Clay, Phosphate Adsorption, Dispersion, and Rheology

Soluble phosphate is a common ingredient of fertilizer used in agriculture production all over the world. This chemical mixed with soil is transported into the water and marine environment via rainfall causing a range of environmental problems such as toxic algae bloom. Kaolin clay is a common material found in soil and is used as a model system to understand the effects of phosphate adsorption on the flocculation/dispersion of the clay slurries. In the topics, torrential downpours are common. The large water flow will easily disperse the unflocculated or weakly flocculated sediments over a wide area including river and marine environments. Phosphate adsorption was found to weaken the interparticle forces between clay platelets in the slurries. At high enough concentration, it will completely deflocculate the clay slurries, i.e. the net interparticle force is repulsive. A deflocculated slurry is characterised by a low viscosity and no yield stress. As a result, it is much easier to disperse this slurry over a wide area possible even in a small downpour. This study will present the flow and yield stress behaviour of kaolin clay slurries under the influence of adsorbed phosphate.     

Waste incineration,PVC, and dioxins

Waste incineration is becoming increasingly necessary to tackle the rapidly rising amounts of municipal solid waste (MSW); in China many large cities are already surrounded by a girdle of landfills. Still, the not-in-my-backyard (nimby) syndrome holds strong. This attitude stems from fear of dioxins. These have been associated with incineration (‘dioxin factories’) and at times also with polyvinylchloride. In this paper this issue is analysed. China should build additional trust in MSW incineration, following promulgation of stricter emission standards, enforced by stringent controls.     

Zinc,lead, and cadmium tolerance and accumulation in Cistus libanotis,Cistus albidus,and Cistus salviifolius: Perspectives on phytoremediation

Heavy metal contamination is of particular concern for human health and the environment. Phytoremediation is an emerging cost‐effective strategy to remediate heavy metal contaminated soil. However, this technique is limited by the small number of plants that are tolerant to heavy metals and are also accumulators. This study assayed zinc, lead, and cadmium tolerance and accumulation in Cistus libanotis, Cistus albidus, and Cistus salviifolius. The plants were cultivated in hydroponic conditions and exposed to different concentrations of Pb(NO₃)₂ (100 and 200 µM), ZnSO₄ (100 and 200 µM), or CdCl₂ (10 and 20 µM) for 3 weeks. Plant biomass and metal accumulation in roots and aboveground parts varied greatly among the species. All three species appeared to be sensitive to Zn. However, C. albidus displayed strong tolerance to Pb and accumulated large quantities of Pb and Cd in its roots. C. libanotis accumulated large quantities of Pb and Cd in its aboveground parts. C. libanotis can thus be classified as a Pb and Cd accumulator species. The study results show that C. albidus is suitable for phytostabilization of Pb‐contaminated soils, while C. libanotis can be used for phytoextraction of both Pb and Cd.     

Atmospheric Metal Pollutants-Archives, Methods, and History

Pollution of the atmosphere with cadmium (Cd), mercury (Hg), and lead (Pb) is a consequence of human activities. Natural archives are necessary to reconstruct the long-term history of metal deposition because accurate measurement of atmospheric deposition is a recent accomplishment. Reconstructions require: (1) accurate determination of concentrations of elements and isotopes, (2) accurate chronology of archives, and (3) archives that faithfully record atmosphere deposition. The most useful long-term archives are accumulations of ice and snow, peat, and lake sediment. Quantification of Cd deposition is uncommon because of its low concentration and substantial chemical mobility. Nonetheless, trends in peat and lake sediment are similar to those of Hg and Pb since ca. 1800 a.d. Both Hg and Pb are relatively chemically immobile and thus the peat and lake archives are believed to record historic trends of atmospheric deposition. Isotopic and concentration studies of Pb indicate a history of northern hemisphere atmospheric pollution extending back prior to 0 a.d. Although measurements of Hg concentration are now routine, isotopic measurements are in their infancy. Some Hg pollution sources have unique isotopic ratios, thereby contributing unique signals to the total Hg. Maximum accumulation rates of Hg and Pb occur up to 10 years later than for Cd (1970s versus 1960s in eastern North America, perhaps slightly later in Europe). By 2004, deposition of Cd, Hg, and Pb had declined from peak values in eastern North America more than 75, 75, and 90%, respectively.     

