Particleboard manufacturing: an innovative way to recycle paper sludge

This paper presents the results on a study to use paper mill sludge for particleboard production. Single-layer board and three-layer board, with paper sludge on the surface, were fabricated. Four levels of mixing ratios of paper sludge to wood particles (0:100, 15:85, 30:70, and 45:55) were used. The boards were produced with 3% and 4% methylene diphenyl diisocyanate (MDI), and 10% and 12% urea-formaldehyde (UF) adhesives. The bending and shear strengths, water absorption, and thickness swelling of the boards were investigated. The results indicated that the mechanical properties of the boards were negatively affected by the paper sludge amount. Overall, UF-bonded particleboards gave superior mechanical performance, water resistance, and thickness swell than MDI-bonded particleboards. The strengths of the UF-bonded board decreased much more than those of MDI-bonded board as paper sludge content increased. The three-layer boards made from 15% paper sludge with 12% UF satisfied fully the minimum requirements set by EN, ASTM D 1037-99, and ANSI A208.1 standards for general uses.     

Effect of organic residues addition on the technological properties of clay bricks

The objective of this study is to investigate the utilization potential of several organic residues in clay bricks. Sawdust, tobacco residues, and grass are widespread by-products of industrial and agricultural processes in Turkey. These residue materials have long cellulose fibres. Sawdust and tobacco residues generally are used as fuel, and the grass is utilized for agricultural purposes. The insulation capacity of brick increases with the increasing porosity of the clay body. Combustible, organic types of pore-forming additives are most frequently used for this purpose. For this reason, increasing amounts of organic residues (0%, 2.5%, 5% and 10% in wt.) were mixed with raw brick-clay. All samples were fired at 900 degrees C. Effects on shaping, plasticity, density, and mechanical properties were investigated. The organic residue additions were found to be effective for pore-forming in the clay body with the clay maintaining acceptable mechanical properties. It was observed that the fibrous nature of the residues did not create extrusion problems. However, higher residue addition required a higher water content to ensure the right plasticity. As a result, sawdust, tobacco residues, and grass can be utilized in an environmentally safe way as organic pore-forming agents in brick-clay.     

The general utilization of scrapped PC board

The traditional burning process is used to recover copper from scrapped PC board (printed circuit board) but it causes serious environmental problems. In this research a new process was developed which not only prevents pollution problems, but also maximizes the utility of all the materials on the waste board. First, the scrapped PC board was crushed and grounded, then placed in the NH₃/NH₅CO₃ solution with aeration in order to dissolve copper. After distilling the copper NH₃/NH₅CO₃ solution and then heating the distilled residue of copper carbonate, pure copper oxide was obtained with particle size of about 0.2 μm and the shape elliptical. The remaining solid residue after copper removal was then leached with 6 N hydrochloric acid to remove tin and lead. The last residue was used as a filler in PVC plastics. The PVC plastics with PC board powder as filling material was found to have the same tensile strength as unfilled plastics, but had higher elastic modulus, higher abrasion resistance, and was cheaper.     

Properties of Composite Panels Made from Tetra-Pak and Polyethylene Waste Material

The objective of this study was to evaluate some of the properties of experimental composite panels manufactured from waste packaging materials without using any additional binders. Particles from three types of materials, namely Tetra-Pak, food packaging films (FPEF) as recycled stretch wraps, and candy polyethylene wrappers (CPEW) were used at different ratios in the panels at a target density of 900 kg/m³. Modulus of rupture (MOR), screw holding strength and dimensional stability in the form of thickness swelling and water absorption of the panels were determined according to European (EN) standards. Based on the findings in this work it was determined that the ratio of different raw materials significantly influenced overall properties of the samples. The highest MOR value of 15.5 MPa was determined for the samples having 40 % Tetra-Pak and 60 % CPEW particles. Modulus of rupture values of the panels decreased with decreasing content of CPEW in the samples. The increased content of Tetra-Pak particles in the samples also resulted in reduction of their strength characteristics and dimensional stability. Properties of the samples considered in this work satisfied minimum requirements of typical particleboard stated in EN standards. It appears that such waste material would have potential to be used as raw material for value-added composite production using no adhesive in the panels and, therefore, such panels would possibly create significant ecological impact as green product.     

