Unprecedented Chitin and Chitosan: A Chemical Overview

Chitin and Chitosan are polysaccharide polymers. Polysaccharide is a carbohydrate whose molecules consist of a number of sugar molecules bonded together. It contains more than 5,000 acetylglucosamine and glucosamine (sugar) units, respectively and their molecular weights are over one million Daltons. Most of the naturally occurring polysaccharides are neutral or acidic in nature, whereas Chitin and Chitosan are examples of highly basic polysaccharides. Chitin is isolated from crab and shrimp waste and is a renewable resource. It is widely accepted that this biopolymer is an important biomaterial in many aspects. This review explores the various aspects of Chitin research.     

Biogeochemistry: Some Opportunities and Challenges for the Future

There are major opportunities for big, important questions to drive biogeochemical research in the future. Some suggestions are presented, such as: what are the controls on N loss and retention in watershed-ecosystems; what are the rates and controls on biological N fixation and denitrification in diverseecosystems; how does scale (temporal and spatial) control biogeochemical flux and cycling; what controls the apparent and actual weathering rates in terrestrial ecosystems and what is the fate of the weathered products; how can biogeochemical function best be integrated on regional to global scales; and what are the quantitative interrelationships between hydrologiccycles and biogeochemical cycles? Some brief examples and approaches to address such questions, for example, the value of multidisciplinary teams for addressing complicated questions,and the use of sophisticated tools (e.g., stable isotopes, spatial statistics, remote sensing), are presented.     

Odour management and treatment technologies: an overview

There is a large variety of options available for the effective treatment of odorous emissions. The most important physical, chemical and biological treatment processes are shortly described and their favourable applications, as well as their limits, are highlighted. But for a sustainable solution of an industrial odour problem, there is more involved than just the installation of a waste gas treatment system. This article focuses on a general and systematic approach towards extensive odour management. First of all, an odour assessment should be worked out where all actual and potential odour emission sources are recorded and characterised. A special focus should be set on fugitive emissions, which may have an enormous impact on the overall odour problem. They need to be captured before they can be supplied to a treatment system. According to the composition and condition of the waste gases, an appropriate treatment system must be selected. For this purpose, test systems have been developed and are presented in this article.     

Biodegradation of keratin waste: Theory and practical aspects

Keratin-rich by-products, i.e. bristles, horns and hooves, chicken feathers and similar, are a source of nutrients for animals (amino acids) and plants (N, S). Contemporary developments in the management of keratin waste in feeds and fertilizers comply with human and animal health protection regulations and respect the principles of ecological development. Biotechnological methods employing keratinolytic bacteria and microscopic fungi play a key role in processing keratin waste.This study reviews the current knowledge on the ecology and physiology of keratinolytic microorganisms and presents the biodegradation mechanism of native keratin. The structure and chemical composition of keratin proteins are described, and methods of keratin waste biotransformation into products of practical industrial and natural value, especially composts, are discussed.     

Biodegradable Soy-Based Plastics: Opportunities and Challenges

Today's plastics are designed with little consideration for their ultimate disposability or the effect of the resources (feedstocks) used in making them. This has resulted in mounting worldwide concerns over the environmental consequences of such materials when they enter the mainstream after their intended uses. This led to the concept of designing and engineering new biodegradable materials–materials that have the performance characteristics of today's materials but that undergo biodegradation along with other organic waste to soil humic materials. Hence, the production of biodegradable materials from annually renewable agricultural feedstocks has attracted attention in recent years. Agricultural materials such as starches and proteins are biodegradable and environmentally friendly. Soybean is a good candidate for manufacturing a large number of chemicals, including biodegradable plastics, as it is abundantly available and cheap. Soy protein concentrate, isolate, or flakes could be compounded with synthetic biodegradable plastics such as polycaprolactone or poly (lactic acid) to make molded products or edible films or shopping bags and make the environment cleaner and greener.     

Quantifying construction and demolition waste: An analytical review

Quantifying construction and demolition (C&D) waste generation is regarded as a prerequisite for the implementation of successful waste management. In literature, various methods have been employed to quantify the C&D waste generation at both regional and project levels. However, an integrated review that systemically describes and analyses all the existing methods has yet to be conducted. To bridge this research gap, an analytical review is conducted. Fifty-seven papers are retrieved based on a set of rigorous procedures. The characteristics of the selected papers are classified according to the following criteria - waste generation activity, estimation level and quantification methodology. Six categories of existing C&D waste quantification methodologies are identified, including site visit method, waste generation rate method, lifetime analysis method, classification system accumulation method, variables modelling method and other particular methods. A critical comparison of the identified methods is given according to their characteristics and implementation constraints. Moreover, a decision tree is proposed for aiding the selection of the most appropriate quantification method in different scenarios. Based on the analytical review, limitations of previous studies and recommendations of potential future research directions are further suggested.     

