Waste treatment integration in space

The circumstances and criteria for space-based waste treatment bioregenerative life-support systems differ in many ways from those needed in terrestrial applications. In fact, the term “waste” may not even be appropriate in the context of nearly closed, cycling, ecosystems such as those under consideration. Because of these constraints there is a need for innovative approaches to the problem of “materials recycling”. Hybrid physico-chemico-biological systems offer advantages over both strictly physico-chemico or biological approaches that would be beneficial to material recycling. To effectively emulate terrestrial cycling, the use of various microbial consortia (“assemblies of interdependent microbes”) should be seriously considered for the biological components of such systems. This paper will examine the use of consortia in the context of a hybrid-system for materials recycling in space.     

Selection criteria for waste management processes in manned space missions

Management of waste produced during manned space exploration missions will be an important function of advanced life support systems. Waste materials can be thrown away or recovered for reuse. The first approach relies totally on external supplies to replace depleted resources while the second approach regenerates resources internally. The selection of appropriate waste management processes will be based upon criteria which include mission and hardware characteristics as well as overall system considerations. Mission characteristics discussed include destination, duration, crew size, operating environment, and transportation costs. Hardware characteristics include power, mass and volume requirements as well as suitability for a given task. Overall system considerations are essential to assure optimization for the entire mission rather than for an individual system. For example, a waste management system designed for a short trip to the Moon will probably not be the best one for an extended mission to Mars. The purpose of this paper is to develop a methodology to identify and compare viable waste management options for selection of an appropriate waste management system.     

OPTIMIZATION OF INFECTIOUS HOSPITAL WASTE MANAGEMENT IN ITALY: PART II. WASTE CHARACTERIZATION BY ORIGIN

This second paper in a two-part series offers more detailed data on the physico-chemical characteristics of normal (NHW) and infectious (IHW) hospital waste determined experimentally in a large sanitary district that includes four hospitals, public and private, with 164 sanitary departments, 40 analytical laboratories and 2500 rehabilitation beds, near the town of Bari (Southern Italy). The wide variation of experimental results may be better understood if reference is made to the origin of such waste, i.e. to the types of medical departments and sanitary services wherein waste production appears to be related strictly to the therapeutic or diagnostic procedures adopted. In all cases, IHW was shown to be classified as “non-toxic” deserving 950°C rather than 1200°C incineration temperature according to Italian legislation.     

Life cycle assessment of a packaging waste recycling system in Portugal

Life Cycle Assessment (LCA) has been used to assess the environmental impacts associated with an activity or product life cycle. It has also been applied to assess the environmental performance related to waste management activities. This study analyses the packaging waste management system of a local public authority in Portugal. The operations of selective and refuse collection, sorting, recycling, landfilling and incineration of packaging waste were considered. The packaging waste management system in operation in 2010, which we called “Baseline” scenario, was compared with two hypothetical scenarios where all the packaging waste that was selectively collected in 2010 would undergo the refuse collection system and would be sent directly to incineration (called “Incineration” scenario) or to landfill (“Landfill” scenario). Overall, the results show that the “Baseline” scenario is more environmentally sound than the hypothetical scenarios.     

Environmental behaviour of a construction made of a mixture of hydraulic binders and air pollution control residues from municipal solid waste incineration Part 1. Physico-chemical characterisation and modelling of the source term

