No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
TESTING THE BIODEGRADABILITY AND BIODEGRADATION RATES OF DEGRADABLE/BIODEGRADABLE PLASTICS WITHIN SIMULATED ENVIRONMENT
Abstract
The objective of this study was to evaluate and compare the biodegradability and biodegradation rates of ‘single-use' plastic bags available on the market and labeled as degradable/biodegradable. The test was carried out under both aerobic and anaerobic conditions. The project length was 20 months. The biodegradation results in the laboratory conditions demonstrate that none of the degradable/ biodegradable bags showed visual changes and/or were broken into pieces and none of them experienced any disintegration or degradation. The cellulose filter paper (CFP) completely degraded after 10 days in the aerobic conditions and after 5 month in the anaerobic conditions, implying that the conditions required for biodegradation to occur in a sampling environment were present.
... For the aerobic environment, biodegradability is measured on the basis of CO2 analysis. For an anaerobic environment, a parameter is used, which is the amount of Dissolved Organic Carbon (DOC) [13]. ...
Biodegradable materials and their applications are now a widespread topic of scientific activities and publications, mainly due to their ever-expanding possibilities for use in biomedical fields. Advances in the study and evaluation of materials often require different methods to determine the properties and consequences of degradation, whether changes in structure, mass changes, morphological changes or differences in the mechanical properties of the material before and after degradation. The aim of this work is to summarize the available and used methods, as well as to compare the information obtained for the design of a suitable method. The procedures are described on the basis of studies that have addressed the issue of biodegradation of materials using in vitro methods.
... ─ исследуемые в работе образцы PLA легко подвергаются деструкции в водных системах, обладают достаточной эластичностью и стойкостью к механическому проколу; ─ результаты, полученные методом термогравиметрической и дифференциальносканирующей колориметрии (ТГ и ДСК) позволили установить наличие неорганического компонента в составе исследуемых образцов биополимера, что может указывать на наличие в них связующих и модифицирующих добавок неорганического происхождения; ─ синтетические полимерные материалы, по основным физико-механическим параметрам незначительно превосходят биоразлагаемые полимерные материалы, однако в отличии от биополимеров практически не утилизируются в природе естественным путем; ─ по показателям водопоглощения исследуемые образцы биоразлагаемых полимеров в сравнение с ПЭНП характеризуются лучшей гидрофобностью (кроме образца PLA № 2); ─ для улучшения эксплуатационных свойств биополимера рекомендуется использовать специальные модифицирующие (упрочняющие и гидрофобизирующие) добавки [14][15][16][17][18][19][20]. ...
The article deals with the actual problem of environmental friendliness of packaging materials used in the food industry. The aim of the work was to study the physical and mechanical characteristics of biodegradable and synthetic polymers, with the aim of updating the replacement of synthetic packaging materials with more environmentally friendly materials. The article discusses the main characteristics of innovative biodegradable materials based on polylactides (PLA). A comparative analysis of the strength and sorption properties of both biodegradable and synthetic polymeric materials is presented. A comparative analysis of the materials under study was carried out according to the following parameters: water absorption, puncture resistance, deformation-strength and thermophysical characteristics. The paper also presents the results of a study of the water-absorbing capacity of the analyzed polymeric materials. The results of tests are presented, which make it possible to establish the temperature-time parameters of the processing of polylactide by the melt method. The data obtained by the DSC method on the establishment of relaxation and phase transitions that occur in the polymer during thermolysis are analyzed. During the experiment, experimental studies of the chemical properties of biodegradable materials based on polylactides (PLA), made in China were carried out. The main advantages and disadvantages of synthetic and natural polymeric materials are considered. In addition, the paper analyzes the environmental aspects of the practical application of the studied polymeric materials. Conclusions are formulated about the possibility and safety of using the presented materials in various branches of the food industry. Based on the results of the experiment, it was found that synthetic polymer materials slightly exceed biopolymer materials in terms of the investigated physical and mechanical parameters, however, given the environmental friendliness and the possibility of complete utilization in natural conditions, this fact does not reduce the relevance of using biopolymers in the food industry. In addition, the analysis of data on the chemical composition of the studied biopolymers based on polylactides (PLA) showed that the decrease in the strength parameters of the presented samples can be neutralized by introducing modifying strengthening and hydrophobizing additives.
