome the limitations of conventional batch cultivations. However, the use of fed-batch, perfusion, or continuous modes to drive processes at high cell density (HCD) and overextended operating times has so far been little explored in large-scale viral vaccine manufacturing. Also, possible reductions in cell-specific virus yields for HCD cultivations have been reported frequently. Taking into account that vaccine production is one of the most heavily regulated industries in the pharmaceutical sector with tough margins to meet, it is understandable that process intensification is being considered by both academia and industry as a next step toward more efficient viral vaccine production processes only recently. Compared to conventional batch processes, fed-batch and perfusion strategies could result in ten to a hundred times higher product yields. Both cultivation strategies can be implemented to achieve cell concentrations exceeding 10 cells/mL or even 10 cells/mL, while keeping low levels of metabolites that potentially inhibit cell growth and virus replication. The trend towards HCD processes is supported by development of GMP-compliant cultivation platforms, i.e., acoustic settlers, hollow fiber bioreactors, and hollow fiber-based perfusion systems including tangential flow filtration (TFF) or alternating tangential flow (ATF) technologies. In this review, these process modes are discussed in detail and compared with conventional batch processes based on productivity indicators such as space-time yield, cell concentration, and product titers. In addition, options for the production of viral vaccines in continuous multi-stage bioreactors such as two- and three-stage systems are addressed. While such systems have shown similar virus titers compared to batch cultivations, keeping high yields for extended production times is still a challenge. Overall, we demonstrate that process intensification of cell culture-based viral vaccine production can be realized by the consequent application of fed-batch, perfusion, and continuous systems with a significant increase in productivity. The potential for even further improvements is high, considering recent developments in establishment of new (designer) cell lines, better characterization of host cell metabolism, advances in media design, and the use of mathematical models as a tool for process optimization and control. [ABSTRACT FROM AUTHOR]

Two vertical rotating immobilized cell reactors (VRICRs), one with the bacteriaBacillussp. BDCC-TUSA-3 and the other withR. erythropolis, were constructed, with polyurethane foams as an attachment support. They were optimized for surfactin production and biodesulfurization (BDS) of dibenzothiophene (DBT), respectively. Then, the two bioreactors were combined to form a two-stage VRICR where an appropriate fraction ofBacillussp. reactor effluent, containing surfactin, was mixed with the influent fed intoR. erythropolisbioreactor, containing DBT in hexadecane. The BDS rate and volumetric reactor productivity were greatly increased to 210.5 mM 2HBP.kg−1.h−1and 16.6 mM 2HBP.L−1.h−1, respectively. Sulfur concentration decreased from 398 down to <5 ppm. Additionally, surfactin was produced at high concentration (4.8 g.L−1) with a volumetric reactor productivity of 720 mgsurfactin·L−1.h−1, which represents an extra added-value product that could markedly decrease operating costs. This study presents a feasible technology for efficient removal of sulfur from sulfur-containing fossil fuels and the production of biosurfactant as well. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen from renewable energy is considered a promising alternative to traditional petroleum-based transportation fuels. Potato steam peels can be used as feedstock to produce hydrogen through fermentation processes. Life cycle assessment is used as an analytical tool to evaluate the main environmental benefits and burdens of using potato steam peals to produce hydrogen rather than to feed animals. Inventory data are derived from the literature and ecoinvent. Impacts are evaluated using IMPACT 2002+. The results show that producing hydrogen from potato steam peels offers clear advantages over a direct use of peels to feed animals. A factor of two to three is observed in the reduction of greenhouse gas emissions, in the savings of non-renewable resources and in the reduction of human health impacts. The two-stage bioreactor is observed to consume around 25MJ and to emit between 1000 and 1500g of per kilogram of hydrogen produced. [Copyright &y& Elsevier]

Abstract: Groundwater, used in this study, contaminated predominantly with aromatic compounds, was biologically treated in a fluidized-bed reactor (FBR) with immobilized cells. The aromatics were completely decomposed, while cis-1,2-dichloroethylene (cis-DCE) and trichloroethylene (TCE) were decomposed only approximately 20% and 5%, respectively. In these studies a significant improvement of the decomposition efficiency for chlorinated ethylenes was achieved by utilizing cometabolism. Methanol (MeOH) and toluene were used as the substrate in the case of one-stage reactor (Single Reactor). MeOH (187mgl−1) increased the decomposition efficiency up to 40% and 60% for cis-DCE and TCE, respectively, while toluene (20mgl−1) increased the decomposition efficiency of cis-DCE to 92% and the decomposition efficiency of TCE to 76%. In the case of two-stage reactor system (Reactor 1 and Reactor 2), MeOH and methane (CH4) were used as the substrate. In this system, cells grown on MeOH or CH4 in the Reactor 1 were continuously fed into Reactor 2 and groundwater was fed into Reactor 2 only. When MeOH (384mgl−1d−1) was used as substrate the decomposition efficiency of cis-DCE and TCE were 60% and 70%, respectively. Similar decomposition efficiency was observed for a small amount of CH4 (19.3mgl−1d−1). [Copyright &y& Elsevier]