The reuse of waste materials requires the development of assessment methods for the long-term release of pollutants (source term) from wastes (or materials containing wastes) in contact with water. These methods depend on the scenario conditions: characteristics of the materials (especially physical structure and composition), contact with water. The scenario studied here is a water storage reservoir for fire fighting. The reservoir construction is made of a mixture of hydraulic binders and air pollution control (APC) residues from a municipal solid waste incinerator (MSWI). The modelling of the source term is performed in 5 steps ranging from the physico-chemical characterisation of the material to the validation of the proposed model by means of field simulation devices. This article presents the first steps of the methodology: physico-chemical characterisation of the source term, identification of the main transfer mechanisms and laboratory scale modelling of the source term. During the physico-chemical characterisation, it has been shown that the solidified waste shows a high basic capacity and that a relative decrease in pH during leaching favours retention of the main pollutants. During the first leaching sequences, the dynamic leaching tests show that the release of pollutants such as cadmium, arsenic, zinc and lead is extremely low but that the release of alkaline species (sodium and potassium) and chloride is very high from the beginning, whereas the release of calcium remains very high even after 3600 h of leaching. Identification of the main transfer mechanisms concludes that the release of soluble pollutants is the combined result of diffusional transfer of pollutants in the solution and the physico-chemical specificity of the species. The modelling based on these features enables a good simulation of the release but reveals a deviation from the experimental results after 500 h for alkaline species and 1000 h for Ca and Cl leaching. However, this deviation only appears after release of the major part of these elements.     

Cross-cultural comparison of concrete recycling decision-making and implementation in construction industry

Waste management is pressing very hard with alarming signals in construction industry. Concrete waste constituents major proportions of construction and demolition waste of 81% in Australia. To minimize concrete waste generated from construction activities, recycling concrete waste is one of the best methods to conserve the environment. This paper investigates concrete recycling implementation in construction. Japan is a leading country in recycling concrete waste, which has been implementing 98% recycling and using it for structural concrete applications. Hong Kong is developing concrete recycling programs for high-grade applications. Australia is making relatively slow progress in implementing concrete recycling in construction. Therefore, empirical studies in Australia, Hong Kong, and Japan were selected in this paper. A questionnaire survey and structured interviews were conducted. Power spectrum was used for analysis. It was found that “increasing overall business competitiveness and strategic business opportunities” was considered as the major benefit for concrete recycling from Hong Kong and Japanese respondents, while “rising concrete recycling awareness such as selecting suitable resources, techniques and training and compliance with regulations” was considered as the major benefit from Australian respondents. However, “lack of clients’ support”, “increase in management cost” and “increase in documentation workload, such as working documents, procedures and tools” were the major difficulties encountered from Australian, Hong Kong, and Japanese respondents, respectively. To improve the existing implementation, “inclusion of concrete recycling evaluation in tender appraisal” and “defining clear legal evaluation of concrete recycling” were major recommendations for Australian and Hong Kong, and Japanese respondents, respectively.     

Collection and management of fecal wastes for space missions

An improved type of human waste collection subsystem has been developed for Space Station Freedom which is designed to meet the challenges of zero gravity collection and system performance. Fecal collection is followed by passive storage for relatively short duration missions. The benefits of utilizing components in solid wastes as part of a partial or completely closed Environmental Control and Life Support System (ECLSS) become more apparent as the duration of the mission increases. The purpose of this review is to summarize the development issues associated with the current waste management subsystem for Space Station Freedom. Also reviewed are current ideas associated with the evolutionary development of this waste management subsystem for longer duration missions.     

Terrestrial approaches to integration of waste treatment

Solar energy driven physical, chemical and biological recycling of nutrients is the characteristic of the Earth-Sun system which permits life on earth to continue. Natural recycle of nutrients on Earth may literally require thousands or even millions of years to be complete, but for modern civilization to continue on Earth or in space, mankind must take charge of, and accelerate, the recycle of all essentials of life. In this paper we describe studies of two accelerated recycle systems; a solar powered energy system and an integrated feed lot. Both systems require special infrastructures permitting the accelerated physical, chemical and biological processing to occur. These systems do not integrate respiratory carbon dioxide as must be done in a complete closed ecological life support system (CELSS). The Algatron, a more complete system involving microalgal bacterial waste treatment with water, oxygen and carbon dioxide recycle was designed for use in Space Stations over 20 years ago.     

