Safe Recycling Research Articles

The Role of Bacteria in the Breakdown of Carcinogenic Substances (PCBs) in Wastewater for Safe Recycling Purposes – A Review

Water is one of the most essential natural resources for daily human activities, yet it is so scarce. Treated wastewater and untreated sewage contain bacteria that can be advantageous to the recycling process. The composition of effluent originates from various industries, such as pharmaceutical industries, mining industries, agricultural sector, household waste, chemical industries, and various manufacturing industries, including the oil manufacturers. These introduce potential health-threatening compounds to wastewater. These compounds that remain for a long time without being broken down or changed in their chemical composition and/or structure in the environment are referred to as recalcitrant compounds. Polychlorinated Biphenyls (PCBs) are examples of such compounds. These compounds have serious negative health effects on humans (act as mutagens and carcinogens). The capacity of Polychlorinated Biphenyl’s (PCBs) degradation by bacteria (biodegradation) depends on the diversity and characteristics of naturally occurring populations and their response to environmental conditions. Conventional physical and chemical methods that are used to decontaminate wastewater contaminated by these substances are time and energy consuming. The use of Moringa oleifera seeds, which is currently under trial, is also very costly and not sustainable. This threatens the economic security of most developing countries. Biodegradation is the metabolic ability of microorganisms to transform or mineralize organic contaminants into less harmful, non-hazardous substances, which are then integrated into natural biochemical cycles. This process is not only cost effective, but it is also environmentally friendly. Wastewater that has gone through effective biodegradation can be fully recycled, thus conserving raw water and at the same time ensuring safe available water for all.

An Orientation Method Fit for the Photogrammetry of the Excavating Face in a Coal Mine

Geological logging is a fundamental technical practice in a coal mine and also one of the most important technical jobs for the production of the coal mine, having important significance for the coal mine’s safe production and source recycling. Irregular shapes of the excavating faces make current photographic geological logging mode and methods unfeasible, so this paper studies critical techniques and methods of underground excavating face photographic geological logging in coal mines and proposes a new close-range photogrammetry control method, orienting the excavating face’s stereoscopic image using the directing laser and the plumb line, and proves through experiments that the positional accuracy of this method meets the requirement of the geological logging and that this photogrammetry orientation method is suitable for geological logging of the roadway excavating face images of coal mines.

Thermal treatment for pathogen inactivation as a risk mitigation strategy for safe recycling of organic waste in agriculture

Thermal treatment at temperatures between 46.0°C and 55.0°C was evaluated as a method for sanitization of organic waste, a temperature interval less commonly investigated but important in connection with biological treatment processes. Samples of dairy cow feces inoculated with Salmonella Senftenberg W775, Enterococcus faecalis, bacteriophage ϕX174, and porcine parvovirus (PPV) were thermally treated using block thermostats at set temperatures in order to determine time-temperature regimes to achieve sufficient bacterial and viral reduction, and to model the inactivation rate. Pasteurization at 70°C in saline solution was used as a comparison in terms of bacterial and viral reduction and was proven to be effective in rapidly reducing all organisms with the exception of PPV (decimal reduction time of 1.2 h). The results presented here can be used to construct time-temperature regimes in terms of bacterial inactivation, with D-values ranging from 0.37 h at 55°C to 22.5 h at 46.0°C and 0.45 h at 55.0°C to 14.5 h at 47.5°C for Salmonella Senftenberg W775 and Enterococcus faecalis, respectively and for relevant enteric viruses based on the ϕX174 phage with decimal reduction times ranging from 1.5 h at 55°C to 16.5 h at 46°C. Hence, the study implies that considerably lower treatment temperatures than 70°C can be used to reach a sufficient inactivation of bacterial pathogens and potential process indicator organisms such as the ϕX174 phage and raises the question whether PPV is a valuable process indicator organism considering its extreme thermotolerance.

