Life Cycle Assessment of Poly(Lactic Acid) (PLA): Comparison Between Chemical Recycling,Mechanical Recycling and Composting

This paper presents a life cycle assessment (LCA) comparing three forms of poly(lactic acid) (PLA) disposal: mechanical recycling, chemical recycling and composting. The LCA data was taken from lab scale experiments for composting and hydrolysis steps. Polymerization data in chemical recycling was obtained from computer simulation. Mechanical recycling data from lab scale were combined with the data from a plastics commercial mechanical recycling plant. The analysis considered two different product systems based on the input of the recycled PLA in the product system. Considering the categories: climate change, human toxicity and fossil depletion, the LCA showed that mechanical recycling presented the lowest environmental impact, followed by chemical recycling and composting. Among the forms of recycling, the most important input was the electricity consumption.     

A life cycle approach to the management of household food waste - A Swedish full-scale case study

Environmental impacts from incineration, decentralised composting and centralised anaerobic digestion of solid organic household waste are compared using the EASEWASTE LCA-tool. The comparison is based on a full scale case study in southern Sweden and used input-data related to aspects such as source-separation behaviour, transport distances, etc. are site-specific. Results show that biological treatment methods - both anaerobic and aerobic, result in net avoidance of GHG-emissions, but give a larger contribution both to nutrient enrichment and acidification when compared to incineration. Results are to a high degree dependent on energy substitution and emissions during biological processes. It was seen that if it is assumed that produced biogas substitute electricity based on Danish coal power, this is preferable before use of biogas as car fuel. Use of biogas for Danish electricity substitution was also determined to be more beneficial compared to incineration of organic household waste. This is a result mainly of the use of plastic bags in the incineration alternative (compared to paper bags in the anaerobic) and the use of biofertiliser (digestate) from anaerobic treatment as substitution of chemical fertilisers used in an incineration alternative. Net impact related to GWP from the management chain varies from a contribution of 2.6 kg CO₂-eq/household and year if incineration is utilised, to an avoidance of 5.6 kg CO₂-eq/household and year if choosing anaerobic digestion and using produced biogas as car fuel. Impacts are often dependent on processes allocated far from the control of local decision-makers, indicating the importance of a holistic approach and extended collaboration between agents in the waste management chain.     

Thermal conversion of municipal solid waste via hydrothermal carbonization: comparison of carbonization products to products from current waste management techniques

Hydrothermal carbonization (HTC) is a novel thermal conversion process that may be a viable means for managing solid waste streams while minimizing greenhouse gas production and producing residual material with intrinsic value. HTC is a wet, relatively low temperature (180-350 °C) thermal conversion process that has been shown to convert biomass to a carbonaceous residue referred to as hydrochar. Results from batch experiments indicate HTC of representative waste materials is feasible, and results in the majority of carbon (45-75% of the initially present carbon) remaining within the hydrochar. Gas production during the batch experiments suggests that longer reaction periods may be desirable to maximize the production of energy-favorable products. If using the hydrochar for applications in which the carbon will remain stored, results suggest that the gaseous products from HTC result in fewer g CO(2)-equivalent emissions than the gases associated with landfilling, composting, and incineration. When considering the use of hydrochar as a solid fuel, more energy can be derived from the hydrochar than from the gases resulting from waste degradation during landfilling and anaerobic digestion, and from incineration of food waste. Carbon emissions resulting from the use of the hydrochar as a fuel source are smaller than those associated with incineration, suggesting HTC may serve as an environmentally beneficial alternative to incineration. The type and extent of environmental benefits derived from HTC will be dependent on hydrochar use/the purpose for HTC (e.g., energy generation or carbon storage).     

Review and meta-analysis of 82 studies on end-of-life management methods for source separated organics

