Hazardous waste generation and management in China: a review

Associated with the rapid economic growth and tremendous industrial prosperity, continues to be the accelerated increase of hazardous waste generation in China. The reported generation of industrial hazardous waste (IHW) was 11.62milliontons in 2005, which accounted for 1.1% of industrial solid waste (ISW) volume. An average of 43.4% of IHW was recycled, 33.0% was stored, 23.0% was securely disposed, and 0.6% was discharged without pollution controlling. By the end of 2004, there were 177 formal treatment and disposal centers for IHW management. The reported quantity of IHW disposed in these centers was only 416,000tons, 65% of which was landfilled, 35% was incinerated. The quantity of waste alkali and acid ranked the first among IHW categories, which accounted for 30.9%. And 39.0% of IHW was generated from the raw chemical materials and chemical products industry sectors. South west China had the maximum generation of IHW, accounted for 40.0%. In addition, it was extrapolated that 740,000tons of medical wastes were generated per year, of which only 10% was soundly managed. The generation of discarded household hazardous waste (HHW) is another important source of hazardous waste. A great proportion of HHW was managed as municipal solid waste (MSW). Hazardous waste pollution controlling has come into being a huge challenge faced to Chinese environmental management.     

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

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

Manganese recovery from secondary resources: a green process for carbothermal reduction and leaching of manganese bearing hazardous waste

During the hydrometallurgical extraction of zinc by electrowinning process, a hazardous solid waste called anode mud is generated. It contains large quantity of manganese oxides (55-80%) and lead dioxide (6-16%). Due to the presence of a large quantity of lead, the anode mud waste is considered hazardous and has to be disposed of in secure landfills, which is costly, wastes available manganese and valuable land resources. For recovery of manganese content of anode mud, a process comprising of carbothermal treatment using low density oil (LDO) followed by sulphuric acid leaching is developed.     

Fluid–structure interaction of FRP wind turbine blades under aerodynamic effect

Structural analysis of FRP wind turbine blades must take into account phenomena associated with aerodynamics as well as fluid–structure coupling, because aerodynamic loading causes blades to bend mostly in the flapwise direction, and simultaneously causes foil sections to rotate to create new fluid fields around the foils. This study developed an analytical process for calculating fluid–structure interaction, while considering the effects of aerodynamic pressure and finite element analysis in the design of wind turbine blades. In addition, we calculated turbine power efficiency to evaluate the results of fluid–structure interaction displaying approximately power capacity loss of 17% at a wind speed of 25 m/s, and proposed three feasible improvements to enhance the performance of wind turbines. The presented study provided a comprehensible means by which to interpret changes in the aeroelastic response of blades, and was helpful to modify the original wind turbine model.     

Sources, characteristics and treatment and disposal of industrial wastes containing hexachlorobenzene

Hexachlorobenzene (HCB) is a hazardous component of certain industrial wastes. The hazardous characteristics of HCB stem from its toxicity, potential for bioaccumulation and environmental persistence. A study was conducted to identify the sources and characteristics of manufacturing wastes containing hexachlorobenzene and to review and document methods currently used for treatment and disposal of HCB wastes.The chlorinated solvents and pesticide industries were found to account for nearly all HCB wastes produced (4,305 tons per year) by the 14 industries reviewed as sources of HCB wastes.Waste storage methods which are used prior to ultimate disposal include storage of solid waste cubes under plastic cover and use of water-covered lagoons. Methods for transportation of HCB wastes include use of forklift, truck, pipeline, heated tank trucks and rail. Ultimate waste disposal methods include land disposal, incineration (with or without by-product recovery), resource recovery, discharge to municipal sewage treatment plants, and emission to the atmosphere. The majority of the HCB waste handled by the industrial facilities reviewed is currently disposed of in two industrial landfills using a soil cover of 4 to 6 ft. with a polyethylene film placed at approximately the mid-depth of the soil cover. Incineration at a sufficiently elevated temperature can effectively destroy HCB; HCl can be recovered as a by-product.Very limited actual disposal cost data are available on existing facilities handling HCB wastes.     