Remediation,land use,and risk at Rocky Flats,and a comparison with Hanford

US Department of Energy (US DOE) responsibilities for its former national atomic weapons complex include remediation of the Rocky Flats facility near Denver, Colorado. In 1993, the site's primary mission shifted from “production'' of plutonium components for atomic weapons to cleanup of extensive radioactive and chemical contamination representing the legacy of production activities. Remediation was governed by the agreements between the US DOE as the responsible party and the US Environmental Protection Agency and the state of Colorado as joint regulators. In 1995, the Rocky Flats Future Use Working Group issued its final report, recommending among other features that long‐term cleanup reduce contamination levels to background. This article describes the circumstances that led the US DOE to complete the Rocky Flats cleanup more quickly and makes comparisons to the situation at the US DOE's Hanford site. © 2011 Wiley Periodicals, Inc.     

Remediation,land use,and risk at Hanford

U.S. Department of Energy (US DOE) remediation responsibilities include the Hanford site in Washington State. Cleanup is governed by the Tri‐Party Agreement (TPA) between the US DOE as the responsible party and the U.S. Environmental Protection Agency and Washington State Department of Ecology as joint regulators. In 2003, the US DOE desired to implement a “Risk‐Based End State” (RBES) policy at Hanford, with remediation measures driven by acceptable risk standards using exposure scenarios based on the 1999 Hanford Comprehensive Land‐Use Plan. Facing resistance from regulators and stakeholders, the US DOE solicited public input on its policy. This led to a Hanford Site End State Vision in 2005 and a commitment that the TPA would continue to control remediation. This article describes how regulator and public participation modified RBES to an end‐state vision. © 2010 Wiley Periodicals, Inc.     

Trends in Fish Community Structure,Biomass, and Production in Three Algoma,Ontario, Lakes

Long-term (i.e. >10 years) whole community fish dataincluding catch-per-unit-effort, abundance, biomass, andproduction from three lakes were used: 1) to examine variabilityin fish population and community measures among years using wholelake assessments of fish populations derived from mark recaptureexperiments, 2) to assess implications arising from monitoringindividual species vs. the whole fish community, and 3) toascertain whether, in fisheries assessments (science) a commonlyused surrogate measure, [catch-per-unit-effort (CPUE)] reflectedannual changes in the fish assemblage, and thus may be a goodestimator of abundance. High, long-term variability was evident in the abundance andbiomass of a fish species in our lakes, yet the communityremained relatively stable in terms of its biomass andproduction. Changes in total fish community biomass appear drivenby large species, which, relative to small fish species, remainstable among years. Among years, species richness remainedstable; however, fish species changed in the community. AnnualCPUE was found to be a suitable surrogate for abundance (N) ofsmall fishes; CPUE x mean weight of the catch (bCPUE) was asuitable surrogate for biomass (B) of large fishes. Prior toconcluding that a change in a fish population has occurred as aresult of a stressor, care must be taken to critically examinethe level of population assessment in order to avoid acceptingpotentially invalid conclusions.     

Tensile Strength, Elongation, Hardness, and Tensile and Flexural Moduli of PLA Filled with Glycerol-Plasticized DDGS

