Thermal plasma technology for the treatment of wastes: a critical review

This review describes the current status of waste treatment using thermal plasma technology. A comprehensive analysis of the available scientific and technical literature on waste plasma treatment is presented, including the treatment of a variety of hazardous wastes, such as residues from municipal solid waste incineration, slag and dust from steel production, asbestos-containing wastes, health care wastes and organic liquid wastes. The principles of thermal plasma generation and the technologies available are outlined, together with potential applications for plasma vitrified products. There have been continued advances in the application of plasma technology for waste treatment, and this is now a viable alternative to other potential treatment/disposal options. Regulatory, economic and socio-political drivers are promoting adoption of advanced thermal conversion techniques such as thermal plasma technology and these are expected to become increasingly commercially viable in the future.     

Evaluation of cleaner production audit in pharmaceutical production industry: case study of the pharmaceutical plant in Dalian,P. R. China

The pharmaceutical industry in China makes an important contribution to the national economy. However, the associated pollution problems cause gradual deterioration of the environment and impact adversely on the local community. Cleaner production (CP) technology, an effective way to reduce waste emission and save resources, has been widely employed in the pharmaceutical industry in the developed countries. Such technologies have been applied in a number of factories in China, although there is no integrated assessment and implementation procedure for implementing CP technologies in pharmaceutical plants. To solve such problems, a series of CP options are proposed and assessed here. CP is a powerful tool for decreasing waste production, limiting environmental pollution and natural resource depletion. Moreover, the return on investment in CP is quick, so it would seem that CP activities should be very much in demand by enterprises. Reality is less optimistic: frequently only limited interest is expressed, even after an explanation; business people hesitate to become actively involved. The processes in the pharmaceutical production industry produce a vast amount of waste, including wastewater with high concentrations of organic substances (the principal component), solid waste, and organic off-gas. To solve such problems, a series of CP options are proposed and assessed in this study. Having consideration to environmental impacts and economic efficiency, four groups of medium/high cost CP options were screened in an integrated assessment. To verify the proposed options, a case study was conducted in Degussa Luyuan, Northeast China. The characteristics of resource consumption and waste emission during the production process were identified. The proposed options were evaluated according to different aspects. An integrated CP system based on the proposed options was designed and then implemented in the factory. In three years of practical use, the productivity and quality of alcohol product were improved, with a reduction in waste and pollution and a marked increase in water/energy savings. This study provides theoretical and practical support for the extensive application of CP technologies and sustainable development in China’s pharmaceutical industry. These methods include ways to clean up production that are incorporated in the process design, reforming present production technologies, updating the equipment, exploiting new producing flowcharts, using cleaner energy, building recycling into the manufacturing process, recycling waste, enhancing management, developing environmental protection technology, and ensuring satisfactory end-of-pipe disposal.     

Global trends of solid waste research from 1997 to 2011 by using bibliometric analysis

This study explores a bibliometric approach to quantitatively assessing current research trends on solid waste, by using the related literature published between 1997 and 2011 in journals of all the subject categories of the Science Citation Index. The articles acquired from such literature were concentrated on the general analysis by publication type and language, characteristics of articles outputs, country, subject categories and journals, and the frequency of title-words and keywords used. Over the past 15 years, there had been a notable growth trend in publication outputs, along with more participation of countries/territories. The seven major industrialized countries (G7) published the majority of the world articles, while their article share was being replacing by other countries represented by BRIC countries. An analysis of the title-words, author keywords and keywords plus showed that municipal solid waste and sludge were the major research types of solid wastes and “anaerobic digestion”, “wastewater” and “heavy metals” were recent major topics of solid waste research. Meanwhile, the analysis indicated the analysis technologies, represented by solid-phase extraction and tandem mass-spectrometry, were more and more widely used for solid waste research. Besides, life cycle assessment and health risk assessment were the most two frequently environmental assessment tools used for solid waste research in the 15-year research period.     

