In India, the significant increase in the generation of municipal solid waste (MSW) during the last few decades is due to the rapid population and economic development. Though the appropriate attempts are made through the 3-'R' principles, waste management still needs to be envisaged seriously by everybody for a cleaner and greener environment. Rag-pickers, who contribute to solid waste management to some extent, are the people who rummage through garbage bins to pick out 'rags' for their livelihood. These rag-pickers usually collect the materials that have good re-sale value as these materials are mostly recycled or re-used. In the present study, the collection and the management of solid waste and the level of microbial pollution generated through air, soil and solid waste were studied. A questionnaire survey based on age, sex, educational status, socio-economic status, habits and health effects was conducted from 65 randomly selected rag-pickers from various places of Tiruchirappalli city The results revealed that they can be properly educated and trained to protect themselves from unhygienic practices and addiction. Either the Government or non-governmental organizations (NGOs) should devise a suitable proposal to monitor and make use of these unorganized rag-pickers who are indispensable to the society.

Nowadays, separate collection plays an irreplaceable role in municipal solid waste management and incineration in a waste-to-energy plant is one of the main disposal options. The objective of this study is to evaluate the effect of separate collection on the characteristics of residual municipal solid waste in terms of lower calorific value and ash production. Starting from the average Italian municipal solid waste composition, several separate collection scenarios have been considered evaluating the main characteristics of the residual waste (e.g. composition, water content, lower calorific value). Moreover, in order to have the opportunity of estimating the lower calorific value of residual waste for waste composition and separate collection scenarios different from those tested, a regression model is proposed, calibrated and partially validated.

The inhibition effects and mechanisms of chlorinated methane, anthraquinone and acetylene on methanogenesis in the anaerobic digestion process of biodegradable solid wastes were investigated. It was found that both chloroform and acetylene could effectively inhibit methanogens. Acetylene inhibited the activity of methanogens, while chloroform inhibited metabolic process of methanogenesis. A central composite design (CCD) and response surface regression analysis (RSREG) were employed to determine the optimum conditions and interaction effects of chloroform and acetylene in terms of methane and hydrogen production. Acetylene promoted the inhibition efficiency (F = 31.14; P < 0.01) more effectively than chloroform (F = 2.46; P > 0.05). In addition, a maximum hydrogen production of 1.6 ml was estimated under the optimum conditions of chloroform concentration of 6.69 mg kg^–1 and acetylene concentration of 3.08 x 10^–3 (v/v). Chloroform had a significant effect on enhancing the production of propionic acid and a minimum molar ratio of acetic acid to propionic acid of 0.707 was reached with the chloroform concentration of 9.24 mg kg^–1 and acetylene concentration of 4.0 x 10^–3 (v/v). Hence, methanogens can be inhibited while the stabilization process of solid wastes can still work well. Moreover, co-inhibition technology practice at landfills was feasible and the environmental damage was negligible, according to the analysis and experimental results.

Olive-mill wastes represent a significant environmental problem in Mediterranean areas due to their significant production during a short period of time. Their high polyphenol, lipid and organic acid concentrations make them phytotoxic wastes. Composting is one of the technologies used for the valorization of those wastes, producing a fertilizer useful for poor soils. The present study is an attempt to elaborate upon organic matter transformations and define the parameters for product maturity by adapting chemical and spectroscopic methods during composting. The aim of this work was to study the changes involved in the composting process of four piles during 200 days, and follow up the maturity of the final product during composting. Fourier transform infrared (FTIR) spectroscopy has been proven to be an appropriate analytical method for the qualitative assessment of compost stability. FTIR spectroscopy results revealed enrichment in aromatic structures and a degradation of the aliphatic and alcoholic structures indicating stabilization of the final compost. The results showed that stability of the final product was reached after 7 months of composting. The phytotoxic effects of olive mill wastes and animal manures was assessed by germination index. Indeed, the germination indices of piles 1, 2, 3 and 4 reached 131.31%, 72%, 90.56%, and 105.37%, respectively, at the end of the process. This demonstrated the absence of phytotoxicity in the majority of mature composts.

Solid waste management (SWM) is becoming a major issue in most cities where the provision of such public service had hitherto been the sole responsibility of central government. However, the costs involved and the rate of waste generation have virtually forced city authorities to seek new arrangements with the private sector. This paper reviews public–private partnership (PPP) in SWM in the Greater Accra Metropolitan Area (GAMA) and reveals that the policy worked well until one of the stakeholders failed to deliver. It maintains that harnessing the social support, acceptability and participation is key to sustainable PPP. The paper calls for institutional and private sector collaboration.

Municipal solid waste management is a complex and multidisciplinary problem, involving a number of impact factors associated with various uncertainties. In this study, a hybrid interval-parameter possibilistic programming (IPP) approach was developed and applied for planning municipal solid waste management under dual uncertainties. The IPP improves upon the existing management approaches by allowing possibility distributions of the lower and upper bounds of some interval parameters in the objective function and interval information in the modelling coefficients to be effectively incorporated within its optimization. By introducing the concept of possibilistic interval numbers, the dual uncertainties can be communicated into the optimization process and the resulting solutions, such that the generated decision schemes can effectively reflect the highly complex system features under uncertainty. The results of the case study indicate that useful information can be obtained for providing feasible decision schemes for waste flow allocation. Different decision schemes can be generated by adjusting waste flow allocation patterns within the solution intervals. Lower decision variable values should be used to obtain lower system cost of waste treatment and disposal under advantageous conditions, and higher decision variable values should be used under demanding conditions (worst case conditions). A strong desire to acquire the lower system cost will lead to the decreased probability of meeting the treatment and disposal requirements (i.e. the increased risk of unforeseen conditions); willingness to accept the upper limit of the system cost will guarantee that waste treatment and disposal requirements are met.

This study examines the possibility for enhancing the use of stone cutting sludge waste in the production of building bricks and terrazzo tiles, which would reduce both the environmental impact and the production costs. Stone cutting wastes in the form of sludge is currently generated at several factories in Jordan. At the Samara factory, incorporation of the sludge in the batch formulations of bricks and terrazzo tiles was examined. The physicochemical and mineralogical characteristics of the sludge were analyzed to identify the major components. Results indicated that the sludge generated from stone cutting could be used in producing concrete bricks. Mixtures of aggregates with added amounts of sludge were used successfully to produce non-load bearing bricks. Sludge was also used to produce terrazzo tiles and the results indicate that the transverse strength, water absorption and tile measurements, for all the taken samples, comply with Jordanian standards. The transverse strength decreased while water absorption increased as the sludge ratio increased.

The presence of organic materials plays an important role in the fate of heavy metals that are co-disposed together with municipal solid wastes. As a part of an on-going research project, which aims to find out the most effective attenuation mechanism of heavy metal removal in landfills, sorption batch experiments were performed to assess the sorption behaviour of iron, copper, nickel and zinc on synthetic solid wastes containing 76% (W1) and 45% (W2) food waste percentages and waste-to-solution ratios ranging from 1:4 to 1:16. The analysis of sorption data suggested that the data fit a Freundlich equilibrium isotherm. The time required for reaching equilibrium conditions varied for each metal investigated, but all generally reached equilibrium conditions within 7 h. For both solid waste compositions, metal sorption increased with increase in waste-to-solution ratio, with the order of metal removal percentages consistently found to be Zn > Ni > Cu > Fe. The results also show that a large fraction of the heavy metals could be attenuated by sorption on the solid waste. The removal percentages for Zn and Ni were slightly higher for W2, whereas the removal percentages for Fe and Cu were approximately equal for both waste types. Overall, this study demonstrates that sorption is a viable process that can mitigate the potential adverse impacts of landfill leachate.

