Influences of phosphate nutritional level on the phytoavailability and speciation distribution of cadmium and lead in soil

IntroductionNorth-east China is one of the most importantindustrial bases and also a main agriculturalproduction area. Land disposal of wastes and irrigatingwith sewage have led to increasing heavy metalcontents in soil (Chen, 1996) and the problemsinduce…     

Current status and strategy of hazardous waste management in China

This paper deals briefly with the pollution caused by hazardous wastes in China, the hazardous waste management at present and the strategy that should be taken for hazardous waste management in the future. Hazardous waste problem has become one of the important environmental concerns in China. Hazardous waste have resulted in ecological and environmental destruction, caused damage to human health, and restricted economic development. Although a great effort has been devoted to the management of hazardous wastes, there remain many issues in legislation, experience, technology and finance to be solved. Some recommendations are made on the strategic measures for improving the hazardous waste management in China, particularly relating to legislation, technical development and international cooperation.     

Thermogravimetric,kinetic study and gas emissions analysis of the thermal decomposition of waste-derived fuels

A wide range of wastes can potentially be used to generate thermal and electrical energy.The co-combustion of several types of waste as part of water-containing waste-derived fuels is a promising method for their recovery. In this research, we use thermogravimetric analysis and differential scanning calorimetry to study the thermal behavior and kinetics of coal slime, biomass, waste oils, and blends on their basis. We also analyze the concentrations of gaseous emissions. The results show that bi...     

Effects of introducing energy recovery processes to the municipal solid waste management system in Ulaanbaatar,Mongolia

Currently, most developing countries have not set up municipal solid waste management systems with a view of recovering energy from waste or reducing greenhouse gas emissions. In this article, we have studied the possible effects of introducing three energy recovery processes either as a single or combination approach, refuse derived fuel production,incineration and waste power generation, and methane gas recovery from landfill and power generation in Ulaanbaatar, Mongolia, as a case study. We concluded that incineration process is the most suitable as first introduction of energy recovery. To operate it efficiently,3Rs strategies need to be promoted. And then, RDF production which is made of waste papers and plastics in high level of sorting may be considered as the second step of energy recovery.However, safety control and marketability of RDF will be required at that moment.     

An environmental approach for used oil management in Asian cities: a Bangkok' s experience

This paper addresses increasing concern about the pollution threat of used oil being illegally dumped and the impact of oil on air pollution and freshwater ecosystems in Asian countries. Used oil is a very serious waste management problem. These results call for management action such as maximising the collection and recovery of used oil. The Thai government recognizes the need to recycle used oil and has been active in encouraging programs to accomplish this goal. Thus unless new approaches and incentives are developed, used oil generation may become an increasing serious problem to our environment. The purpose of this study is to examine the technical and economic feasibility, of recycling used oils. In addition, this paper briefly discusses the problems to be overcome and outlines potential mechanisms for providing the necessary disposal controls in order to maximize the protection to public health and environmental quality from potential hazards posed by used lube oil disposal.     

Antimony smelting process generating solid wastes and dust：Characterization and leaching behaviors

A large amount of solid waste has been produced by the antimony smelting process in the＂World Capital of Antimony＂, Xikuangshan area in China. This study comprehensively investigated the physical and chemical characteristics of the various solid wastes, as well as the leaching behavior of the solid wastes, which included water-quenched slag,arsenic-alkali residue, desulfurized slag and blast furnace dust. These four types of waste were enriched in a variety of heavy metals and metalloids and more specifically with As and Sb levels up to 8.6 × 104 and 3.16 × 105mg/kg, respectively, in arsenic-alkali residue. For desulfurized slag and water-quenched slag, the leaching concentration of Sb significantly exceeded the acceptable limits during the leaching tests using the toxicity characteristic leaching procedure and the synthetic precipitation leaching procedure. In addition, As leaching in arsenic-alkali residue was extraordinarily hazardous, being three orders of magnitude higher than the regulatory level of As. According to the results of the extraction tests, all the tested wastes were classified as hazardous waste.     

