Municipal sewage sludge use in forests of the pacific northwest,U.S.A.: Environmental concerns

Forest applications of dewatered municipal sludge in Washington State, U.S.A. were monitored for heavy metals, pathogens, and nitrates. Heavy metals did not leach from the sludge in significant quantities and remained associated with the sludge for at least four years. Tree seedlings grown in sludge-amended soil and compost accumulated moderate metal levels, but growth was not adversely affected. Populus seedlings took up more metal than coniferous seedlings. Some coniferous seedlings grown directly in unamended sludge had reduced growth and developed symptoms of nutrient imbalances. Fecal coliform and total coliform levels in sludge were initially high, but decreased to background levels in 1.0–1.5 years, suggesting that site access should be limited for a time after application. Bacterial movement in the soil was limited and very few viable bacteria reached the groundwater. Aerosols may be generated during sludge applications. Nitrogen leaching is a major environmental concern or sludge application. Heavy applications resulted in high NO₃⁻ levels in soils and groundwater. A significant fraction of the nitrogen loss was in gaseous form. Sludge applications in forests can be environmentally sound if application rates are matched to site characteristics.     

Enhanced anaerobic treatment of CSTR-digested effluent from chicken manure: The effect of ammonia inhibition

The effect of ammonia inhibition was evaluated during the enhanced anaerobic treatment of digested effluent from a 700 m³ chicken-manure continuous stirred tank reactor (CSTR). A 12.3 L internal circulation (IC) reactor inoculated with an anaerobic granular sludge and operated at 35 ± 1 °C was employed for the investigation. With a corresponding organic loading rate of 1.5-3.5 kg-COD/m³ d over a hydraulic retention time of 1.5 d, a maximum volumetric biogas production rate of 1.2 m³/m³ d and TCOD (total COD) removal efficiency ranging from 70% to 80% was achieved. However, the continual increase in the influent TAN content led to ammonia inhibition in the methanogenesis system. The SCOD/TAN (soluble COD/total ammonia nitrogen) ratio was presented to be the key controlling factor for the anaerobic treatment of semi-digested chicken manure, and further validation through shock loading and ammonia inhibition experiments was conducted. The threshold value of the SCOD/TAN ratio was determined to be 2.4 (corresponding to a TAN of 1250 mg/L) at an influent pH of 8.5-9.     

Environmental modelling of use of treated organic waste on agricultural land: a comparison of existing models for life cycle assessment of waste systems.

Modelling of environmental impacts from the application of treated organic municipal solid waste (MSW) in agriculture differs widely between different models for environmental assessment of waste systems. In this comparative study five models were examined concerning quantification and impact assessment of environmental effects from land application of treated organic MSW: DST (Decision Support Tool, USA), IWM (Integrated Waste Management, U.K.), THE IFEU PROJECT (Germany), ORWARE (ORganic WAste REsearch, Sweden) and EASEWASTE (Environmental Assessment of Solid Waste Systems and Technologies, Denmark). DST and IWM are life cycle inventory (LCI) models, thus not performing actual impact assessment. The DST model includes only one water emission (biological oxygen demand) from compost leaching in the results and IWM considers only air emissions from avoided production of commercial fertilizers. THE IFEU PROJECT, ORWARE and EASEWASTE are life cycle assessment (LCA) models containing more detailed land application modules. A case study estimating the environmental impacts from land application of 1 ton of composted source sorted organic household waste was performed to compare the results from the different models and investigate the origin of any difference in type or magnitude of the results. The contributions from the LCI models were limited and did not depend on waste composition or local agricultural conditions. The three LCA models use the same overall approach for quantifying the impacts of the system. However, due to slightly different assumptions, quantification methods and environmental impact assessment, the obtained results varied clearly between the models. Furthermore, local conditions (e.g. soil type, farm type, climate and legal regulation) and waste composition strongly influenced the results of the environmental assessment.     

热电联产发展中存在的环保问题及对策

结合我国热电联产项目发展现状,对其存在的主要问题进行了系统分析,从优化布局、清洁生产、节能降耗、推广热电冷联供、强化运行和管理等方面,提出了促进热电联产项目健康发展的对策建议.     