AN APPROPRIATE HUMAN BODY WASTES DISPOSAL SYSTEM FOR WATERFRONT DWELLERS IN PORT HARCOURT METROPOLIS

In this study, analysis of an appropriate toilet system for the slums of Port Harcourt metropolis was carried out in order to improve the existing toilet system for the slums within the metropolis. Disposal of human feaces is one of the pressing public health problems in most of the urban areas. A critical look at the existing toilet systems of the slums was observed and analyzed. Considerations were made with respect to the slums, environmental factors, provision of sanitation system, physical, social and cultural factors. Four different locations were sampled this include Elabuchi, Marine Base, Abonnema Wharf and Nember Waterside. At Elabuchi 165 households disposes faeces directly into the River while 25 house holds have bucket latrine. At Marine base, 65 households disposes faces directly into the river, while 25 households have bucket latrine. Abonnema Wharf has 80 households disposing feaces directly into the river while 10 households have bucket latrine and for Nembe waterfront has 75 households disposing faeces directly into the river while 15 households have bucket latrine. A comparison of composted and uncomposted feaces was observed. The result showed that composting reduced ascarid egg count to zero while the un-composted does not which is why the composting privy is regarded as one of the prospective alternatives and favourable as a tool to accomplish sustainable sanitation system, because it can utilize human excrements as compost. A safe recycling of this feaces will benefit agricultural production and to reclaim swamps is more desirable.

A Review on Corrosion Protection of Iron and Steel

Ferrous based-metals, e.g., iron metal and metal alloys containing iron (mild steel), and steels are routinely used in the construction of cooling systems and in other fields due to their low cost and availability. Environmental considerations have been of paramount importance. Corrosion resistant stainless steel or “super alloys” have been used in applications where prevention of corrosion of steel structures or pipes was absolutely essential. These materials are expensive and more difficult to produce than conventional steel materials. Iron and steels undergo inhibition, passivation and corrosion protection treatments to make these materials economical and durable for variety of applications. Numerous techniques are available in the literature to provide these treatments. Heavy metals, chromates, phosphates and fluorides are employed as effective materials for inhibition, passivation and corrosion prevention. A lot of research is underway to remove these materials due to their toxicity. In Europe rules have been established to limit the Chromium content (due to its toxicity) for easy and safe recycling of the materials. There still exists a need for finding out economical, efficient processes and materials which will reliably adhere to the surface being treated in chemically adverse or saline environment and can provide protection against corrosion. For these reasons tremendous efforts are being made to develop/invent new processes for inhibition, passivation and corrosion protection. Keywords: Corrosion, hindering, inhibition, passivation, steels.

Political Ecologies of Electronic Waste: Uncertainty and Legitimacy in the Governance of E-Waste Geographies

Geographers broadly, and political ecologists in particular, have been at the forefront of analyzing the progressive linking of Northern consumption practices with livelihoods elsewhere, problematizing the devolution that places ‘citizen-consumers’, NGOs, and corporate actors as key political agents of protecting workers and environments, promoting ‘ethical’ trade, and ‘greening’ economies through their purchasing choices. Utilizing empirical work on the development of certification and labeling schemes designed to ensure the safe recycling of used electronics, or e-wastes, across a global supply chain, this paper extends lessons learned from these critical analyses of consumer politics to ongoing debates about e-waste, trade, and recycling. I highlight the ambiguities and democratic deficits that emerge from promoting global environmental justice politics through market-driven disposal choices. I analyze the practices of representation through which NGOs and institutions produce e-waste as an object of regulation/commodification that is amenable to consumer action and argue that there is a disconnect between the abstractions necessary to sell ‘ethical’ e-waste recycling and the nuances of place-specific recycling practices. Like other fair trade schemes, certifications for ethical electronics recyclers rely upon narratives, such as environmental justice, that construct the e-waste problem in ways that render it governable, or ‘legible’ in Scott's sense. However, given the complexity of global commodity-networks like those for used electronics, these governing narratives rely on abstractions that oversimplify and rework the fetish of what e-waste is, where it goes, and how it should be managed. In unearthing both what labels do as well as the silences and ambiguities embedded within them, the limits and opportunities of consumer-driven waste politics come more clearly into view.