This article reports on a literature review and meta-analysis of 82 studies, mostly life cycle assessments (LCAs), which quantified end-of-life (EOL) management options for organic waste. These studies were reviewed to determine the environmental preferability, or lack thereof, for a number of EOL management methods such as aerobic composting (AC), anaerobic digestion (AD), gasification, combustion, incineration with energy recovery (often denoted as waste-to-energy incineration), mechanical biological treatment, incineration without energy recovery (sometimes referenced by just the word “incineration”), and landfill disposal with and without energy recovery from generated methane. Given the vast differences in boundaries as well as uncertainty and variability in results, the LCAs among the 82 studies provided enough data and results to make conclusions regarding just four EOL management methods – aerobic composting, anaerobic digestion, mass burn waste-to-energy (WTE), and landfill gas-to-energy (LFGTE). For these four, the LCAs proved sufficient to determine that aerobic composting and anaerobic digestion are both environmentally preferable to either WTE or LFGTE in terms of climate change impacts.For climate change, LCA results were mixed for WTE versus LFGTE. Furthermore, there is a lack of empirically reliable estimates of the amount of organics input to AD that is converted to energy output versus remaining in the digestate. This digestate can be processed through aerobic composting into a compost product similar to the compost output from aerobic composting, assuming that the same type of organic materials are managed under AD as are managed via AC. The magnitude of any trade-off between generation of energy and production of compost in an AD system appears to be critical for ranking AC and AD for differing types of organics diversion streams. These results emphasize how little we generally know, and exemplify the fact that in the reviewed literature no single EOL management method consistently topped all other management options across all environmental impacts, and that future studies must strive to match existing analytical boundaries and alternatives assessed to increase knowledge if as a community we expect to be able to make even more generalized conclusions.     

Environmental impacts of post-consumer material managements: Recycling,biological treatments,incineration

The environmental impacts of recycling, mechanical biological treatments (MBT) and waste-to-energy incineration, the main management strategies to respond to the increasing production of post-consumer materials are reviewed and compared. Several studies carried out according to life-cycle assessment (LCA) confirm that the lowest environmental impact, on a global scale, is obtained by recycling and by biological treatments (composting and anaerobic fermentations) if compost is used in agriculture. The available air emission factors suggest that, on a local scale, mechanical biological treatments with energy recovery of biogas, may be intrinsically safer than waste-to-energy incinerators. Several studies confirm the capability of biological treatments to degrade many toxic xenobiotic contaminating urban wastes such as dioxins and polycyclic aromatic hydrocarbons, an important property to be improved, for safe agricultural use of compost. Further LCA studies to compare the environmental impact of MBTs and of waste-to-energy incinerators are recommended.     

Environmental assessment of sewage sludge recycling options and treatment processes in Tokyo

Tokyo has historically suffered from a shortage of final disposal sites for the treated sewage sludge. Given this situation, sludge recycling and incineration have been promoted to reduce the volume of treated sludge conveyed to the disposal site, and the recycling options have changed since the late 1990s. This study aims to revisit the sewage sludge treatment and recycling processes in Tokyo and to evaluate different recycling options (brick, aggregate, refuse derived fuel and slag) from the energy consumption perspective by clarifying the complex flow of treated sludge within Tokyo's 23 wards. The study also estimates environmental loads associated with the operation of the whole sludge management system in the area. The environmental loads include: (1) total energy consumption and (2) gas emissions (greenhouse and acidification gases). The estimation was carried out for the years 1995, 1997, 1999 and 2001, during which a drastic change in recycling options occurred. The results indicated that the production of refuse derived fuel was the most energy consuming recycling option while aggregate production is the least energy consuming. They also showed that despite the increasing sludge volume, the energy consumption associated with the operation of the whole system decreased during the period while the gas emissions increased.     

Optimal utilization of waste-to-energy in an LCA perspective

Energy production from two types of municipal solid waste was evaluated using life cycle assessment (LCA): (1) mixed high calorific waste suitable for production of solid recovered fuels (SRF) and (2) source separated organic waste. For SRF, co-combustion was compared with mass burn incineration. For organic waste, anaerobic digestion (AD) was compared with mass burn incineration. In the case of mass burn incineration, incineration with and without energy recovery was modelled. Biogas produced from anaerobic digestion was evaluated for use both as transportation fuel and for heat and power production. All relevant consequences for energy and resource consumptions, emissions to air, water and soil, upstream processes and downstream processes were included in the LCA. Energy substitutions were considered with respect to two different energy systems: a present-day Danish system based on fossil fuels and a potential future system based on 100% renewable energy. It was found that mass burn incineration of SRF with energy recovery provided savings in all impact categories, but co-combustion was better with respect to Global Warming (GW). If all heat from incineration could be utilized, however, the two alternatives were comparable for SRF. For organic waste, mass burn incineration with energy recovery was preferable over anaerobic digestion in most impact categories. Waste composition and flue gas cleaning at co-combustion plants were critical for the environmental performance of SRF treatment, while the impacts related to utilization of the digestate were significant for the outcome of organic waste treatment. The conclusions were robust in a present-day as well as in a future energy system. This indicated that mass burn incineration with efficient energy recovery is a very environmentally competitive solution overall.     

