Application of hyperspectral imaging and chemometrics for classifying plastics with brominated flame retardants

Most plastics need to incorporate flame retardants to meet fire safety standards requirements. The amount and the type of flame retardants can differ, so that in waste plastics a large variety of polymers and flame retardants can be found. The recycling of plastics containing flame retardants is increasing. However, only plastics of the same polymer type and the same additive content can be recycled together. Three models based on different chemometrics techniques applied to hyperspectral imaging in the near infrared range were developed [partial least square-discriminant analysis, decision tree (DT) and hierarchical model (HM)]. Optimal results were obtained for all classification techniques. HM shows the highest error at all levels due to the noisy spectra of the black plastics. However, DT classification gave outstanding results, considering that the sensitivity was higher than 0.9 in all cases. Thus, the application of DT with hyperspectral imaging could be used to sort plastic samples with respect to the type of polymer and the flame retardant used with a high degree of accuracy in an automated way. These findings are highly valuable for the plastic and waste management industries

Targeted conversion of protein and glucose waste streams to valatile fatty acids by metabolic models

Mixed-culture fermentations are recognised as suitable processes to valorise organic wastes and convert them into added-value products. One of the main issues of these processes is that the stoichiometry of the fermentations is highly dependent on operational conditions such as the pH or the concentrations of the different substrates. In this work we developed a mathematical model for the production of volatile fatty acids from wastes featuring high concentrations of carbohydrates and proteins. The model reproduces experimental results, predicting the tendencies of the product spectrum when varying pH values and at different proportions of carbohydrates and proteins in the feeding. This model can be the core of a tool for the computer-aided design of mixed-culture fermentationsThe authors would like to acknowledge the support of the Spanish Ministry of Education (FPU14/05457) and ERA-IB-2 project BIOCHEM (PCIN 2016-102) funded by MINECO. The authors belong to the Galician Competitive Research Group ED431C2017/029 and to the CRETUS Strategic Partnership (ED431E 2018/01), both programmes are co-funded by FEDER (UE

Designing mixed-culture bioprocesses by means of bioenergetics models

Symposium “Novel Anaerobes 2017”, 10th November 2017 University of Minho, Braga, PortugalMixed culture fermentations (MCFs) are recognised as an inexpensive means to produce high-added-valueproducts from low-grade biomass. However, developing a new bioprocess based on this technology is a challenging task. Although mixed cultures are advantageous when treating complex substrates in a continuous operation, they also pose a fundamental challenge: we are not able to fully understand the mechanisms that control these populations. In consequence, it is difficult to control the operation and to foresee the outcome of the process. In this context, BIOCHEM project (Figure 1) aims at designing a methodology for the development of a novel process based on MCFs focusing on two aspects: reaching a high productivity and achieving a high selectivity of the desired product(s)This activity is supported by ERA-IB-2 project BIOCHEM (PCIN2016-102), funded by MINECO, and by the Spanish Ministry of Education through the FPU scholarship (FPU14/05457

A metabolic model for targeted volatile fatty acids production by cofermentation of carbohydrates and proteins

Anaerobic mixed-culture fermentations are interesting processes to valorise organic wastes by converting them to volatile fatty acids. One of the main issues is that certain operational conditions (e.g. pH or different substrate concentrations) can vary significantly the product spectrum. So far, there are no tools that take into the account the characteristic features of cofermentation processes, which hinders the possibility of designing processes that use real wastes as substrates. In this work a mathematical model was developed for the production of volatile fatty acids from organic wastes with a high concentration of carbohydrates and proteins. The model reproduces satisfactorily experimental results and is also able of giving mechanistic insight into the interactions between carbohydrates and proteins that explain the observed changes in the product spectrum. We envision this model as the core of an early-stage design tool for anaerobic cofermentation processes, as shown in this work with different examplesThe authors would like to acknowledge the support of the Spanish Ministry of Education (FPU14/05457) and project BIOCHEM (ERA-IB-2 7th call, ERA-IB-16-052) funded by MINECO (PCIN 2016-102). The authors belong to the Galician Competitive Research Group ED431C2017/029 and to the CRETUS Strategic Partnership (ED431E 2018/01), both programmes are co-funded by ERDF (EU)S

Understanding the effect of trace elements supplementation on volatile fatty acids production from proteins

This investigation studies the impact of trace elements supplementation on protein anaerobic conversion into volatile fatty acids (VFAs). Two continuous reactors were operated with two model substrates, casein and gelatin, at acid (pH 5) and neutral (pH 7) conditions, with the addition of macro and micronutrients. Micronutrients increased the acidification degree of both proteins from 40% to 50% to more than 60% only at pH 7, which was consistent with a greater amino acid consumption at neutral conditions. Furthermore, trace elements modified the process selectivity, promoting valeric acids production and other variations dependant on protein composition. Isomerisation and chain elongation processes were identified as a consequence of the observed deviations between amino acid consumption and VFA production. Overall, this study demonstrated that the supplementation of micronutrients can be useful to enhance and steer the anaerobic fermentation of protein-rich streamsThis project has received funding from the Spanish Government through the European Union’s ERA-IB programme under grant agreement number PCIN-2016-102 and from the Spanish Ministry of Education (FPU14/05457). The authors belong to a Galician Competitive Research Group (ED431C2017/029; ED431E 2018/01), co-funded by Xunta de Galicia (Spain) and the European Regional Development Fund (ERDF-EU)S

Chain elongation may occur in protein mixed-culture fermentation without supplementing electron donor compounds

This study focuses on verifying the occurrence of elongation processes during protein mixed culture fermentation, without the supplementation of electron donor compounds. During casein mixed-culture fermentation at pH 5, it was observed that longer chain volatile fatty acid production increased, which could not be justified by the associated amino acid consumption. Consequently, the occurrence of chain elongation processes was hypothesized. To verify this hypothesis, three casein batch tests, with and without acetic acid initial supplementation, were performed at pH 5. The results suggest that acetic and propionic acids are indeed consumed to selectively generate n-valeric acid through the coupling with electron donor amino acids, whose consumption was further verified through the amino acid analysis. Prolonged simultaneous availability of suitable amino acids and short chain volatile fatty acids and an acid equivalent concentration threshold were identified as key parameters for the occurrence of chain elongation. The supplementation of acetic acid at the beginning of the test changed the selectivity of the elongation process, promoting n-butyric and iso-valeric production. The associated mechanisms were preliminary conceptualized, constituting a first step for further studies on the subject. To the best of our knowledge, this is the first study demonstrating the feasibility of chain elongation processes during protein mixed culture fermentation without electron donor supplementationThis project has received funding from the Spanish Government through BIOCHEM project (PCIN-2016-102, ERA-IB-2 7th call, ERA-IB-16-052)S

Protein composition determines the preferential consumption of amino acids during anaerobic mixed-culture fermentation

This research was funded by the Spanish Government through BIOCHEM project (PCIN-2016-102, ERA-IB-2 7th call, ERA-IB-16-052) and by the Spanish Ministry of Education (FPU14/05457). Authors belong to the CRETUS Strategic Partnership (ED431E 2018/01) and to the Galician Competitive Research Group (ED431C2017/029). All these programs are co-funded by ERDF (EU)S