12 years of leaching of contaminants from Pb smelter slags: Geochemical/mineralogical controls and slag recycling potential

Lead slags from two different metallurgical technologies (primary slag from Pb-ore processing and secondary slag from car battery recycling) were submitted to 12-year batch leaching at a L/S ratio of 10 and the leaching data were compared with the previously obtained results from a ⩽1-year leaching test. In the long-term, the Pb release is efficiently controlled by the precipitation of cerussite (PbCO3), Pb-phosphates and anglesite (PbSO4) and by sorption onto newly formed hydrous ferric oxides. In contrast, Zn is the most important contaminant that is continuously released from the primary slag and, after leaching for 12years, its concentration exceeds more than 40× the regulatory limit value for hazardous wastes (200mg/kg). For this reason, the recycling of primary slag for civil engineering purposes (concrete technology, gravel-like material) cannot be recommended, because of the long-term Zn leaching. In terms of the leaching of metals (Pb, Zn, Cu) and metalloids (As, Sb), the secondary slag mostly fulfils the limit criteria for inert waste according to the EU legislation even for long-term leaching. However, high release of Ba exceeding more than 10× the limit values for hazardous waste was observed, despite the massive formation of barite (BaSO4) on the slag surface. These results indicate that less common contaminants (e.g. Ba), which have been overlooked so far, should also be considered during assessment of the leaching behaviour of smelting slags with a view to their safe recycling in civil engineering.

Possible utilization of ash from meat and bone meal and dried distillers grains gasification as a phosphorus fertilizer: crop growth response and changes in soil chemical properties

Purpose Gasification process is regarded as a viable option for disposal of various types of organic waste. Its application to meat and bone meal (MBM) and dried distillers grains (DDG) is a new concept that is recently receiving more attention as possible strategy for safe recycling of these materials to benefit from their energy and nutrient value. Besides, this process produces ash that is rich in phosphorus (P) and may be suitable for utilization as a P fertilizer. Therefore, the objective of this study was to evaluate the effectiveness of these specific types of ashes as P fertilizer via evaluating their direct effect on canola growth, P uptake, apparent P recovery and changes in some selected soil chemical properties after their addition to a P-deficient soil.

In vitro biological effects of raw and thermally treated asbestos-containing materials

Asbestos cement, the main asbestos-containing material (ACM) manufactured in Italy in the past, is a health hazard whose elimination is a priority concern. Asbestos fibers can be transformed into potentially non-hazardous silicates by high-temperature treatment via complete solid-state transformation. In this study human A549 cells were directly exposed to raw cement asbestos (RCA), chrysotile and cement asbestos subjected to an industrial process at 1200 °C (HT-CA) and raw commercial grey cement (GC) for 24 and 48h, or treated with conditioned culture medium up to 96 h. In our previous studies we demonstrated that the final product of heat treatment of cement asbestos was considerably more inert and had lower cytotoxic potential than the original asbestos material. However, to better evaluate the risks of interactions with the materials, further in vitro investigations were performed concerning fiber-cell superficial interactions, immuno-hystochemical expression of cytochines p53, p53 homologue p73, TNF-related apoptosis- inducing ligand (TRAIL), and conditioned medium effects on cell viability. Data showed more severe cytotoxic damage by raw cement-asbestos compared to the heat treated materials and different expressions of cytochines that exert critical role in regulating the cell response to asbestos-induced DNA damage. These data should be taken in consideration for a safe recycling of thermal transformed asbestos materials.

Advanced techniques for characterization of organic matter from anaerobically digested grapemarc distillery effluents and amended soils

The effects of grapemarc distillery effluents on the quality of soil organic matter is extremely important to ensure the environmentally-safe and agronomically efficient use of these materials as organic amendment. In this work, the effects of the application of untreated (UG) and anaerobically digested grapemarc distillery effluents, either added with (AGM) or without mycorrhiza (AG), on soil humic acid (HA) were investigated in field plot experiments in comparison to HAs from a control soil and an inorganic fertilized soil. The humic acid-like fractions (HALs) isolated from UG, AG and soils were characterized for compositional, structural and functional properties by the use of elemental and functional group analysis, and ultraviolet/visible, Fourier transform infrared and fluorescence spectroscopies. Results obtained indicated that anaerobic digestion of effluents produced an extended mineralization with loss of organic C and stabilization of residual organic matter by increasing the content of HALs in the effluent. With respect to control soil HA, HALs isolated from UG and AG were characterized by smaller acidic functional group contents, a prevalent aliphatic character and smaller aromatic polycondensation and humification degrees. The chemical and spectroscopic characteristics of native soil HA were not substantially modified by application of UG, AG and AGM to soil, which suggests the occurred incorporation of the effluent HAL into native soil HA. In conclusion, these results showed the possibility of a beneficial and safe recycling of grapemarc distillery effluents as soil amendment.

