Optimized thermochemical detoxification of asbestos-containing waste using chemical additives and microwave heat treatment

Journal of Material Cycles and Waste Management - Owing to the increasing ACW generation, asbestos detoxification and recycling technologies are required for environmental and economic reasons....     

微波技术在废物处理中的应用

综述了微波在废物处理中的应用,主要介绍了微波加热的机理及特点,微波在处理放射性废物、废旧电路板、污泥、医疗垃圾、废轮胎中的应用,展望了微波技术在废物处理中的应用前景.     

Dechlorination and decomposition of Aroclor 1242 in real waste transformer oil using a nucleophilic material with a modified domestic microwave oven

This research was done to assess the dechlorination and decomposition of polychlorinated biphenyls (PCBs) in real waste transformer oil through a modified domestic microwave oven (MDMW). The influence of microwave power (200–1000 W), reaction time (30–600 s), polyethylene glycol (PEG) (1.5–7.5 g), iron powder (0.3–1.5 g), NaOH (0.3–1.5 g), and H₂O (0.4–2 ml) were investigated on the decomposition efficiency of PCBs existing in real waste transformer oil with MDMW. Obtained data indicate that PEG and NaOH have the greatest influence on decomposition of PCBs; while, iron did not influence, and H₂O decreased, the decomposition efficiency of PCBs. Experimental data also indicated that with the optimum amount of variables through a central composites design method (PEG = 5.34 g, NaOH = 1.17 g, Fe = 0.6 g, H₂O = 0.8 ml and microwave power 800 W), 78 % of PCBs was degraded at a reaction time of about 6 min. In addition, the PCBs decomposition without using water increased up to 100 % in the reactor with the MDMW at 6 min. Accordingly, results showed that MDMW was a very efficient factor for PCBs decomposition from waste transformer oil. Also, using microwave irradiation, availability and inexpensive materials (PEG, NaOH), and iron suggest this method as a fast, effective, and cheap method for PCB decomposition of waste oils.     

Biomedical solid waste management in an Indian hospital: a case study

The objectives of this study were: (i) to assess the waste handling and treatment system of hospital bio-medical solid waste and its mandatory compliance with Regulatory Notifications for Bio-medical Waste (Management and Handling) Rules, 1998, under the Environment (Protection Act 1986), Ministry of Environment and Forestry, Govt. of India, at the chosen KLE Society's J. N. Hospital and Medical Research Center, Belgaum, India and (ii) to quantitatively estimate the amount of non-infectious and infectious waste generated in different wards/sections. During the study, it was observed that: (i) the personnel working under the occupier (who has control over the institution to take all steps to ensure biomedical waste is handled without any adverse effects to human health and the environment) were trained to take adequate precautionary measures in handling these bio-hazardous waste materials, (ii) the process of segregation, collection, transport, storage and final disposal of infectious waste was done in compliance with the Standard Procedures, (iii) the final disposal was by incineration in accordance to EPA Rules 1998, (iv) the non-infectious waste was collected separately in different containers and treated as general waste, and (v) on an average about 520 kg of non-infectious and 101 kg of infectious waste is generated per day (about 2.31 kg per day per bed, gross weight comprising both infectious and non-infectious waste). This hospital also extends its facility to the neighboring clinics and hospitals by treating their produced waste for incineration.     

Measurement and management of hospital waste in southern Iran: a case study

One of the requirements for development of human societies is the establishment of new healthcare centers. A variety of wastes are generated in healthcare centers depending on the type of activities. This study was conducted to identify, measure and manage different types of hospital wastes as a case study in a hospital located in southern Iran. For this purpose, a questionnaire was initially designed and distributed among the relevant experts to survey the current trend of waste management in the hospital in terms of waste collection, storage and disposal. Afterwards, the hospital waste was sampled during two seasons of fall and winter. The samples were weighted for seven consecutive days in the middle of each season. Approximately, 10 % of the total waste bags per day collected round the clock were selected for further analysis. The obtained results indicated that infectious-hazardous and pseudo-household wastes were, respectively, about 3.79 kg/day/bed, 1.36 kg/day/bed and 2.43 kg/day/bed of the total generated waste in the hospital. As the research findings suggest, proper separation of infectious and pseudo-household wastes at the source would be an essential step towards mitigating environmental and health risks and minimizing the cost of the hospital waste management.     

