Sludge Powder Research Articles

Mercury leaching characteristics of waste treatment residues generated from various sources in Korea

In this study, mercury (Hg) leaching characteristics of the waste treatment residues (fly ash, bottom ash, sludge, and phosphor powder) generated from various sources (municipal, industrial, medical waste incinerators, sewage sludge incinerator, oil refinery, coal-fired power plant, steel manufacturing plant, fluorescent lamp recycler, and cement kiln) in Korea were investigated. First, both Hg content analysis and toxicity characteristic leaching procedure (TCLP) testing was conducted for 31 collected residue samples. The Hg content analysis showed that fly ash from waste incinerators contained more Hg than the other residue samples. However, the TCLP values of fly ash samples with similar Hg content varied widely based on the residue type. Fly ash samples with low and high Hg leaching ratios (RL) were further analyzed to identify the major factors that influence the Hg leaching potential. Buffering capacity of the low-RL fly ash was higher than that of the high-RL fly ash. The Hg speciation results suggest that the low-RL fly ashes consisted primarily of low-solubility Hg compounds (Hg2Cl2, Hg0 or HgS), whereas the high-RL fly ashes contain more than 20% high-solubility Hg compounds (HgCl2 or HgSO4).

Production and properties of foamed reservoir sludge inorganic polymers

The feasibility of using reservoir sludge as a raw material in the production of foamed inorganic polymers with different densities is investigated in this work. Reservoir sludge is first crushed, ground down and then calcined at the temperature of 850°C for 6h to become calcined reservoir sludge (CRS) powders. A mixture of 30% blast furnace slag and 70% CRS powders is alkali-activated by mixing with different alkaline activating solutions of water, sodium hydroxide and sodium silicate. The viscosities and compressive strengths of the resulting inorganic binders are measured and compared with each other. Furthermore, the inorganic binder paste that has the maximum compressive strength and best workability is mixed with various amounts of preformed air bubbles to produce foamed reservoir sludge inorganic polymer (FRSIP) specimens with different densities. The effects of density on the water absorption, pore size distribution, compressive strength, bending strength and transmission loss of the FRSIP specimens are evaluated.

Self-compacting concrete using Marble Sludge Powder and Crushed Rock Dust

Self Compacting Concrete (SCC) has had a remarkable impact on the concrete construction industry, especially the precast concrete industry. Crushed Rock Dust (CRD) and Marble Sludge Powder (MSP) are discarded in the nearby land and the natural fertility of the soil is spoiled. MSP and CRD can be used as filler and helps to reduce the total voids content in concrete. Consequently, this contributes to improve the strength of concrete. An experimental investigation has been carried out to study the combined effect of addition of MSP and CRD on the strength and durability of SCC. The study on physical, chemical and mechanical properties such as compressive strength and split tensile strength and the durability tests include water absorption test, water permeability, rapid chloride permeability; electrical resistivity and half cell potential are carried out in this study. From the results it is confirmed that compressive strength increases with increase in percentage replacement of MSP up to 15% of CRD in place of FA. It is found that split tensile strength is directly proportional to the compressive strength. The highest electrical resistivity values were obtained for Normal Concrete with 100% CRD and significant increase in resistivity values for SCC.

POSSIBILITY OF USING WASTE PAINTING POWDER FOR METAL SURFACE FINISHING SLUDGE STABILIZATION

The process of powder coating produces two kinds of waste: metal surfaces finishing sludge and waste painting powder. Before disposal, waste painting powder is sintered and converted into a solid mass. This work investigated the possibility of using waste painting powder for metal surface finishing (phosphating) sludge stabilization. Tests for heavy metal leaching from three different phosphating sludges and from sintered samples were carried out. The content of hexane soluble substances in the sludge and in the stabilized samples was also tested. The investigation has shown that waste painting powder sintering is not suitable for metal finishing sludge stabilization since due to this method the leachability of Zn was reduced by 67%, Fe – 54%, and Cu – just by 42%. DOI: http://dx.doi.org/10.5755/j01.ct.60.2.1718

Effect of Temperature and Carbon Contents on the Synthesis of β-SiC from Silicon Sludge by Direct Carbonization Method

β-SiC powder was synthesized using silicon sludge from photovoltaic silicon-wafer production by varying heat treatment temperature and carbon contents. The synthesized β-SiC powder and silicon sludge was analyzed by XRD, SEM, FT-IR and Particle size analysis. It is known that the conversion of SiC from the mixture of Silicon and Carbon is mainly affected by the mole ratio of C/Si and heat treatment temperature. In this study, the influence of reaction temperature and carbon contents on the synthesis of β-SiC from silicon sludge was examined.