Comparison of percolation to batch and sequential leaching tests: Theory and data

Leaching tests are becoming more relevant in assessing solid waste material, particularly with respect to groundwater risks. In the field, water infiltration is the dominant leaching mechanism, which is simulated in the lab with batch and column tests. In this study, we compared percolation, through analytical solutions of the advection–dispersion equation, to laboratory batch and sequential leaching tests. The analytical solutions are supported with comprehensive data from various field and laboratory leaching of different solutes from waste materials and soils collected in long-term joint research projects funded by the German Federal Ministry for Education and Research and the Federal Environment Agency. The comparison of theory and data is facilitated if concentrations and cumulative release are plotted versus the liquid–solid ratios (LS). Both theory and data indicate that leaching behaviour is independent of duration and physical dimensions of the leaching tests. This holds even if field lysimeters are compared to laboratory columns of different size, different flow velocities as well as different contact times. In general, laboratory batch tests over predict effluent concentrations (for LS < K_d). Leaching of solutes from solid samples of certain materials (e.g. chloride from incineration ashes or sulphate from demolition waste) in column and lysimeter tests compares very well and agrees with the analytical solutions. Overall, reproducibility and agreement with theory of column tests are better than batch tests, presumably because the latter are prone to artefacts (e.g. in liquid–solid separation steps). Theory and data fit surprisingly well, despite the fact that the theory is based on the local equilibrium assumption; non-linear sorption and chemical reactions in the solid waste materials are not considered.     

Environmental impacts and costs of solid waste: a comparison of landfill and incineration

The methodology for evaluating the impacts and damage costs ('external costs') due to pollution from waste treatment is described and the results are presented, based on the ExternE project series of the European Commission. The damage costs of landfill and incineration of municipal solid waste are compared, with due account for energy and materials recovery, as well as possible differences in transport distance. We have not been able to quantify the total damage costs of leachates because of the complexity of the environmental pathways and of the long time horizon of some persistent pollutants, but we consider an extreme scenario to show that they are not worth worrying about in the sense that reducing the pollutants in leachates beyond current regulations would bring negligible benefit in comparison with the abatement of other sources of the same pollutants. The damage costs due to the construction of the waste treatment facility are negligible. The damage costs of waste transport, which are illustrated by an arbitrary choice of a 100 km round trip by a 16 tonne truck, are also negligible. The benefits of materials recovery make a small contribution to the total damage cost. The only significant contributions come from direct emissions (of the landfill or incinerator) and from avoided emissions due to energy recovery (from an incinerator). Damage costs for incineration range from about 4 to 21 EUR tonne waste(-1), and they are extremely dependent on the assumed scenario for energy recovery. For landfill the cost ranges from about 10 to 13 EUR tonne waste(-1); it is dominated by greenhouse gas emissions because only a fraction of the CH4 can be captured (here assumed to be 70%). Amenity costs (odour, visual impact, noise) are highly site-specific and we only cite results from a literature survey which indicates that such costs could make a significant contribution, very roughly on the order of 1 EUR tonne waste(-1).     

Development and Application of Green Composites: Using Coffee Ground and Bamboo Flour

Environmental degradation and global warming are increasing as a result of the use of petroleum. Therefore, many industries are seeking more eco-friendly materials that will decrease the level of environmental contamination and economic cost. Recently, the level of coffee consumption has increased rapidly. Therefore, the amount of coffee grounds discarded is increasing. In this study, polylactic acid, coffee grounds and bamboo flour were compounded for green composites. Coffee grounds are used in the recycling of food waste. In addition, 4,4-methylene diphenyl diisocyanate (MDI) was used as a coupling agent. The mechanical strength of green composites decreased with increasing natural filler content. However, mechanical and thermal properties were increased by the addition of MDI as a coupling agent. The hydroxyl groups of natural fillers reacted with the isocyanate group of MDI, and a urethane linkage was created between the polymer and natural fillers.     

Decision support models for solid waste management: Review and game-theoretic approaches

This paper surveys decision support models that are commonly used in the solid waste management area. Most models are mainly developed within three decision support frameworks, which are the life-cycle assessment, the cost–benefit analysis and the multi-criteria decision-making. These frameworks are reviewed and their strengths and weaknesses as well as their critical issues are analyzed, while their possible combinations and extensions are also discussed. Furthermore, the paper presents how cooperative and non-cooperative game-theoretic approaches can be used for the purpose of modeling and analyzing decision-making in situations with multiple stakeholders. Specifically, since a waste management model is sustainable when considering not only environmental and economic but also social aspects, the waste management bargaining game is introduced as a specific decision support framework in which future models can be developed.     