Sludge as dioxins suppressant in hospital waste incineration

Nitrogen containing compounds such as ammonia, urea and amines can effectively inhibit the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Sewage sludge accumulates both sulfur and nitrogen during wastewater treatment so it could be used to reduce PCDD/Fs formation. Indeed, it is observed in this study that the gas evolving from the sludge drying process can significantly suppress chlorobenzene (CBz) and PCDD/Fs formation from fly ash collected from a hospital waste incinerator. For instance, the reduction of hexachlorobenzene (HxCBz) and PCDD/Fs amount was 92.1% and 78.7%, respectively, when the drying gas evolving from 2g sludge flew through 2g fly ash. These tests were conducted in the frame of projects devoted to hospital waste incineration. The disposal technology for hospital waste (HW), developed in this institute, features rotary kiln pyrolysis combined with post-combustion followed by flue gas cleaning. Hence, some preliminary tests were devoted to investigate dioxins suppression by co-pyrolysis and co-combustion of polyvinyl chloride (PVC) and sludge in lab scale. More experimental research will be conducted to appropriately assess these effects of sludge on PCDD/Fs emissions during co-pyrolysis/combustion of HW and sludge.     

Results of a hospital waste survey in private hospitals in Fars province, Iran

Hospital waste is considered dangerous because it may possess pathogenic agents and can cause undesirable effects on human health and the environment. In Iran, neither rules have been compiled nor does exact information exist regarding hospital waste management. The survey presented in this article was carried out in all 15 private hospitals of Fars province (Iran) from the total numbers of 50 governmental and private hospitals located in this province, in order to determine the amount of different kinds of waste produced and the present situation of waste management. The results indicated that the waste generation rate is 4.45 kg/bed/day, which includes 1830 kg (71.44%) of domestic waste, 712 kg (27.8%) of infectious waste, and 19.6 kg (0.76%) of sharps. Segregation of the different types of waste is not carried out perfectly. Two (13.3%) of the hospitals use containers without lids for on-site transport of wastes. Nine (60%) of the hospitals are equipped with an incinerator and six of them (40%) have operational problems with the incinerators. In all hospitals municipal workers transport waste outside the hospital premises daily or at the most on alternative days. In the hospitals under study, there aren't any training courses about hospital waste management and the hazards associated with them. The training courses that are provided are either ineffective or unsuitable. Performing extensive studies all over the country, compiling and enacting rules, establishing standards and providing effective personnel training are the main challenges for the concerned authorities and specialists in this field.     

Report: The assessment of hospital waste management:a case study in Tehran

Hospital waste management is an important process that must be dealt with diligently. The management of hazardous waste material requires specific knowledge and regulations and it must be carried out by specialists in the field. In this cross-sectional study, we assessed the main stages of hospital waste management including separation, containment, removal and disposal of waste materials in public hospitals affiliated with Tehran University of Medical Sciences (TUMS). We selected 108 units of six hospitals (three general hospitals and three subspecialty hospitals) from those hospitals supervised by TUMS using the cluster sampling method. The measurement was conducted through a questionnaire and direct observation by researchers. Association analysis was done by statistical tests; Fisher exact test and chi-squared using SPSS software. According to the results obtained by the questionnaire, most of the studied wards scored moderately in terms of quality of their performance in all stages of waste management. About one-fifth of the wards were suffering from poor management of their medical waste and only a minority of wards obtained good scores for managing their waste materials. The findings also revealed significant associations between temporary waste storage and collection and the level of education of the managers (P = 0.040, P = 0.050, respectively). In summary, the study indicated a moderate management in all processes of separation, collection, containment, removal and disposal of waste materials in hospitals with several observed problems in the process.     

Developing a master plan for hospital solid waste management: a case study

Disposal of about 1750tons of solid wastes per day is the result of a rapid population growth in the province of Khuzestan in the south west of Iran. Most of these wastes, especially hospital solid wastes which have contributed to the pollution of the environment in the study area, are not properly managed considering environmental standards and regulations. In this paper, the framework of a master plan for managing hospital solid wastes is proposed considering different criteria which are usually used for evaluating the pollution of hospital solid waste loads. The effectiveness of the management schemes is also evaluated. In order to rank the hospitals and determine the share of each hospital in the total hospital solid waste pollution load, a multiple criteria decision making technique, namely analytical hierarchy process (AHP), is used. A set of projects are proposed for solid waste pollution control and reduction in the proposed framework. It is partially applied for hospital solid waste management in the province of Khuzestan, Iran. The results have shown that the hospitals located near the capital city of the province, Ahvaz, produce more than 43% of the total hospital solid waste pollution load of the province. The results have also shown the importance of improving management techniques rather than building new facilities. The proposed methodology is used to formulate a master plan for hospital solid waste management.     

