Waste Gypsum Board Research Articles

Experimental study on water content measurement of recycled gypsum derived from waste gypsum board

Experimental study on water content measurement of recycled gypsum derived from waste gypsum board

A study on measurement of water content of recycled gypsum derived from waste gypsum board using refractive index of aqueous glycerol solution

A study on measurement of water content of recycled gypsum derived from waste gypsum board using refractive index of aqueous glycerol solution

Effect on Rotation Speed on Thermal Dehydration Characteristics of Waste Gypsum Particles in a Constant Volume Rotary Vessel by Heating.

This study examined the thermal dehydration characteristics of CaSO4∙2H2O in a constant-volume rotary vessel. The experiment used CaSO4∙2H2O particles obtained from the crushed waste gypsum board. The particle size ranged from 850 to 2000 μm, and the experiment was carried out at varying rotation speeds of 1, 10, and 35 rpm, with the vessel temperature heated to 180 °C. Temperature and pressure inside the vessel were measured simultaneously using the thermocouple and the pressure sensor. The XRPD measurement analyzed the transition of CaSO4∙2H2O after the heating of particles. The result showed that the temperature growth rate was similar for high rotation speeds of 10 and 35 rpm, while periodic temperature changes occurred at the low rotation speed of 1 rpm. A distinguishing flow pattern was observed at the low rotation speed, and the particles inside the vessel collapsed periodically downward. This particle behavior was related to the temperature distribution of the rotation speed of 1 rpm. Additionally, the pressure in the vessel increased rapidly at higher rotation speeds. This trend indicates the desorption of the crystal water of CaSO4∙2H2O due to the increasing temperature in the case of high rotation speed. Also, the XRPD measurement results showed the appearance of CaSO4∙0.5H2O under the higher rotation speed conditions, and the mass fraction of CaSO4∙0.5H2O increased with the rotation speed. Overall, the present study suggests that rotation speed plays a crucial role in determining the heat conduction and heat transfer of particles in a constant-volume rotary vessel.

Valorization of waste gypsum board as a green adsorbent for efficient fluoride removal in groundwater and wastewater treatment

The escalating generation of construction waste during building reconstruction and remodeling underscores the significance of recycling for environmental preservation and resource conservation. In this context, we propose the valorization of waste gypsum board (WGB), a common construction waste material, as a value-added environmental purification agent. WGB, composed primarily of CaSO4, displays the potential to react with fluoride to form CaF2, making it a promising adsorbent for fluoride removal. Through density functional theory analysis, we determined that WGB possesses mesoporous characteristics, with pore sizes ranging from 1 to 20 nm. While thermal treatment has been effective in enhancing fluoride adsorption on other adsorbents, our investigations revealed that the crystalline structure (CaSO4) of WGB remained unchanged under thermal treatment, limiting its impact on the fluoride adsorption capacity. Nevertheless, WGB exhibited a remarkably high fluoride adsorption capacity (285.90 mg/g), surpassing those of other reported adsorbents. Furthermore, the WGB demonstrated excellent fluoride removal performance, even at higher solution pH levels. In artificial wastewater, a dose of 3.33 g/L WGB achieved a remarkable removal efficiency (> 95%). The applicability of WGB was validated by successful fluoride removal in real wastewater and groundwater, with 94% of fluoride in groundwater removed using 0.33 g/L of WGB and 97% of the fluoride in the wastewater removed with 1.67 g/L WGB. This study opens a promising pathway, demonstrating the potential of WGB as a green adsorbent for the effective treatment of fluorine-contaminated wastewater and groundwater, transcending its traditional role in waste recycling.