Phosphorus recovery from municipal solid waste incineration fly ash

The potential of phosphorus (P) recycling from municipal solid waste incineration (MSWI) residue is investigated. Vast and ever increasing amounts of incineration residues are produced worldwide; these are an environmental burden, but also a resource, as they are a major sink for the material flows of society. Due to strict environmental regulations, in combination with decreasing landfilling space, the disposal of the MSWI residues is problematic. At the same time, resource scarcity is recognized as a global challenge for the modern world, and even more so for future generations.This paper reports on the methods and efficiency of P extraction from MSWI fly ash by acid and base leaching and precipitation procedures. Phosphorus extracted from the MSWI residues generated each year could meet 30% of the annual demand for mineral phosphorus fertiliser in Sweden, given a recovery rate of 70% achieved in this initial test.The phosphorus content of the obtained product is slightly higher than in sewage sludge, but due to the trace metal content it is not acceptable for application to agricultural land in Sweden, whereas application in the rest of the EU would be possible. However, it would be preferable to use the product as a raw material to replace rock phosphate in fertilizer production. Further development is currently underway in relation to procedure optimization, purification of the phosphorus product, and the simultaneous recovery of other resources.     

Recycling of organic materials and solder from waste printed circuit boards by vacuum pyrolysis-centrifugation coupling technology

Here, we focused on the recycling of waste printed circuit boards (WPCBs) using vacuum pyrolysis-centrifugation coupling technology (VPCT) aiming to obtain valuable feedstock and resolve environmental pollution. The two types of WPCBs were pyrolysed at 600°C for 30 min under vacuum condition. During the pyrolysis process, the solder of WPCBs was separated and recovered when the temperature range was 400-600°C, and the rotating drum was rotated at 1000 rpm for 10 min. The type-A of WPCBs pyrolysed to form an average of 67.91 wt.% residue, 27.84 wt.% oil, and 4.25 wt.% gas; and pyrolysis of the type-B of WPCBs led to an average mass balance of 72.22 wt.% residue, 21.57 wt.% oil, and 6.21 wt.% gas. The GC-MS and FT-IR analyses showed that the two pyrolysis oils consisted mainly of phenols and substituted phenols. The pyrolysis oil can be used for fuel or chemical feedstock for further processing. The recovered solder can be recycled directly and it can also be a good resource of lead and tin for refining. The pyrolysis residues contained various metals, glass fibers and other inorganic materials, which could be recovered after further treatment. The pyrolysis gases consisted mainly of CO, CO(2), CH(4), and H(2), which could be collected and recycled.     

Evaluation of metals in the residue of paper sludge after recovery of pulp components using an ionic liquid

The quantity of sludge produced by the paper industry in Japan in 2011 was estimated to be 27.91 million tons wet weight. This amount is the third largest among all industrial wastes. To explore ways of reusing recovered paper pulp and safely disposing of the residue, we investigated the distribution of metals in the process of recovery of pulp from two types of paper sludge using an ionic liquid. 32 and 46 % of pulp from paper sludge A and B was recovered using ionic liquid, respectively; the resultant weight reduction of the solid mass was comparable to that of incineration. There were virtually no heavy metals but aluminum in the recovered pulp, which makes its reuse viable at present. The characteristics of the metals in the residues differed according to the treatment used and properties of the paper sludge. Copper accounted for ~10 % in the ionic liquid used for recovery of pulp from the paper sludges. This suggests that [bmIm]Cl has the potential to dissolve a specific amount of copper compared to other metals.     

Leaching studies for tin recovery from waste e-scrap

Printed circuit boards (PCBs) are the most essential components of all electrical and electronic equipments, which contain noteworthy quantity of metals, some of which are toxic to life and all of which are valuable resources. Therefore, recycling of PCBs is necessary for the safe disposal/utilization of these metals. Present paper is a part of developing Indo-Korean recycling technique consists of organic swelling pre-treatment technique for the liberation of thin layer of metallic sheet and the treatment of epoxy resin to remove/recover toxic soldering material. To optimize the parameters required for recovery of tin from waste PCBs, initially the bench scale studies were carried out using fresh solder (containing 52.6% Sn and 47.3% Pb) varying the acid concentration, temperature, mixing time and pulp density. The experimental data indicate that 95.79% of tin was leached out from solder material using 5.5M HCl at fixed pulp density 50g/L and temperature 90°C in mixing time 165min. Kinetic studies followed the chemical reaction controlled dense constant size cylindrical particles with activation energy of 117.68kJ/mol. However, 97.79% of tin was found to be leached out from solder materials of liberated swelled epoxy resin using 4.5M HCl at 90°C, mixing time 60min and pulp density 50g/L. From the leach liquor of solder materials of epoxy resin, the precipitate of sodium stannate as value added product was obtained at pH 1.9. The Pb from the leach residue was removed by using 0.1M nitric acid at 90°C in mixing time 45min and pulp density 10g/L. The metal free epoxy resin could be disposed-of safely/used as filling material without affecting the environment.     