Current status of waste management at home-visit nursing stations and during home visits in Japan

A questionnaire survey was conducted with the aim of examining the problems involved in the disposal of infectious waste at home-visit nursing stations and in its handling during home visits by nurses. From among the home-visit nursing stations registered with the National Association for Home-Visit Nursing Care, 1,965 offices were selected at random and questionnaires were sent to the selected offices. Nurses at 1,314 offices (66.9?%) responded to the survey and responses from 1,283 offices were identified as suitable for analysis after excluding 26 offices that closed and five offices whose main field of care was psychiatry. Offices were classified by management configuration. Offices attached to hospitals were classified as “attached office” and all others were classified as “independent office”. More attached office nurses recovered medical waste from patients’ homes than did independent office nurses. They were also more likely to transport waste with them during the course of a day’s visits. There was a significant difference between attached and independent offices in the burden of expense for waste disposal. Both offices have strong concern about waste treatment containers and handling in improvement in home medical care (HMC) waste disposal. Thus, in order to alleviate these concerns, it is necessary to provide nurses with containers for medical waste suited to home-visit nursing care and tools for preventing injuries. Japanese government should address HMC waste disposal more comprehensively through necessary legislation, subsidization and standardization.     

Plants for water recycling,oxygen regeneration and food production

During long-duration space missions that require recycling and regeneration of life support materials the major human wastes to be converted to usable forms are CO₂, hygiene water, urine and feces. A Controlled Ecological Life Support System (CELSS) relies on the air revitalization, water purification and food production capabilities of higher plants to rejuvenate human wastes and replenish the life support materials. The key processes in such a system are photosynthesis, whereby green plants utilize light energy to produce food and oxygen while removing CO₂ from the atmosphere, and transpiration, the evaporation of water from the plant. CELSS research has emphasized the food production capacity and efforts to minimize the area/volume of higher plants required to satisfy all human life support needs. Plants are a dynamic system capable of being manipulated to favour the supply of individual products as desired. The size and energy required for a CELSS that provides virtually all human needs are determined by the food production capacity. Growing conditions maximizing food production do not maximize transpiration of water; conditions favoring transpiration and scaling to recycle only water significantly reduces the area, volume, and energy inputs per person. Likewise, system size can be adjusted to satisfy the air regeneration needs. Requirements of a waste management system supplying inputs to maintain maximum plant productivity are clear. The ability of plants to play an active role in waste processing and the consequence in terms of degraded plant performance are not well characterized. Plant-based life support systems represent the only potential for self sufficiency and food production in an extra-terrestrial habitat.     

Mechanical properties of Municipal Solid Waste by SDMT

In the paper the results of a geotechnical investigation carried on Municipal Solid Waste (MSW) materials retrieved from the “Cozzo Vuturo” landfill in the Enna area (Sicily, Italy) are reported and analyzed. Mechanical properties were determined both by in situ and laboratory large-scale one dimensional compression tests.While among in situ tests, Dilatomer Marchetti Tests (DMT) is used widely in measuring soil properties, the adoption of the DMT for the measurements of MSW properties has not often been documented in literature. To validate its applicability for the estimation of MSW properties, a comparison between the seismic dilatometer (SDMT) results and the waste properties evaluated by laboratory tests was carried out.Parameters for “fresh” and “degraded waste” have been evaluated. These preliminary results seems to be promising as concerns the assessment of the friction angle of waste and the evaluation of the S-wave in terms of shear wave velocity. Further studies are certainly required to obtain more representative values of the elastic parameters according to the SDMT measurements.     

Social aspects of public waste management in Switzerland

It is becoming increasingly evident that a waste management program, and especially a waste treatment technique, which ignores social aspects, is doomed to failure. Aspects concerning the problems of public acceptance, public participation in planning and implementation, consumer behaviour and changing value systems are no less important than the technical or economic aspects in waste management research and decision-making. As part of the Integrated Research Project “Waste”, Swiss Priority Program Environment (SPPE) 1996–1999 (funded by the Swiss National Science Foundation), this sub-project focuses on the results from two main areas. 1. Results of the three-round written Delphi-Expertquestioning “Contributions to the development of waste management in Switzerland” show that decision transparency, interregional cooperation, information policy and public participation are important factors with regard to the public acceptance of waste management in Switzerland. 2. The much discussed problem area of public acceptance of waste policies is directly linked to the concept of Social Compatibility, which is identified as an essential component of sustainable and successful waste management. As an additional aspect, the significance of mediation as a participatory process for public acceptance will be investigated. Public dialogues on concrete waste management projects not accepted by parts of the population, will therefore be initiated, monitored and evaluated.     