Effect of microwave irradiation on anaerobic degradability of model kitchen waste

High temperature and pressure microwave (MW) irradiation was investigated as a pre-treatment to enhance anaerobic biodegradability and methane production from a model kitchen waste (KW). Heating rates of 7.8, 3.9 and 1.9 °C/min from room temperature to a final pre-treatment temperature of 175 °C with 1 min temperature holding time were tested. MW irradiation was successful in solubilization of particulate chemical oxygen demand (COD) resulting in higher soluble COD, protein and sugar concentrations in the supernatant phase (<0.45 μm) as well as in the whole fraction of pretreated KW compared to controls (not pretreated). Anaerobic biodegradability of the supernatant and whole fractions of pretreated KW was assessed by using a batch biochemical methane potential assay (BMP) at 33 °C. Although the highest level of solubilization was achieved at a heating rate of 1.9 °C/min, improvement in anaerobic biodegradability was observed only at the fastest heating rate of 7.8 °C/min for whole waste and for all conditions with the supernatant phase. BMP indicated increased biodegradability of between 5% and 16% for the supernatant fraction relative to controls. For the whole fraction, anaerobic biodegradability improved by 9% at a heating rate of 7.8 °C/min.     

Resource recovery treatment of waste sludge using a solubilizing reagent

The dewatering of waste sludge continues to be a major problem in wastewater treatment. In this study, the solubilization treatment of waste sludge and extracellular polymeric substances using a solubilizing reagent was examined experimentally. For this purpose, a compression test of thickened waste sludge obtained after solubilization treatment was carried out. The total solid content of the dewatered cake was over 30% when using hydrochloric acid or acetic acid as the solubilizing reagent; however, it was about 20% when using sodium hydroxide. The thickened waste sludge was effectively solubilized when the concentration of acetic acid in the sludge, assuming that it was diluted by free water and not bound water in the sludge, was greater than 0.3 kmol/m³. A flocculated sedimentation test using the supernatant water after solubilization treatment was also carried out, revealing that it functions in a similar manner to commercial flocculant in aggregating solid particles under gravity. This result indicates that the supernatant water can act as a bioflocculant. Methane fermentation of the supernatant water was subsequently carried out. The findings showed that by using acetic acid as a solubilizing reagent, solubilized organic substances in the supernatant water could be recovered as a bioenergy resource.     

Treatment of methylacetate waste gas using a trickle-bed air biofilter

The trickle-bed air biofilter (TBAB) performance for methylacetate (MA) removal from waste gases was evaluated under different gas flow rates and influent concentrations. In the pseudo-steady-state conditions, the elimination capacity increased but the removal efficiency decreased with the increase of MA loading. More than 95 and 90% removal efficiencies were achieved for influent MA loadings below 390 and 727 g/m3/h, respectively. The TBAB appears to be a very effective treatment process for controlling MA emission under low to high loading conditions, and the effectiveness could be maintained over 190 days of laboratory operation.     

Estimation of methane emission rate changes using age-defined waste in a landfill site

Long term methane emissions from landfill sites are often predicted by first-order decay (FOD) models, in which the default coefficients of the methane generation potential and the methane generation rate given by the Intergovernmental Panel on Climate Change (IPCC) are usually used. However, previous studies have demonstrated the large uncertainty in these coefficients because they are derived from a calibration procedure under ideal steady-state conditions, not actual landfill site conditions. In this study, the coefficients in the FOD model were estimated by a new approach to predict more precise long term methane generation by considering region-specific conditions. In the new approach, age-defined waste samples, which had been under the actual landfill site conditions, were collected in Hokkaido, Japan (in cold region), and the time series data on the age-defined waste sample’s methane generation potential was used to estimate the coefficients in the FOD model. The degradation coefficients were 0.050 1/y and 0.062 1/y for paper and food waste, and the methane generation potentials were 214.4 mL/g-wet waste and 126.7 mL/g-wet waste for paper and food waste, respectively. These coefficients were compared with the default coefficients given by the IPCC. Although the degradation coefficient for food waste was smaller than the default value, the other coefficients were within the range of the default coefficients. With these new coefficients to calculate methane generation, the long term methane emissions from the landfill site was estimated at 1.35 × 10⁴ m³-CH₄, which corresponds to approximately 2.53% of the total carbon dioxide emissions in the city (5.34 × 10⁵ t-CO₂/y).     