Use of Fenton reaction for the treatment of leachate from composting of different wastes

The oxidation of leachate coming from the composting of two organic wastes (wastewater sludge and organic fraction of municipal solid wastes) using the Fenton's reagent was studied using different ratios [Fe(2+)]/[COD](0) and maintaining a ratio [H(2)O(2)]/[COD](0) equal to 1. The optimal conditions for Fenton reaction were found at a ratio [Fe(2+)]/[COD](0) equal to 0.1. Both leachates were significantly oxidized under these conditions in terms of COD removal (77 and 75% for leachate from wastewater sludge composting and leachate from organic fraction of municipal solid wastes, respectively) and BOD(5) removal (90 and 98% for leachate from wastewater sludge composting and leachate from organic fraction of municipal solid wastes, respectively). Fenton's reagent was found to oxidize preferably biodegradable organic matter of leachate. In consequence, a decrease in the biodegradability of leachates was observed after Fenton treatment for both leachates. Nevertheless, Fenton reaction proved to be a feasible technique for the oxidation of the leachate under study, and it can be considered a suitable treatment for this type of wastewaters.     

我国生物柴油产业发展的探讨

介绍了美国、欧盟等和我国生物柴油产业发展的最新进展,包括产能、标准和政策等。从原料供应和生产经济性角度分析了我国生物柴油产业发展面临的困境,并建议采用废弃油脂作为起点,推动我国生物柴油产业发展,特别是要用生物柴油(脂肪酸甲酯)和甘油来生产高附加值的化工产品,大幅度提高利润。     

A review of biodiesel production from microalgae

As the search for alternatives to fossil fuels continues, microalgae have emerged as a promising renewable feedstock for biodiesel. Many species contain high lipid concentrations and require simple cultivation—including reduced freshwater and land area needs—compared to traditional crops used for biofuels. Recently, technological advancements have brought microalgae biodiesel closer to becoming economically feasible through increased efficiency of the cultivation, harvesting, pretreatment, lipid extraction, and transesterification subsystems. The metabolism of microalgae can be favorably manipulated to increase lipid productivity through environmental stressors, and “green” techniques such as using flue gas as a carbon source and wastewater as a media replacement can lower the environmental impact of biodiesel production. Through life cycle assessment and the creation of process models, valuable insights have been made into the energy and material sinks of the manufacturing process, helping to identify methods to successfully scale up microalgae biodiesel production. Several companies are already exploring the microalgae industry, offsetting operating costs through isolation of co-products and careful unit operation selection. With numerous examples drawn from industry and the literature, this review provides a practical approach for creating a microalgae biodiesel facility.     

Comparison of ecological footprint for biobased PHA production from animal residues utilizing different energy resources

Realizing a sustainable development of our planet requires a reduction of waste production, harmful emissions, and higher energy efficiency as well as utilization of renewable energy sources. One pathway to this end is the design of sustainable biorefinery concepts. Utilizing waste streams as raw material is gaining great importance in this respect. This reduces environmental burden and may at the same time contribute to economic performance of biorefineries. This paper investigates the utilization of slaughtering waste to produce biodegradable polyesters, polyhydroxyalkanoates (PHA), via bioconversion. PHA are the target product while production of high quality biodiesel along with meat and bone meal (MBM) as by-products improves the economic performance of the process. The paper focuses on ecological comparison of different production scenarios and the effect of geographical location of production plants taking different energy production technologies and resources into account; ecological footprint evaluation using Sustainable Process Index methodology was applied. Keeping in mind that the carbon source for PHA production is produced from waste by energy intensive rendering process, the effect of available energy mixes in different countries becomes significant. Ecological footprint results from the current study show a bandwidth from 372,950 to 956,060 m²/t PHA production, depending on the energy mix used in the process which is compared to 2,508,409 m²/t for low density polyethylene.     

Energy recovery from waste incineration: economic aspects

If we consider the desirability of reducing fossil fuel consumption, together with the increasing production of combustible solid wastes, there is clearly a need for waste treatment systems which achieve both volume reduction and energy recovery. Direct incineration method is one such system. The aim of this work was to analyze the municipal solid waste incineration situated in the Province of Turin (Piedmont, North Italy), especially its economical effects in consequence of the energy recovery that can be achieved. In order to perform this analysis, two kinds of energy recovery have been studied: electric energy (electrical configuration) only, and both electric and thermal energy (cogenerative configuration). So after a reconstruction of the economic situation, by considering all the costs and revenues, for both the possible energetic configurations the correspondence between the environmental convenience (that was evaluated in a previously work) and the economic convenience has been defined. The main obtained results highlight that currently the environmental convenience corresponds to the cogenerative configuration; instead the economical convenience in the actual condition corresponds to the only electric configuration. Anyway, by working on the thermal energy price, it is possible to obtain at the same time an environmental and economic convenience.     