FULL-SCALE EXPERIENCES WITH LEACHATE RECIRCULATING LANDFILLS: CASE STUDIES

Leachate recirculation has been shown in lysimeter, pilot-scale and full-scale investigations to reduce the time required for waste stabilization, improve leachate quality, provide the opportunity for leachate volume reduction, and to enhance the rate of gas production. New generation full-scale landfills are implementing recirculation as a leachate management tool with increasing frequency. Leachate recirculation techniques used at full-scale landfills include pre-wetting of waste, leachate spraying, surface ponds, vertical injection wells and horizontal introduction systems. From observations of operating full-scale recirculating landfills, it appears to be important to provide flexibility in design, minimize low permeability daily and intermediate cover, include adequateex situstorage volume, control infiltration into the landfill, and utilize waste moisture holding capacity efficiently.     

Risk management for outsourcing biomedical waste disposal – Using the failure mode and effects analysis

Using the failure mode and effects analysis, this study examined biomedical waste companies through risk assessment. Moreover, it evaluated the supervisors of biomedical waste units in hospitals, and factors relating to the outsourcing risk assessment of biomedical waste in hospitals by referring to waste disposal acts. An expert questionnaire survey was conducted on the personnel involved in waste disposal units in hospitals, in order to identify important factors relating to the outsourcing risk of biomedical waste in hospitals. This study calculated the risk priority number (RPN) and selected items with an RPN value higher than 80 for improvement. These items included “availability of freezing devices”, “availability of containers for sharp items”, “disposal frequency”, “disposal volume”, “disposal method”, “vehicles meeting the regulations”, and “declaration of three lists”. This study also aimed to identify important selection factors of biomedical waste disposal companies by hospitals in terms of risk. These findings can serve as references for hospitals in the selection of outsourcing companies for biomedical waste disposal.     

Medical wastes management in the south of Brazil

Medical (clinical) wastes are costly in disposal and carry risks of infection, or physical injury, and of exposure to potentially harmful pharmaceuticals, as well as being aesthetically unacceptable. Technological advances in disposal, together with the introduction of rigorous emission standards for incinerators and similarly stringent control standards for non-burn “alternate” disposal technologies, continue to drive improvements in waste management. Are these improvements attainable in developing countries?Where adequate resources and a robust infrastructure are lacking, investment in advanced disposal technologies may be counterproductive. Developments must be appropriate to and manageable by the communities served; sustainable low-technology approaches may be preferable. There remains a need for affordable technical innovation, as well as underlying political support and international financial and technical assistance, to sustain meaningful improvements in waste management in remote and isolated regions and more generally in developing countries.     

Waste streams in a crewed space habitat

A compilation of generation rates and chemical compositions of potential waste streams in a typical crewed space habitat was made in connection with the waste-management aspect of NASA's Physical/Chemical Closed-Loop Life Support Program. Waste composition definitions are needed for the design of waste-processing technologies involved in closing major life support functions in future, long-duration, human space missions. Data for the constituents and chemical formulae of the following waste streams are presented and/or discussed: human urine, feces, hygiene (laundry and shower) water, cleansing agents, trash, humidity condensate, dried sweat, and trace contaminants. Data on dust generation are also presented and discussed.     