Rapid growth of the biofuel industry is generating large amounts of coproducts such as distillers dried grains with solubles (DDGS) from ethanol production and glycerol from biodiesel. Currently these coproducts are undervalued, but they have application in the plastics industry as property modifiers. The objective of this research effort is to quantify the effects on mechanical properties of adding DDGS and glycerol to polylactic acid (PLA). The methodology was to physically mix DDGS, as filler, with PLA pellets and injection mold the blends into test bars using glycerol as a plasticizer. The bars were subject to mechanical testing procedures to obtain tensile strength, tensile and flexural moduli, elongation to break, and surface hardness of blends from 0 to 90?%, by weight, of plasticized filler. Blends were typically relatively brittle with little or no yielding prior to fracture, and the addition of glycerol enabled molding of blends with high levels of DDGS but did not increase strength. Any presence of filler decreased the tensile strength of the PLA, and 20?C30?% filler reduced strength by 60?%. The 35?C50?% filled PLA had about one-fifth the value for pure PLA; at 60?C65?% filler level, about 10?% tensile strength remained; and over 80?% filler, 95?% of the strength was lost. Over 20?% filler, the tensile modulus decreased. The 35?% plasticized, filled blend yielded about one-half the stiffness as the pure PLA case; flexural modulus trended in the same manner but demonstrated a greater loss of stiffness. Most blends had less than 3?% elongation to break while surface hardness measurements indicated that up to 60?% filler reduced Shore D hardness by less than 20?%. The tensile strength and modulus data are consistent with the findings of other researchers and indicate that the type of filler and amount and sequence of plasticization are secondary effects, and the total PLA displaced is the dominant factor in determining the mechanical strength of the PLA and DDGS blends. Up to 65?% plasticized DDGS filler can be injection molded, and sufficient mechanical strength exists to create a variety of products. Such a novel material provides higher-value utilization of the biofuel coproducts of glycerol and DDGS and maintains the biodegradable and biocompatible nature of PLA.     

Inventory of twenty-six combustible wastes as sources of potentially toxic elements: B,Cr, Cu,Zn, As,Sb, Ba,and Pb

Journal of Material Cycles and Waste Management - Municipal solid waste (MSW) is converted to various materials through treatment processes, which in turn distributes potentially toxic elements...     

Behaviour of Cd,Cr, Mn,Ni, Pb,and Zn in sewage sludge incineration by fluidised bed furnace

Cd, Cr, Mn, Ni, Pb, and Zn behaviour during sewage sludge incineration was investigated in seven pilot tests using a circulating fluidised bed furnace. Dewatered sludge at a solids concentration of 15-18% was fed to the furnace either alone (two tests) or spiked with chlorinated organic compounds (five tests). The behaviour of metals in the fluidised bed furnace was studied by comparing metal concentrations in the two main ash streams: ash separated from the cyclone immediately following the fluidised bed furnace, and fly ash recovered in the final bag filter. A metal enrichment factor was defined as the ratio of metal concentration between filter ash and cyclone ash. Only Cd and Pb showed any significant enrichment. Their enrichment factors were mainly affected by chlorine concentration in the feed sludge. To check whether simple equilibrium models may explain and predict metal behaviour, experimental data were compared with percentage of the metal vaporisation in the combustion chamber predicted using a thermodynamic model. Discrepancies between model predictions and experimental results are accounted for by considering that kinetics may be a limiting factor in the formation of metal chloride gaseous species. Due to the very short sludge residence time in the fluidised bed furnace, the gaseous compounds have little chance to evolve completely.     

Preparation,sintering behavior,and expansion performance of ceramsite filter media from dewatered sewage sludge,coal fly ash,and river sediment

The main aim of this study is to assess the preparation, sintering behavior, and expansion performance of ceramsite filter media (CFM) from dewatered sewage sludge, coal fly ash, and river sediment without using any natural resources. The results showed that the investigated physical properties of lab made CFM met with the China’s industrial standard of CJ/T 299-2008 and the concentration of heavy metals in the lixivium was lower than the threshold of GB 5085.3-2007. During the sintering process, the relationships between ignition loss rate, expansion rate, and sintering temperature could be well described simultaneously by the 3-order polynomial fitting curve, with high correlation coefficient values (R ² > 0.999). The fitting curves of the ignition loss rate and expansion rate had one peak and one valley, respectively, and their cut-off point that is the sintering temperatures were the same (700 °C). The whole sintering process could be divided into two stages. The ignition loss rate was gradually increased in both the stages. At the same time, the expansion rate was decreased in the first stage and then increased in the second stage. The significance of this work is to pursue the concept of sustainable development.     