Current research on the disposal of hazardous wastes

The Solid and Hazardous Waste Research Laboratory is one of six laboratories in the Environmental Protection Agency (EPA), National Environmental Research Center at Cincinnati, Ohio. The laboratory is responsible for research into new and improved systems of solid and hazardous waste management, development of technology, determination of environmental effects, and collection of data necessary for the establishment of processing and disposal guidelines. In the past, the laboratory concentrated on problems associated with municipal solid waste; but recently the emphasis has shifted, and present efforts are directed primarily toward the problem of industrial hazardous waste disposal on land. Under the solid waste program, investigations were initiated on the migration of municipal landfill leachate and leachate containment with synthetic liners. These studies have been underway for more than a year, but they will not be discussed here because of the present emphasis on industrial hazardous waste problems. Although none of our research projects is concerned specifically with the disposal of residues and sorbants generated during cleanup of hazardous material spills, much of the forthcoming information will be applicable to spill-cleanup problems. The extramural projects and program areas described here involve many activities that could be useful in spill problems.     

Mitigation of methane emissions from sanitary landfills and sewage treatment plants in Jordan

Mitigation of Greenhouse gases deals with measures to reduce the vulnerability of a certain sector to climate change through minimizing net emissions. In this paper, mitigation scenarios aimed at reducing Jordan methane emissions from sewage treatment plants and sanitary landfill sites were proposed and investigated. In the case of sewage treatment plants, As-Samra plant (the largest in Jordan) was selected for this mitigation study. Two scenarios (I and II) were proposed, the first was to expand the plant by the year 2005 using waste stabilization ponds the current treatment technology, and the second scenario involved switching the treatment technology to activated sludge type when the expansion starts in the year 2005. For sanitary landfills, the proposed mitigation scenario was the construction of two biogas plants, each with a processing capacity of 1,000 tons of solid waste per day at Rusaifeh and Akaider—the two largest landfills in Jordan at the beginning of the year 2005. For As-Samra plant, the cumulative reduction in methane emissions by the year 2030 was calculated to be 49 and 146 Gg under mitigation scenarios I and II, respectively. On the other hand, the biogas plant scenario reduces the methane emissions at each landfill by 28.1 Gg annually. The total emission reduction from both landfills in the life span (25 years) of the biogas plants will be about 1,406 Gg CH_4. In addition, this scenario generates electricity at a cost of 4.6 cents per kWh, which is less than the Jordan electric long-run marginal cost of generation at 5.5 cents/kWh. Moreover, annual savings of US$4.65 million will be achieved by the replacement of fuel oil with the generated biogas. The mitigation scenarios presented in this paper include measures that positively contribute to the national development of Jordan in addition to considerable reduction in methane emission.. This forms a win–win situation that favors the adoption of investigated mitigation scenarios by the decision-makers of the waste sector in Jordan.     

Possibility of increasing the service life of damaged blades

Results are given of an investigation of the effectiveness of a method of strengthening the working titanium alloy blades of a gas turbine engine compressor. It is established that the proposed strengthening method can lengthen to more than double the service life of damaged blades. In addition it is shown that in these blades, in comparison with nonstrengthened blades, cracks develop in a narrower zone and predominantly on the side of the inlet edge.Translated from Problemy Prochnosti, No. 4, pp. 45–49, April, 1992.     

Mechanical properties of a TiAl-based alloy at room and high temperatures

Intermetallic titanium aluminides have attracted considerable industrial interest for aero and automotive applications owing to their specific strength. These alloys are candidates for high-temperature applications such as turbine blades and turbocharger turbine wheels. In this work, the mechanical behaviour of an as-cast Ti–47Al–3Cr–3Nb (at.-%) alloy was studied. Four-point bending tests were performed to determine the mechanical properties of the alloy at both room and high temperatures. Microhardness and Young’s modulus were evaluated by dynamic indentation tests at room temperature. Analyses of the as-cast alloy showed that, with the selected production process conditions, it has a duplex microstructure. Tests revealed that, while at room temperature the alloy is brittle, between 700 and 900°C it exhibits good ductility and mechanical properties.     

Shark Skin Inspired Riblet Coatings for Aerodynamically Optimized High Temperature Applications in Aeroengines

The shark skin effect is the mechanism of wall friction reduction of a fluid due to a riblet structured surface. A new application for riblet surfaces may be jet engine blades. Riblet structured coatings on the blades would act as oxidation protection and additionally reduce the skin drag on the surface. In this study structuring surface areas of high temperature nickel‐based alloys is investigated. These alloys are used for compressor and turbine blades near the combustion chamber. Experiments are performed by depositing titanium on a nickel base alloy through particular metal grids using magnetron sputtering. For single‐digit micrometer structures, photolithography with subsequent electrodeposition of nickel as well as sputter deposition and thermal evaporation of several materials are investigated. Successfully fabricated structures are oxidized at 900–1 000 °C for up to 100 h and the resulting shape is characterized using scanning electron microscopy. The most accurate structures are obtained using photolithography and subsequent electrodeposition. The reduction of the wall shear stress was measured in an oil channel. The riblet structures prior to oxidation show a reduction of the wall shear stress of up to 4.9%.     