Strength and Permeability Characteristics Study of Self-Compacting Concrete Using Crusher Rock Dust and Marble Sludge Powder

Self-compacting concrete (SCC) is one of the most significant advances in concrete technology over the past two decades. SCC was developed to ensure adequate compaction through self-consolidation and facilitate placement of concrete in structures with congested reinforcement and in restricted areas. This paper aims to focus permeability study of self-compacting concrete (SCC) made with industrial wastes, i.e., marble sludge powder (MSP) from marble processing and crusher rock dust (CRD) from stone crushing industries. MSP can be used as filler and it helps to reduce the total voids content in concrete. Consequently, this contributes to improve the strength of concrete. An experimental investigation has been carried out to study the combined effect of addition of MSP and CRD on the durability of SCC. Water absorption, water permeability (flow), Ionic flow (Rapid Chloride ion penetrability) tests were conducted to measure the permeability of SCC and the results were compared with the normal concrete made up of river sand (NCRS) and the normal concrete made up of CRD (NCCRD). Test results indicate that the replacement of river sand with MSP and CRD in SCC reduces the permeability and does not affect the compressive strength.

Recycling CMP sludge as a resource in concrete

Sludge, a byproduct of chemical mechanical polishing (CMP) used in integrated-circuit (IC) industries, is composed of hazardous materials such as nano-particles of SiO2, Al2O3, CaF2, and unknown organics. These nano-particles are potentially dangerous if released into the environment. Preliminary studies are carried out on sludge-blended cement concrete (SBCC) formed into specimens of cylindrical concrete with 10cm diameter and 20cm height. They are with 10wt.% cement replaced by CMP sludge powder. Three water/cementitious (W/C) ratios were selected to mold the specimens for setting time, XRD analysis, TCLP analysis and compressive strength and stress–strain tests, respectively. TCLP test results revealed that the concentrations of leached heavy metals were substantially below the regulatory thresholds. The strengths of the SBCC specimens were comparable to those of the ordinary Portland cement concrete (OPCC) specimens with 3-day curing and about 22–38% much higher than those of OPCC cylindrical concrete specimens at 7–91days of age. These results demonstrate the feasibility of recycling CMP sludge into construction materials, a positive step for sustainable development.

Properties improvement of paper mill sludge-based granular activated carbon fillers for fluidized-bed bioreactor by bentonite (Na) added and acid washing

Properties improvement of paper mill sludge (PMS) based granular activated carbon fillers for fluidized-bed bioreactor (FBBR) was investigated in this study. Bentonite (Na) powders were blended in the dewatered paper mill sludge powders to strengthen the abrasion resistance strength of the fillers. Different acid washing treatments were studied to produce FBBR fillers with optimum performance. The results indicated that granulation was easy and the abrasion resistance strength of the fillers increased by 15% with 8wt% of bentonite (Na) added. Acid washing treatment prior to activation had a better effect on the removal of Fe than post-activation acid washing treatment. HCl was the most appropriate acid during the acid washing treatment. The optimum acid washing treatment was carried out prior to activation with 2M HCl soaking for 6h. After acid washing treatment, the fillers with grain density of 1170kg/m3, specific surface area of 176m2/g were obtained.