Behavior of As,Cd, Co,Cr, Cu,Pb, Ni,and Zn at the soil/plant interface around an uncontrolled landfill (Casablanca,Morocco)

The present work undertaken in the environmental context aims to study the distribution of heavy metals in plants that grow naturally around uncontrolled landfills. The study's goal was to identify plants that can be used to remediate contaminated soils. For this purpose, 14 plants species and their rhizospheric soil samples were collected and analyzed for arsenic, cadmium, cobalt, chromium, copper, lead, nickel, and zinc by inductively coupled plasma‐atomic emission spectrometry. The results showed the presence of elevated metal concentrations in soil, many exceeding the regulatory values, and that many species exhibited an ability to accumulate multiple metals in their shoots and roots without sustaining toxicity. This was confirmed by bioconcentration and translocation factors generally higher than 1.     

Tensile Strength, Elongation, Hardness, and Tensile and Flexural Moduli of Injection-Molded TPS Filled with Glycerol-Plasticized DDGS

Continuing growth of biofuel industries is generating large amounts of coproducts such as distillers dried grains with solubles (DDGS) from ethanol production and glycerol from biodiesel. Currently these coproducts are undervalued, but they have application in the plastics industry as property modifiers. This research effort has quantified the effects on mechanical properties of adding DDGS and glycerol to a commercial thermoplastic starch (TPS). The methodology was to physically mix DDGS, as filler, with the TPS pellets and injection mold the blends into test bars using glycerol as a processing aid. The bars were then mechanically tested with blends from 0 to 65 %, by weight, of plasticized filler. The test bars were typically relatively brittle with little yielding prior to fracture with elongation between 1 and 3 %. The addition of glycerol enabled molding of blends with high levels of DDGS but did not increase strength. Any presence of filler decreased the tensile strength of the starch, and up to 30 % filler, the tensile strength drops about 15 %. The 20 and 50 % blends (without glycerol) have slightly greater stiffness than pure starch. With some other blends, the presence of plasticized filler degrades the tensile modulus with 35 % filler yielding about 1/3 the stiffness. Changes in the flexural modulus are much more pronounced as 20–25 % filled TPS has a 30 % increase in flexural stiffness. In terms of surface hardness, blends up to 60 % filler are within 20 % of the TPS baseline.     

Arsenic,selenium, and chromium speciation in fly ash

Journal of Material Cycles and Waste Management - Arsenic (As), selenium (Se), and chromium (Cr) are harmful to humans at certain concentrations, and can possibly be eluted from coal ash (fly ash)...     

Estimation of nitrogen flow change in Beijing,China, for the years 1995, 2000, and 2004

Rapid economic growth in China has led to environmental pollution. Recycling nutrients is essential for sustainable agriculture, and it is necessary to estimate the amount of available organic resources in order to achieve this. Using nitrogen as a tracer, we estimated the organic resource flows in 1995, 2000, and 2004 in Beijing. The agricultural nitrogen flow was calculated from the fertilizer, agricultural product, and byproduct flows. The livestock nitrogen flow was calculated from the feed, excretion, and stock flows. The human nitrogen flow was calculated from the food intake, excretion, and food waste flows. The amounts of recyclable organic resources were estimated from these nitrogen flows. The Daxing, Fangshan, Miyun, Shunyi, and Tongzho areas had high nitrogen loads in 2004, as did the outer suburbs, but Beijing proper had an extremely low nitrogen flow and the inner suburbs had low nitrogen flows. The estimated amount of compost that could be produced from domestic organic waste across Beijing was equivalent to 88,100 t of nitrogen. The Beijing area contains 394,100 ha of farmland, so, if the compost was applied at an equivalent of 100 kg of nitrogen per hectare, the equivalent of 48,000 t of nitrogen would be surplus.     