Cyclic strength of turbine blades made of cast nickel-based alloys

We study the cyclic strength and durability of service-exposed turbine blades made of IN-738, ZMI-3U, and éP539LM nickel alloys, some of them with a protective coating, upon a long operating time in gas turbine compressor sets. The blades of IN-738 alloy are found to have the highest cyclic strength. The cyclic strength of uncoated IN-738 blades is about 10% higher than that of coated blades. __________ Translated from Problemy Prochnosti, No. 2, pp. 5–14, March–April, 2007.     

去除光刻胶的新干法工艺

除去干刻或高剂量等离子注入后的光刻胶，一般是采用化学溶剂和酸类等湿刻法，以前有时采用干燥氧的等离子灰化法，然而成本高，具有危险性和污染性的化学湿刻法直接造成了环境污染，使得全球气候变暖，能源的大量消耗，地下水受到污染等等，一种新的干式去胶并且处理后可用去离子水DI清洗残留物的工艺方法（ENVIRO）已经在半导体芯片厂被成功地使用了12个多月。对于产量10000片／周的芯片厂，相对于化学湿刻法一年可以节省5百万美元溶剂消耗。     

Factors affecting hazardous waste solidification/stabilization: a review

Solidification/stabilization is accepted as a well-established disposal technique for hazardous waste. As a result many different types of hazardous wastes are treated with different binders. The S/S products have different property from waste and binders individually. The effectiveness of S/S process is studied by physical, chemical and microstructural methods. This paper summarizes the effect of different waste stream such as heavy metals bearing sludge, filter cake, fly ash, and slag on the properties of cement and other binders. The factors affecting strength development is studied using mix designs, including metal bearing waste alters the hydration and setting time of binders. Pore structure depends on relative quantity of the constituents, cement hydration products and their reaction products with admixtures. Carbonation and additives can lead to strength improvement in waste-binder matrix.     

Characteristics of the medical waste generated at the Jordanian hospitals

Recently, Jordan has witnessed increased amounts of medical waste generated at different healthcare facilities. This has resulted in issuance of Medical Waste Regulation that aimed at regulating the management processes of such hazardous waste. To provide information on medical waste generation rates, composition and statistical characteristics, a comprehensive sampling survey was initiated after a regulatory definition of the medical waste was established. Hospitals from Public, private and educational categories were covered by the survey. This paper presents the findings of the survey. The average generation rates ranged from 0.29 to 1.36 kg/bed/day, while in terms of patient numbers it is from 0.36 to 0.87 kg/patient/day. The total daily amount of medical waste generated at the Jordanian hospitals was estimated to be 6 tones/day. The daily amounts of medical waste generated at King Abdullah University Hospital were found to follow a log normal probability distribution. Physical composition analysis of the medical waste, which conducted based on the categories identified by the Jordanian Regulation, indicated that the infectious waste category is the highest, followed by sharps category and finally pathological, cytotoxic and pharmaceutical categories were the lowest. The study concluded that all hospitals covered by the survey are practicing segregation of hazardous medical waste from general medical waste. However, the segregation process in some hospitals is still inefficient and there is a potential for improvements toward minimizing the hazardous medical waste generation.     

Autoclaved aerated concrete with sulphate content: an environmentally friendly,durable and recyclable building material

Autoclaved aerated concrete (AAC) contains a small quantity of sulphate. For example, a modern quality class PP2‐0,35 AAC (λ = 0.09 W/(mK)) from Xella contains about five per cent by mass of sulphate in the form of gypsum or anhydrite. The addition of sulphate reduces shrinkage and enhances compressive strength and durability. AAC thus has an almost unrestricted lifetime. Regarding the environmental acceptability of sulphate, dogmatic discussions have been held for years. What is certain: sulphate is not a hazardous substance. Calcium sulphate (gypsum) has been categorised according to the Directive (EC) No. 1272/2008 (CLP) as not hazardous. Xella's voluntary environmental declarations for AAC confirm not only the excellent ecological balance of this product but also the absence of hazardous substances. For construction and demolition (C&D) waste from AAC, disposal is ensured in Germany with landfill class I (“Non‐hazardous waste, domestic waste”). In order to save disposal costs, Xella offers to take back unmixed cutting waste, which arises in the course of new building or refurbishment, without charge at the Ytong‐factories. Xellas long‐term aim is a closed recycling loop for AAC. A collaborative pilot project between Xella and the Otto Dörner Entsorgung GmbH has shown that from the point of view of process and materials technology, production of high‐quality AAC is even possible under utilization of crushed AAC from demolition.     