Municipal solid waste (MSW) landfills in seismic zones are subjected to the seismic forces both in the horizontal and vertical directions. The stability of landfills against these seismic forces was evaluated by computing the factor of safety of landfills with different modes of failure among which failures of landfills due to translation are very common. Conventionally, the seismic stability of landfill is evaluated by using pseudo-static limit equilibrium method. In the present study, seismic stability of landfills is evaluated by both the conventional pseudo-static and modern pseudo-dynamic method. The pseudo-dynamic method is superior as it takes into account the effect of duration and frequency of earthquake motion and corresponding body waves in addition to the variation of earthquake accelerations along depth and time. In the present study, the effects of cohesion and fill amplification on seismic stability of landfill are also taken into account. It was noticed that, neglecting cohesion of fill material as well as liner material, results in a lower factor of safety and, hence, a very conservative/uneconomic design. Also, fill amplification is found to reduce the factor of safety values computed only by using the pseudo-dynamic method, showing its advantage. Generalized expressions are developed for factor of safety and yield acceleration against translational failure, which can be used for evaluating the seismic stability of MSW landfills. Comparisons of results under static condition with existing, similar methodology show a very good agreement. However, the present study seems to provide unique results for the seismic case.

Bhutan lacks the solid waste data which are essential parameters for planning and scheduling of municipal solid waste management (MSWM) systems. The first ever large-scale research survey on solid waste generation and characterization in the urban areas of Bhutan was conducted between November 2007 and January 2008 using the method of waste sampling at source. The MSW generation rates in the urban centres were 0.53 kg capita^–1 day^–1, which consists predominantly of organic waste materials of up to 58% indicating a great opportunity for composting. Domestic waste from the households contributed the maximum (47%) component of the total MSW generated from the urban centres followed by wastes from the commercial establishments. Attempt to study the correlation between household monthly income and the waste per capita generation rates did not yield any conclusive result.

Batch experiments were carried out to investigate the kinetics of adsorption of lead ions by steel slag on the basis of the external diffusion, intraparticle diffusion and adsorption reaction model (pseudo-first-order, pseudo-second-order). The results showed that the controlling step for the adsorption kinetics changed with experimental parameters varied. When the particle size of steel slag was larger than 120 mesh, intraparticle diffusion of Pb²⁺ was the controlling step; when the initial concentration of Pb²⁺ was less than 150 mg L^–1 or the shaking rate was lower than 150 rpm, external diffusion of Pb²⁺ was promoted. Contrary to the former experimental conditions, the adsorption reaction was the controlling step, and the adsorption followed second-order kinetics, with an adsorption rate constant of 13.26 g mg^–1 min^–1. The adsorption isotherm of Pb²⁺ with steel slag followed the Langmuir model, with a correlation coefficient of 0.99.

Utilization of by-products or waste materials in concrete production are important subjects for sustainable development and industrial ecology concepts. The usages as mineral admixtures or fine aggregates improve the durability properties of concrete and thus increase the economic and environmental advantages for the concrete industry. The effect of clay waste (CW) containing boron on the mechanical properties of concrete was investigated. CW was added in different proportions as cement additive in concrete. The effect of CW on workability and strength of concrete were analysed by fresh and hardened concrete tests. The results obtained were compared with control concrete properties and Turkish standard values. The results showed that the addition of CW had a small effect upon the workability of the concrete but an important effect on the reduction of its strength. It was observed that strength values were quite near to that of control concrete when not more than 10% CW was used in place of cement. In addition to concrete specimens, replacing cement with CW produced mortar specimens, which were investigated for their strength and durability properties. The tests of SO₄^2– and Cl^– effect as well as freeze–thaw behaviour related to the durability of mortar were performed. Consequently, it can be said that some improvements were obtained in durability properties even if mechanical properties had decreased with increasing CW content.

Aimed at controlling the nitrogen loss during composting, the mixture of magnesium hydroxide (Mg(OH)₂) and phosphoric acid (H₃PO₄) (molar ratio 1:2) were utilized as additives to avoid increasing total salinity. In trial TA, the additives were put into absorption bottles connecting with a gas outlet of fermentor (ex situ method); in trial TB, the additives were directly added to the composting materials (in situ method). During the 26 day composting period, the temperature, pH, total organic carbon (TOC), total nitrogen (TN), ammonium nitrogen (NH₄⁺-N), total phosphorus (TP), available phosphorus (AP) and germination index (GI) were measured. The experimental results show that the additives reduced the pH, while NH₄⁺-N and TN were obviously improved. NH₄⁺-N was 11.9 g kg^–1 and 3 g kg^–1 in amended compost trial (TB) and unamended compost trial (TA), respectively; TN increased from 26.5 g kg^–1 to 40.3 g kg^–1 in TB and increased from 26.5 g kg^–1 to 26.8 g kg^–1 in TA. Analysis of the TOC and carbon mass revealed that absorbents accelerated the degradation of organic matter. The germination index test showed the maturity of TB (102%) was better than TA (82%) in final compost. Furthermore, TP and AP were also obviously improved. X-ray diffraction analysis of precipitation showed that the precipitation in absorption bottle of TA was newberyite (MgHPO₄ 3H₂O), however, the crystal in the TB compost was struvite (MgNH₄PO₄ 6H₂O: magnesium ammonium phosphate). These results indicated that Mg(OH)₂ and H₃PO₄ could reduce the ammonia emission by struvite crystallization reaction. Optimal conditions for struvite precipitation should be determined for different systems.

Fly ash is a solid waste generated in huge quantities from coal-fired thermal power stations during the combustion of coal. Rich in metal oxides, it has tremendous potential as a coating material on structural and engineering components. This work aims at developing and characterizing a new class of such coatings made of fly ash by a novel technique – plasma spraying. Plasma spray technology has the advantage of being able to process various low-grade ore minerals to obtain value-added products and also to deposit ceramics, metals and a combination of these, generating near-homogeneous coatings with the desired microstructure on a range of substrates. In the present investigation, coatings are developed on aluminium substrates using fly ash premixed with aluminium powder in different weight proportions at various plasma torch input power levels ranging from 9–18 kW DC. The coatings are characterized in terms of interface adhesion strength and deposition efficiency. Maximum adhesion strength of about 35 MPa is recorded with coatings deposited at 12 kW power level. It was noticed that the quality and properties are significantly affected by the operating power level of the plasma sprayer. This work identifies fly ash as a potential coating material, suitable for possible tribological applications.

Anisotropic cortical cells were extracted from waste wool fibres by formic acid-ultrasonic treatment and successively included in different proportions in a chitosan matrix to make film-forming composites, suitable for film casting and filament spinning. The morphological, chemical, thermal and mechanical properties of the composite film were investigated by scanning electron microscopy (SEM), light microscopy, X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetric (DSC) and tensile tests, respectively. The cortical cells/chitosan composite is capable of forming translucent composite films with acceptable mechanical and thermal properties. The chitosan composite film with addition of 30 wt.% cortical cells showed values of 29.6 ± 2.9 MPa for ultimate strength, 5.6 ± 0.3% for ultimate elongation and 35.3 ± 1.4 MPa for Young's modulus, all higher than that of the pure chitosan film. DSC results revealed that the decomposition temperature of the composite film shifted to a higher temperature compared to the base materials, by increasing the mass fraction of cortical cells. XRD patterns showed that the crystallinity of biocomposite films increased with the addition of cortical cells. In addition, the FT-IR spectra of the composite film indicated that no chemical reaction occurs between cortical cells and chitosan; only a physical mixture of its constituents was present.