Quantifying and managing regional greenhouse gas emissions：Waste sector of Daejeon, Korea

A credible accounting of national and regional inventories for the greenhouse gas （GHG） reduction has emerged as one of the most significant current discussions. This article assessed the regional GHG emissions by three categories of the waste sector in Daejeon Metropolitan City （DMC）, Korea, examined the potential for DMC to reduce GHG emission, and discussed the methodology modified from Intergovernmental Panel on Climate Change and Korea national guidelines. During the last five years, DMC＇s overall GHG emissions were 239 thousand tons C02 eq./year from eleven public environmental infrastructure facilities, with a population of 1.52 million. Of the three categories, solid waste treatment/disposal contributes 68%, whilst wastewater treatment and others contribute 22% and 10% respectively. Among GHG unit emissions per ton of waste treatment, the biggest contributor was waste incineration of 694 kg CO2 eq./ton, followed by waste disposal of 483 kg CO2 eq./ton, biological treatment of solid waste of 209 kg CO2 eq./ton, wastewater treatment of 0.241 kg CO2 eq./m3, and public water supplies of 0.067 kg CO2 eq./m3. Furthermore, it is suggested that the potential in reducing GHG emissions from landfill process can be as high as 47.5% by increasing landfill gas recovery up to 50%. Therefore, it is apparent that reduction strategies for the main contributors of GHG emissions should take precedence over minor contributors and lead to the best practice for managing GHGs abatement.     

Recent advances based on the synergetic effect of adsorption for removal of dyes from waste water using photocatalytic process

The problem of textile dye pollution has been addressed by various methods,mainly physical,chemical,biological,and acoustical.These methods mainly separate and/or remove the dye present in water.Recently,advanced oxidation processes(AOP)have been focused for removal of dye from waste water due to their advantages such as ecofriendly,economic and capable to degrade many dyes or organic pollutant present in water.Photocatalysis is one of the advance oxidation processes,mainly carried out under irradiation of light and suitable photocatalytic materials.The photocatalytic activity of the photocatalytic materials mainly depends on the band gap,surface area,and generation of electron–hole pair for degradation dyes present in water.It has been observed that the surface area plays a major role in photocatalytic degradation of dyes,by providing higher surface area,which leads to the higher adsorption of dye molecule on the surface of photocatalyst and enhances the photocatalytic activity.This present review discusses the synergic effect of adsorption of dyes on the photocatalytic efficiency of various nanostructured high surface area photocatalysts.In addition,it also provides the properties of the water polluting dyes,their mechanism and various photocatalytic materials;and their morphology used for the dye degradation under irradiation of light along with the future prospects of highly adsorptive photocatalytic material and their application in photocatalytic removal of dye from waste water.     

Effects of introducing energy recovery processes to the municipal solid waste management system in Ulaanbaatar, Mongolia

Currently, most developing countries have not set up municipal solid waste management systemswith a viewof recovering energy fromwaste or reducing greenhouse gasemissions. In this article, we have studied the possible effects of introducing three energy recovery processes either as a single or combination approach, refuse derived fuel production, incineration and waste power generation, and methane gas recovery from landfill and power generation in Ulaanbaatar, Mongolia, as a case study. We concluded that incineration process is the most suitable as first introduction of energy recovery. To operate it efficiently, 3Rs strategies need to be promoted. And then, RDF production which is made of waste papers and plastics in high level of sortingmay be considered as the second step of energy recovery. However, safety control and marketability of RDF will be required at that moment.     