环境治理工程评标的双基点模型及应用

动用多指标综合排序的双基点法，建立了环境治理工程评标的数学模型。应用实例表明，该模型可以为环境治理工程评标提供客观、合理的方法。     

Chemical and microbiological hazards associated with recycling of anaerobic digested residue intended for agricultural use

In the present study, three full-scale biogas plants (BGP) were investigated for the concentration of heavy metals, organic pollutants, pesticides and the pathogenic bacteria Bacillus cereus and Escherichia coli in the anaerobically digested residues (ADR). The BGPs mainly utilize source-separated organic wastes and industrial food waste as energy sources and separate the ADR into an ADR-liquid and an ADR-solid fraction by centrifugation at the BGP. According to the Norwegian standard for organic fertilizers, the ADR were classified as quality 1 mainly because of high zinc (132-422 mg kg(-1) DM) and copper (23-93 mg kg(-1) DM) concentrations, but also because of high cadmium (0.21-0.60 mg kg(-1) DM) concentrations in the liquid-ADR. In the screening of organic pollutants, only DEHP (9.7-62.1 mg kg(-1)) and ∑ PAH 16 (0.2-1.98 mg kg(-1) DM) were detected in high concentrations according to international regulations. Of the 250 pesticides analyzed, 11 were detected, but only imazalil (<0.30-5.77 mg kg(-1) DM) and thiabendazol (<0.14-0.73 mg kg(-1) DM) were frequently detected in the ADR-fiber. Concentrations of imazalil and thiabendazol were highest during the winter months, due to a high consumption of citrus fruits in Norway in this period. Ten percent of the ADR-liquid samples contained cereulide-producing B. cereus, whereas no verotoxigenic E. coli was detected. The authors conclude that the risk of chemical and bacterial contamination of the food chain or the environment from agricultural use of ADR seems low.     

Synthesis of3H- polyethylene and its use for fate studies on degradable plastics

Determining the fate of xenobiotic materials in the environment can be aided by the use of radioactive isotope technology. Previous research on the degradation of polymers such as polyethylene (PE) was aided by the utilization of radiotracers. In order to study the environmental fate of degradable (PE/starch) plastics, we synthesized³H-labeled PE. Results of soil incubation studies indicate that only minimal degradation of the PE component, as indicated by the production of water-soluble metabolites, occurred during 2 years of incubation in soil. Despite the minimal degradation, the³H label did not allow for detection of the degradation products. In addition, the³H-PE was particularly useful for tracing the fate of degradable plastics after consumption by terrestrial isopods. The detection of aqueous-soluble radioactivity in isopod frass was used to indicate degradation of the plastic film.     

Hidden values in bauxite residue (red mud): Recovery of metals

Bauxite residue (red mud) is a hazardous waste generated from alumina refining industries. Unless managed properly, red mud poses significant risks to the local environment due to its extreme alkalinity and its potential impacts on surface and ground water quality. The ever-increasing generation of red mud poses significant challenges to the aluminium industries from management perspectives given the low proportion that are currently being utilized beneficially. Red mud, in most cases, contains elevated concentrations of iron in addition to aluminium, titanium, sodium and valuable rare earth elements. Given the scarcity of iron supply globally, the iron content of red mud has attracted increasing research interest. This paper presents a critical overview of the current techniques employed for iron recovery from red mud. Information on the recovery of other valuable metals is also reviewed to provide an insight into the full potential usage of red mud as an economic resource rather than a waste. Traditional hydrometallurgy and pyrometallurgy are being investigated continuously. However, in this review several new techniques are introduced that consider the process of iron recovery from red mud. An integrated process which can achieve multiple additional values from red mud is much preferred over the single process methods. The information provided here should help to improve the future management and utilization of red mud.     

Characterization of oily sludge from a wastewater treatment plant flocculation-flotation unit in a petroleum refinery and its treatment implications

Partly due to the complex and variable composition of oily sludge generated by the petroleum industry, cost-effective treatment and proper disposal pose considerable challenges worldwide. In this study, an extended component-based analysis of the oily sludge from a flocculation-flotation unit of a wastewater treatment system in a refinery in Sweden was carried out over 1 year. The heterogeneity of the oily sludge is illustrated by the wide ranges of concentrations found for different chemical components, particularly metals. Among the petroleum hydrocarbons, the most abundant compounds were nonpolar aliphatic hydrocarbons (63.7 ± 16.7 g kg⁻¹); from the benzene, toluene, ethylbenzene, and xylene group, xylenes (91–240 mg kg⁻¹) were most abundant; and among polycyclic aromatic hydrocarbons, naphthalene (25.7 ± 21.4), fluorene (27.25 ± 10.0), and phenanthrene (43.8 ± 18.4 mg kg⁻¹) were most abundant (all results in terms of dry matter). Based on the EU guidelines and the mean concentration values for metals found in the oily sludge, e.g., Pb (135.4 ± 125.8), Cu (105.2 ± 79.1), Hg (42.8 ± 31.3), Ni (320 ± 267.4), and Zn (1321.7 ± 529.9 mg kg⁻¹), disposal of oily sludge even in landfills for hazardous waste is not allowed. The organic content of the sludge can be reduced through biotreatment, but not the metal content. A multistep component-based treatment scheme is therefore needed.     