Leaching assessment of concrete made of recycled coarse aggregate: Physical and environmental characterisation of aggregates and hardened concrete

Each year, millions of tonnes of waste are generated worldwide, partially through the construction and demolition of buildings. Recycling the resulting waste could reduce the amount of materials that need to be manufactured. Accordingly, the present work has analysed the potential reuse of construction waste in concrete manufacturing by replacing the natural aggregate with recycled concrete coarse aggregate.However, incorporating alternative materials in concrete manufacturing may increase the pollutant potential of the product, presenting an environmental risk via ground water contamination.The present work has tested two types of concrete batches that were manufactured with different replacement percentages. The experimental procedure analyses not only the effect of the portion of recycled aggregate on the physical properties of concrete but also on the leaching behaviour as indicative of the contamination degree. Thus, parameters such as slump, density, porosity and absorption of hardened concrete, were studied. Leaching behaviour was evaluated based on the availability test performed to three aggregates (raw materials of the concrete batches) and on the diffusion test performed to all concrete.From an environmental point of view, the question of whether the cumulative amount of heavy metals that are released by diffusion reaches the availability threshold was answered. The analysis of concentration levels allowed the establishment of different groups of metals according to the observed behaviour, the analysis of the role of pH and the identification of the main release mechanisms. Finally, through a statistical analysis, physical parameters and diffusion data were interrelated. It allowed estimating the relevance of porosity, density and absorption of hardened concrete on diffusion release of the metals in study.     

Refuse derived soluble bio-organics enhancing tomato plant growth and productivity

Municipal bio-refuse (CVD), containing kitchen wastes, home gardening residues and public park trimmings, was treated with alkali to yield a soluble bio-organic fraction (SBO) and an insoluble residue. These materials were characterized using elemental analysis, potentiometric titration, and 13C NMR spectroscopy, and then applied as organic fertilizers to soil for tomato greenhouse cultivation. Their performance was compared with a commercial product obtained from animal residues. Plant growth, fruit yield and quality, and soil and leaf chemical composition were the selected performance indicators. The SBO exhibited the best performance by enhancing leaf chlorophyll content, improving plant growth and fruit ripening rate and yield. No product performance-chemical composition relationship could be assessed. Solubility could be one reason for the superior performance of SBO as a tomato growth promoter. The enhancement of leaf chlorophyll content is discussed to identify a possible link with the SBO photosensitizing properties that have been demonstrated in other work, and thus with photosynthetic performance.     

液相法芒硝制碱中苛化废渣的利用

研究了用液相法芒硝制碱的苛化废渣制取轻质ＣａＣＯ３的工艺及用轻质ＣａＣＯ３填充母料对聚乙烯进行改性。试验结果表明,本研究所制取的轻质ＣａＣＯ３的质量符合ＧＢ４７９４－８４一级品规格,用其制成母料对低密度聚乙烯填充改性,不仅可消除苛化废渣对环境的污染,降低聚乙烯制品的生产成本,而且可在制品的拉伸强度、断裂伸长率和冲击强度降低不多的情况下,提高制品的硬度、弹性模量、热稳定性及耐蠕变性。     

Construction materials as a waste management solution for cellulose sludge

Sustainable waste management system for effluents treatment sludge has been a pressing issue for pulp and paper sector. Recycling is always recommended in terms of environmental sustainability. Following an approach of waste valorisation, this work aims to demonstrate the technical viability of producing fiber-cement roof sheets incorporating cellulose primary sludge generated on paper and pulp mills.From the results obtained with preliminary studies it was possible to verify the possibility of producing fiber-cement sheets by replacing 25% of the conventional used virgin long fiber by primary effluent treatment cellulose sludge. This amount of incorporation was tested on an industrial scale. Environmental parameters related to water and waste, as well as tests for checking the quality of the final product was performed. These control parameters involved total solids in suspension, dissolved salts, chlorides, sulphates, COD, metals content. In the product, parameters like moisture, density and strength were controlled.The results showed that it is possible to replace the virgin long fibers pulp by primary sludge without impacts in final product characteristics and on the environment.This work ensures the elimination of significant waste amounts, which are nowadays sent to landfill, as well as reduces costs associated with the standard raw materials use in the fiber-cement industrial sector.     