Greenhouse gas emission and its potential mitigation process from the waste sector in a large-scale exhibition

As one of the largest human activities, World Expo is an important source of anthropogenic Greenhouse Gas emission (GHG), and the GHG emission and other environmental impacts of the Expo Shanghai 2010, where around 59,397 tons of waste was generated during 184 Expo running days, were assessed by life cycle assessment (LCA). Two scenarios, i.e., the actual and expected figures of the waste sector, were assessed and compared, and 124.01 kg CO₂-equivalent (CO₂-eq.), 4.43 kg SO₂-eq., 4.88 kg NO₃^--eq., and 3509 m³ water per ton tourist waste were found to be released in terms of global warming (GW), acidification (AC), nutrient enrichment (NE) and spoiled groundwater resources (SGWR), respectively. The total GHG emission was around 3499 ton CO₂-eq. from the waste sector in Expo Park, among which 86.47% was generated during the waste landfilling at the rate of 107.24 kg CO₂-eq., and CH₄, CO and other hydrocarbons (HC) were the main contributors. If the waste sorting process had been implemented according to the plan scenario, around 497 ton CO₂-eq. savings could have been attained. Unlike municipal solid waste, with more organic matter content, an incineration plant is more suitable for tourist waste disposal due to its high heating value, from the GHG reduction perspective.     

Abatement of waste gases and water during the processes of semiconductor fabrication

The purpose of this article is to examine the methods and equipment for abating waste gases and water produced during the manufacture of semiconductor materials and devices. Three separating methods and equipment are used to control three different groups of electronic wastes. The first group includes arsine and phosphine emitted during the processes of semiconductor materials manufacture. The abatement procedure for this group of pollutants consists of adding iodates, cupric and manganese salts to a multiple shower tower ( MST ) structure. The second group includes pollutants containing arsenic, phosphorus, HF, HCI, NO2, and SO3 emitted during the manufacture of semiconductor materials and devices. The abatement procedure involves mixing oxidants and bases in an oval column with a separator in the middle. The third group consists of the ions of As, P and heavy metals contained in the waste water. The abatement procedure includes adding CaCO3 and ferric salts in a flocculation-sedimentation compact device equipment. Test results showed that all waste gases and water after the abatement orocedures oresented in this article passed the discharge standards set by the State Environmental Protection Administration of China.     

The progress of catalytic technologies in water purification： A review

Catalytic technologies have been paid increasing attention in refractory pollutants abatement due to its practical and potential values in water purification. As e ective and e cient approaches for water purification, Fenton’s reagent, ozonation, electrochemical and photocatalytic methods have been widely studied and applied in di erent aspects and have been reviewed by several articles. In recent years, some novel catalytic processes based on above processes have been developed for enhancing the e ciency of removing the organics from water. This review emphasized on the recent development of heterogeneous catalytic ozonation, electrocatalysis in respect of novel electrodes and electro-Fenton method, photoelectrocatalysis process and photoelectron-Fenton in water purification. It was also an attempt to propose general ideas about mechanism and principle enhancing the catalytic e ciency for the degradation and the mineralization of organics in water.     

Development of low-and non-waste technologies in China

Water pollution is one of the most serious environmental problems in China. In order to reduce the discharge of waste water per RMB 1000 Yuan of the industrial output value, the author offered a proposal on the development of low-and non-waste technologies as follows: 1. Changing distribution and structures of industrial production; 2. Innovation in techniques and eliminating industrial wastewater in the process of manufacture; 3. Comprehensive utilization of wastes and wastewater; 4. Strengthening environmental management and supervision of industrial enterprises.     

Comparison between controlled landfill reactor and conditioned landfill bioreactor

Bioreactor landfills allow a more active landfill management that recognizes the biological, chemical and physical processes involved in a landfill environment. The laboratory-scale simulators of landfill reactors treating municipal solid wastes were studied, the effect of solid waste size, leachate recirculation, nutrient balance, pH value, moisture content and temperature on the rate of municipal solid waste (MSW) biodegradation were determined, and it indicated the optimum pH value, moisture content and temperature decomposing MSW. The results of waste biodegradation were compared with that of the leachate-recirculated landfill simulator and conservative sanitary landfill simulator. In the control experiment the antitheses of a decreasing trend of the organic load, measured as biological oxygen demand and chemical oxygen demand, was shown. An obvious enhancement of effective disposal from conservative sanitary landfill (CSL) simulator, to the leachate-recirculated landfill (LRL) simulator and to the conditioned bioreactor landfill(CBL) simulator would be noted, through displaying the compared results of solid waste settlement, heavy, metal concentration in leachate, methane production rate, biogas composition, BOD and COD as well as their ratio.     