Reuse of waste water from ready‐mixed concrete plants

PurposeThe purpose of this study is the examination of the properties of waste water obtained from a ready‐mixed concrete plant and its utilization potential as mixing water for concrete production.Design/methodology/approachSamples of waste water from several points of a water recycling process from a ready‐mixed concrete plant were examined for their chemical properties (Cl‐, SO42‐, alkalies, total solids, pH) and compared with the specifications applied for concrete mixing water. Also samples of dry sludge powder from the water‐recycling process tank were taken and tested for their chemical composition, particle size distribution, mineralogical composition and thermogravimetrical results. The water samples were examined for their behavior in concrete specimens with and without admixtures and also for their effect in water demand and setting times in cement pastes.FindingsAll tests showed that waste water is suitable for concrete mixing water and that it can be used without any treatment or dilution, thus contributing to water saving.Practical implicationsWaste water from ready‐mixed concrete plants is classified as waste hazardous for disposal due to its high pH value (over 11.5). Very few ready‐mixed concrete plants that recycle waste water follow a complicated process through multiple overflows and a stage of neutralization, with HClaq addition.Originality/valueIt is obvious that the results of this investigation contribute to the protection of the environment from hazardous waste water disposal and the ready‐mixed concrete industry from fresh water costs and any additional cost for buying and conserving an unnecessarily complicated water‐recycling system.

Analysis of the Influence of Dimensionless Vibration Number on the Drying of Pastes in Vibrofluidized Beds

The purpose of this work is to evaluate the operation of a vibrofluidized bed of inert particles in the transient and steady-state regimes for water evaporation and for drying of domestic sewage sludge. The feeding rate was initially set on 10 mL/min and this value has been gradually raised at 4 mL/min increments until saturated moist conditions were obtained at the bed exit. The bed was operated at 80 and 100°C, with inlet air velocities 20 and 40% above the minimum fluidization velocity. The dimensionless vibration numbers (Γ) were 0.00 and 4.00, the latter one with amplitudes of 0.003 and 0.015 m. For the conditions investigated, the effect of Γ on the drying dynamics was observed to depend on the amplitude and frequency of vibration. The use of vibration with lower amplitude and higher frequency provided the highest powder production. For paste feeding rates from 14 to 38 mL/min, the moisture content of the dried sewage sludge powder varied from around 5 to 10% on a wet basis, tending to increase with the increase of paste feeding rates.

225 Al粉末とアルマイトスラッジを用いた放電プラズマ焼結体のころがり摩耗試験とFEM解析(粉末成形とその評価(1),ものづくりにおける基礎研究と先端技術の融合)

225 Al粉末とアルマイトスラッジを用いた放電プラズマ焼結体のころがり摩耗試験とFEM解析(粉末成形とその評価(1),ものづくりにおける基礎研究と先端技術の融合)

혼합재 치환율에 따른 경량소재의 물리적 특성

Lightweight materials were fabricated using glass abrasive sludge, bottom ash and slag powder in this study. This study tried to draw the correlation between physical properties and internal pore of lightweight material. The content of bottom ash and slag powder was from 10% to 50% and firing temperature from 760℃ to 800℃ in rotary kiln. The lightweight material containing bottom ash or slag powder had a specific gravity of 0.21~0.70 at particle size 2~4 ㎜. Replacement ratio of the admixture increasing with specific gravity increased. Fracture strength of panel made with various lightweight materials was 32~55 ㎏f/㎠ and flexural strength was 11~18 ㎏f/㎠. Fracture strength increased by 72% and flexural strength was 63% compared with reference. Thermal conductivities of panel was 0.07~0.11W/m· k. The water absorption ratios of panel with lightweight materials containing bottom ash were 1.8~2.8% and slag powder were 2.65~2.8%. Excellent results on resistant of water absorption.

Conversion of secondary pulp/paper sludge powder to liquid oil products for energy recovery by direct liquefaction in hot-compressed water