Remediation of PCB-contaminated sediments: Volatility and solubility considerations

Through volatilization and long distance atmospheric transport, polychlorinated biphenyls (PCBs) have been redistributed throughout the global environment. Over the last 70 years, these compounds have permeated every known environmental niche including the remote polar regions of the globe. In this article, the solubility and volatility of the PCB congeners are reviewed relative to the remedial technologies that are currently in use or under consideration. The following discussion focuses primarily on the management options for PCB-contaminated, subaqueous solids that require removal, dewatering, drying, and other treatment to degrade the target contaminants and/or containment in engineered facilities including constructed islands, upland secure landfills and subaqueous pits. Environmental mobility resulting from natural and engineered processes is discussed in relation to the potential for contributing to the global loading and redistribution of PCBs. Additionally, select emerging technologies and management options are reviewed relative to their potential to produce secondary environmental impacts resulting from the soluble and/or volatile redistribution of PCBs. Based on a lack of long-term experience and the recognition that contaminants will remain unaltered for decades, technologies involving engineered containment structures should be considered temporary remedial measures until cost-competitive, destructive processing of contaminated sediments is feasible.     

Aromatic Copolyester-based Nano-biocomposites: Elaboration, Structural Characterization and Properties

Biodegradable polymers are one of the most promising ways to replace non-degradable polymers. But, to be a real alternative to classical synthetic polymers and find applications, biopolymer (biodegradable polymer) properties have to be enhanced. Nano-biocomposites, which are obtained by incorporation of nanofillers into a biomatrix, are an interesting way to achieve these improvements. Modified and unmodified montmorillonites have been introduced into a biodegradable aromatic copolyester, poly(butylene adipate-co-terephthalate) (PBAT). Structural characterization, thermal and mechanical tests have been carried out to understand better the relations between the nanofillers structuring and the final nano-biocomposite properties. Main results show that clay incorporation and the obtained intercalated structures improve PBAT properties (enhanced thermal stability, increased stiffness) and thus may increase the attractiveness of this biopolymer.     

Environmental and economic assessment methods for waste management decision-support: possibilities and limitations.

A large number of methods and approaches that can be used for supporting waste management decisions at different levels in society have been developed. In this paper an overview of methods is provided and preliminary guidelines for the choice of methods are presented. The methods introduced include: Environmental Impact Assessment, Strategic Environmental Assessment, Life Cycle Assessment, Cost-Benefit Analysis, Cost-effectiveness Analysis, Life-cycle Costing, Risk Assessment, Material Flow Accounting, Substance Flow Analysis, Energy Analysis, Exergy Analysis, Entropy Analysis, Environmental Management Systems, and Environmental Auditing. The characteristics used are the types of impacts included, the objects under study and whether the method is procedural or analytical. The different methods can be described as systems analysis methods. Waste management systems thinking is receiving increasing attention. This is, for example, evidenced by the suggested thematic strategy on waste by the European Commission where life-cycle analysis and life-cycle thinking get prominent positions. Indeed, life-cycle analyses have been shown to provide policy-relevant and consistent results. However, it is also clear that the studies will always be open to criticism since they are simplifications of reality and include uncertainties. This is something all systems analysis methods have in common. Assumptions can be challenged and it may be difficult to generalize from case studies to policies. This suggests that if decisions are going to be made, they are likely to be made on a less than perfect basis.     

Urban solid waste management in Chongqing: challenges and opportunities

The dual influences of the resource supply and protection in ecological environments will pose a significant challenge to China's sustainable development. Solid waste management offers opportunities to improve profits by conserving resources and improving environmental performance. This paper examines municipal solid waste (MSW) management in urban Chongqing, the nation's fourth largest municipality after Beijing, Shanghai and Tianjin. In this paper, we will provide information on the quantity and composition of MSW, as well as give an overview of different methods for collection, transport, treatment and disposal of MSW. At present the daily amount of MSW generated per person is about 1.08 kg; food waste accounts for about 59% of total MSW. MSW in Chongqing has a higher moisture content (64.1%) and a lower LHV (3728 kJ/kg) than other cities in Asia, which is an obstruction for incineration. Landfills are the main method of disposal in Chongqing, but pollution caused by simple landfills and lack of backup MSW disposal capacity are becoming major problems in the main districts of Chongqing. In this paper, the challenges being faced and opportunities to MSW in Chongqing are analyzed and some suggestions are given for improving the MSW system in the future.     

Protecting environmental audits and reports: Balancing self-examination and self-protection

Recently, some companies have begun making environmental reports and internal audits public. Other companies have chosen not to do so. The desire to engage in a critical and thorough self-examination is often thwarted by the fear that audits and other reports may be used against a company in later litigation or administrative proceedings. However, there are some legal, regulatory, and procedural safeguards that can protect a company that chooses to make reports and audits public. This article examines these safeguards, their strengths and weaknesses, and their role in balancing self-examination and self-protection.     