The ability of rotifers and cladocerans to convert primary to secondary production in wastewaters was tested. Scenedesmus acutus was cultured on Bold's (defined) medium, wastewater from the tertiary phase of water treatment and a mixture of both. The algal growth rates (µ) ranged from 0.4 to 0.7 day^–1, being highest in defined medium. The demographic characteristics of Brachionus rubens and Moina macrocopa were tested using algae at a density of 1.0 x 10⁶ cells mL^–1. Into each test jar, we introduced 20 neonates (< 12-h-old) of either B. rubens or M. macrocopa. Daily (for M. macrocopa) or twice a day (for B. rubens), dead adults and the neonates were enumerated and removed. Average life-span and generation time of B. rubens were not significantly influenced by the algal treatment type. Gross and net reproductive rates were significantly influenced by the medium on which the algae was cultured; in the case of B. rubens, they ranged from 20–36 and 10–22 offspring female^–1; the corresponding values for M. macrocopa were higher (38–110 and 13–31 offspring female^–1, respectively). The rate of population increase was higher for Brachionus (0.41–0.65 day^–1) compared to Moina (0.28–0.57 day^–1). Brachionus had significantly higher growth rates on algae cultured on Bold medium than on treated wastewater while Moina grew significantly better on Scenedesmus cultured on Bold medium or a mixture of treated wastewater and Bold medium than on treated wastewater alone.

In this study, oily sludge samples generated from a Tehran oil refinery (Pond I) were evaluated for their contamination levels and to propose an adequate remediation technique for the wastes. A simple, random, sampling method was used to collect the samples. The samples were analyzed to measure Total petroleum hydrocarbon (TPH), polyaromatic hydrocarbon (PAH) and heavy metal concentrations in the sludge. Statistical analysis showed that seven samples were adequate to assess the sludge with respect to TPH analyses. The mean concentration of TPHs in the samples was 265,600 mg kg^–1. A composite sample prepared from a mix of the seven samples was used to determine the sludge's additional characteristics. Composite sample analysis showed that there were no detectable amounts of PAHs in the sludge. In addition, mean concentrations of the selected heavy metals Ni, Pb, Cd and Zn were 2700, 850, 100, 6100 mg kg^–1, respectively. To assess the sludge contamination level, the results from the analysis above were compared with soil clean-up levels. Due to a lack of national standards for soil clean-up levels in Iran, sludge pollutant concentrations were compared with standards set in developed countries. According to these standards, the sludge was highly polluted with petroleum hydrocarbons. The results indicated that incineration, biological treatment and solidification/stabilization treatments would be the most appropriate methods for treatment of the sludges. In the case of solidification/stabilization, due to the high organic content of the sludge, it is recommended to use organophilic clays prior to treatment of the wastes.

The evolution of domestic waste management practices in an urban residential condominium complex in Brazil is reported. A sustained effort over 10 years has created a benchmark for landfill diversion by private initiative. The project was initiated in 1998 when the prevailing practice was to tip all waste at the landfill. In the presently attained situation, which is available for imitation elsewhere, 67% of all domestic waste produced in the complex is recycled without cost to the municipal administration. Instead of separating the inert recyclables, the effort was turned to separating the biodegradable material. The management programme derived from waste analyses and the work with people evolved into a two-stage source-separation procedure combined with the participation of handpicked reverse logistics operators. City crews now take only 33% of all waste to the landfill. Although this description is strictly valid only for Brazil, the story in itself might be of wider interest.

In any copper smelter large quantities of copper slag are discarded as waste material causing space and environmental problems. This discarded slag contains important amounts of metallic values such as copper and iron. The recovery of copper values from an Indian smelter slag that contains 1.53% Cu, 39.8% Fe and 34.65% SiO₂ was the focus of the present study. A complete investigation of the different phases present in the slag has been carried out by means of optical microscopy, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) techniques. It is observed that iron and silica are mostly associated with the fayalite phase whereas copper is present in both oxide and sulfide phases. These oxide and sulfide phases of copper are mostly present within the slag phase and to some extent the slag is also embedded inside the oxide and sulfide phases. The recovery of copper values from the discarded slag has been explored by applying a flotation technique using conventional sodium isopropyl xanthate (SIX) as the collector. The effects of flotation parameters such as pH and collector concentration are investigated. Under optimum flotation conditions, it is possible to achieve 21% Cu with more than 80% recovery.

A detailed investigation of the development of the mineral composition and crystallinity of fly ash (FA) activated by an integrated process, as well as the relation between that development and phosphate uptake (PU) in solution, was conducted. This process, consisting of pretreatment (mechanical milling), alkali fusion (sodium hydroxide) at 550 °C and acid attack (3 mol L^–1 sulfuric acid), exhibited a remarkable activation effect. One-hour grinding could enhance PU from 0.67 to 1.66 mg PO₄^3–-P g^–1 FA, and then under the optimum chemical conditions with the ratio of NaOH to FA of 0.5 g g^–1 and that of H₂SO₄ to FA of 3 mL g^–1, the PU was further improved to 7.14 mg g^–1. Results also indicated that the PU performance was closely linked with the crystallinity and mineral composition of FA, that is, the treated material with the lowest crystallinity and least crystal phase could achieve the highest PU. For the purpose of destroying original minerals in raw FA farthest and avoiding the production of new crystals, therefore, control on the ratio of NaOH to FA and that of acid to FA was very important during the chemical treatment.

Laboratory-scale reactors containing mixtures of municipal solid waste and wastewater treatment biosolids were monitored to assess the effect of biosolids on refuse decomposition and on phosphorus (P) cycling and speciation among orthophosphate, acid-hydrolysable P, and organic P. The co-disposal of 10 to 20% (by wet weight) aerobically-digested biosolids with residential refuse was compatible with refuse decomposition although the biosolids did not increase either the maximum methane production rate or the cumulative yield, and did not reduce lag times to the onset of methane production. The results of this study indicated that dissolved reactive phosphorus (DRP) was the dominant dissolved P fraction throughout refuse decomposition and that it was negatively correlated with the methane production rate and pH (r² = 0.35 for both). P was not found to limit methane production. Biosolids increased dissolved P as well as ammonia-N in some reactors, but this did not have a significant impact on maximum methane production rates. The maximum tolerated Na⁺ and K⁺ concentrations during active methane production were at least 4100 mg Na⁺ L^–1 and 800 mg K⁺ L^–1, respectively.

This paper presents a quantitative methodology and an empirical case study in Taiwan on modelling municipal solid waste (MSW) discards based on the consumption and MSW policy effects through a simultaneous equation system (SES) model. The results indicate that per capita consumption expenditures on 'food', 'household appliances' and 'amusement & education' are associated with the changes of the discards of most of the waste streams in Taiwan from 1992 to 2004. The developed model, meanwhile, identifies the effects of several important MSW policy measures. With regard to the model implication, consumers could try to reduce their unnecessary consumption, producers may rethink their responsibility on reducing MSW discards, and municipalities could evaluate the effectiveness of the existing policy measures to improve it upon based on the quantitative analysis. The backcasts and estimates of the discards of MSW streams could enable the planning, designing and executing of MSW system. The findings of this study would facilitate the consumer behaviour and support the policy design towards a low-waste-discard society.

A case study and a literature review have been carried out to address the two questions: how can waste flow data from collection systems be interpreted and compared? and which factors are decisive in the results of recycling programmes in household waste collection systems? The aim is to contribute to the understanding of how recycling programmes affect the quantity of waste and sorting activities. It is shown how the results from various waste sorting systems can be interpreted and made comparable. A set of waste flow indicators is proposed, which together with generic system descriptions can facilitate comparisons of different collections systems. The evaluation of collection systems depends on the system boundaries and will always be site-specific to some degree. Various factors are relevant, e.g. environmental objectives, technical function, operating costs, types of recyclable materials collected separately, property-close collection or drop-off systems, economic incentives, information strategies, residential structure, social codes, etc. Kerbside collection of recyclables and weight-based billing led to increased waste sorting activities in the case study. Forty-three decisive factors are listed and discussed.