... The biodegradability of various bioplastics under simulated landfill conditions was investigated by many scientists earlier [101][102][103][104]. By employing anaerobic digested sludge, they found that natural aliphatic polyester such as poly(3hydroxybutyrate-co-3-hydroxyvalerate) (PHB/HV; 92/8, w/w) degraded within 20 days of cultivation, while synthetic aliphatic polyesters such as poly-lactic acid, poly(butylene succinate) and poly(butylene succinate-co-ethylene succinate) did not degrade at all in 100 days [105]. ...
The global bioplastics market shows tremendous growth potential in producing sustainable products for diverse applications. The production of polyhydroxybutyrate (PHB) from natural and unutilized (wasted) organic compounds is especially advantageous for achieving simultaneous resource recovery and pollution prevention. This paper investigates the possible avenues to enhance the PHB production from different types of wastewater by virtue of their inherent microorganisms and carbon sources. In contrast to the common notion, waste activated sludge (WAS) is reported to be a highly promising substrate for PHB production; however, it necessitates proper nutrient balancing. It is confirmed that significant recovery of essential nutrients can be obtained by optimizing the substrate-microbe combination, reactor selection and process control techniques. The study further identifies latest technological developments in improving the metabolic pathways for different combinations of carbon and nutrients sources, by varying the operational conditions and identifying suitable microorganisms so that PHB production can be maximized. The study also highlights the scope of possible end-of-life applications for bioplastics in commensuration with achieving sustainable economic feasibility in their processing. Thus, this study aims to present a comprehensive overview on the production, application and reuse options for PHB as a sustainable bioplastic with emphasis on resource recovery strategies.
Graphical abstract
A desinformação é considerada uma das maiores ameaças ao processo democrático. As redes sociais, enquanto plataformas de acesso fácil e barato, permitem que qualquer utilizador crie e partilhe informação, sem que esta seja primeiro revista e comprovada. Adicionalmente, o seu potencial para rápida disseminação, contribuiu para a propagação cada vez maior de notícias falsas. A manipulação da opinião pública através das notícias falsas tem consequências graves para as diferentes áreas da sociedade incluindo a saúde, a ciência e o ambiente. Por exemplo, com o aumento da importância dos temas ambientais no debate político, algumas empresas, cujas práticas prejudicam o meio ambiente, apropriaram-se destas tendências para os seus próprios fins comerciais, através do greenwashing. O interesse de certos grupos e entidades em influenciar as decisões dos órgãos políticos também implica que, por vezes, recorram à partilha de desinformação.
Este projeto pretende contribuir para o combate à desinformação através da educação, promovendo o sentido crítico do público e dotando-o das ferramentas necessárias para filtrar e analisar a informação com que se depara. Adicionalmente, pretende-se identificar as áreas em que a população revela estar mais desinformada, de modo a realizar ações de divulgação científica sobre esses temas, contribuindo para a consciencialização dos cidadãos.
Degradable polymers have been appearing on the market for about 30 years and they are a supplement to packaging
materials made of synthetic polymers. The aim of the methodology is to provide both professional and non-professional
public with all information regarding the manner of evaluating the decomposition of degradable polymeric materials
and materials marketed as degradable in real composting conditions.