Sequential electrokinetic treatment and oxalic acid extraction for the removal of Cu, Cr and As from wood

Removal of Cu, Cr and As from utility poles treated with chromated copper arsenate (CCA) was investigated using different one- to three-step combinations of oxalic acid extraction and electrokinetic treatment. The experiments were carried out at room temperature, using 0.8% oxalic acid and 30 V (200 V/m) of direct current (DC) or alternating current in combination (DC/AC). Six-hour extraction removed only 15%, 11% and 28% and 7-day electrokinetic treatment 57%, 0% and 17% of Cu, Cr and As from wood chips, respectively. The best combination for all the metals was a three-step process consisting of pre-extraction, electrokinetics and post-extraction steps, yielding removals of 67% for Cu, 64% for Cr and 81% for As. Oxalic acid extraction prior to electrokinetic treatment was deleterious to further removal of Cu, but it was necessary for Cr and As removal. Chemical equilibrium modelling was used to explain the differences in the behaviour of Cu, Cr and As. Due to the dissimilar nature of these metals, it appeared that even more process sequences and/or stricter control of the process conditions would be needed to obtain the >99% removals required for safe recycling of the purified wood material.

Influence of Fly Ash and Sewage Sludge Application on Cadmium and Lead Sorption by an Acidic Alfisol

The safe recycling of fly ash (FA) and sewage sludge (SS) in the agricultural processes comprises an important environmental technology on waste management. Soils amended with FA and SS may change their ability to adsorb heavy metals due to either increase of soil pH or decomposition of sludge-borne organic matter. Thus, Cd and Pb sorption was investigated by 1-month incubation under soil moisture content at field capacity and room temperature with an acidic Typic Haploxeroalf from central Greece amended with varying amounts of FA and SS. Batch experiments were conducted by equilibrating the soil samples with CaCl 2 solutions containing 0–400 mg Pb L −1 or 0–100 mg Cd L −1. The results showed that the Freundlich equation described well the Cd and Pb sorption. Distribution coefficient ( K d) values of Pb were higher than those of Cd in all the treatments of this study. Application of FA increased K d values for Cd and Pb to 8.2 and 2.3 times more than the controls, respectively. Simultaneous applications of FA and SS caused a K d increase of 3.8 and 2.1 times compared to the treatments that received only SS for Cd and Pb, respectively. Treatment of SS alone did not significantly change Cd and Pb sorption compared to the controls. The sorption reactions seemed to be mainly affected by soil pH, which was revealed by the significant correlations of Cd and Pb sorption with soil pH. These suggested that fly ash was very useful as a low-cost adsorbent for Cd and Pb and could be used as an ameliorant for biosolid-amended acidic soils.

EFFECT OF OIL SHALE ASH APPLICATION ON LEACHING BEHAVIOR OF ARABLE SOILS: AN EXPERIMENTAL STUDY

Oil shale ash contains mineral ingredients of agricultural importance and could be used for treatment of soils. However, the ash contains several hazardous ingredients, i.e. toxic trace metals which could be mobile and create environmental concerns. Beneficial use of the oil shale ash in agriculture and forestry requires better knowledge of leaching characteristics of soil-ash systems. In this study two different ash samples have been added to two types of soil, particularly Rendzic Leptosol and Podzolic Gleysols, in order to investigate the leaching characteristics of soil/ash mixtures using the traditional leaching scheme and a scheme modified by pretreatment (incubation) of solid in wet conditions. The pH, conductivity and concentration of Cd, Pb, Cr, Zn and Ni in leachates are determined. The results revealed that transport of hazard components to the water phase was highly dependent on the type of soil and ash and leaching method used. Throughout the experiment, concentrations of heavy metals in leachates of any combination of soil and fly ash are low. The most mobile metals are found to be nickel, zinc and chromium. Application of oil shale ash to soil might increase mobile fraction of Ni in soil. For the safe recycling of oil shale wastes in agriculture, it is recommended to take into account the leaching behavior of trace elements as ingredients in combustion ash.