Lack of consistent and available information for the entire tyre industry has often hindered adequate understanding of current and future issues that need to be addressed for improving the sustainable end-of-life tyre management. The aim of this paper is to review related best available technologies and techniques for Greece, ranging from simple mechanical processing, up to complex multistep, mechanochemical and/or thermal treatment. End-of-life tyre management guidelines in the form of a manual for supporting future entrepreneurs in this field are also discussed. Extensive data mining, classification and inventorying was performed, both in the field via questionnaires and in the literature, for the purpose of accurately determining Hellenic conditions, in order to pinpoint encountered problems, propose interventions and determine new entrepreneurship opportunities.

A method to obtain processed residue from mixed construction and demolition waste (mixed C&D-W) – free from environmental pollutants – for deposition in landfill is discussed. In particular, additional sieving, the presence of gypsum board in mixed C&D-W at the first stage of manual presorting, and the color of processed residue were studied for the basic characterization of the different fractions. Considerable precautions should be taken to prevent leaching of hazardous substances, such as T-Hg, Pb, Cr⁶⁺, As, and fluoride and its compounds, when processed residue, particularly in crushed fraction at an intermediate treatment facility, is used as construction material. A relatively high content of gypsum was noted in processed residue generated at demolition work compared to that generated at construction work in processed residue from mixed C&D-W in which the presence of gypsum board was observed at the first stage of manual presorting, and in white processed residue. Additional sieving for removal was ineffective because gypsum and wood have wide particle size distributions. To obtain processed residue having low gypsum and wood contents, white processed residue should be removed to eliminate gypsum (content, 59% of initial sample), and brown or brown and yellow processed residue should be removed to eliminate wood (content, 32% of initial sample) without mixing with processed residue containing other colors at stockyards. The removed residue should be deposited in a controlled-type landfill site.

This paper describes a bioreactor set-up used to simulate degradation of petroleum hydrocarbons in a static biopile. The large-scale test was performed in a 28 m³ custom-designed reactor. Oily sludge (40% by weight, having 7% dry matter [DM], and hydrocarbons C₁₀–C₄₀ 160,000 mg kg^–1 DM) was mixed with organic-rich amendments – mature oil-compost (40%) and garden waste compost (20%). Within the reactor, the temperature and soil gases were monitored continuously during 370 days via 24 measurement points. Also, moisture content was continuously recorded and airflow through compost mix occasionally measured. Three-dimensional ordinary kriging spatial models were created to describe the dynamic variations of temperature, air distribution, and hydrocarbon concentration. There were large temperature differences in horizontal and vertical sections during initial months of composting only. Water content of the mixture was uneven by layers, referring on relocation of moisture due to aeration and condensation. The air distribution through the whole reactor varied largely despite of continuous aeration, while the concentration of O₂ was never reduced less than 1–2% on average. The results showed that composting of sludge using force-aerated static biopile technology was justified during the first 3–4 months, after which the masses could be re-mixed and heaped for further maturation in low-tech compost windrows. After 370 days of treatment, the content of hydrocarbons (C₁₀–C₄₀) in the compost mixture was reduced by 68.7%.

Dioxins are highly toxic halogenated organic compounds formed as an unintentional by-product of many industrial processes involving chlorine and combustion. At the Negev Monte Carlo Research Center (NMCRC) and the Green Processes Center at the Shamoon College of Engineering (SCE), Israel, we have developed a code for the first-order estimation of dioxin emissions from waste incinerators and the subsequent atmospheric dispersion. The NMCRC-Atmos (Atmospheric Evaluator) program will allow public planners and facility operators to estimate and predict the effect of current and potential waste incineration facilities on nearby population centres. This information can also be used by plant operators to decide whether to run the facilities at maximum capacity based on weather conditions. With the NMCRC-Atmos tool, the user has the ability to easily establish location-based fallout from the average conditions (both facility and atmospheric) surrounding the waste incineration plant. This program currently focuses on dioxin emissions from waste incinerators, but can eventually be expanded to include other emission sources and atmospheric effects, as well as internet connectivity for real-time data acquisition. NMCRC-Atmos is a Windows^® program that has been tested on Windows XP Service Pack 2 with the .NET Framework 2.0 installed.

This study investigated the dental waste management practices and safety measures implemented by dentists in the Nablus district, Palestine. A comprehensive survey was conducted for 97 of the 134 dental clinics to assess the current situation. Focus was placed on hazardous waste produced by clinics and the handling, storage, treatment and disposal measures taken. Mercury, found in dental amalgam, is one of the most problematic hazardous waste. The findings revealed that there is no proper separation of dental waste by classification as demanded by the World Health Organization. Furthermore, medical waste is often mixed with general waste during production, collection and disposal. The final disposal of waste ends up in open dumping sites sometimes close to communities where the waste is burned. Correct management and safety procedures that could be effectively implemented in developing countries were examined. It was concluded that cooperation between dental associations, government-related ministries and authorities needs to be established, to enhance dental waste management and provide training and capacity building programs for all professionals in the medical waste management field.

The calorific values and the chlorine contents of refuse-derived fuels were measured in the pilot combustion plant (PCP) by means of combustion experiments followed by mass and energy balancing. This plant reaches an increased precision by measuring the integrated values throughout the whole experimental period of three hours, based on a fuel capacity of 10 kg per test, allowing a more reliable measurement of pollutants than for experimental analysis of only a few grams of the sample. The combustion experiments are shown for the verification of the quality of the chlorine balancing in the PCP. The test evaluation was carried out by balancing the inputs and outputs of chlorine in the mass streams, and the recovery rates for chlorine were determined. An emission pattern for the chlorine is described by the transfer coefficients and via the temporal fluctuation of the hydrogen chloride concentration in the flue gas. The results of the combustion experiments prove that the balancing via combustion experiments in the PCP provides reliable data on the chlorine concentrations in the fuels, and is a new and reliable method for measuring polluting chlorine in refuse-derived fuels.

In India, millions of tons of press mud (PM) are generated by sugar mills every year. This paper reports the potential of vermitechnology to convert sugar industry waste PM mixed with cow dung (CD) into vermicompost, employing an epigeic earthworm Eisenia fetida. A total of six different reactors were established having different ratios of PM and CD including one control (CD only). The growth and fecundity of E. fetida was monitored for 13 weeks. Maximum growth was recorded in 100% CD, but earthworms grew and reproduced favourably up to 1:1 PM and CD feed composition. However, greater percentages of PM in different reactors significantly affected the growth and fecundity of worms. Vermicomposting resulted in a decrease in carbon concentration and an increase in nitrogen, phosphorus and calcium concentrations of the vermicompost. Investigations indicated that vermicomposting could be an alternative technology for the management of PM into useful fertilizing material, if mixed at maximum 50% with CD.

Stillage re-use in the fermentation stage in ethanol production is a technique used for the reduction of water and fermentation nutrients consumption. However, the inhibitory effect on yeast growth of the by-products and feed components that remains in stillage increases with re-use and reduces the number of possible recycles. Several methods such as ultrafiltration, electrodialysis and advanced oxidation processes have been used in stillage treatment prior its re-use in the fermentation stage. Nevertheless, few studies evaluating the effect of solvent extraction as a stillage treatment option have been performed. In this work, the inhibitory effect of serial stillage recycling over ethanol and biomass production was determined, using acetic acid as a monitoring compound during the fermentation and solvent extraction process. Raw palm oil methyl ester showed the highest acetic acid extraction from the aqueous phase, presenting a distribution coefficient of 3.10 for a 1:1 aqueous phase mixture:solvent ratio. Re-using stillage without treatment allowed up to three recycles with an ethanol production of 53.7 ± 2.0 g L^–1, which was reduced 25% in the fifth recycle. Alternatively, treated stillage allowed up to five recycles with an ethanol final concentration of 54.7 1.3 g L^–1. These results show that reduction of acetic acid concentration by an extraction process with raw palm oil methyl ester before re-using stillage improves the number of recycles without a major effect on ethanol production. The proposed process generates a palm oil methyl ester that contains organic acids, among other by-products, that could be used for product recovery and as an alternative fuel.