Environmental assessment of recycled printing and writing paper: a case study in China

A life cycle assessment was conducted using IMPACT2002+ to estimate the environmental impact of producing printing and writing paper, which is entirely made with wastepaper. To confirm and add credibility to the study, uncertainty analysis was conducted using Taylor series expansion. Printing and writing paper produced from wood pulp was assessed for comparison. Compared with the wood pulp contained scenario, printing and writing paper made from wastepaper represented environmental benefit on non-carcinogens, respiratory inorganics, global warming, and non-renewable energy categories. In both scenarios, the technologies significantly contribute to the potential impacts of non-carcinogens, respiratory inorganics, terrestrial ecotoxicity, global warming, and non-renewable energy. The influence of the technologies on the way other categories affect the environment was negligible. Improved efficiency in electricity consumption, decreased transport distance from raw material buyers to suppliers, and change in the end-life treatment of solid waste from landfill to incineration are the key factors in reducing the overall environmental impact.     

Strategies for the enhancement of automobile shredder residues (ASRs) recycling: Results and cost assessment

With reference to the European regulation about the management of End-of-Life Vehicles (ELVs), Directive 2000/53/EC imposes the achievement of a recycling target of 85%, and 95% of total recovery by 2015. Over the last few years many efforts have been made to find solutions to properly manage the waste coming from ELVs with the aim of complying with the targets fixed by the Directive.This paper focuses on the economical evaluation of a treatment process, that includes physical (size and density), magnetic and electrical separations, performed on the light fraction of the automobile shredder residue (ASR) with the aim of reducing the amount of waste to dispose of in a landfill and enhancing the recovery of valuable fractions as stated by the EU Directive. The afore mentioned process is able to enhance the recovery of ferrous and non-ferrous metals of an amount equal to about 1% b.w. (by weight) of the ELV weight, and to separate a high energetic-content product suitable for thermal valorization for an amount close to (but not higher than) 10% b.w. of the ELV weight.The results of the economical assessment led to annual operating costs of the treatment ranging from 300,000 €/y to 350,000 €/y. Since the considered plant treats about 13,500 metric tons of ASR per year, this would correspond to an operating cost of approximately 20–25 €/t. Taking into account the amount and the selling price of the scrap iron and of the non magnetic metal recovered by the process, thus leading to a gain of about 30 €/t per ton of light ASR treated, the cost of the recovery process is balanced by the profit from the selling of the recovered metals. On the other hand, the proposed treatment is able to achieve the fulfillment of the targets stated by Directive 2000/53/EC concerning thermal valorization and reduce the amount of waste generated from ELV shredding to landfill.     

Evaluation of a lime-mediated sewage sludge stabilisation process. Product characterisation and technological validation for its use in the cement industry

This paper describes an industrial process for stabilising sewage sludge (SS) with lime and evaluates the viability of the stabilised product, denominated Neutral, as a raw material for the cement industry. Lime not only stabilised the sludge, raised the temperature of the mix to 80-100 °C, furthering water evaporation, portlandite formation and the partial oxidation of the organic matter present in the sludge.Process mass and energy balances were determined. Neutral, a white powder consisting of portlandite (49.8%), calcite (16.6%), inorganic oxides (13.4%) and organic matter and moisture (20.2%), proved to be technologically apt for inclusion as a component in cement raw mixes. In this study, it was used instead of limestone in raw mixes clinkerised at 1400, 1450 and 1500 °C. These raw meals exhibited greater reactivity at high temperatures than the limestone product and their calcination at 1500 °C yielded clinker containing over 75% calcium silicates, the key phases in Portland clinker. Finally, the two types of raw meal (Neutral and limestone) were observed to exhibit similar mineralogy and crystal size and distribution.     