Potential useful products from solid wastes

Wastes have been aptly defined as “items i.e. resources, that have been discarded because their possessors no longer have an apparent use for them”. Accordingly, “wastes” have a significance only in relation to the items and those who have discarded them. The discarded items now are resources awaiting reclamation. Reclamation usually involves either salvage or conversion—or in modern terminology, “reuse” or “recycling”. Reclamation for reuse consists in refurbishing or other upgrading without significantly altering original form and composition. Examples of wastes amenable to reuse are containers (bottles, etc.), cartons and repairable tires. With “recycling” (i.e. conservation), the discarded items are processed such that they become raw material i.e. resources in the manufacture of “new” products. The variety of processes is wide, ranging from simply physical (grinding) through thermal (melting, gasification, combustion), to biological (composting, biogasification, hydrolysis, microbial protein production). In the paper, reuse and recycling (conversion) are evaluated in terms of advantages and disadvantages (limitations) and their respective technologies are described and discussed in detail.     

Effect of informal recycling on waste collection and transportation: the case of Chiclayo city in Peru

This paper analyses the evolution of national solid waste policy in Peru and the increasing relevance of informal recycling. Despite this rise in relevance, source separation and incorporation of informal recyclers within municipal plans is still slow, and collection of mixed waste is being considered. Waste collection and transportation costs represent the main share in municipal budgets and this research calculates cost reductions as a result of informal recycling and waste picking. The city of Chiclayo in Peru is presented as a case study. The paper finds that so far, waste picking has resulted in a reduction of two collection rounds but not a reduction in the number of vehicles collecting waste. Looking to the future, recovery of the remaining materials will not have an effect on collection rounds and number of vehicles. The research concludes that synergy between municipal systems and informal recycling can be maximized if new operational conditions are implemented. It introduces the concepts of “critical work shift,” which is the time of the day when the system requires maximum quantity of resources (i.e. vehicle-hours), and “sensitivity to variations in waste amounts,” and proposes strategies to promote recycling based on these new operational concepts.     

A new approach to metal- and polymer-recovery from metallized plastic waste using mechanical treatment and subcritical solvents

Galvanized or “chromium-plated” plastics are well known to the consumer from the automotive sector and sanitary area. Polymers such as acrylonitrile butadiene styrene (ABS) are typically coated with a layer system of chromium, nickel and copper to obtain the characteristic optical surface and resistance properties. Due to the complex manufacturing process and high quality requirements, the production of these plastic metal composites generates 10–30% of rejects. We, therefore, developed an innovative process cascade for the recovery of both components (metal and polymer) applying established technologies (mechanical pre-treatment, classification, melt filtration, CreaSolv^® Process) and were able to obtain ABS regranulate having excellent properties regarding the characteristic values for strength but slight compromises in impact characteristics. Blends with different amounts of virgin ABS, virgin PC and recycled ABS material as well as the pure cases were successfully re-metallized, all of them passing adhesion test, thermal shock resistance and CASS test. The high purity of the recovered materials led to increased redemption prices for metal and polymer by a factor of 6 and 2.5, respectively. Thus, the value added of metallized plastic waste is maximized, revealing a highly positive economic prognosis of a commercial implementation of the developed process—even at moderate scale.     

Waste recycling policy in Hong Kong

The positive non-intervention policy adopted by the Hong Kong Government has successfully led Hong Kong to an economically prosperous stage. Nevertheless, the extension of this policy to the area of waste management and waste recycling is a major reason for the sluggish waste recovery rate in Hong Kong even given the fact that Hong Kong is experiencing perhaps the greatest pressure from waste disposal in the world. The official approach to waste recycling is one of bottom-up promotion and encouragement of recycling through environmental education. While environmental education is indispensable in the course of promoting waste recycling, the use of top-down measures, such as legislation and fiscal policies, may be needed for a sustainable waste management. Waste management in Hong Kong has meant “coping with” the continuous growth in waste volume. However, in other areas of environmental management, such as air, water and noise, economic and regulatory instruments like tax differentiation and legislative control have been employed thus showing that a deviation from the minimal regulation requirement is sometimes considered justifiable. The low priority given to waste management and waste recycling for top-down measures leads to the loss of a lot of precious and non-renewable resources, and detriment to the welfare of future generations.