Chemical properties of heavy metals in typical hospital waste incinerator ashes in China

Incineration has become the main mechanism for hospital waste (HW) disposal in China after the outbreak of Severe Acute Respiratory Syndrome (SARS) in 2003. However, little information is available on the chemical properties of the resulting ashes. In the present study, 22HW ash samples, including 14 samples of bottom ash and eight samples of fly ash, were collected from four typical HW incineration plants located across China. Chemical analysis indicated that the HW ashes contained large amounts of metal salts of Al, Ca, Fe, K, Mg, Na with a concentration range of 1.8-315gkg(-1). Furthermore, the ashes contained high concentrations of heavy metals such as Ag, As, Ba, Bi, Cd, Cr, Cu, Mn, Ni, Pb, Ti, Sb, Sn, Sr, Zn with a vast range of 1.1-121,411mgkg(-1), with higher concentrations found in the fly ash samples. Sequential extraction results showed that Ba, Cr, Ni and Sn are present in the residual fraction, while Cd existed in the exchangeable and carbonate fractions. As, Mn, Zn existed in the Fe-Mn oxide fraction, Pb was present in the Fe-Mn oxide and residual fractions, and Cu was present in the organic matter fraction. Furthermore, toxicity characteristic leaching procedure (TCLP) results indicated that leached amounts of Cd, Cu and Pb from almost all fly ash samples exceeded the USEPA regulated levels. A comparison between the HW ashes and municipal solid waste (MSW) ash showed that both HW bottom ash and fly ash contained higher concentrations of Ag, As, Bi, Cd, Cr, Cu, Pb, Ti, and Zn. This research provides critical information for appropriate HW incineration ash management plans.     

Stabilization and utilization of hospital waste as road and asphalt aggregate

This article reports the operational results of the effective utilization of hospital waste molten slag produced using a high-temperature melting system, and being operated at a hospital in Selangor, Malaysia. The hospital waste is incinerated and subsequently melted at 1200°C. Scanning election microscope (SEM)/EDX results showed that the slag produced after melting contained amounts of SiO₂, CaO, and Al₂O₃ in excess of 53%, 9%, and 16%, respectively. The results from a leaching analysis on the slag produced proved that the melting process had successfully stabilized the heavy metals. The use of this slag as an alternative material to replace conventional aggregates for road construction was studied. The results from aggregate and asphalt mix tests showed that the slag produced fulfills all the requirements of an alternative aggregate. The average asphalt content, or the optimum asphalt content to be mixed with hospital waste molten slag, was found to be about 5.53%.     

Choosing a sustainable demolition waste management strategy using multicriteria decision analysis

This paper presents an application of the ELECTRE III decision-aid method in the context of choosing a sustainable demolition waste management strategy for a case study in the city of Lyon, France. This choice of waste management strategy takes into consideration the sustainable development objectives, i.e. economic aspects, environmental consequences, and social issues. Nine alternatives for demolition waste management were compared with the aid of eight criteria, taking into account energy consumption, depletion of abiotic resources, global warming, dispersion of dangerous substances in the environment, economic activity, employment, and quality of life of the local population. The case study concerned the demolition of 25 buildings of an old military camp. Each alternative was illustrated with different waste treatments, such as material recovery, recycling, landfilling, and energy recovery. The recommended solution for sustainable demolition waste management for the case study is a selective deconstruction of each building with local material recovery in road engineering of inert wastes, local energy recovery of wood wastes, and specific treatments for hazardous wastes.     

Impacts of microwave pretreatments on the semi-continuous anaerobic digestion of dairy waste activated sludge

Microwave (MW) irradiation is one of the new and possible methods used for pretreating the sludge. Following its use in different fields, this MW irradiation method has proved to be more appropriate in the field of environmental research. In this paper, we focused on the effects of MW irradiation at different intensities on solubilization, biodegradation and anaerobic digestion of sludge from the dairy sludge. The changes in the soluble fractions of the organic matter, the biogas yield, the methane content in the biogas were used as control parameters for evaluating the efficiency of the MW pretreatment. Additionally, the energetic efficiency was also examined. In terms of an energetic aspect, the most economical pretreatment of sludge was at 70% intensity for 12 min irradiation time. At this, COD solubilization, SS reduction and biogas production were found to be 18.6%, 14% and 35% higher than the control, respectively. Not only the increase in biogas production was investigated, excluding protein and carbohydrate hydrolysis was also performed successfully by this microwave pretreatment even at low irradiation energy input. Also, experiments were carried out in semi continuous anaerobic digesters, with 3.5 L working volume. Combining microwave pretreatment with anaerobic digestion led to 67%, 64% and 57% of SS reduction, VS reduction and biogas production higher than the control, respectively.     

Intensity of hospital waste generation and disposal in the selected hospitals in Kerala,India: an analysis based on hospital ownership

Journal of Material Cycles and Waste Management - Management of hospital wastes has been considered as an integral part of hospital hygiene and infection control, which in turn depends on the...