Brominated flame retardants and heavy metals in automobile shredder residue (ASR) and their behavior in the melting process

The End-of-life Vehicles Recycling Act went into effect on January 1, 2005, in Japan and requires the proper treatment of airbags, chlorofluorocarbons (CFCs), and automobile shredder residue (ASR). The need for optimal treatment and recycling of ASR, in particular, has been increasing year after year because ASR is regarded as being difficult to treat. Dioxin-related compounds, brominated flame retardants (BFRs), heavy metals, chlorine and organotin compounds are all present in high concentrations in ASR. The authors conducted ASR melting treatment tests using a 10-tons/day-scale direct melting system (DMS), which employs shaft-type gasification and melting technology. The results obtained showed that dioxin-related compounds and BFRs were decomposed by this melting treatment. The high-temperature reducing atmosphere in the melting furnace moved volatile heavy metals such as lead and zinc into the fly ash where they were distributed at a rate of more than 90% of the input amount. This treatment was also found to be effective in the decomposition of organotin, with a rate of decomposition higher than 99.996% of the input amount. Via the recovery of heavy metals concentrated in the fly ash, all the products discharged from this treatment system were utilized effectively for the complete realization of an ASR recycling system that requires no final disposal sites.     

Hydrothermal recycling of waste and performance of the recycled wooden particleboards

Recycling today constitutes the most environmentally friendly method of managing wood waste. A large proportion of the wood waste generated consists of used furniture and other constructed wooden items, which are composed mainly of particleboard, a material which can potentially be reused. In the current research, four different hydrothermal treatments were applied in order to recover wood particles from laboratory particleboards and use them in the production of new (recycled) ones. Quality was evaluated by determining the main properties of the original (control) and the recycled boards. Furthermore, the impact of a second recycling process on the properties of recycled particleboards was studied. With the exception of the modulus of elasticity in static bending, all of the mechanical properties of the recycled boards tested decreased in comparison with the control boards. Furthermore, the recycling process had an adverse effect on their hygroscopic properties and a beneficial effect on the formaldehyde content of the recycled boards. The results indicated that when the 1st and 2nd particleboard recycling processes were compared, it was the 2nd recycling process that caused the strongest deterioration in the quality of the recycled boards. Further research is needed in order to explain the causes of the recycled board quality falloff and also to determine the factors in the recycling process that influence the quality degradation of the recycled boards.     

催化裂解法处理有机硅高沸物

采用催化裂解法处理有机硅高沸物,解决高沸物储存过程中的安全、环保问题。研究了催化剂种类、HCl加入量和精馏高沸物加入量对高沸物转化率的影响。实验结果表明:在以N,N-二丁基-1-丁胺为催化剂、合成高沸物为原料、HCl加入量为13%(w)的条件下,高沸物转化率为83.10%,二甲基二氯硅烷收率为23.78%;合成高沸物中精馏高沸物加入量为9.0%(w)时,高沸物转化率最高,为85.58%。     

A review of corn masa processing residues: generation, properties, and potential utilization

The production of corn masa-based products in the US has been increasing over the last several years, and as a result, so has the quantity of waste materials being generated from this industry. Although currently landfilled, these byproduct streams may have potential for value-added processing and utilization, which are options that simultaneously hold the promise of increased economic benefit for masa processors as well as decreased potential pollution for the environment. Fundamental to any byproduct development effort is knowledge of the characteristics of the residue stream, because physical and chemical properties are vital for the proper design of subsequent processing operations and applications. Data for masa byproduct materials are currently not readily available, however. Thus, the objective of this study was to fully investigate, review, and summarize the existing literature in order to develop a comprehensive knowledge base for these residue streams. The most substantial findings from this study were that masa residues currently are not being utilized as coproducts, but instead are being landfilled; they have a high fiber content, and thus much untapped potential exists for its extraction and value-added utilization vis-à-vis human and industrial applications, including phytosterol and ethanol production. It was also determined that masa byproducts, due to the high fiber content, may also be suitable for use as livestock feed additives, especially for ruminant animals that can digest these materials. Furthermore, due to substantial calcium content, masa byproducts could also potentially be used as a calcium resource. Under current processing practices, though, these residues have very high moisture contents. Before they can be effectively and economically utilized, they must be dehydrated in order to reduce transportation costs, decrease microbial activity, and increase shelf life.     

