A BOD monitoring disposable reactor with alginate-entrapped bacteria

Biochemical oxygen demand (BOD) is a measure of the amount of dissolved oxygen that is required for the biochemical oxidation of the organic compounds in 5 days. New biosensor-based methods have been conducted for a faster determination of BOD. In this study, a mathematical model to evaluate the feasibility of using a BOD sensor, based on disposable alginate-entrapped bacteria, for monitoring BOD in situ was applied. The model considers the influences of alginate bead size and bacterial concentration. The disposable biosensor can be adapted according to specific requirements depending on the organic load contained in the wastewater. Using Klein and Washausen parameter in a Lineweaver–Burk plot, the glucose diffusivity was calculated in 6.4 × 10⁻¹⁰ (m²/s) for beads of 1 mm in diameter and slight diffusion restrictions were observed (n = 0.85). Experimental results showed a correlation (p < 0.05) between the respirometric peak and the standard BOD test. The biosensor response was representative of BOD.     

Life cycle assessment of bio-based products: a disposable diaper case study

Purpose

In this study, a life cycle assessment of a bioplastic based diaper was performed. The product has several innovative elements, due to the implementation of eco-design principles, such as: (1) introduction of biopolymers (namely polylactic acid (PLA) and Mater-bi®), (2) relevant reduction of petrochemical plastics, and (3) minimization of energy consumptions and use of renewable energy in manufacturing. The aim of the study is to evaluate the environmental benefits gained through eco-innovation, while identifying further areas of improvement.

Methods

The bio-based diaper has been evaluated using a “cradle-to-gate” analysis. The functional unit is one diaper, assuming an average size among the different commercial options. A case study of an enterprise in Italy (WIP S.p.A) was carried out to collect as much reliable primary data as possible. In order to highlight potential areas of improvement and to compare the environmental performance of the product, a sensitivity analysis based on three different impact assessment methods (adopting ReCiPe 2008, IMPACT 2002+ and Cumulative Energy Demand (CED)) and a comparison with a standard commercial diaper were performed. Finally, three possible end-of-life scenarios including composting of WIP diaper were hypothesized and tested.

Results and discussion

Contribution analysis suggested that sourcing and production of raw materials used in WIP diaper manufacturing contributed most significantly to the potential environmental impacts. Adopting ReCiPe method, pulp, and sodium polyacrylate present the highest environmental burdens in WIP diaper system. Applying IMPACT2002+ method, PLA relative contribution to the toxicity increases, due to the generation of the electricity used in corn production and in PLA production phases. For both methods, impacts related to energy consumption of the WIP diapers’ production process look to be negligible. WIP diaper performance has room for improvement, since critical points were detected in the life cycle stages of raw materials used. However, the results of the normalization step, according to ReCiPe method, state that WIP diapers can bring environmental benefits, compared to standard ones. Moreover, if composting end-of-life scenario is included in the assessment, there is a significant improvement in WIP diaper environmental performance compared to a standard diaper.

Conclusions

Integrating eco-innovation and eco-design principles in the production of the bio-based diaper leads to a better environmental profile, compared to the standard one. Nevertheless, there are several areas of concerns to be considered in order to further improve its environmental performance. So far, the possible improvements identified from the case study are: (1) the selection of biopolymers suppliers with better production systems from an environmental point of view, (2) the reduction of distances along the supply chain, and (3) the implementation of composting procedures for the end of life. In conclusion, the introduction of biopolymers in diaper composition could lead them to be preferable compared to standard diapers, but criticisms arise, which need to be solved, to avoid the risk of burdens shifting.     

Legal aspects of reuse and re-sterilization of disposable products in the hospital]

What consequences may follow if the hospital administration decides to introduce recycling and resterilisation of disposable medical products? While some consider the chief executive administrators and doctors to be seriously endangered by the legal implications of the German Medical Products Act (MPG), others consider recycling and resterilisation to be clearly admissible. A closer look at what constitutes an offence as described in sec. 43, para 1 No. 1 of the MPG reveals that mere presumptions do not suffice to incur the respective penalties; rather, a concrete, scientifically sound basis for assuming an endangerment of safety or health are required for penal measures to be justified. The manufacturer's designation "for once-only use" may not be considered "intended purpose" as stipulated in sec. 4, para 1 No. 1 of the MPG. If recycling or resterilisation be confined to self-made disposables, there is no necessity for CE marking. Information of the patient and individual documentation must be extended to cover the use of recycled or resterilised disposable products only if the use of the latter may constitute a significant additional danger to the patient.     

On-line monitoring of oxygen in Tubespin, a novel, small-scale disposable bioreactor

A novel, optical sensor was fixed in a new type of disposable bioreactor, Tubespin, for the on-line (real-time) monitoring of dissolved oxygen concentrations during cell culture. The cell density, viability and volumetric mass transfer coefficient were also determined to further characterize the bioreactors. The k_La value of the Tubespin at standard conditions was 24.3 h⁻¹, while that of a spinner flask was only 2.7 h⁻¹. The maximum cell density in the Tubespin bioreactor reached 6 × 10⁶ cells mL⁻¹, which was two times higher than the cell density in a spinner flask. Furthermore, the dynamic dissolved oxygen level was maintained above 90% air-saturation in the Tubespin, while the value was only 1.9% in a spinner flask. These results demonstrate the competitive advantage of using the Tubespin system over spinner flasks for process optimization and scale-down studies of oxygen transfer and cell growth.     