Anaerobic co-digestion of hazardous tannery solid waste and primary sludge: biodegradation kinetics and metabolite analysis

Generation of solid waste is inherent to manufacture of leather from skin and hide. Solid wastes generated at various unit operations of the tanning process considerably vary in quantity and composition. Fleshing is a type of animal tissue waste generated during the preparatory leather processing stage in relatively larger quantities as compared to other types of solid waste in the tanning industry. Fleshing mainly contains fat and protein and residual chemicals such as lime and sulphide used in the ‘unhairing’ process of beam house operation. Another type of solid waste in tanning industry which requires safe disposal is the primary sludge from tannery wastewater treatment plant. This study shows that both fleshing and primary sludge contains a significant quantity of volatile solids amenable for biodegradation. Different proportions of waste fleshing and primary sludge were subjected to anaerobic digestion. The studies were carried out in a laboratory scale reactor with an aim of developing an appropriate technology for recovery of bioenergy from the waste and subsequently ensure their safe disposal. Volatile solid destruction between 41 and 52%, specific gas production between 0.419 and 0.635 l/g volatile solids feed and methane yield between 71 and 77% were achieved. Further, the biomethanation potential of animal fleshing and substrate specific kinetics of the reaction process were also examined.     

In search of a reliable technique for the determination of the biological stability of the organic matter in the mechanical-biological treated waste

The biological stability determines the extent to which readily biodegradable organic matter has decomposed. In this work, a massive estimation of indices suitable for the measurement of biological stability of the organic matter content in solid waste samples has been carried out. Samples from different stages in a mechanical-biological treatment (MBT) plant treating municipal solid wastes (MSW) were selected as examples of different stages of organic matter stability in waste biological treatment. Aerobic indices based on respiration techniques properly reflected the process of organic matter biodegradation. Static and dynamic respirometry showed similar values in terms of aerobic biological activity (expressed as oxygen uptake rate, OUR), whereas cumulative oxygen consumption was a reliable method to express the biological stability of organic matter in solid samples. Methods based on OUR and cumulative oxygen consumption were positively correlated. Anaerobic methods based on biogas production (BP) tests also reflected well the degree of biological stability, although significant differences were found in solid and liquid BP assays. A significant correlation was found between cumulative oxygen consumption and ultimate biogas production. The results obtained in this study can be a basis for the quantitative measurement of the efficiency in the stabilization of organic matter in waste treatment plants, including MBT plants, anaerobic digestion of MSW and composting plants.     

Incineration and gasification technologies completed with up-to-date off-gas cleaning system for meeting environmental limits

It is shown how gasification can be used for processing wastes including “waste to energy” system. First, an analysis of incineration of wastes taking into account environmental limits is performed. This analysis is aimed at a typical arrangement of a conventional oxidizing incineration plant consisting of waste storage and feeding systems, two-stage incinerator (primary and secondary combustion chambers), heat recovery system involving co-generation and off-gas cleaning system. It is also focused on a new arrangement where the primary combustion chamber (rotary kiln) is substituted by gasification reactor. The proposed concept with a fluidised bed reactor utilizes results of experimental research with various mixtures of wastes (e.g. shredded textile and rubber) considering typical conditions of operation. Experiments provide us with various important characteristics (heat value of produced syngas vs. temperature in the gasification reactor, temperature in the secondary combustion chamber vs. oxygen concentration in outlet flue gas and heat value of syngas, etc.). Then it is possible to make a comparison of conventional incineration and gasification for a concrete industrial process involving a unit for thermal treatment of hazardous industrial waste mixed with municipal solid wastes with capacity of 10,000 t/year. The application of gasification technology brings about the whole range of benefits like minimizing the consumption of auxiliary fuel and decreasing size of the secondary combustion chamber and other subsystems of the incineration plants. Involving such a system with energy and investment cost reduction into an industrial process contributes to meeting cleaner production and environmental legislation regulations.     

Aerobic in-vessel composting versus bioreactor landfilling using life cycle inventory models