The present work demonstrated that secondary pulp/paper sludge powder, with a higher heating value of 18.3 MJ/kg on a dry basis, could be effectively converted into liquid oil products by direct liquefaction in hot-compressed water with and without catalyst. Treatments of secondary pulp/paper sludge in water at 250–380 °C for 15–120 min in the presence of N 2 atmosphere resulted in yields of water-soluble oils at 20–45 wt% and yields of heavy oils at 15–25 wt%, with higher heating values of 10–15 and >35 MJ/kg, respectively. The higher caloric values for the heavy oil products were accounted for by their compositions of long-chain carboxylic acids, heterocyclic nitrogen compounds and phenolic compounds and derivatives as evidenced by the gas chromatograph (GC)/MS measurements. The liquefaction product yields were significantly influenced by the liquefaction temperature, the residence time, the initial biomass concentration, catalysts and the liquefaction atmosphere (inert or reducing). Within the temperature range (250–380 °C) tested, the lowest temperature produced the highest yield of total oils (at 60 wt%), while the greatest yield of heavy oil (at about 24 wt%) was obtained at 350 °C. If the temperature was fixed at 280 °C, a greater yield of heavy oil (reaching as high as 25 wt% for 120 min) was obtained as the length of reaction time increased. Similarly, a higher initial biomass concentration produced a greater yield of heavy oil but a reduced yield of water-soluble oil. The presence of 0.1 M K 2CO 3 dramatically enhanced organic conversion, but suppressed the formation of both heavy oil and water-soluble oil. The use of the two alkaline earth metal catalysts, i.e., Ca(OH) 2 and Ba(OH) 2, did not alter organic conversion, but it catalyzed the formation of water-soluble oil and produced higher yields of total oil products. It was also demonstrated that the reducing atmosphere (i.e., H 2) in the liquefaction process promoted the heavy oil formation while suppressing the water-soluble oil formation. With the presence of 0.1 M Ca(OH) 2 and 2 MPa H 2, liquefaction of the sludge powder in water at 280 °C for 60 min produced a higher yield of heavy oil (26 wt%), almost two times as high as that in N 2 (13.6 wt%), resulting in a greater net energy efficiency. It was thus suggested that direct liquefaction of secondary pulp/paper sludge in hot-compressed water with Ca(OH) 2 catalyst and in the presence of H 2 could be an effective approach to recovering energy from the waste for production of liquid oil products.

Moisture Adsorption and Desorption Behavior of Sludge Powder

In this work, the moisture adsorption and desorption isotherms were determined with the aim of defining the range of moisture content for storage of sludge powder. Equilibrium moisture content provides the basis for information not only on how much water has been taken out of a system but also on how fast drying is taking place (drying rate). Once the drying process is accomplished, the main concern rests on the storage of the dried final product. Still, the equilibrium moisture content is valuable information in that it has a major effect on the product physical and chemical properties. The present work also addresses the problem of selecting the best fit for equilibrium moisture content of sludge powder out of six well-known correlations for moisture sorption isotherms of solids: Henderson, Henderson-Thompson, Chung-Pfost, Chen-Clayton, Modified Halsey and Oswin. The equilibrium moisture content was determined by the static method (saturated salt solutions), in which the atmosphere surrounding the product is in equilibrium with the product without mechanical movement of the air or the product. Experiments were carried out under isothermal conditions at 20 and 40 °C. By calculating the regression coefficient, the residuals and the bias measure of Box for the equilibrium moisture content, the study showed that the Oswin Model was the most suitable. The range enclosed within the adsorption isotherm at 40°C and the desorption isotherm at 20°C defines the moisture extremes for storage in most tropical areas of the world.

Recycle of rare earth sintered magnet powder scraps as electromagnetic wave absorbers in gigahertz range

Abstract The electromagnetic (EM) wave absorbers were prepared from the magnetite powders obtained as a byproduct in the recycle process for the sludge powder scraps of NdFeB-type sintered magnets. The resulting EM wave absorbers showed the minimum RL value of −32 dB at 16.5 GHz with 1.2 mm thickness. Reduction of the magnetite powders leads to improve the EM wave absorption properties (RL

Evaluation of water treatment sludge as a catalyst for aqueous ozone decomposition