The removal of iron, titanium and aluminium from colourless and green waste glasses has been studied under various experimental conditions in order to optimize the process parameters and to decrease the metal content in the waste glass by acidic leaching. Statistical design of experiments and ANOVA (analysis of variance) were performed in order to determine the main effects and interactions between the investigated factors (sample ratio, acid concentration, temperature and leaching time). A full factorial experiment was performed by sulphuric acid leaching of glass for metal removal. After treating, the iron content was 530 ppm, corresponding to 1880 ppm initial concentration of Fe₂O₃ in the original colourless sample. This result is achieved using 1M H₂SO₄ and 30% sample ratio at 90°C leaching temperature for 2 hours. The iron content in the green waste glass sample was reduced from 3350 ppm initial concentration to 2470 ppm after treating.

Two kinds of vinegar production residues, sorghum vinegar residue (SVR) and corn vinegar residue (CVR), were used as a substrate for phytase production in solid-state fermentation (SSF) by Aspergillus ficuum. Various process parameters influencing phytase production were evaluated by single factor design experiments; further study involved CVR and its goodness-of-fit levels. An incubation time of 48 hours, initial moisture of 55% and an inoculum of 1.2 x 10⁷ spores per millilitre were the optimum cultural conditions for the production of phytase in waste corn vinegar residue, without adding in vitro nutrient elements by orthogonal design experiment. Results showed that vinegar production residue as substrates for phytase production by Aspergillus ficuum through microbiology fermentation could be applied to treatment of an integrated system for waste from vinegar processing.

The increasing amount of oil field waste is a matter of concern. This study proposes the Slurry Fracture Injection (SFI) technique as an alternative waste disposal method. The proposed waste disposal method is complete and leaves few future liabilities. The entire waste can be injected into an isolated deep geologic zone with no contamination of water-bearing formations or formations outside the targeted zone. The method can lead to the reclamation of oil industry landfills and the oil pits and dumps. We propose a two-tiered screening method for evaluating the feasibility of this technology and identification of a suitable target zone. A stringent environmental monitoring program should complement the SFI process to ensure environmental compatibility.

The spread of municipal solid waste (MSW) in Zanzibar municipality has been associated with environmental pollution, unpleasant city conditions, contamination of water sources and coastal areas together with harbouring of malaria vectors. The contamination has a close relationship with eruption of diarrhoea, cholera and typhoid which claim the lives of the residents. Most of the wastes are of domestic and market origin and have the potential for compost production. This study examined the possibility of composting MSW from Zanzibar municipality as an alternative way of SW management and assessed the nutrient contents of the compost for application in agricultural production. Two major classes of SW were selected for the study: municipal solid waste and rice milling by-products. The samples were composted aerobically and anaerobically. The results showed that aerobic composting reduced about 60% of the waste volume. This volume reduction suggests that composting can be a promising SW management technique by reducing the large demand of space for landfilling. Municipal solid waste composted under anaerobic conditions produced compost with relatively higher concentrations of dissolved species than that produced under aerobic conditions. The trace metal contents were higher in MSW than in rice milling by-products. It was found that the unmanaged compost collected from the dumping site had low nutrient contents and was enriched with trace metals. Generally, physico-chemical characteristics, nutrients and trace metal levels suggest that Zanzibar municipal solid waste can produce high-quality compost for application to a wide range of soil types to improve their fertility, under proper management.

Silica fume (SF) is an inorganic waste material which is generated during the elemental silicon and ferro-silicon alloy production. Due to the unique properties, it is utilized in several industries. However, very little information is available on the utilization potential of SF in traditional clay brick industry. In this study, the effect of different quantities of SF addition on the properties of fired clay brick was investigated. Test samples were produced by uniaxial pressing and fired at 800, 900, 1000 and 1100°C. The microstructures of the samples were investigated by Scanning Electron Microscopy (SEM). The strength of the fired samples at 1000 and 1100°C were significantly improved with SF addition. It was concluded that the reactive amorphous nature of SF particles enhances the sintering action locally and this gives better strength behaviour. SF addition also improved the efflorescence behaviour of the bricks. It was concluded that the effect of SF addition on the fired clay brick mainly depends on the firing temperature. At low firing temperatures, SF addition has a tendency to decrease the bulk density. However at higher firing temperatures, SF addition allows better sintering action with a drastic increase in bulk density.

In this paper, various microbial characteristics of degrading refuse in three lysimeters were compared to bioassess the operating conditions with and without leachate recycling and pH adjustment. Laboratory lysimeters with leachate recycling produced more gas and took less time to reach the highest methane percentage than a lysimeter without leachate recycling. Generally, lysimeters with leachate recycling showed high ATP (adenosine triphosphate) contents in the leachate. But there were no significant differences in dehydrogenase activities among the lysimeters. Leachate of all lysimeters inhibited the bioluminescence activities of the strain tested. Bioluminescence activity was more inhibited by the lysimeter with no leachate recycling (high inhibition corresponds to high toxicity of leachate). Generally, less inhibition was observed in the middle of the operation phase, which was related with the biodegradation activity.

Improper management of pig manure has resulted in environmental problems such as surface water eutrophication, ground water pollution, and greenhouse gas emissions. This study develops and compares 14 alternative manure management scenarios aiming at energy and nutrient extraction. The scenarios based on combinations of thermal pretreatment, anaerobic digestion, anaerobic co-digestion, liquid/solid separation, drying, incineration, and thermal gasification were compared with respect to their energy, nutrient and greenhouse gas balances. Both sole pig manure and pig manure mixed with other types of waste materials were considered. Data for the analyses were obtained from existing waste treatment facilities, experimental plants, laboratory measurements and literature. The assessment reveals that incineration combined with liquid/solid separation and drying of the solids is a promising management option yielding a high potential energy utilization rate and greenhouse gas savings. If maximum electricity production is desired, anaerobic digestion is advantageous as the biogas can be converted to electricity at high efficiency in a gas engine while allowing production of heat for operation of the digestion process. In conclusion, this study shows that the choice of technology has a strong influence on energy, nutrient and greenhouse gas balances. Thus, to get the most reliable results, it is important to consider the most representative (and up-to-date) technology combined with data representing the area or region in question.

Fuel consumption during seven different daily activities of a garbage co-collection truck and a normal packer truck was estimated from the trucks’ global positioning system (GPS) data and fuel consumption records. The co-collection and the normal garbage packer consumed approximately 1.8 L and 1.26 L of diesel per km, respectively, while travelling within the collection areas. Using these fuel rates and the GPS data, the results show that both types of trucks consumed more than 60% of daily total fuel while actually collecting waste on the route. The average daily fuel consumption was 2–4 times higher on rural routes compared to urban areas. Fuel consumption varied significantly depending on the housing density along the collection route. In addition, approximately 5–6 times as much fuel was required to collect a kilogram of waste on a rural route compared to an urban route. Potential methods of reducing fuel consumption were examined. Consistent use of optimal collection routes could potentially save an average of 7.5 L of fuel per truck per day. Reducing the loading time per stop was also studied, but the results suggest that this method does not have significant potential to reduce fuel consumption.

Chemical composition of chitinous residue and fermentation liquor fractions, obtained from fermented shrimp biowaste, was evaluated in order to explore their potential for further utilization. Lyophilization of the liquor fraction obtained after fermentation resulted in a powder rich in both protein (30%) and carotenoids (217.18 ± 2.89 µg/g). The yield of chitinous residue was 44% (w/w) whereas the yield of lyophilized powder was >25% (w/v). About 69% of total carotenoids were recovered by fermentation. Fermentation resulted in the removal of both protein as well as ash content from the shrimp biowaste, as indicated by ~92% deproteination and >76% demineralization, respectively. Post fermentation, the residue had a chitin content of >90%. The lyophilized liquor fraction had all the essential amino acids (except threonine) in quantities comparable to Food & Agriculture Organization/World Health Organization reference protein. The composition of fermentation liquor is indicative of its potential for application as an amino acid supplement in aquaculture feed formulations.