Comparison of leaching tests to determine and quantify the release of inorganic contaminants in demolition waste

The changes in waste management policy caused by the massive generation of waste materials (e.g. construction and demolition waste material, municipal waste incineration products) has led to an increase in the reuse and recycling of waste materials. For environmental risk assessment, test procedures are necessary to examine waste materials before they can be reused. In this article, results of column and lysimeter leaching tests having been applied to inorganic compounds in a reference demolition waste material are presented. The results show a good agreement between the leaching behaviour determined with the lysimeter unit and the column units used in the laboratory. In view of less time and system requirements compared to lysimeter systems, laboratory column units can be considered as a practicable instrument to assess the time-dependent release of inorganic compounds under conditions similar to those encountered in a natural environment. The high concentrations of elements in the seepage water at the initial stage of elution are reflected by the laboratory column leaching tests. In particular, authorities or laboratories might benefit and have an easy-to-use, but nevertheless reliable, method to serve as a basis for decision-making.     

Possibility of using waste tire rubber and fly ash with Portland cement as construction materials

The growing amount of waste rubber produced from used tires has resulted in an environmental problem. Recycling waste tires has been widely studied for the last 20 years in applications such as asphalt pavement, waterproofing systems and membrane liners. The aim of this study is to evaluate the feasibility of utilizing fly ash and rubber waste with Portland cement as a composite material for masonry applications. Class C fly ash and waste automobile tires in three different sizes were used with Portland cement. Compressive and flexural strength, dry unit weight and water absorption tests were performed on the composite specimens containing waste tire rubber. The compressive strength decreased by increasing the rubber content while increased by increasing the fly ash content for all curing periods. This trend is slightly influenced by particle size. For flexural strength, the specimens with waste tire rubber showed higher values than the control mix probably due to the effect of rubber fibers. The dry unit weight of all specimens decreased with increasing rubber content, which can be explained by the low specific gravity of rubber particles. Water absorption decreased slightly with the increase in rubber particles size. These composite materials containing 10% Portland cement, 70% and 60% fly ash and 20% and 30% tire rubber particles have sufficient strength for masonry applications.     

Use of life cycle assessment as decision-support tool for water reuse and handling of residues at a Danish industrial laundry.

This analysis presents the results of a life cycle assessment (LCA) carried out on six alternative options for the recycling of water at a Danish industrial laundry for workwear. The study focuses on the handling and disposal of the wet residues generated when wastewater is treated for recycling, and in accounting for long-term potential toxicity impacts. The analysed options are a combination of two water-upgrading technologies: biofilter and ultrafiltration, and three residue disposal alternatives: biogas followed by incineration of sludge at local wastewater treatment plant, thermal vitrification treatment for production of vitrified sand, and mineralization in a sludge bed. It is concluded from the results that with the current Danish environmental policy priorities, the environmental impacts of highest priority are the toxicity effects derived from the presence of heavy metals in the residues. Heavy metals originate from the dirt in the workwear that is washed in the laundry. It is further concluded that the studied water treatment technologies satisfy both the need of clean water for recycling and simultaneously help controlling a safe disposal of pollutants by concentration of the residues. The results of the study also confirm the potential of LCA as a decision-support tool for assisting water recycling initiatives and for residue handling management. The handling of residues has been identified as a stage of the water recycling strategy that bears important environmental impacts. This holistic perspective provided by LCA can be used as input for the definition of environmental management strategies at an industrial laundry, and the prioritization of investments to the environmental profile of laundry processes. In this case-study, the results of the LCA are made operational by, for example, selecting the water treatment technology which is associated wih a safe disposal of the wet residue. It is important to bear in mind that such prioritization depends on national boundary conditions. In the case study analysed, the boundary conditions steer the weighing of the environmental impacts, following the current Danish environmental policy priorities.     

Environmental and Cost Assessment of a Polypropylene Nanocomposite

This paper describes a study on the use of a polypropylene (PP)/layered silicate nanocomposite as packaging film, agricultural film, and automotive panels. The study’s main question was “Are the environmental impacts and costs throughout the life cycle of nanocomposite products lower than those of products manufactured from conventional materials?” The conventional (benchmark) materials studied were pure polypropylene as packaging film, pure polyethylene as agricultural film, and glass fiber-reinforced polypropylene as automotive panels. In all three cases, the use of the PP nanocomposite resulted in a reduction of the amount of material used, while ensuring the same functionality. Material reduction was estimated using Ashby’s material indices and amounted to ?9% for packaging film, ?36.5% for agricultural film, and ?1.25% for automotive panels. It goes without saying that a product’s impact on the environment will decrease when less material is used. The production and incorporation of nanoparticles, however, may have additional impacts. We found clear environmental benefits throughout the entire life cycle when the PP nanocomposite is used in the manufacture of agricultural film. We noted some cost benefits when the nanocomposite is used in the production of agricultural film and automotive panels. If the price of nanoclay is at most €5,000 tonne then the cost of nanocomposite packaging film is also lower than that of the conventionally produced product.