Degradabilities of four kinds of commercial biodegradable plastics (BPs), polyhydroxybutyrate and hydroxyvalerate (PHBV) plastic, polycaprolactone plastic (PCL), blend of starch and polyvinyl alcohol (SPVA) plastic and cellulose acetate (CA) plastic were investigated in waste landfill model reactors that were operated as anaerobically and aerobically. The application of forced aeration to the landfill reactor for supplying aerobic condition could potentially stimulate polymer-degrading microorganisms. However, the individual degradation behavior of BPs under the aerobic condition was completely different. PCL, a chemically synthesized BP, showed film breakage under the both conditions, which may have contributed to a reduction in the waste volume regardless of aerobic or anaerobic conditions. Effective degradation of PHBV plastic was observed in the aerobic condition, though insufficient degradation was observed in the anaerobic condition. But the aeration did not contribute much to accelerate the volume reduction of SPVA plastic and CA plastic. It could be said that the recalcitrant portions of the plastics such as polyvinyl alcohol in SPVA plastic and the highly substituted CA in CA plastic prevented the BP from degradation. These results indicated existence of the great variations in the degradability of BPs in aerobic and anaerobic waste landfills, and suggest that suitable technologies for managing the waste landfill must be combined with utilization of BPs in order to enhance the reduction of waste volume in landfill sites.
The biodegradability and the biodegradation rate of two kinds biodegradable polymers; poly(caprolactone) (PCL)-starch blend and poly(butylene succinate) (PBS), were investigated under both aerobic and anaerobic conditions. PCL-starch blend was easily degraded, with 88% biodegradability in 44 days under aerobic conditions, and showed a biodegradation rate of 0.07 day(-1), whereas the biodegradability of PBS was only 31% in 80 days under the same conditions, with a biodegradation rate of 0.01 day(-1). Anaerobic bacteria degraded well PCL-starch blend (i.e., 83% biodegradability for 139 days); however, its biodegradation rate was relatively slow (6.1 mL CH(4)/g-VS day) compared to that of cellulose (13.5 mL CH(4)/g-VS day), which was used as a reference material. The PBS was barely degraded under anaerobic conditions, with only 2% biodegradability in 100 days. These results were consistent with the visual changes and FE-SEM images of the two biodegradable polymers after the landfill burial test, showing that only PCL-starch blend had various sized pinholes on the surface due to attack by microorganisms. This result may be use in deciding suitable final disposal approaches of different types of biodegradable polymers in the future.
Lack of degradability and the closing of landfill sites as well as growing water and land pollution problems have led to concern about plastics. With the excessive use of plastics and increasing pressure being placed on capacities available for plastic waste disposal, the need for biodegradable plastics and biodegradation of plastic wastes has assumed increasing importance in the last few years. Awareness of the waste problem and its impact on the environment has awakened new interest in the area of degradable polymers. The interest in environmental issues is growing and there are increasing demands to develop material which do not burden the environment significantly. Biodegradation is necessary for water-soluble or water-immiscible polymers because they eventually enter streams which can neither be recycled nor incinerated. It is important to consider the microbial degradation of natural and synthetic polymers in order to understand what is necessary for biodegradation and the mechanisms involved. This requires understanding of the interactions between materials and microorganisms and the biochemical changes involved. Widespread studies on the biodegradation of plastics have been carried out in order to overcome the environmental problems associated with synthetic plastic waste. This paper reviews the current research on the biodegradation of biodegradable and also the conventional synthetic plastics and also use of various techniques for the analysis of degradation in vitro.
The degradation of a commercial environmentally degradable polyethylene was investigated in two stages. Firstly by abiotic oxidation in an air oven to simulate the effect of the compost environment and secondly in the presence of selected microorganisms. Initial biofilm formation was followed by fluorescence microscopy and the subsequent growth of bacteria on the surface of the plastic was observed by scanning electron microscopy (SEM). It was observed that microbial growth occurred on the presence of PE samples that had been compression moulded to thick sections but had not been deliberately pre-oxidised. Molecular enlarge-ment and broadening of molecular weight distribution occurred after preheating in air at 60 C but not at ambient temperatures but colonisation of microorganisms occurred on all samples. Erosion of the film surface was observed in the vicinity of the micro-organisms and the decay of oxidation products in the surface of the polymer film was measured by FTIR measurements and was found to be associated with the formation of protein and polysaccharides, attributable to the growth of the microorganisms.