We report on the findings of a study on the problems of solid waste management (SWM) on Mountain Kilimanjaro (MK) which is located within Kilimanjaro National Park (KINAPA) in Northern Tanzania. The study was prompted by the fact that flourishing tourism on the mountain over the years has resulted in an increase in the tonnage of solid waste (SW) generated, posing serious challenges in its collection and disposal. The methodology employed in this study included physical observations and questionnaire surveys, as well as waste sorting and weighing to quantify and characterize waste loads collected from each tourist route station covered in this study. On the basis of the established SW generation rate (0.6 kg ca^–1 day^–1) a total amount of SW generated was estimated to range from about 87 tonnes (in 2003) to 125 tonnes (in 2006). An improvement in SW collection from 64% in 2003 to 94% in 2006 was also noted. This improvement can be attributed to the trash-in-trash-out (TITO) system of SW collection which is currently practiced by the management of KINAPA for SWM on MK. The study also highlights potential environmental pollution including air pollution from open burning and pit disposal of SW. Based on average percentage values of waste components and the estimated quantity of waste generated, it was established that the total waste quantum contains about 34% of recyclables. The study recommends that resource recovery and conservation measures through waste recycling and re-use be instituted as one of the options for sustainable SWM on MK.

Environments in the vicinity of the lead (Pb) smelters are contaminated by emissions containing high concentrations of antimony (Sb) and arsenic (As). Air-pollution-control (APC) residues from bag-type filters from a secondary Pb smelter were subjected to leaching experiments to elucidate the controlling mechanisms of Sb and As release. Kinetic batch leaching tests at a liquid-to-solid (L/S) ratio of 10 L kg^–1 within the time frame of 720 hours and batch leaching at various L/S ratios (ranging from 1 to 1000 L kg^–1) were performed. In contrast to other inorganic contaminants (Pb, Cd, Zn), less than 1% of the total Sb and As content was leached from the residues. At a L/S ratio of 10, the As and Sb concentrations in the leachates exceeded the EU limit values for non-hazardous waste (0.2 and 0.07 mg L^–1). According to PHREEQC-2 calculations, the concentrations of As and Sb are controlled by the precipitation of complex arsenates and antimonates mainly at low L/S ratios. The washing and related chemical/mineralogical transformation of APC residues was suggested as a technological pre-treatment process before their re-smelting in a blast furnace. The Ferrox-like processing of the resulting contaminated process water/leachate was simulated using the PHREEQC-2 code. Significant reduction was obtained in the concentration of some key contaminants (As, Cu, Pb, Zn) related to sorption on newly formed hydrous ferric oxides, whereas Sb and Cd exhibited only limited attenuation.

Cold cathode fluorescent lamps (CCFLs) are globally used components of high technology products. A large amount of mercury in waste CCFLs is being recovered by thermal desorption technology in Taiwan. However, the complexity of the samples affects the thermal desorption efficiency and increases costs. This study identifies the mercury release behaviour of amalgam, phosphor and mercury-containing components as well as waste CCFLs by bench scale thermal desorption test. The results show that the mercury was released from amalgam and mercury/fluorescent powder from a real treatment plant at temperatures between 550°C to 850°C, which is much higher than from cinnabar at 300°C to 380°C and that of pure mercury, high pressure mercury lamps, and fluorescent tubes containing mercury/fluorescent-powder at 50°C to 250°C. In addition, the experiment also showed the mercury release peak of the mercury/fluorescent powders from a real treatment plant occurs at much higher temperatures than that of commercial phosphor at 50°C to 200°C. Thus, complete separation of the cracked CCFLs is necessary to effectively recover phosphor and mercury at low financial and energy cost.

In order to study the distribution and partitioning of heavy and alkali metals in the flue gases of a sewage sludge incinerator, an experiment was carried out in a pilot scale combustor. The results indicated that it was feasible to separate part of metals from flue gases by collecting fly ash at different temperatures. On the basis of their separation temperature, heavy and alkali metals could be divided into three groups: group A included Zn, K and P, which converted from gaseous phase to liquid or solid when temperature was above 600°C. Pb and Cu were the metals of group B, with optimum transformation temperature of 400°C. Na and As belonged to group C, with conversion temperatures of 300°C. Moreover, the effect of temperature gradient on heavy and alkali metal gas-solid transformation was also experimentally investigated. It was observed that the temperature gradient could promote the gas-solid conversion of heavy and alkali metals. However, too high a temperature gradient would suppress the formation of fine particles. The peak of conversion rate for K, Pb and Na occurred at 434°C s^–1, while that of P and Cu was 487°C s^–1.

We present the development stage of the sanitary landfills in Brazil in the context of urban solid residue management, demonstrating the necessity and importance of the employment of economic models. In the article, a cost estimate model is proposed as the basis for studies to be applied by sector management, including the city council, companies, consultants and engineers, contributing to the choice of new areas, public bids, municipal consortia and private public partnerships.

Construction activity in Europe has increased substantially in the past decade. Likewise, there has also been a commensurate rise in the generation of construction and demolition waste (C&DW). This, together with the fact that in many European countries the rate of recycling and reuse of C&DW is still quite low has engendered a serious environmental problem and a motivation to develop strategies and management plans to solve it. Due to its composition, there is a significant potential to reuse and/or recycle C&DW, and thereby, contribute to improving the sustainability of construction and development, but practical procedures are not yet widely known or practiced in the construction industry. This article (a) summarizes the different applications that are presently practiced to optimize the recovery and/or application of C&DW for reuse, and (b) proposes various measures and strategies to improve the processing of this waste. The authors suggest that to enhance environmental effectiveness, a conscious and comprehensive C&DW management plan should be implemented in each jurisdiction. More precisely, this study presents a holistic approach towards C&DW management, through which environmental benefits can be achieved through the application of new construction methods that can contribute to sustainable growth.

E-waste refers to both electronic and electrical waste materials; namely any items which rely on an electric current or electromagnetic fields in order to operate, and contain a hard-drive or significant electronic components and/or a printed circuit board. E-waste is outstripping the general growth of the municipal waste stream. Increasingly, smaller and cheaper electronic items are being disposed of in municipal waste systems and this, coupled with an increase in the number of, and turnover of manufacturers and suppliers, may see local councils assuming a key role in future e-waste management. A survey of local councils across Australia was undertaken to determine the current level of understanding and action on e-waste, and to solicit key responses regarding the identification of areas where improvements could be made. The survey achieved an overall response rate of 35%. Survey results identified key barriers experienced by councils regarding the collection and treatment of e-wastes, such as access to reprocessing facilities and the limited or complete unawareness by the public of the issues. With regards to who should pay for e-waste disposal at end-of-life, consumers and producers were most commonly cited, depending on the state with the preferred funding mechanisms being 'advanced recycling fee' and Expanded Producer Responsibility. Overwhelmingly, 88% of respondents believed that federal legislation was required to manage e-waste. Overall, the results did not indicate differences in views between states for most questions.

This study focuses on the effect of temperature on the compost quality and the processing time. Two temperature, namely 46°C (high temperature) and 30°C (low temperature) were considered for the composting trials. A mixture of 60% ground corn cob, 30% dried sports grass and 10% bio-activator was used as composting material. The composting process lasted for 120 days. The maturity indices at the end of composting indicate that, for the high-temperature treatment, the compost show an improved quality as compared to the low-temperature treatment. The maturity indices, namely carbon to nitrogen ratio, water extractable organic carbon, ratio of cation exchange capacity to total organic carbon and germination index, determined for the high temperature treatment are: 13.9, 1.48 mg mL^–1, 2.21, and 86%, respectively. On the basis of the compost characteristics, the processing time for the high- and low-temperature treatments was 75 days and 105 days, respectively. It can be concluded that treatment at the high-temperature level considered in this study presents a more suitable option for improvement of composting.