Approach of technical decision-making by element flow analysis and Monte-Carlo simulation of municipal solid waste stream

This paper deals with the procedure and methodology which can be used to select the optimal treatment and disposal technology of municipal solid waste （MSW）, and to provide practical and effective technical support to policy-making, on the basis of study on solid waste management status and development trend in China and abroad. Focusing on various treatment and disposal technologies and processes of MSW, this study established a Monte-Carlo mathematical model of cost minimization for MSW handling subjected to environmental constraints. A new method of element stream （such as C, H, O, N, S） analysis in combination with economic stream analysis of MSW was developed. By following the streams of different treatment processes consisting of various techniques from generation, separation, transfer, transport, treatment, recycling and disposal of the wastes, the element constitution as well as its economic distribution in terms of possibility functions was identified. Every technique step was evaluated economically. The Mont-Carlo method was then conducted for model calibration. Sensitivity analysis was also carried out to identify the most sensitive factors. Model calibration indicated that landfill with power generation of landfill gas was economically the optimal technology at the present stage under the condition of more than 58% of C, H, O, N, S going to landfill. Whether or not to generate electricity was the most sensitive factor. If landfilling cost increases, MSW separation treatment was recommended by screening first followed with incinerating partially and composting partially with residue landfilling. The possibility of incineration model selection as the optimal technology was affected by the city scale. For big cities and metropolitans with large MSW generation, possibility for constructing large-scale incineration facilities increases, whereas, for middle and small cities, the effectiveness of incinerating waste decreases.     

Distribution characteristics and source identification of polychlorinated dibenzo-p-dioxin and dibenzofurans, and dioxin-like polychlorinated biphenyls in the waters from River Kanzaki, running through Osaka urban area, Japan

This is the first to elucidate the distribution and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs),and dioxin-like polychlorinated biphenyls in the waters from Kanzaki River,which is one of the most heavily polluted rivers in Japan.The World Health Organization (WHO)-toxic equivalent quantities (TEQs) in waters from the mainstream exceeded the Japanese environmental standard (1.0 pg-TEQ/L).The PCDD/PCDFs were dominated by highly chlorinated DFs,which predominantly contributed to the WHO-TEQs,suggesting that the main causes would be the incineration-related wastes.To find the sources,the dioxin congener concentrations in water and sediment samples from its tributary small waterways were determined.Abnormally high WHO-TEQs were detected in a water (50 pg-TEQ/L) and a sediment sample (41,000 ng-TEQ/kg dry weight) near the industrial solid waste incinerators (ISWIs).The PCDD/PCDF characteristics agreed well with those of the incinerator-related wastes as seen in the mainstream.These facts indicate that the dioxin pollution in the mainstream could be largely related to the industrial wastes from the ISWIs.Here,a TEQ apportionment method was used to understand the contribution of the pyrogenic sources to the WHO-TEQs.The average contribution ratios of the pyrogenic sources to WHO-TEQs were more than 80% for river waters from the mainstream,indicating that the elevated WHO-TEQs in the mainstream had been largely caused by the ISWIs.     

Composition analysis of colored dissolved organic matter in Taihu Lake based on three dimension excitation-emission fuorescence matrix and PARAFAC model, and the potential application in water quality monitoring

Taihu Lake is one of the five biggest lakes in China. Surface water samples from 26 sampling sites of Taihu Lake were collected. Furthermore wet chemical analysis (CODCr and BOD5) and measurement of three dimensional excitation-emission matrix (3DEEM) spectra in the laboratory have been conducted. Using parallel factor analysis (PARAFAC) model, three components of colored dissolved organic matter (CDOM) have been identified successfully, based on the analysis of 3DEEM data. The characteristics of the three components also have been described by comparing them to some components of CDOM, identified in earlier researches. Meanwhile, spatial variations of concentration for the three components in Taihu Lake have been analyzed, and the result indicates that the concentration of component 1 depends more on the situation of wastewater pollution and can be used as the indicator of wastewater pollution. The relationship between the concentrations of the three components and results of the wet chemical analysis show that none of the three components can be used as indicators of gross organic matter in water. However, the concentrations of all the three components have obvious linear relationships with the BOD5 value, especially for component 1 (r=0.72878). Finally, the potential applications of the composition analysis based on 3DEEM and PARAFAC model in water quality monitoring have been illuminated.     