Chain-Length Shortening of Methyl Ethyl Hydroxyethyl Cellulose: An Evaluation of the Material Properties and Effect on Foaming Ability

During the past century, plastics have become a natural element in our every-day life. Lately however, an awareness about the fossil origin and often non-degradable nature of many plastics is rising. This has resulted in the emergence of some bio-based and/or biodegradable plastics, often produced from renewable resources. One possible candidate for bioplastics production could be found in cellulose. This paper aims at contributing information regarding a cellulose derivative, which could possibly be used in foamed plastics applications. Therefore, the reduction of the chain-length of a methyl ethyl hydroxyethyl cellulose (MEHEC), assessed by size exclusion chromatography, and the effect of chain-length on the foaming behaviour were studied. The foaming was accomplished with a hot-mould technique using aqueous polymer solutions. The generated steam was here used as the blowing agent and important parameters were polymer concentration and solution viscosity. The density of the produced foams was assessed and was in some cases comparable to that of commodity foams. It was found that reducing the chain-length enabled an increase of the initial polymer concentration for the foaming process. This is believed to be beneficial for creating more structurally stable foams of this type.     

Environmental fads and fallacies

Recycling, believed by many to be accomplished by separate collection or central separation, only increases the cost of waste management until someone buys the junk.Reuse with refundable deposits removes valuable items from the waste stream at the earliest possible point and directly rewards the person who does the work.Biodegradable plastics increase greenhouse gases in comparison to conventional plastics if deposited in a landfill. Biofuels have a very minor effect on greenhouse gases because they represent only a few years retention of carbon, in contrast to fossil fuels which have been stored for millions of years.Composting is not recycling, but the destruction of one-half of the energy value of wastes with the production of a humus similar to, but not as good as, that produced in all good soils. As NPK fertilizer, compost is seldom worth the energy necessary to spread it although it has many special uses to improve poor soils.A large number of the perceived risks from e.g. PVC, dioxins, incineration, furnace ash, waste fuel oil, etc. are derived from assumptions that have been unsupported or refuted by later studies, but which remain strongly entrenched in the public mind.Since it is not possible to set a practical scientific definition of hazardous wastes, legal definitions are established. Some of these limits are influenced by active lobbying of interested commercial parties and may bear little relation to environmental or health risks.Competition between environmental authorities to set the lowest limits for toxic emissions has led to scientifically absurd and destructively expensive legal limits on “popular” pollutants. The result is a greater exposure to other hazards that must be neglected due to lack of funds.     

The use of LCA in selecting the best MSW management system

This paper focuses on the study of eleven environmental impact categories produced by several municipal solid waste management systems (scenarios) operating on a provincial scale in Southern Italy. In particular, the analysis takes into account 12 management scenarios with 16 management phases for each one. The only difference among ten of the scenarios (separated kerbside collection of all recyclables, glass excepted, composting of putrescibles, RDF pressed bales production and incineration, final landfilling) is the percentage of separated collection varying in the range of 35–80%, while the other two scenarios, for 80% of separate collection, consider different alternatives in the disposal of treatment residues (dry residue sorting and final landfilling or direct disposal in landfill). The potential impacts induced on the environmental components were analysed using the life cycle assessment (LCA) procedure called “WISARD” (Waste Integrated System Assessment for Recovery and Disposal). Paper recycling was the phase with the greatest influence on avoided impacts, while the collection logistics of dry residue was the phase with the greatest influence on produced impacts. For six impact categories (renewable and total energy use, water, suspended solids and oxydable matters index, eutrophication and hazardous waste production), for high percentages of separate collection a management system based on recovery and recycling but without incineration would be preferable.     