Developments of cast superalloys and technology for gas turbine blades in BIAM

Since 1960's many important subjects relating to cast turbine blades including alloy developments, directional solidification (DS) and single crystal (SC) technique and casting technology for blades have been performed with great successes in Beijing Institute of Aeronautical Materials (BIAM) in order to meet the requirements for developing new aero-engines in China.Abbreviations CC conventional cast - DS directional solidification - FC fine grain cast - SC single crystal     

Influence of soil components on adsorption-desorption of hazardous organics-development of low cost technology for reclamation of hazardous waste dumpsites

The waste disposal practices on land frequently lead to the deposition of hazardous waste at geologically/hydrogeologically unsuitable locations, resulting in surface and groundwater contamination. The movement of chemicals through soil is not only dependent on the physical, chemical and biological properties of the waste but also on the characteristics of the soil of the disposal site. In this paper the authors report their results on the influence of soil components on adsorption-desorption of certain industrially widely used hazardous organics like phenol, p-nitrophenol, 4-chloro-2-nitrophenol and 2,4-dichlorophenol on typical soils of Patancheru industrial area (Hyderabad, AP, India). The data on nature of organics, soil organic matters, clay, free iron and aluminum oxides of soils are known to influence the adsorption-desorption process are presented. There was reduction up to 67.5% (organic matter removed), 53.8% (clay removed) and 24.2% (iron and aluminum oxides removed) in the adsorption capacity of the soils when compared to untreated soils indicating the role played by these soil components in adsorption process. Desorption isotherms of soil adsorbed hazardous organics exhibited hysteresis at higher initial concentration indicating the degree of irreversibility of adsorption-desorption process. Mixed microbial cultures were developed which can degrade the hazardous organics to complete mineralisation by utilizing them as sole source of carbon and their corresponding biokinetic constants were evaluated. Preparation of dumpsites with suitable soil surface having high holding capacity for organics and their in situ biodegradation by mixing with specific microbial cultures can be exploited as a cost effective technology for reclamation of hazardous waste dumpsites.     

Fatigue of VT20 titanium alloy with vacuum-plasma coatings at high temperatures

We study the influence of vacuum–plasma TiN, (TiAl)N, and (TiC)N coatings on the high-cycle fatigue of VT20 titanium alloy in the temperature range 350–640°C for a loading frequency of 10 kHz. It is shown that, in this temperature range, the fatigue limits of VT20 alloy with the indicated coatings 6 μm in thickness become 15–25% higher than for the material without coating. The possibility of replacement of steel blades with titanium blades with vacuum-plasma coatings is demonstrated. Translated from Problemy Prochnosti, No. 4, pp. 101–107, July–August, 2009.     

INFLUENCE OF ADIABATIC SHEAR BANDS ON THE FATIGUE STRENGTH OF A TITANIUM ALLOY

An experimental investigation is reported of the possible effects of adiabatic shear bands, caused by projectile impact, on the fatigue strength of a titanium alloy (Ti-6%A1-4%V). No significant reduction in fatigue strength due to the presence of adiabatic shear bands was found, nor did the fatigue cracks initiate from the bands. The results are relevant to the problem of foreign object impact damage to compressor blades in gas turbine aeroengines.     

Evaluation of various pre-treatment processes on tannery sludge for enhancement of soluble chemical oxygen demand

Overall sludge generation during the treatment of tannery wastewater is in the range of 18,200–165,200 tons per annum in India. One of the major problems faced by the tanning industry in India is the disposal of sludge. In recent years, increased attention has been given to minimization of waste sludge in wastewater treatment process. At present, each tannery is spending around Rs. 700–750 per ton for disposal of sludge into secured landfill facilities. Anaerobic digestion is one of the options for generation of biogas from primary and secondary sludge and to reduce sludge volume. In order to make anaerobic digestion more effective, pre-treatment of sludge before anaerobic digestion is the recent technological advancement employed to accelerate the rate of hydrolysis process. Various pre-treatment processes such as ozonation, sonication, hydrogen peroxide, alkaline, and alkaline thermal treatment were evaluated in the present study for increasing the soluble chemical oxygen demand separately in primary and secondary sludge generated during treatment of tannery wastewater. It was observed from the results obtained from the study that the increase in SCOD by various pre-treatments were in the order of ozonation > alkaline thermal treatment > sonication > alkaline treatment > hydrogen peroxide. The increase in the ratio of SCOD to TCOD by pre-treatments was effective for secondary sludge rather than primary sludge.