The susceptibility of polycaprolactone/starch (PCL/S) and sisal fibre-reinforced polycaprolactone/starch blends (SF-PCL/S) to different degrading environments was evaluated. The composites and the unfilled matrix showed hydrolytic stability at pH 7.2 at two different temperatures (25 °C and 40 °C). Fibres were stable under hydrolytic conditions and seemed to favour the entrance of water and then, the swelling and the hydrolysis of the starch (the most bio-available component). At higher fibre content, the composites become more hydrolytically stable probably due to the presence of a fibre–fibre physical network. Microbial attack in biotic aqueous medium was evidenced by the presence of a biofilm, especially on the fibre surface. In soil burial, PCL/S and 15%SF–PCL/S were degraded to about 50% of the initial mass. The weight loss pattern showed by the composite was associated with the presence of strong fibre–fibre and fibre–matrix interactions, which are absent in the neat matrix.
The use of engineering plastics, especially polyolefins has increased significantly in recent decades largely due to their low cost, good mechanical properties and light weight. However, this increase in usage has also created many challenges associated with disposal and their impact on the environment. This is because polyolefins do not easily degrade in the natural environment and hence the need for degradable polyolefins has become a major topic of research. Degradable polyolefins are designed to retain functionality as a commodity plastic for the required service life but degrade to non-toxic end products in a disposal environment. They are typically designed to oxo-degrade while undergoing changes in chemical structure as a result of oxidation in air, thus causing the breakdown of the molecules into small fragments that are then bioassimilated. This article presents (i) a comprehensive review of the chemistry of additives for the degradation of polyolefins, (ii) a patent and scientific literature summary of technologies including commercially available systems, (iii) the mechanisms of degradation and biodegradation, (iv) testing methods and (v) toxicity.
Thermo-oxidative degradation of polyethylene films containing pro-oxidant has been studied at three temperatures that normally occur during composting conditions. Besides temperature, oxygen concentration was also varied. After various periods, the effects of thermo-oxidation were evaluated by measurements of molecular mass of the materials. It is shown that while temperature is the most important factor influencing the rate of thermo-oxidative degradation of the materials, oxygen concentration is of negligible importance. The investigation has also shown that when the material is degraded into low molecular mass products, it is bioassimilated. The rate of aerobic biodegradation of the oxidation products was evaluated under controlled composting conditions using measurements of produced carbon dioxide. The degree of bioassimilation in our case was about 60%, and still increasing, after 180 days.
Oxo-biodegradation of carbon-only backbone polymers is receiving ever increasing attention for the practical implications that some re-engineered thermoplastic polymer formulations based on conventional biostable polymeric materials may satisfy in terms of environmental friendliness and acceptance by commodity plastic manufacturers.In this respect, as part of our continuing activity in the area of bioactive polymeric materials for biomedical and environmental applications, we report the results of an investigation of the effects of different degradation conditions on the oxidative degradation of polyethylene (PE) film samples containing pro-oxidant additives and formulated according to a proprietary technology. The effects of temperature and relative humidity have been evaluated by monitoring, with time, several parameters associated to oxidation and cleavage of the macromolecules, such as the weight variation due to oxygen uptake, film wettability, carbonyl index, molecular weight and the extractability with polar solvents of oxidized PE samples.
Thermally degradable low-density polyethylene samples containing TDPA™ pro-oxidant additives from EPI Inc. were submitted to an investigation aimed at evaluating their ultimate biodegradation (e.g. mineralization) in soil and mature compost incubation media. Respirometric tests aimed at simulating soil burial and composting (mature compost) conditions, were used for testing the potential biodegradability of polyolefins in the environment. An LDPE-TDPA film sample provided by EPI Inc. was also submitted to a thermal oxidative degradation treatment in order to mimic the thermophilic phase of a full scale composting process. Retrieved degradation specimens, their solvent extracts and residues were also tested in soil burial respirometric tests in order to evaluate their potential biodegradability. Original and test samples submitted to biotic environments were characterized by means of spectroscopic analysis. LDPE-TDPA sample replicates undergo biodegradation as mediated by soil microorganisms in respirometric experiments. High mineralization levels were observed, above 60%, comparable to those occurring in the case of several natural polymers in natural environments; the time for biodegradation, though, is relatively longer. However, it is clear from the positive biodegradation profile that biodegradation continues. The degradation process is accompanied by a dramatic change in the structural characteristics of the test samples. To the best of our knowledge, this is the first study clearly indicating the biodegradation and assimilation of a synthetic polyolefin at a substantial level, even though reached at fairly long incubation time.