Enhanced Mineralization of PLA Meltblown Materials Due to Plasticization

Polylactic acid (PLA) is one of the important biodegradable polymers. It is widely used in many industrial applications such as films and fibers. Its biodegradability is based on data derived mostly from composting processes. For a broad application of the PLA material in personal care products, an understanding of anaerobic biodegradability is essential because soiled personal care products are usually disposed of in sanitary landfills, where biodegradability mechanisms are predominately in anaerobic conditions. Extensive laboratory results are acquired to elucidate the effects of the temperature on the PLA anaerobic sludge biodegradation. When the temperature is higher than PLA glass transition temperature (T_g), anaerobic degradation is accelerated. A plausible mechanism to explain this observation is that amorphous part of the polymer is easily accessible by microorganisms. When the degrading temperature is below PLA glass transition temperature, sample mineralization under anaerobic conditions is apparently slowed. The mechanisms elucidated by T_g modification can be utilized to control the rate of PLA biodegradation for sustainable waste management.     

Current EU-27 technical potential of organic waste streams for biogas and energy production

Anaerobic digestion of organic waste generated by households, businesses, agriculture, and industry is an important approach as method of waste treatment – especially with regard to its potential as an alternative energy source and its cost-effectiveness. Separate collection of biowaste from households or vegetal waste from public green spaces is already established in some EU-27 countries. The material recovery in composting plants is common for biowaste and vegetal waste. Brewery waste fractions generated by beer production are often used for animal feeding after a suitable preparation. Waste streams from paper industry generated by pulp and paper production such as black liquor or paper sludge are often highly contaminated with toxic substances. Recovery of chemicals and the use in thermal processes like incineration, pyrolysis, and gasification are typical utilization paths. The current utilization of organic waste from households and institutions (without agricultural waste) was investigated for EU-27 countries with Germany as an in-depth example. Besides of biowaste little is known about the suitability of waste streams from brewery and paper industry for anaerobic digestion. Therefore, an evaluation of the most important biogas process parameters for different substrates was carried out, in order to calculate the biogas utilization potential of these waste quantities. Furthermore, a calculation of biogas energy potentials was carried out for defined waste fractions which are most suitable for anaerobic digestion. Up to 1% of the primary energy demand can be covered by the calculated total biogas energy potential. By using a “best-practice-scenario” for separately collected biowaste, the coverage of primary energy demand may be increased above 2% for several countries. By using sector-specific waste streams, for example the German paper industry could cover up to 4.7% and the German brewery industry up to 71.2% of its total energy demand.     

Composting,anaerobic digestion and biochar production in Ghana. Environmental–economic assessment in the context of voluntary carbon markets

In some areas of Sub-Saharan Africa appropriate organic waste management technology could address development issues such as soil degradation, unemployment and energy scarcity, while at the same time reducing emissions of greenhouse gases. This paper investigates the role that carbon markets could have in facilitating the implementation of composting, anaerobic digestion and biochar production, in the city of Tamale, in the North of Ghana. Through a life cycle assessment of implementation scenarios for low-tech, small scale variants of the above mentioned three technologies, the potential contribution they could give to climate change mitigation was assessed. Furthermore an economic assessment was carried out to study their viability and the impact thereon of accessing carbon markets. It was found that substantial climate benefits can be achieved by avoiding landfilling of organic waste, producing electricity and substituting the use of chemical fertilizer. Biochar production could result in a net carbon sequestration. These technologies were however found not to be economically viable without external subsidies, and access to carbon markets at the considered carbon price of 7 EUR/ton of carbon would not change the situation significantly. Carbon markets could help the realization of the considered composting and anaerobic digestion systems only if the carbon price will rise above 75–84 EUR/t of carbon (respectively for anaerobic digestion and composting). Biochar production could achieve large climate benefits and, if approved as a land based climate mitigation mechanism in carbon markets, it would become economically viable at the lower carbon price of 30 EUR/t of carbon.     