Abstract A new, novel, efficient, and stable green catalyst has been successfully used as a catalyst in aqueous ozone decomposition in acidic medium. The catalyst was characterized by using X-ray fluorescence (XRF), transmission electron microscope (TEM), scanning electron microscope (SEM), and X-ray diffraction (XRD) techniques. The sludge mainly consists of various metal and non-metal oxides. The effect of various experimental parameters such as catalyst loading, initial ozone concentrations, and various metal oxide catalysts on the decomposition of ozone was investigated. The decomposition of dissolved ozone was substantially enhanced by increasing the catalyst loading from 125 to 750 mg and by increasing the initial ozone concentration. The ozone decomposition efficiencies of Al 2 O 3 , SiO 2 , TiO 2 , Fe 2 O 3 , ZnO, and sludge have been studied and the efficiencies of these catalysts were found to be in the following order: ZnO ≈ sludge > TiO 2 > SiO 2 > Al 2 O 3 ≈ Fe 2 O 3 . The catalytic stability was also investigated for up to four successive cycles and it was found that the catalyst was stable and ozone did not affect the catalyst morphology and its composition. However, the surface area of the catalyst increased after 1st cycle then it became stable. It was concluded that the sludge powder used in this study was a promising catalyst for aqueous ozone decomposition.

Concrete Sludge Powder for Soil Stabilization

Concrete sludge is an industrial waste produced from ready-mixed concrete plants. Every year, a large quantity of concrete sludge is produced in Japan. At the same time, practical, large-scale disposal options for the concrete sludge are limited, and the cost of disposal is high. Furthermore, the disposed concrete sludge may cause serious environmental and land use problems. A new way to recycle the concrete sludge and reuse large amounts of it is much desired. An innovative technology to cost-effectively recycle concrete sludge and use the recycled material in road construction was developed. Experiments were conducted to study the suitability and effectiveness of the dried sludge powder as a soil stabilizer to improve the load-bearing strength for a clay soil with high moisture content. The tests results showed that adding dried sludge powder to the selected soil with high moisture content can significantly decrease the water content, plasticity index, and frozen heave of the soil while greatly improving the load-bearing strength. The stabilizing effectiveness of the dried sludge powder is greater than that of quicklime in early stages. However, to obtain the best benefit and the best construction quality, some measures should be taken.

Effect of sludge water from ready-mixed concrete plant on properties and durability of concrete

Besides the increasing disposal cost, sludge water, a wastewater washout from ready-mixed concrete plant, has caused environmental impact problems. This paper investigates the utilization and recycling of sludge water as mixing water for concrete production. The basic properties of sludge water were obtained according to ASTM standards. The properties of dry sludge powder such as chemical compositions and physical properties were investigated. The properties of fresh concrete studied were unit weight, slump, and temperature rise. The mechanical properties of concrete, such as compressive strength and modulus of elasticity, were studied. The durability aspects, such as drying shrinkage and weight loss due to acid attack, were investigated. For parametric study, sludge water was used as a replacement of tap water varying from 0% to 100% by weight. The water-to-cement ratios were 0.5, 0.6, and 0.7, respectively. In this study the sludge water tested has a high alkalinity and the total solids content exceeding the limit of ASTM C94, contributing to the more porous and weaker matrix. As a result, when increasing the percentage of sludge water in mixing water, the drying shrinkage and weight loss due to acid attacks increased, and the slump and strength decreased. However, the unit weight and temperature of fresh concrete were not affected by the use of sludge water.

Fabrication of Composite Material Using Alumina Agglomerated Sludge and Aluminum Powder by Spark Plasma Sintering

Fabrication of Composite Material Using Alumina Agglomerated Sludge and Aluminum Powder by Spark Plasma Sintering

Electromagnetic wave absorption properties of iron/rare earth oxide composites dispersed by amorphous carbon powder

The sludge powders of Nd–Fe–B sintered magnets were oxidized at 250–325 °C for 2 h and then the α-Fe/Fe 2B/Nd 2O 3/amorphous carbon (a-C) nanocomposite powders were prepared by ball-milling the sludge with the a-C powder for 12–40 h. The resin composites of 75 mass% of these nanocomposite powders showed excellent electromagnetic wave absorption properties in GHz range. The effective absorption of RL <−20 dB were observed in a range of 7.6–18.0 GHz and the minimum absorption peaks around −58.5 dB appeared at 12.0 GHz with matching thickness of 1.9 mm for the samples heated at 300 °C for 2 h and then ball-milled with 4.8 mass% a-C for 30 h.