Performance and Environmental Impact of Biodegradable Films in Agriculture: A Field Study on Protected Cultivation

The performance, the degradability in soil and the environmental impact of biodegradable starch-based soil mulching and low tunnel films were assessed by means of field and laboratory tests. The lifetime of the biodegradable mulches was 9 months and of the biodegradable low-tunnel films 6 months. The radiometric properties of the biodegradable films influenced positively the microclimate: air temperature under the biodegradable low tunnel films was 2 °C higher than under the low density polyethylene films, resulting in an up to 20% higher yield of strawberries. At the end of the cultivation period, the biodegradable mulches were broken up and buried in the field soil together with the plant residues. One year after burial, less than 4% of the initial weight of the biodegradable film was found in the soil. According to ecotoxicity tests, the kinetic luminescent bacteria test with Vibrio fischeri and the Enchytraeus albidus ISO/CD 16387 reproduction potential, there was no evidence of ecotoxicity in the soil during the biodegradation process. Furthermore, there was no change in the diversity of ammonia-oxidizing bacteria in the soil determined on the basis of the appearance of amoA gene diversity in denaturing gradient gel electrophoresis.     

Evolution of solid waste management in Malaysia: impacts and implications of the solid waste bill, 2007

Solid waste generation and its implications for people and the environment are global issues. The complexity of the waste composition and the ever-increasing percapita waste generation is a challenge for waste managers, particularly in developing countries. Thus, the need to have a clear policy on waste management and legislation to realize that policy is imperative. Malaysia is developing rapidly and problems such as the waste generation associated with development and industrialization are evident. The Solid Waste and Public Cleansing Management Bill, which was approved in August 2007 after a 10-year delay, is envisaged to have serious consequences in waste management practices and implementation in Malaysia. This article explores the main features of this all-encompassing bill and its impacts on the waste management scenario in Malaysia. In addition, a comparative evaluation is also discussed to explore the policies/legislation of selected countries vis-àvis the Malaysian bill.     

Environmental effects of heavy metals derived from the e-waste recycling activities in China: A systematic review

As the world’s leading manufacturing country, China has become the largest dumping ground for e-waste, resulting in serious pollution of heavy metals in China. This study reviews recent studies on environmental effects of heavy metals from the e-waste recycling sites in China, especially Taizhou, Guiyu, and Longtang. The intensive uncontrolled processing of e-waste in China has resulted in the release of large amounts of heavy metals in the local environment, and caused high concentrations of metals to be present in the surrounding air, dust, soils, sediments and plants. Though the pollution of many heavy metals was investigated in the relevant researches, the four kinds of heavy metals (Cu, Pb, Cd and Cr) from e-waste recycling processes attracted more attention. The exceedance of various national and international standards imposed negative effects to the environment, which made the local residents face with the serious heavy metal exposure. In order to protect the environment and human health, there is an urgent need to control and monitor the informal e-waste recycling operations.     

Metabolic and Environmental Control on Methane Emission from Soils: Mechanistic Studies of Mesotrophic Fen in West Siberia

The biological mechanisms regulating methane emission fromnatural wetlands are the focus of this article. A novel techniqueprovides estimates of the distribution of CH₄ sources withinan undisturbed soil profile by recording the transient gasdynamics after soil enclosure by deep (50 cm) chamber. Thecombined use of conventional surface and soil chambers across a200-m fen transect allowed us to relate the observed methaneemission to its instant generation and uptake. Surprisingly, themethane generation was relatively constant (9–12 mg CH₄-C hr^-1 m^-2) and highly variable net emission (0.2–20 mg CH₄-C hr^-1 m^-2) was closely correlated (r = –0.809)with methane uptake. In laboratory incubations, CH₄ uptakefollowed Michaelis-Menten kinetics. Added chloride and nitrateirrespective of the cation's nature suppressed uptake as a strongnoncompetitive inhibitors (K _i 0.5 mM). The methaneformation turned out to be unstable and under anaerobicincubation, the formation of CH₄, CO₂ andH₂displayed sustained weekly oscillations. We conclude that effectsof environmental factors alone are not sufficient topredict the variation in emission, which depends also on metabolic control of respective soil organisms. The multitude ofsuch controls is dependent on diversity of respective soilorganisms and could be grouped into a limited number ofcategories considerably simplifying large-scale simulations.     