Real-time monitoring of shake flask fermentation and off gas using triple disposable noninvasive optical sensors

Bioprocess development is a data-driven process requiring a large number of experiments to be conducted under varying conditions. Small-scale upstream bioprocess development is often performed in shake flasks because they are inexpensive and can be operated in parallel. However, shake flasks are often not equipped to accurately monitor critical process parameters such as pH, dissolved oxygen, and CO2 concentrations. Therefore, there is no definitive information on oxygen supply of growing cells, CO2 formation, and pH changes. Here we describe several shake flask fermentations where all three parameters are monitored by disposable noninvasive optical sensors. The sensitive element of these sensors is a thin, luminescent patch affixed inside the flask. Small electronic devices for excitation and fluorescence detection are positioned outside the shake flask for noninvasive monitoring. By measuring the process parameters throughout the course of the E. coli fermentations, we obtain information that is not routinely available in shake flask fermentations. For example, for cultures with only a few millimeters liquid depth, oxygen limitation can occur at relatively low agitation speeds. Under certain conditions oscillations in dissolved oxygen can occur. An increase in shaker speed and a decrease in culture volume can increase the oxygen availability and reduce the duration of oxygen limitation.     

Degradation of polyribonucleotides: Biocatalysis and the monitoring of products

Macroporous monolithic materials containing covalently linked ribonuclease A were used to create high-performance flow-through heterogeneous biocatalysts (bioreactors). The kinetic parameters of the degradation of polycytidylic acid were identified, and the properties of the obtained systems were compared. A HPLC method has been developed for monitoring of products of biocatalytic degradation of RNA, and the possibility of using biocatalytic and HPLC columns in RNA degradation processes in a multicomponent mixture of biological molecules was shown.     

Bioassays for evaluation of medical products derived from bacterial toxins

Bioassays play central role in evaluation of biological products and those derived from bacterial toxins often rely exclusively on in vivo models for assurance of safety and potency. This chapter reviews existing regulatory approved methods designed to provide information on potency and safety of complex biological medicines with an insight into strategies considered for alternative procedures.     

Safety evaluation of two bacterial strains used in Asian probiotic products

Probiotics, known for their prophylactic and therapeutic properties, are routinely used by the medical community in various regions of the world. In some Asian countries, these products are controlled as pharmaceutical substances and must adhere to strict regulatory guidelines. However, outside of Europe where the European Food Safety Authority has recently adopted a Qualified Presumption of Safety approach for probiotics used in food and feed, current safety requirements do not necessitate screening for the presence of virulence and other risk factors, which may result in the inadvertent use of probiotic strains harboring harmful genes. A safety evaluation was conducted on Enterococcus faecium R0026 and Bacillus subtilis R0179 used in several commercial probiotic products marketed in Asia. Molecular techniques were used to verify the identity of each strain and antibiotic resistance profiles were determined towards clinically relevant antibiotics. Strains were subsequently screened for the presence of enterotoxins and virulence factors and were subjected to 28 days of repeated high-dose oral toxicity testing in rats. No risk factors or aberrant activities were identified using such a detailed approach. Thus, both microbes were deemed to pose low risk to the consumer and, therefore, safe for use as probiotics.     

The physiologic and medical rationale for intrapartum fetal monitoring

In the United States and most industrialized countries, intrapartum fetal surveillance is performed primarily by electronic fetal heart rate monitoring. Following implementation of this technology into clinical practice, a reduction in perinatal mortality has been accompanied by a concomitant increase in the cesarean section rate to concerning levels. Although these trends are not solely due to one factor such as electronic fetal heart rate monitoring, it is well-recognized that this method of surveillance is hampered by subjectivity in interpretation and by a high false-positive (falsely nonreassuring) rate. The purpose of this review is to assess the physiologic rationale for intrapartum assessment, the significant limitations of current primary and ancillary monitoring methods, and the development of new technologies such as fetal oxygen saturation monitoring (pulse oximetry) that potentially hold great promise for the future.     

Physicochemical, toxicological and hygienic aspects of ethylene oxide application for the sterilization of medical products. III. Setting hygienic norms in sterilized medical products

Some of the drawbacks are discussed associated with hygienic norms for gaseous sterilizing agents in polymeric products for medical applications. A new approach is proposed for regulating ethylene oxide (EO) in such products. To this end, limiting types of biological effect and its pathways have been determined and substantiated as well as the reliability factor for establishing hygienic norms for EO in medical products. Daily threshold EO limit values were calculated for momentary and repeated exposure of humans. The duration of long-term and short-term exposure of the patient to sterilized products was evaluated on the basis of EO extraction kinetics from a variety of materials. Using daily threshold limit values, threshold residual values (TRV) of EO were calculated for different groups of polymeric products for medical applications.     

Issues in the development of medical products based on human plasma

Product development and process validation are shown in the case of several products obtained from human plasma. These are virus-inactivated plasma, intravenous immunoglobulins and the clotting factors VIII and IX. Different analytical methods are presented, which are used for product control and in-process control. For the production of virus-inactivated human plasma a down-scale protocol is presented, allowing a simulation of the production on a laboratory scale. Virus validation has shown that the reduction of transfusion-relevant viruses in the process was higher than six log steps. Determination of leachables from the RP-column, which was used in this production, proved that they appear in the final product in quantities below the detection limits only. It was also shown that the chemicals used for virus inactivation could be quantitatively removed from the product. For the isolation of other products, here intravenous gamma globulins and the clotting factors VIII and IX, similar validation steps had to be taken. In the case of clotting factor VIII the following data were determined, the reduction of viruses, the amount of leachables from the column, the residues of chemicals from the solvent/detergent treatment for virus inactivation. Virus reduction was successfully performed as well as the removal of chemicals used for virus inactivation. The amount of leachables from the columns used for chromatographic purification was found to be far below the permissible levels.