Experimental study on combustion characteristics of municipal solid waste

As incineration provides a relatively safe means of disposal, significant reduclaon ot welglat anti volume, ana energy recovery from the waste, it was adopted by many countries. For the experimental investigation on the combustion characteristics of municipal solid waste( MSW),a lab scale fluldized bed facility was constructed. Many kinds of combustion runs were conducted in this fluidized bed combustion facility. The examined parameters were bed temperature(773 to 1143K), form of fuels ( scrap or whole), moisture of fuels and so on. Concentration of CO2,CO,SO2, O2 and NOx in the flue gas were monitored and recorded every 5 seconds. The temperatttres along the reactor are recorded every 10 seconds. Experimental. results were given and analyzed.     

Composition analysis of colored dissolved organic matter in Taihu Lake based on three dimension excitation-emission fluorescence matrix and PARAFAC model, and the potential application in water quality monitoring

Taihu Lake is one of the five biggest lakes in China. Surface water samples from 26 sampling sites of Taihu Lake were collected. Furthermore wet chemical analysis （CODCr and BOD5） and measurement of three dimensional excitation-emission matrix （3DEEM） spectra in the laboratory have been conducted. Using parallel factor analysis （PARAFAC） model, three components of colored dissolved organic matter （CDOM） have been identified successfully, based on the analysis of 3DEEM data. The characteristics of the three components also have been described by comparing them to some components of CDOM, identified in earlier researches. Meanwhile, spatial variations of concentration for the three components in Taihu Lake have been analyzed, and the result indicates that the concentration of component 1 depends more on the situation of wastewater pollution and can be used as the indicator of wastewater pollution. The relationship between the concentrations of the three components and results of the wet chemical analysis show that none of the three components can be used as indicators of gross organic matter in water. However, the concentrations of all the three components have obvious linear relationships with the BOD5 value, especially for component 1 （r = 0.72878）. Finally, the potential applications of the composition analysis based on 3DEEM and PARAFAC model in water quality monitoring have been illuminated.     

Prediction of effluent concentration in a wastewater treatment plant using machine learning models

Of growing amount of food waste, the integrated food waste and waste water treatment was regarded as one of the efficient modeling method. However, the load of food waste to the conventional waste treatment process might lead to the high concentration of total nitrogen(T-N) impact on the effluent water quality. The objective of this study is to establish two machine learning models—artificial neural networks(ANNs) and support vector machines(SVMs), in order to predict 1-day interval T-N concentration of effluent from a wastewater treatment plant in Ulsan, Korea. Daily water quality data and meteorological data were used and the performance of both models was evaluated in terms of the coefficient of determination(R~2), Nash–Sutcliff efficiency(NSE), relative efficiency criteria(d rel). Additionally, Latin-Hypercube one-factor-at-a-time(LH-OAT) and a pattern search algorithm were applied to sensitivity analysis and model parameter optimization, respectively. Results showed that both models could be effectively applied to the 1-day interval prediction of T-N concentration of effluent. SVM model showed a higher prediction accuracy in the training stage and similar result in the validation stage.However, the sensitivity analysis demonstrated that the ANN model was a superior model for 1-day interval T-N concentration prediction in terms of the cause-and-effect relationship between T-N concentration and modeling input values to integrated food waste and waste water treatment. This study suggested the efficient and robust nonlinear time-series modeling method for an early prediction of the water quality of integrated food waste and waste water treatment process.