Residential Flood Damage After Hurricane Floyd,Mold, Household Remediation,and Respiratory Health

We conducted a retrospective, cross‐sectional study of flooding, mold exposure, remediation, and respiratory symptom prevalence on a random sample of respondents from Bound Brook, New Jersey, a community that received extensive flood damage from Hurricane Floyd in September 1999. Over 3,000 homes were impacted, some with water damage to the second floor. Many required condemnation. In 2001 to 2002 we conducted a randomized telephone survey of 29 families still living in flood‐damaged and repaired homes and 18 families who had not experienced flood damage from Floyd. Flood status was the last question on the interview, leaving the interviewer effectively blinded as to status. Flood damage was a strong predictor of mold growth (p < 0.001), and there was a strong association between flooding and physician‐confirmed respiratory symptoms in the aftermath of the flood (28 of 29 cases vs. 10 of 18 referents; p < 0.001). There was also an association between flood status and continued symptom prevalence in the month prior to the interviews (22 of 29 cases vs. 6 of 18 referents; p < 0.01). Most flooded homes required removal and replacement of various building materials, which was usually delayed for days or weeks pending re‐occupancy. Many occupants participated in the renovation without adequate personal protection. Persons assisting with cleanup work were more likely to report five or more symptoms (p < 0.002). Smokers with mold damage reported five or more symptoms in the 30 days before the interviews, more frequently than nonsmokers with mold damage. These results are consistent with previous reports of flooding, mold, and illness, but demonstrate that self‐remediation of mold (particularly with lack of training and personal protective equipment) and smoking are significant risk factors for mold‐related symptoms. Exposure during cleanup of moldy materials was a significant contributor to symptoms, and recommendations should include more reliance on professionals and enhanced personal protective equipment. © 2013 Wiley Periodicals, Inc.     

Integrated Environmental and Hydraulic Design of Xerias River,Corinthos, Greece,Training Works

The modern design of flood protection and training works in cases of major natural streams and creeks, requires a fine balance between a sound engineering approach in all engineering aspects on one hand, and an environmentally acceptable solution on the other. Progress in integrating environmental and hydraulic design has been achieved over the years due to different factors, like proper collaboration of engineering disciplines, hydraulic modeling enhancement, development and use of suitable materials, amelioration of the construction methods, and proper restoration and use of the affected areas. In this paper, a synopsis of the experience that has been gained by our firm over the years in designing flood protection and river training works for urban and rural areas is presented, including the general design principles to be used as guidelines, and illustrated with the case study of river Xerias, Greece. The river Xerias is located in Peloponnese, Greece. It flows from south to north and has a catchment area of 170 km². For the last 1500 m before discharging into the Corinthian gulf, the river flows through the city of Corinthos. This is the reach, which overflowed and flooded the city during the January 1997 flood, causing a lot of damage and human life casualties.     

Toxicity potentials from waste cellular phones,and a waste management policy integrating consumer,corporate, and government responsibilities

Cellular phones have high environmental impact potentials because of their heavy metal content and current consumer attitudes toward purchasing new phones with higher functionality and neglecting to return waste phones into proper take-back systems. This study evaluates human health and ecological toxicity potentials from waste cellular phones; highlights consumer, corporate, and government responsibilities for effective waste management; and identifies key elements needed for an effective waste management strategy. The toxicity potentials are evaluated by using heavy metal content, respective characterization factors, and a pathway and impact model for heavy metals that considers end-of-life disposal in landfills or by incineration. Cancer potentials derive primarily from Pb and As; non-cancer potentials primarily from Cu and Pb; and ecotoxicity potentials primarily from Cu and Hg. These results are not completely in agreement with previous work in which leachability thresholds were the metric used to establish priority, thereby indicating the need for multiple or revised metrics. The triple bottom line of consumer, corporate, and government responsibilities is emphasized in terms of consumer attitudes, design for environment (DfE), and establishment and implementation of waste management systems including recycling streams, respectively. The key strategic elements for effective waste management include environmental taxation and a deposit-refund system to motivate consumer responsibility, which is linked and integrated with corporate and government responsibilities. The results of this study can contribute to DfE and waste management policy for cellular phones.