Carbon--making the right choice for waste management in developing countries

Due to initiatives such as the clean development mechanism (CDM), reducing greenhouse gas emissions for a developing country can offer an important route to attracting investment in a variety of qualifying project areas, including waste management. To date CDM projects have been largely confined to schemes that control emission from landfill, but projects that avoid landfilling are beginning to be submitted. In considering the waste options which might be suitable for developing countries certain ones, such as energy from waste, have been discounted for a range of reasons related primarily to the lack of technical and other support services required for these more sophisticated process trains. The paper focuses on six options: the base case of open dumping; three options for landfill (passive venting, gas capture with flaring, and gas capture with energy production), composting and anaerobic digestion with electricity production and composting of the digestate. A range of assumptions were necessary for making the comparisons based on the effective carbon emissions, and these assumptions will change from project to project. The highest impact in terms of carbon emissions was from using a sanitary landfill without either gas flaring or electricity production; this was worse than the baseline case using open dumpsites. Landfills with either flaring or energy production from the collected gas both produced similar positive carbon emissions, but these were substantially lower than both open dumping and sanitary landfill without flaring or energy production. Composting or anaerobic digestion with energy production and composting of the digestate were the two best options with composting being neutral in terms of carbon emissions and anaerobic digestion being carbon negative. These generic conclusions were tested for sensitivity by modifying the input waste composition and were found to be robust, suggesting that subject to local study to confirm assumptions made, the opportunity for developing CDM projects to attract investment to improved waste management infrastructure is significant. Kyoto credits in excess of 1 tCO2e/t of waste could be realised.     

CH4 and N2O from mechanically turned windrow and vermicomposting systems following in-vessel pre-treatment

Methane (CH4) and nitrous oxide (N2O) are included in the six greenhouse gases listed in the Kyoto protocol that require emission reduction. To meet reduced emission targets, governments need to first quantify their contribution to global warming. Composting has been identified as an important source of CH4 and N2O. With increasing divergence of biodegradable waste from landfill into the composting sector, it is important to quantify emissions of CH4 and N2O from all forms of composting and from all stages. This study focuses on the final phase of a two stage composting process and compares the generation and emission of CH4 and N2O associated with two differing composting methods: mechanically turned windrow and vermicomposting. The first stage was in-vessel pre-treatment. Source-segregated household waste was first pre-composted for seven days using an in-vessel system. The second stage of composting involved forming half of the pre-composted material into a windrow and applying half to vermicomposting beds. The duration of this stage was 85 days and CH4 and N2O emissions were monitored throughout for both systems. Waste samples were regularly subjected to respirometry analysis and both processes were found to be equally effective at stabilising the organic matter content. The mechanically turned windrow system was characterised by emissions of CH4 and to a much lesser extent N2O. However, the vermicomposting system emitted significant fluxes of N2O and only trace amounts of CH4. In-vessel pre-treatment removed considerable amounts of available C and N prior to the second stage of composting. This had the effect of reducing emissions of CH4 and N2O from the second stage compared to emissions from fresh waste found in other studies. The characteristics of each of the two composting processes are discussed in detail. Very different mechanisms for emission of CH4 and N2O are proposed for each system. For the windrow system, development of anaerobic zones were thought to be responsible for CH4 release. High N2O emission rates from vermicomposting were ascribed to strongly nitrifying conditions in the processing beds combined with the presence of de-nitrifying bacteria within the worm gut.     

Home composting as an alternative treatment option for organic household waste in Denmark: An environmental assessment using life cycle assessment-modelling

An environmental assessment of the management of organic household waste (OHW) was performed from a life cycle perspective by means of the waste-life cycle assessment (LCA) model EASEWASTE. The focus was on home composting of OHW in Denmark and six different home composting units (with different input and different mixing frequencies) were modelled. In addition, incineration and landfilling was modelled as alternatives to home composting. The most important processes contributing to the environmental impact of home composting were identified as greenhouse gas (GHG) emissions (load) and the avoided emissions in relation to the substitution of fertiliser and peat when compost was used in hobby gardening (saving). The replacement of fertiliser and peat was also identified as one of the most sensible parameters, which could potentially have a significant environmental benefit. Many of the impact categories (especially human toxicity via water (HTw) and soil (HTs)) were affected by the heavy metal contents of the incoming OHW. The concentrations of heavy metals in the compost were below the threshold values for compost used on land and were thus not considered to constitute a problem. The GHG emissions were, on the other hand, dependent on the management of the composting units. The frequently mixed composting units had the highest GHG emissions. The environmental profiles of the home composting scenarios were in the order of −2 to 16 milli person equivalents (mPE) Mg⁻¹ wet waste (ww) for the non-toxic categories and −0.9 to 28 mPE Mg⁻¹ ww for the toxic categories. Home composting performed better than or as good as incineration and landfilling in several of the potential impact categories. One exception was the global warming (GW) category, in which incineration performed better due to the substitution of heat and electricity based on fossil fuels.     