Earthworms feed readily upon sludge components, rapidly converting them into vermicompost, reduce the pathogens to safe levels and ingest the heavy metals. Volume is significantly reduced from 1 m³ of wet sludge (80% moisture) to 0.5 m³ of vermicompost (30% moisture). Earthworms have real potential both to increase the rate of aerobic decomposition and composting of organic matter and also to stabilize the organic residues in the sludge – removing the harmful pathogens (by devouring them and also by discharge of antibacterial coelomic fluid) and heavy metals (by bio-accumulation). They also mineralize the essential nutrients nitrogen, phosphorus and potassium from the sludge. It may not be possible to remove toxic substances completely, but at least change the ‘chemical make-up’ of the sludge to make it harmless to the soil and enable its use as a nutritive organic fertilizer. This method has been found to comply with grade A standards for sludge stabilization.

This paper discusses the ecological optimisation of municipal waste management systems. The purpose of this paper is to help local decision-makers in designing integrated waste management solutions that are ecologically optimal. The study uses life-cycle assessment (LCA) methodology to build a model and test different waste management scenarios in order to see whether the waste management hierarchy is influenced by regional conditions. The study also tests to which variables in waste management systems the end results of the LCA are most sensitive. The discussion is built around a case study in Lithuania where several waste management scenarios have been analysed and compared in the LCA framework. The paper reveals several methodology-related issues and discusses what implications waste-related policy intervention would have on the environmental outcomes of different waste management scenarios.

Fluorescent lamps are widely used world-wide due to their long life and energy saving capability. These lamps contain mercury (Hg) as a source of fluorescent radiation. The object of this study is a new technology for physicochemical treatment of waste fluorescent lamps. The residuals of the technological process were evaluated for potential leaching of heavy metals into the environment. Evaluation was performed using standardized extraction tests. Additionally, X-ray diffractometry (XRD) analysis, as well as tests with complex-forming agents and under pH-stable conditions were performed aiming to predict stability of the residuals in various environmental conditions. According to the XRD analysis, the minerals fluorapatite and hydroxylapatite were dominant in analyzed samples. The results of total extraction by aqua regia revealed that residuals contain relatively high total concentrations of Hg, Mn, and Zn. Concentrations of heavy metals, leaching to aqueous solution, were compared to leaching limit values (according to EU legislation). The concentrations of available Hg in the waste fluorescent lamp treatment products, according to its solubility in the water, exceed the limit values. The measured water-leachable Hg concentration was 4.88 mg kg^–1, while the value for waste acceptable at hazardous waste landfill sites is 2 mg kg^–1. Concentrations of other measured heavy metals did not exceed the limit values. According to the results, Hg stabilization potential for presented technology exceeds 99%.

Some samples of semi-dry flue gas desulfurization (FGD) ash were taken from sinter gas of a steel factory. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were employed to identify the samples in order to investigate their physical and chemical characteristics. The results show that semi-dry FGD ash from a steel factory is stable under atmospheric conditions. It has irregular shape, a smooth surface and loose construction. The size of FGD ash particles is around 0.5–25 µm, the average size is about 5 µm and the median diameter is 4.18 µm. Semi-dry FGD ash from a steel factory consists of CaSO₃, CaSO₄, CaCO₃, some amorphous vitreous material and unburned carbon. An experimental method was found to study the oxidation characteristics of ash. A prediction model of the oxidation efficiency was obtained based on response surface methodology. The results show that not only the temperature, but also gas:solid ratio, play an important role in influencing the oxidation efficiency. The interactions of the gas:solid ratio with temperature play an essential role. An improved response surface model was obtained which can be helpful to describe the degree of oxidation efficiency of semi-dry FGD ash.

Hydrolysis of cotton fabric waste to produce microcrystalline cellulose (MCC) was carried out using 2.5 N hydrochloric acid at 100°C for 30 min. Characterization of the structure, morphology, particle size as well as the thermal decomposition of the obtained MCC were studied using X-ray diffractometer, scanning electron microscope and laser light scattering particle size analyzer and thermogravimetric analyzer, respectively. These results indicated that the obtained MCC had a fibrous structure of a 40 µm average particle size and possessed a form of highly native crystalline cellulose I. In addition, its maximum degradation temperature was observed at 350°C. The poly(vinyl chloride) (PVC) films in this work were produced by first blending the produced MCC with PVC resin in amounts of 5–30 parts per hundred of resin. The blends were then made into film using a two-roll mill. The tensile properties of the film were measured using a Universal Testing Machine. The biodegradation tests were carried out in soil and in a moisture-controlled chamber. The biodegradability was estimated by the loss of mass, moisture absorption capacity and electron microscope studies. It was found that the tensile strength and Young’s modulus of the blends increased with increasing amounts of MCC. Similarly, moisture absorption and biodegradability of the films were also increased as the amount of MCC increased. The results implied that MCC behaved not only as a reinforcing filler but also as a biodegradability promoter of PVC films.

The need for effective apparel waste management is motivated by the increasing cost and decreasing availability of landfill space and the dwindling of natural resources. The aim of this study was to identify the current solid waste disposal and recycling practices of the apparel industry in South Africa and to determine their attitude and willingness towards recycling, their perception of the feasibility thereof, barriers to recycling and marketing strategies that would be appropriate for products made from recycled materials. A structured questionnaire was mailed to apparel manufacturers in South Africa. The results indicated that most apparel manufacturers use landfills to dispose of their waste, while approximately half recycle some of the waste. They are fairly positive towards recycling, with consideration of economical feasibility. Phi-coefficients show no practically significant relationship between company size and the use of recycled materials. The most important barriers to recycling are lack of equipment and technology, lack of material to recycle and lack of consumer awareness. Marketing strategies for recycled products are recommended. It is concluded that consumer awareness and knowledge regarding recycled apparel products should be developed in order to ensure a market and that apparel manufacturers should be encouraged to recycle more extensively, in order to ensure that resources will not be exhausted unnecessarily and the environment will be preserved optimally.

Co-digestion of the organic fraction of municipal solid waste (OFMSW) and sewage sludge may be an attractive alternative for sustainable management of two separate waste streams produced in large amounts in all countries. This study evaluates calculation-based results of an anaerobic co-digestion process for primary sludge (PS) together with the OFMSW. The calculations were carried out for the anaerobic digester of Kayseri municipal wastewater treatment plant (in Turkey) presently digesting only PS. Two alternatives were proposed using different solid waste contents in co-digesters. For achieving the optimal solids content, some treated wastewater should be recycled to the inlet of the digesters. The municipal solid waste collection method characterized as mechanically sorted (MS-OFMSW; Option 1) is evaluated as well as a source sorted (SS-OFMSW) alternative (Option 2). Utilizing the energy produced by the existing sludge digester, only 30% of the internal energy demand at the wastewater treatment plant can be covered. The aim of this study is to evaluate how energy production would be increased by co-digestion of OFMSW and PS. The best operational condition considering organic loading rate, hydraulic retention time and energy generation could be attained at 10% digester solids content for both options. According to Option 1, almost 77% of the energy demand could be covered by co-digestion of MS-OFMSW and PS. Results indicated that almost 100% energy coverage can be obtained when co-digestion (Option 2) was performed according to SS-OFMSW and PS.