PLA and Montmorilonite Nanocomposites: Properties, Biodegradation and Potential Toxicity

The concern related to solid waste increases efforts to develop products based on biodegradable materials. At present, PLA has one of the highest potentials among biopolyesters, particularly for packaging. However, its application is limited in some fields. In order to optimize PLA properties, organo-modified montmorilonites have been extensively used to obtain nanocomposites. Although PLA nanocomposites studies are widely reported in the literature, there is still few information about the influence of organoclays on de biodegradation process, which is a relevant information, since one of the main purposals related to the final disposal of biopolymers as PLA is composting. Besides, in the last years some research has been conducted in order to evaluate the potential toxicity of montmorilonite, unmodified or organo-modified. Since the use of montmorilonite is expanding in different applications, human exposure and risk assessment are important issues to be investigated. In this context, this review intends to compile available information related to common organoclays used for PLA nanocomposites, its properties, biodegradation analysis and potential toxicity evaluation of nanocomposites, focused on montmorilonite as filler. Two issues of relevance were pointed out. The first is food safety and quality, and the second consideration is the environmental effect.     

Building waste management in Bulgaria: challenges and opportunities

Building waste recycling as aggregates is a modern approach for preventing environmental pollution through both reducing the stocks of waste and decreasing the use of natural aggregates. The reuse of building waste is a relatively new issue for Bulgaria despite the existing considerable quantity of building waste and the significant changes in the environmental rules applied. The paper discusses generated and potential waste streams in Bulgaria in the context of the social and economic restructuring and recent urban development undergone by the country. The main preliminary conditions for developing the recycling activity such as: streams of building waste, experience in recycling, technical and environmental standardization, appropriate technologies, etc. are examined. The authors analyze current practice and research activities with regard to the implementation of advanced EU building-waste recycling methods. Conclusions are drawn about existing opportunities and the priorities of the needed building waste management strategy in the country.     

Belgian MSWI fly ashes and APC residues: a characterisation study

Municipal Solid Waste Incineration (MSWI) produces different sorts of residues, bottom ash, fly ashes and Air Pollution Control (APC) residues. Generally, fly ashes and APC residues are mixed at the MSWI plant and manage as a sole residue. In this study, fly ashes and APC residues have been sampled separately at different Belgian MSWI plant and analysed by X-ray fluorescence in order to highlight the composition differences that may appear between the solids. Ca and Cl are found to be the major elements in most of the samples. Lithophilic elements, such as Al and Si, are richer in furnace and boiler ashes, as can be expected. Leaching tests also show differences between the residues; leachates from furnace and boiler ashes are alkaline while those from bag filter residues present a pH value of 6, which impacts the leaching of heavy metals (Pb and Zn). The results suggest that it could be advantageous to manage fly ashes and APC residues separately by adjusting the treatment to their specificities.     

Electrical and electronic waste management in China: progress and the barriers to overcome.

Serious adverse impacts on the environment and human health from e-waste recycling have occurred in the past and continue to occur in China today, due to a lack of national management strategies. China has made great efforts to face the challenges of the approaching peak increase in the domestic generation of e-waste and the illegal shipment of e-waste from other countries. This study examined recent progress and analysed the main problems associated with this issue in China. It was found that the material and the financial flows of e-waste in China had their own specific characteristics. Nearly 60% of the generated e-wastes were sold to private individual collectors and passed into informal recycling processes. More than 90% of Chinese citizens are reluctant to pay for the recycling of their e-waste. This is due to their traditional understanding that there remained value in these end-of-life products. Regulations concerning e-waste in China have been drafted but their deficiencies are obvious. The extended producer responsibilities (EPR) have been introduced but are not well defined. Eight formal facilities have been planned and are under construction or are in operation along the eastern coast of China but it will be difficult for them to compete with the informal processes for the reasons identified during the study.     

Municipal waste management in Sicily: practices and challenges

There are numerous problems yet to be solved in waste management and although efforts towards waste recovery and recycling have been made, landfills are still the most common method used in the EU and many other industrialised countries. Thermal disposal, particularly incineration, is a tested and viable alternative. In 2004, only 11% of the annual waste production of Italy was incinerated. Sicily, with over five million inhabitants, is the second largest region in Italy where waste management is now a critical problem. The use of landfills can no longer be considered a satisfactory environmental solution; therefore, new methods have to be chosen and waste-to-energy plants could provide an answer. This paper gives details of municipal solid waste management in Sicily following a new Waste Management Plan. Four waste-to-energy plants will generate electricity through a steam cycle; the feedstock will become the residue after material recovery, which is calculated as 20-40% weight of the collected municipal solid waste.