Review Article: The Effects of Radiation Chemistry on Solvent Extraction 3: A Review of Actinide and Lanthanide Extraction

The partitioning of the long‐lived α‐emitters and the high‐yield fission products from dissolved used nuclear fuel is a key component of processes envisioned for the safe recycling of used nuclear fuel and the disposition of high‐level waste. These future processes will likely be based on aqueous solvent‐extraction technologies for light‐water reactor fuel and consist of four main components for the sequential separation of uranium, fission products, group trivalent actinides, and lanthanides, and then trivalent actinides from lanthanides. Since the solvent systems will be in contact with highly radioactive solutions, they must be robust toward radiolytic degradation in an irradiated mixed organic/aqueous acidic environment, with the formation of only benign degradation products. Therefore, an understanding of their radiation chemistry is important to the design of a practical system. In the first paper in this series, we reviewed the radiation chemistry of irradiated aqueous nitric acid and the tributyl phosphate ligand for uranium extraction in the first step of these extractions. In the second, we reviewed the radiation chemistry of the ligands proposed for use in the extraction of cesium and strontium fission products. Here, we review the radiation chemistry of the ligands that might be used for the group extraction of the lanthanides and actinides. This includes traditional organophosphorus reagents such as CMPO and HDEHP, as well as novel reagents such as the amides and diamides currently being investigated.

TRASH OR TREASURE?: Putting Coal Combustion Waste to Work

Even as public debate rages over the question of whether coal should continue to provide the majority of U.S. electric power needs, the U.S. Energy Information Administration predicts in International Energy Outlook 2009 that, absent new policies to the contrary, the United States—along with China and India—is expected to account for 88% of the projected net increase in coal consumption between 2006 and 2030. Meanwhile, coal combustion waste (CCW)—the noncombustible remains from coal burning—continues to pile up at the rate of about 131 million tons per year in the United States alone, and electric utilities are looking to recycle a larger proportion of this material.

Review Article: The Effects of Radiation Chemistry on Solvent Extraction: 2. A Review of Fission‐Product Extraction

The partitioning of the long‐lived α‐emitters and the high‐yield fission products from dissolved nuclear fuel is a key component of processes envisioned for the safe recycling of nuclear fuel and the disposition of high‐level waste. These future processes will likely be based on aqueous solvent‐extraction technologies for light‐water reactor fuel and consist of four main components for the separation of uranium, fission products, and group trivalent actinides and lanthanides and separation of trivalent actinides from lanthanides. Since the solvent systems will be in contact with highly radioactive solutions, they must be robust toward radiolytic degradation in an irradiated, mixed organic and aqueous acidic environment. Therefore, an understanding of their radiation chemistry is important to the design of a practical system. In a previous paper, we reviewed the radiation chemistry of irradiated aqueous nitric acid and the tributyl phosphate ligand used for uranium extraction in the first step of the series of four extractions. In this paper, we review the radiation chemistry of the ligands proposed for use in the second extraction of cesium and strontium fission products. This includes not only the crown ethers and calixarenes but also cobalt dicarbollide and polyethylene glycol. Since many disparate units have been applied for measuring absorbed radiation dose in the literature, we also present a discussion of that topic and provide conversion factors.

Sanitation of faeces from source-separating dry toilets using urea

To develop a reliable and simple method to produce safe fertilizers from human excreta using urea for sanitation of faeces. Urea was added to faecal matter (17% dry matter) at concentrations of 0.5-2% (w/w) and inactivation of Salmonella enterica subspecies 1 serovar Typhimurium (Salm. Typhimurium), Enterococcus spp. and the Salm. Typhimurium bacteriophage 28B was monitored at 14, 24 and 34 degrees C. Urea additions enhanced inactivation and inactivation rates were positively related to increasing NH(3) (aq) concentration and temperature. Salm. Typhimurium was the most sensitive of the organisms studied, while Enterococcus spp. showed more persistence, especially at lower temperatures. The bacteriophage was the most resistant organism studied. Salmonella reduction levels that meet requirements for safe reuse of faeces as fertilizer (i.e. 6 log(10) reduction) can be achieved for 1% urea within 2 months at 14 degrees C or within 1 week at 24 degrees C and 34 degrees C. The relationships between organism inactivation rates and temperature, ammonia and pH were identified. Urea treatment proved to be a robust and efficient option for safe recycling of plant nutrients.