Pilot project of biogas production from pig manure and urine mixture at ambient temperature in Ventanilla (Lima, Peru)

Parque Porcino de Ventanilla has an extension of 840ha with 2200 farmers dedicated to pig production. There is a lack of services in the area (i.e., water supply, electricity, or waste collection). Anaerobic treatment of pig manure would replace current dumping and incineration, reducing environmental pollution and hazards to public health, as well as providing an organic fertilizer and biogas. The objective of the present work was to study the viability of ambient temperature anaerobic digestion of pig manure diluted in urine, by means of on-site pilot scale reactors. The final goal was to establish design parameters for anaerobic digesters to be implemented; since it was part of a project to improve life conditions for the farmers through the incorporation of better management techniques. Experiments were carried out in a low-cost pilot plant, which consists of three anaerobic digesters (225L total volume), without heating or agitation, placed in a greenhouse. The start-up of the digestion process was performed with a mixture of temperature adapted pig manure-sludge and fresh rumen, and showed a good performance regardless of the dilution of pig manure with water or urine, which is a key parameter due to the scarcity of water in the area under study.     

The use of chemical composition data in waste management planning--a case study

As the waste industry continues to move from a disposal-based system to one based on a combination of recovery options, the need for information on the composition of waste increases and this is reflected by the amount of information on the physical composition of municipal solid wastes that is now available. However, there is far less information on the chemical composition of municipal solid waste. The results from a number of chemical surveys from Europe are compared and show a reasonable degree of agreement, but several problems were identified with the data. Chemical and physical compositional data are combined in a case study example to investigate the flow of key potential pollutants in an integrated solid waste management system that uses materials recycling, composting, incineration and landfilling. This case study has shown that an integrated waste management strategy diverts lead and cadmium away from composting and recycling to incineration, which effectively isolates these elements from the environment through efficient capture of the pollutants followed by secure landfilling or recycling of the residues. However, further work is needed to determine the distribution of mercury in incineration residues and its fate when the residues are landfilled.     

Evaluation of food waste disposal options by LCC analysis from the perspective of global warming: Jungnang case, South Korea

The costs associated with eight food waste disposal options, dry feeding, wet feeding, composting, anaerobic digestion, co-digestion with sewage sludge, food waste disposer, incineration, and landfilling, were evaluated in the perspective of global warming and energy and/or resource recovery. An expanded system boundary was employed to compare by-products. Life cycle cost was analyzed through the entire disposal process, which included discharge, separate collection, transportation, treatment, and final disposal stages, all of which were included in the system boundary. Costs and benefits were estimated by an avoided impact. Environmental benefits of each system per 1 tonne of food waste management were estimated using carbon prices resulting from CO(2) reduction by avoided impact, as well as the prices of by-products such as animal feed, compost, and electricity. We found that the cost of landfilling was the lowest, followed by co-digestion. The benefits of wet feeding systems were the highest and landfilling the lowest.     

Determining biodegradability of plastic materials under controlled and natural composting environments

With the advent of recently promulgated Government regulations on plastics in Mauritius, a study was initiated to examine the biodegradability of two different types of plastic, namely Willow Ridge Plastics - PDQ-H additive (Plastic A) and Ecosafe Plastic - TDPA additive (Plastic B) under controlled and natural composting environments. The results obtained from the controlled composting environment showed that the cumulative carbon dioxide evolution for Plastic A was much higher than that for Plastic B. Plastic A therefore showed a higher level of biodegradation in terms of CO2 evolution than Plastic B. However, from the regression analysis, it was found that the level of CO2 varying with time fitted the sigmoid type curves with very high correlation coefficients (R2 values: 0.9928, 0.9921 and 0.9816, for reference material, inoculum and Plastic A, respectively). The corresponding F-values obtained from the ANOVA analysis together with significance levels of p<0.05 indicated that the three treatments analysed in the biodegradability experiment were significant. The other experiment was undertaken to observe any physical change of Plastics A and B as compared to a reference plastic, namely, compostable plastic bag (Mater-Bi product-Plastic C), when exposed to a natural composting environment. Thermophilic temperatures were obtained for about 3-5 days of composting and the moisture content was in the range of 60-80% throughout the degradation process. It was observed that after 55 days of composting, Plastic C degraded completely while Plastic A and Plastic B did not undergo any significant degradation. It can be concluded that naturally based plastic made of starch would degrade completely in a time frame of 60 days, whereas plastics with biodegradable additive would require a longer time.