Often, degradability under anaerobic conditions is desirable for plastics claimed to be biodegradable, e.g. in anaerobic biowaste treatment plants, landfills and in natural anaerobic sediments. The biodegradation of the natural polyesters poly(beta-hydroxybutyrate) (PHB), poly(beta-hydroxybutyrate-co-11.6%-beta-hydroxyvalerate) (PHBV) and the synthetic polyester poly(epsilon-caprolactone) (PCL) was studied in two anaerobic sludges and individual polyester degrading anaerobic strains were isolated, characterized and used for degradation experiments under controlled laboratory conditions. Incubation of PHB and PHBV films in two anaerobic sludges exhibited significant degradation in a time scale of 6-10 weeks monitored by weight loss and biogas formation. In contrast to aerobic conditions, PHB was degraded anaerobically more rapidly than the copolyester PHBV, when tested with either mixed cultures or a single strained isolate. PCL tends to degrade slower than the natural polyesters PHB and PHBV. Four PHB and PCL degrading isolates were taxonomically identified and are obviously new species belonging to the genus Clostridium group I. The depolymerizing enzyme systems of PHB and PCL degrading isolates are supposed to be different. Using one isolated strain in an optimized laboratory degradation test with PHB powder, the degradation time was drastically reduced compared to the degradation in sludges (2 days vs. 6-10 weeks).
Composting is a preferred treatment strategy for biodegradable plastics (BDPs). In this sense, the collection of BDPs together with organic household wastes is a highly discussed possibility. Under the aspect of the behaviour of BDPs in composting facilities, a telephone survey was carried out with selected composting facility operators. They were interviewed with respect to treated wastes, content of impurities, processes for impurity separation, experiences with biodegradable plastics and assumptions to the behaviour of biodegradable plastics in their facility.
A study was conducted on two types of plastic materials, Mater-Bi Novamont (MB) and Environmental Product Inc. (EPI), to assess their biodegradability under aerobic and anaerobic conditions. For aerobic conditions, organic fractions of municipal solid wastes were composted. For the anaerobic process, anaerobic inoculum from a wastewater treatment plant was used. Cellulose filter papers (CFP) were used as a positive control for both mediums. The composting process was monitored in terms of temperature, moisture and volatile solids and the biodegradation of the samples were monitored in terms of mass loss. Monitoring results showed a biodegradation of 27.1% on a dry basis for MB plastic within a period of 72 days of composting. Biodegradability under an anaerobic environment was monitored in terms of biogas production. A cumulative methane gas production of 245 ml was obtained for MB, which showed good degradation as compared to CFP (246.8 ml). However, EPI plastic showed a cumulative methane value of 7.6 ml for a period of 32 days, which was close to the blank (4.0 ml). The EPI plastic did not biodegrade under either condition. The cumulative carbon dioxide evolution after 32 days was as follows: CFP 4.406 cm3, MB 2.198 cm3 and EPI 1.328 cm3. The cumulative level of CO2 varying with time fitted sigmoid type curves with R2 values of 0.996, 0.996 and 0.995 for CFP, MB and EPI, respectively.
- S Bonhomme
- A Cuer
- A-M Delort
- J Lemaire
- M Sancelme
- G Scott
Bonhomme, S., Cuer, A., Delort, A-M., Lemaire, J., Sancelme, M., Scott, G. Environmental
Biodegradation of polyethylene. Polymer Degradation and Stability 81, 2003, s. 441 – 452.
- I Vroman
- L Tighzert
Vroman, I., Tighzert, L. Review Biodegradable Polymers. Materials 2, 2009, s. 307-344.
Mgr. Ing. Magdalena Vaverková, Ph.D.
magda.vaverkova@uake.cz
doc. RNDr.Jana Kotovicová, Ph.D.
kotovicj@node.mendelu.cz
Ing. Dana Adamcová