Potential environmental impacts associated with aerobic in-vessel composting and bioreactor landfilling were assessed using life cycle inventory (LCI) tool. LCI models for solid waste management (SWM) were also developed and used to compare environmental burdens of alternative SWM scenarios. Results from the LCI models showed that the estimated energy recovery from bioreactor landfilling was about 9.6 megajoules (MJ) per kilogram (kg) of waste. Air emissions from in-vessel composting contributed to a global warming potential (GWP) of 0.86 kg of CO₂-equivalent per kg of waste, compared to 1.54 kg of CO₂-equivalent from bioreactor landfill. Waterborne emissions contributing to aquatic toxicity is less coming from in-vessel composting than from bioreactor landfilling. However, emissions to air and water that contribute to human toxicity are greater for the composting option than for the landfill option. Full costs for in-vessel composting is about 6 times greater than for the landfilling alternative. Integration of individually collected commingled recyclables, yard wastes, and residual wastes with windrow composting and bioreactor landfilling produces airborne and waterborne emissions with the least environmental effects among the alternatives considered. It also yields greater energy savings due to the conversion of the landfill gas (LFG) to electrical energy than the option that diverts yard waste, food waste and soiled paper for aerobic in-vessel composting. However, this scenario costs 68% more than that where the commingled collection of wastes is integrated with in-vessel composting and conventional landfilling, owing to increased collection costs.     

Emerging technologies for the control of hazardous wastes

Investigations were conducted of new and emerging technologies for the disposal of hazardous wastes. These methods involve new technologies or a recent variation on an established one. In addition, a survey was made of potential users of hazardous waste information. The need for a data base for emerging hazardous waste techonologies and/or a newsletter was evaluated. Information on the emerging technologies was acquired by computerized search, library searching, and personal contacts. The emerging technologies discussed include molten salt combution, fluidized bed incineration, high energy electron treatment of trace organic compounds in aqueous solution, the catalyzed wet oxidation of toxic chemicals, dehalogenation of compounds by treatment with ultraviolet (UV) light and hydrogen, UV/ chlorinolysis of organics in aqueous solution, the catalytic hydrogenation-dechlorination of polychlorinated biphenyls (PCBs), and ultraviolet/ozone destruction. Theory, specific wastes treated, and economics are discussed.The major technologies investigated in details were molten salt combustion, fluidized bed incineration, and ultra-violet/ozone destruction.Among the waste treated by emerging technologies are PCBs, various Dioxins, pesticides and herbicides, chemical warfare agents, explosives and propellants, nitrobenzene, and hydrazine plus its derivatives.This document encompasses a target audience ranging from laymen to natural scientists. The information presented here was derived solely for application to hazardous wastes. Readers requiring more specific information about theory and the economics of start-up plus operating and maintenance costs for technologies that may by applied to a specific hazardous waste not discussed in this report are referred to the literature cited in this report and to documents about state-of-the-art situations for a particular technology.     

Utilisation des mâchefers d'incinérateur d'ordures ménagères dans la fabrication de pavés en béton

Valorisation of Municipal Solid Waste Incineration Residues-excluding ashes-is a positive advance in sustainable development: saving natural resources, decrease in wastes volume stored, reduction of energy consumption. If good conditions of incineration can be ensured and post-combustion treatments are realised, solid residues are in the form of granular materials usable in construction and civil engineering. Uses in road structures are classical; application for the precasting of paving is quite new and interesting due to the quantity of recycled materials. Mechanical and physical performances of municipal solid waste incineration residues let us to replace a part of the granular skeleton and to obtain similar behaviour as with reference granular composition: splitting resistance, water absorption and resistance to abrasion are optimised. Leaching behaviour is also verified in order to avoid detrimental effect on the environment; it is shown that post-combustion treatments and compacting energy combined with vibration are essential for a good quality product fabrication.     

Structural studies and electrical properties of recycled glasses from glass and incinerator wastes

The electrical behaviour of different glass compositions obtained from mixing waste glass deriving from a community glass recycling program and silicate waste from the incineration of municipal solid residues (from Reggio Emilia city) have been investigated as a function of temperature and frequency. The electrical and dielectric properties were related to structural studies performed on the same glassy materials. As the amount of incinerator wastes increases, on account of lower alkali and higher alkaline-earth content in the final glass composition, conductivity and dielectric losses decrease approaching the behaviour of type E glass fibres, so envisaging a possible use of waste-containing glasses in the production of high voltage insulators.     