The thermal transformation of Man Made Vitreous Fibers (MMVF) and safe recycling as secondary raw materials (SRM)

This work describes the high temperature reaction sequence of commercial Man Made Vitreous Fibers (MMVF) Cerafiber, Superwool, Rock wool and Glass wool which may be used as substitute for asbestos in some industrial applications. Knowledge of the reaction path and transformation sequence is very important to assess whether carcinogenic crystalline phases are formed during devitrification, which may occur when used as insulators. In addition, knowledge about the nature of the phases formed at high temperature is mandatory to assess if thermally transformed MMVF can be safely recycled as secondary raw material (SRM). In this scenario, this study provides useful information for the optimization of the industrial annealing process aimed to attain a safe, recyclable product. The results of this work show that one of the high-temperature products of Cerafiber and Superwool is cristobalite which is classified as a carcinogenic. It was possible to define the temperature interval at which Cerafiber and Superwool fibers can be safely used as thermal insulators (e.g. insulators in tunnel and/or roller kilns, etc.). As cristobalite is formed in both synthetic fiber products at temperatures higher than 1200 °C, their use should be limited to devices operating at lower temperatures. Rock and Glass wool melt upon thermal treatment. As far as the industrial process of inertization is concerned, a maximum firing temperature of 1100 and 600 °C is required to melt Rock wool and Glass wool, respectively, with the high-temperature products that can be safely recycled as SRM. Recycling of these products in stoneware tile mixtures were subsequently attempted. The addition of 1–2 wt.% of the melts of Rock and Glass wool gave promising results in terms of viscous sintering reactions and resistance to staining with the only weak characteristic being the color properties of the fired bodies which tend to worsen.

Decontamination Options of the Packaging Wastes from Toxic Substances

The implementation of Directive 94/62/EC on packaging and packaging waste has meant a great change on the Romanian legislation and on the research priorities in this area in our country. For this reason, the decontamination options of reusable containers became the aim of this paper, which was prepared in order to evaluate the possibilities of safe recycling of clean containers to the manufacturer or supplier. Our studies have developed ultrasonic extraction, original method for the residual pesticides content such as pyrethroid insecticides e.g. as Deltamethrin 2.5 EC from plastic containers used for pesticide packaging. Thus, we considered the need to examine how polar solvents, e.g propylene glycol, behave in the ultrasonic extraction process of residual pesticides from packaging waste. The efficiency of ultrasonic extraction was determined by advanced analytical techniques such as thermal analysis: thermo gravimetrical (TGA) and calorimetrical (DSC) methods in order to provide scientific information about the residue pesticide level in polymeric materials from pesticide packaging waste. The ultrasonic extraction yield for the pyrethroid insecticide Deltamethrin from used polyethylene from Decis 2.5% packaging is over 98%. The optimum extraction time, in the preliminary experiments, was 60 minutes, after which, using the differential calorimetry method, the pesticide Deltamethrin is no longer found in the sonicated polyethylene samples.

In situ ESEM study of the thermal decomposition of chrysotile asbestos in view of safe recycling of the transformation product

The thermal transformation of asbestos into non-hazardous crystalline phases and their recycling is a promising solution for the “asbestos problem”. The most common asbestos-containing industrial material produced worldwide is cement-asbestos. Knowledge of the kinetics of thermal transformation of asbestos fibers in cement-asbestos is of paramount importance for the optimization of the firing process at industrial scale. Here, environmental scanning electron microscopy (ESEM) was used for the first time to follow in situ the thermal transformation of chrysotile fibers present in cement-asbestos. It was found that the reaction kinetics of thermal transformation of chrysotile was highly slowed down in the presence of water vapor in the experimental chamber with respect to He. This was explained by chemisorbed water on the surface of the fibers which affected the dehydroxylation reaction and consequently the recrystallization into Mg-silicates. In the attempt to investigate alternative and faster firing routes for the decomposition of asbestos, a low melting glass was mixed with cement-asbestos and studied in situ to assess to which extent the decomposition of asbestos is favored. It was found that the addition of a low melting glass to cement-asbestos greatly improved the decomposition reaction and decreased the transformation temperatures.