It is essential to the achievement of zero waste that emphasis is concentrated on front-end preventions rather than end-of-pipe (EOP) treatment. Zero waste is primarily based on cleaner production, waste management, the reduction of unnecessary consumption and the effective utilization of waste materials. The aim of this study was to briefly review the tasks undertaken and future plans for achieving zero waste in Taiwan. Waste prevention, source reduction, waste to product, waste to energy, EOP treatment, and adequate disposal are the sequential principal procedures to achieve the goal of zero waste. Six strategies have been adopted to implement the zero waste policy in Taiwan. These are regulatory amendments, consumption education, financial incentives, technical support, public awareness, and tracking and reporting. Stepwise targets have been set for 2005, 2007, 2011, and 2020 for both the municipal solid waste (MSW) and industrial waste to reach the goal of zero waste. The eventual aim is to achieve 70% MSW minimization and 85% industrial waste minimization by 2020. Although tools and measures have been established, some key programmes have higher priority. These include the establishment of a waste recycling programme, promotion of cleaner production, a green procurement programme, and promotion of public awareness. Since the implementation of the zero waste policy started in 2003, the volume of MSW for landfill and incineration has declined dramatically. The recycling and/or minimization of MSW quantity in 2007 was 37%, which is much higher than the goal of 25%. Industrial waste reached almost 76% minimization by the end of 2006, which is 1 year before the target year.

In an era of global warming, rising energy costs and increasing volumes of wastes destined for landfills and incinerators, communities should set up environmentally sustainable services that are cost-effective for their citizens and revenue generators for municipalities. A win-win garbage collection and kerbside recycling program established more than eight years ago in a small rural community in Ohio, US is still going strong. It is offering a relatively inexpensive way for waste disposal by providing an incentive-based and highly participatory kerbside recycling and at the same time bringing in substantial franchise fees for the municipal coffers. Unlike garbage contracts in most communities that are designed for only residential waste collection, this program extends disposal and recycling services to of non-residential establishments. It picks up hard-to-dispose household furniture, appliances and other bulky items without additional costs to the residents. By being creative and assessing local political and socio-economic milieu, public officials can implement a comprehensive service package for taking care of their community throwaways. However, before establishing such programs in partnership with a private firm, city administrators must understand the intricacies of bid specifications customized for municipal wastes and recyclable materials.

The aim of this investigation was to determine odorous compounds in the air over the landfill sites in France and Poland. Air samples were collected by passive and dynamic methods of preconcentration analytes and analysed by GC-MS and GC-FID. The coupling µTD-µGC-MS was also used for on-site analysis of odorous compounds. The achieved results indicated that the concentrations of odorants in the air varied and strongly depended on the sampling site. The highest concentrations were observed at the points situated near biogas wells and above the fresh waste layer. The concentrations were influenced by landfill activities such as failures of the landfill gas collection system, heavy truck traffic, machinery operations and compacting fresh waste.

The environmental performance of two low-organic waste landfill scenarios (‘low-organic-energy’ and ‘low-organic-flare’) was developed and compared with two household waste landfill scenarios ('household-energy' and 'household-flare') by means of LCA-modelling. The LCA-modelling was made for 1 tonne of wet waste landfilled and the environmental aspects were evaluated for a 100-year period after disposal. The data utilized in the LCA-calculations to model the first 10–20 years of landfilling of the two low-organic waste scenarios make extensive use of site-specific data from the Nauerna Landfill (The Netherlands), but average data from other comparable, existing landfills were used too. As data from full-scale landfills do not cover more than 30–40 years of landfilling, data from laboratory simulations and accelerated tests of limited scale were also utilized. The life-cycle impact assessments show that the low-organic waste scenarios achieved better environmental performance than the household waste scenarios with regard to both ordinary and toxicity-related environmental impact categories. This indicates that the reduction of organic matter accepted at landfills (as prescribed by the European Union Landfill Directive: Council Directive 1999/31/EC, EU, Brussels, 1999) can be a successful approach to decrease the environmental loads in several impact categories in comparison with landfilling of waste with significant organic content. However, when utilization of landfill gas is accounted for in the life-cycle impact assessment calculation, the small gas generation in low-organic waste landfills reduced the actual potential for energy generation and therefore the environmental savings obtained were reduced proportionally. Groundwater pollution from input of leachate was also evaluated and the WHO (Guidelines for Drinking-water Quality; WHO, Geneva, 2006) guideline for drinking water quality was assumed as reference. The results show that low-organic waste landfills pose a smaller risk of groundwater contamination, but the impact potentials estimated still remain a lot higher than estimated in other categories.

In this study, the use of crumb tyres as additives to concrete was investigated. For some time, researchers have been studying the physical properties of concrete to determine why the inclusion of rubber particles causes the concrete to degrade. Several methods have been developed to improve the bonding between rubber particles and cement hydration products (C–S–H) with the hope of creating a product with an improvement in mechanical strength. In this study, the crumb tyres were treated with waste organic sulfur compounds from a petroleum refining factory in order to modify their surface properties. Organic sulfur compounds with amphiphilic properties can enhance the hydrophilic properties of the rubber and increase the intermolecular interaction forces between rubber and C–S–H. In the present study, a colloid probe of C–S–H was prepared to measure these intermolecular interaction forces by utilizing an atomic force microscope. Experimental results showed that rubber particles treated with waste organic sulfur compounds became more hydrophilic. In addition, the intermolecular interaction forces increased with the adsorption of waste organic sulfur compounds on the surface of the rubber particles. The compressive, tensile and flexural strengths of concrete samples that included rubber particles treated with organic sulfur compound also increased significantly.

Over the past two decades, the waste reduction problem has been a major issue in environmental protection. Both recycling and waste reduction policies have become increasingly important. As the complexity of decision-making has increased, it has become evident that more factors must be considered in the development and implementation of policies aimed at resource recycling and waste reduction. There are many studies focused on waste management excluding waste reduction. This study paid more attention to waste reduction. Social, economic, and management aspects of waste treatment policies were considered in this study. Further, a life-cycle assessment model was applied as an evaluation system for the environmental aspect. Results of both quantitative and qualitative analyses on the social, economic, and management aspects were integrated via the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) method into the comprehensive decision-making support system of multi-criteria decision-making (MCDM). A case study evaluating the waste reduction policy in Taoyuan County is presented to demonstrate the feasibility of this model. In the case study, reinforcement of MSW sorting was shown to be the best practice. The model in this study can be applied to other cities faced with the waste reduction problems.

Processed sandy residue generated from mixed construction and demolition waste (mixed C&D-W) was investigated for possible deposition in landfill. The basic properties and the components removed in the loss on ignition (LOI) test were examined. The target material for decreasing LOI was elucidated and the validity of LOI used as landfill standard for inert industrial solid waste was discussed. LOI of most of the samples was above 5% and therefore, in principle, processed sandy residue should not be deposited in inert-type landfill. As LOI of sandy residue was mainly due to bound water, the LOI could not be decreased to below 5% even if wood, which is the major organic matter in the sandy residue, was removed. However, decreasing the amount of wood could lead to a subsequent decrease in the amount of dissolved organic matter. Therefore, the LOI of processed mixed C&D-W used as landfill standard for inert industrial solid waste should be re-evaluated.

Product service systems (PSS) are cleaner product concepts which have been developed to achieve improvements in resource productivity which may be realized from modern trends in service delivery. However, there is a paucity of research on the waste prevention performance of PSS in UK household markets. This paper reports the findings of exploratory research which begins to address this gap in knowledge. An exploratory waste prevention assessment was completed on four experimental PSS which were developed in conjunction with a major UK house-builder for delivery on their new housing developments. The results of the assessment show that the selected PSS concepts have potential to prevent high value and harmful Waste Electrical and Electronic Equipment (WEEE) arising in UK household waste streams. Consistent with the canon of exploratory research, the assessment also identifies a number of factors which are thought to influence PSS waste prevention performance. It is recognized that further research is needed to gain an in-depth understanding of these factors as well as to define policy measures which enable the conditions in which PSS prevent household waste on new housing developments in the UK to be created.