Aerobic Biodegradation of Polymers in Solid-State Conditions: A Review of Environmental and Physicochemical Parameter Settings in Laboratory Simulations

During the last few years, biodegradable polymers have been developed to replace petrochemical polymers. Until now, research devoted to these polymers essentially focused on their biodegradability. There is now a need to bear out their nontoxicity. To verify this, the biodegradation must be carried out in accelerated laboratory tests which allow the metabolites and residues to be recovered. To reproduce the natural conditions (compost, field) as closely as possible, degradation experiments must be run on solid-state substrates. We review studies of aerobic degradation in solid-state substrates. This article focuses in particular on the environmental, physical, and chemical parameters (such as substrate nature, moisture, temperature, C/N ratio, and pH) that influence biodegradation kinetics. This study also aims at finding the solid substrate most adapted to residues and metabolite recovery. The most significant parameters would appear to be the substrate type, moisture content, and temperature. Inert substrates such as vermiculite are well suited to residue extraction. This review also opens the field to new research aimed at optimizing conditions for aerobic solid-state biodegradation and at recovering the metabolites and residues of this degradation process.     

Environmental impacts of residual Municipal Solid Waste incineration: A comparison of 110 French incinerators using a life cycle approach

Incineration is the main option for residual Municipal Solid Waste treatment in France. This study compares the environmental performances of 110 French incinerators (i.e. 85% of the total number of plants currently in activity in France) in a Life Cycle Assessment perspective, considering 5 non-toxic impact categories: climate change, photochemical oxidant formation, particulate matter formation, terrestrial acidification and marine eutrophication. Mean, median and lower/upper impact potentials are determined considering the incineration of 1 tonne of French residual Municipal Solid Waste. The results highlight the relatively large variability of the impact potentials as a function of the plant technical performances. In particular, the climate change impact potential of the incineration of 1 tonne of waste ranges from a benefit of ?58 kg CO₂-eq to a relatively large burden of 408 kg CO₂-eq, with 294 kg CO₂-eq as the average impact. Two main plant-specific parameters drive the impact potentials regarding the 5 non-toxic impact categories under study: the energy recovery and delivery rate and the NO_x process-specific emissions. The variability of the impact potentials as a function of incinerator characteristics therefore calls for the use of site-specific data when required by the LCA goal and scope definition phase, in particular when the study focuses on a specific incinerator or on a local waste management plan, and when these data are available.     

ICAROS: An Integrated Computational Environment for the Assimilation of Environmental Data and Models for Urban and Regional Air Quality

Integrated environmental management in urban areas is nowadaysconsidered a sine qua non objective of Community and nationalenvironmental and development policies. A large amount ofscientific information on the state of the environment is nowavailable from a large pool of data sources. This work presentsan innovative method for integration of these data sources andeffective coupling of environmental information with appropriatemodels and decision-support tools. State-of-the-art Earthobservation techniques, ground-based air quality measurements,atmospheric transport and chemical modelling, and multi-criteriadecision-aid systems are used in an integrated information fusionenvironment in support of environmental and health impactassessment and decision-making at the urban and regional scales. Results of the pilot application of the method in the area ofLombardy in Northern Italy demonstrate the validity andusefulness of this novel approach.     

Environmental impact assessment on the construction and operation of municipal solid waste sanitary landfills in developing countries: China case study

An inventory of material and energy consumption during the construction and operation (C&O) of a typical sanitary landfill site in China was calculated based on Chinese industrial standards for landfill management and design reports. The environmental impacts of landfill C&O were evaluated through life cycle assessment (LCA). The amounts of materials and energy used during this type of undertaking in China are comparable to those in developed countries, except that the consumption of concrete and asphalt is significantly higher in China. A comparison of the normalized impact potential between landfill C&O and the total landfilling technology implies that the contribution of C&O to overall landfill emissions is not negligible. The non-toxic impacts induced by C&O can be attributed mainly to the consumption of diesel used for daily operation, while the toxic impacts are primarily due to the use of mineral materials. To test the influences of different landfill C&O approaches on environmental impacts, six baseline alternatives were assessed through sensitivity analysis. If geomembranes and geonets were utilized to replace daily and intermediate soil covers and gravel drainage systems, respectively, the environmental burdens of C&O could be mitigated by between 2% and 27%. During the LCA of landfill C&O, the research scope or system boundary has to be declared when referring to material consumption values taken from the literature; for example, the misapplication of data could lead to an underestimation of diesel consumption by 60–80%.