包装废弃 PET 瓶的处理及再生资源化技术 研究进展

废弃 PET 作为生活与工业中随处可见的固体废弃物之一,因其具有 稳定的物理化学特性而难以在自然界中降解,是目前需要回收处理的重要固 体废弃物之一。概括了废弃 PET 主要有三种回收技术,即物理回收法、化学 回收法和生物回收法,并分别简述三种回收法的原理、优缺点和研究现状。 可见,回收废弃 PET 主要采用物理回收法,化学回收法作为辅助技术,生物 回收法仍处于研究阶段。化学回收法能有效实现废弃 PET 资源的高效利用, 因而我国在废弃物处理技术发展进程中的关键是通过化学回收法将废弃 PET 进行高效率降解转化,再将产物用于制备新型的高纯度化工原料,以提高废 弃 PET 的再生资源化利用率,使利用率达到 90% 以上。     

New proposal for integrated production of sugar and biofuels from sugar beet

The problems related to the traditional technology of sugar-beet processing have became so important that the beet sector in Europe, and particularly in Italy, has been shocked. If we want to produce sugar beet in the future it is necessary to decrease the production costs through a simplification of the technology, a decreasing of the problems related to the energy and water consumptions, the elimination of the solid, liquid and gaseous wastes. We tried in the past to give our contribution for solving these problems but we have found difficulties in convincing the beet sugar world to drastically modify the traditional technology. The problems are so important that an European Project (TOSSIE—TOward Sustainable Sugar Industry in Europe) has the main object of disseminating the results of the research obtained in the last decades. We proposed different solutions including the elimination of calco-carbonic purification process, the utilization of membrane technology and suggesting different processing schemes. Now we would like to propose another possible solution with the elimination of the diffusion process and a balanced production, beside the crystallized sugar, of biofuels. Preliminary results obtained in laboratory and in a pilot plant will be presented and discussed. An erratum to this article can be found at     

Influence of leachate recirculation on aerobic and anaerobic decomposition of solid wastes

In this study, the effect of leachate recirculation on aerobic and anaerobic degradation of municipal solid wastes is determined by four laboratory-scale landfill reactors. The options studied and compared with the traditional anaerobic landfill are: leachate recirculation, landfill aeration, and aeration with leachate recirculation. Leachate quality is regularly monitored by the means of pH, alkalinity, total dissolved solids, conductivity, oxidation-reduction potential, chloride, chemical oxygen demand, ammonia, and total Kjeldahl nitrogen, in addition to generated leachate quantity. Aerobic leachate recirculated landfill appears to be the most effective option in the removal of organic matter and ammonia. The main difference between aerobic recirculated and non-recirculated landfill options is determined at leachate quantity. Recirculation is more effective on anaerobic degradation of solid waste than aerobic degradation. Further studies are going on to determine the optimum operational conditions for aeration and leachate recirculation rates, also with the operational costs of aeration and recirculation.     

Recent development of plasma pollution control technology: a critical review

Gaseous pollution control, solid and liquid waste treatments have been commercialized based on incineration, catalysis, adsorption, disposal with landfill, etc. More recently technology based on plasmas has become significant due to the advantages such as lower costs, higher treatment and energy efficiencies, smaller space volume, etc. In order to commercialize this new technology, the treatment rate, energy efficiency of treatment, pressure drop of reactor, reusable by-products production rate, must be improved, based on the identifications of major fundamental mechanism of processes, optimizations of reactor, and power supply for an integrated system. In this work, recent development of plasma pollution control technology was critically reviewed and the principle of processes and reactor technologies were outlined. Special attention will be focused on material processing generated pollutants.     

Evaluation of microalgae-based biorefinery alternatives

Microalgae-based biorefineries for the production of renewable biofuels like biodiesel, upgraded bio-oil, biochar, biogas and other high-value chemicals have received great attention in recent decades as potential major sources of energy for the future. Microalgae are a suitable species to produce biodiesel and other high energy density by-products; however, it is questionable whether a net energy gain can be realized or not considering the whole processing chain. In the present study, the energy balances of different algae-based biofuel and bioenergy production technologies are investigated in detail and compared to each other corresponding to a cradle-to-grave overall energetic analysis. The study includes cultivation, harvesting, cell pretreatments (cell disruption, drying, grinding), lipid extraction, transesterification, gasification and hydrothermal liquefaction with bio-oil stabilization and hydroprocessing. The energy consumption and energy gain are estimated for each operational step to determine the net energy ratio (NER, energy output over energy input) for the overall technologies studied. Our detailed investigation enables to detect the most energy consuming unit operation, that is, the bottleneck point(s) of the microalgae-based technologies which should be still improved in the future for the sake of more efficient algae-based biorefineries. The investigation makes also possible to evaluate and compare the different large scale alternatives for biomass transformation. Positive energy balances with a NER value of 1.109 and 1.137 are found in two already existing processes: open raceway ponds and closed photobioreactors, respectively. Our work gives also a detailed algorithm that can be followed at the evaluation of other microalgae-based biorefineries.