Permeable Reactive Concrete Using Recycled Waste Materials for Nutrient Contamination Removal in Urban Surface Runoff

In recent years, stormwater control measures (SCMs) such as permeable concrete pavement have been experimentally investigated and used to manage hydrologic and water quality impacts of stormwater runoff. Research revealed the potential of permeable pavement in reducing and delaying peak flow rate, reducing runoff volume, and capturing heavy metals and other particulate-bound pollutants from stormwater runoff. However, few studies have evaluated the effects of permeable pavement on nutrients in stormwater runoff. This research aims to produce permeable reactive concrete (PRC) from waste fly ash, waste gypsum board and waste coco peat and to investigate its effectiveness in removing nutrient contamination present in stormwater or urban surface runoff. The raw materials underwent through granulation process to produce granulated filtering media (GFM). Cylindrical samples of PRC were then made and subjected to various physical and water quality tests. The use of GFM as partial coarse aggregates of PRC for urban surface runoff management and nutrient contamination removal has been tested and evaluated. After performing all the tests, the researchers concluded that GFM as partial coarse aggregates of PRC is effective due to the significant increase in infiltration rate of the entire sample compared to the traditional permeable concrete that has an average infiltration rate of 2-6 mm/s. The results in the water quality test revealed that PRC with GFM as partial coarse aggregates lessen the nitrate, phosphate, and ammonia that are present on urban surface runoff.

Ideal quality control for waste gypsum board recycling and social implementation

Gypsum board is used all around the world as a key material for the construction industry. One of the challenges with this product is the resulting waste, the majority of which is simply thrown away. Dr Kazuto Endo, of the National Institute for Environmental Studies in Japan, has been investigating the issue of gypsum board waste recycling for the past 15 years and has been instrumental in the creation of quality guidelines for recycled gypsum powder and the implementation of these standards across the industry, resulting in higher levels of recycling and safer, more sustainable use of resources. Endo's work, both on recycling gypsum board waste and the development and implementation of quality control guidelines for this process, have the potential to play a significant role in increasing both safety and sustainability of the use of this resource.

Influence of sulfur trioxide in clinker on the hydration heat and physical properties of Portland cement

The cement industry has achieved stable usage of waste gypsum board in clinker production. However, few studies have focused on the heat of hydration and physical properties of cements with high-SO3 clinker with different C3A and gypsum contents. Clinker with different amounts of SO3 and coexisting C3A was prepared in an electric furnace. Cement samples were then prepared by adding gypsum. Increasing the clinker SO3 content accelerated the alite reaction and caused aluminate hydrate reaction to occur later. Compressive strength at 3 days increased with SO3 content whereas that after 28 days decreased. The drying shrinkage strain of mortar decreased with increasing SO3 content of the clinker and gypsum at each C3A content. The decrease of drying shrinkage attributed to SO3 in the clinker was smaller than that caused by gypsum SO3. As the clinker SO3 content increases, cement physical properties can be maintained by adjusting the gypsum content.

Water Purification Properties of Silica-Coated Waste Gypsum Board

Water Purification Properties of Silica-Coated Waste Gypsum Board

Mineralogical study of high SO3 clinker produced using waste gypsum board in a cement kiln

Portland-cement clinker with a SO3 content up to 3.4% was produced in a cement kiln using waste gypsum board, and the influence of SO3 content on the clinker mineral was investigated. Formation of anhydrite (CaSO4) in the clinker with over 1.6%-SO3 was attributed to a thermodynamic effect but not to the residual waste gypsum board. The mineral composition with a higher SO3 content exhibited a similar trend to those found in the previous studies. The measured alite and belite contents in the clinker agreed with the calculated values derived from modified Bogue’s equation which considers the substitution of sulfur and aluminum by silicon in belite. This substitution increased the lattice parameters of belite. The M1 phase in the alite increased with an increase in SO3 content in the clinker. These characteristics of the high-SO3 clinker indicates that the waste gypsum was decomposed stably to clinker minerals in the cement kiln.

Study on Recycling Method of Waste Gypsum Board Paper

Study on Recycling Method of Waste Gypsum Board Paper

Theoretical Study on the Production of Environment-Friendly Recycled Cement Using Inorganic Construction Wastes as Secondary Materials in South Korea

The cement industry endeavors to reduce CO2 emissions from cement manufacturing by utilizing industrial by-products as alternative fuels and developing secondary concrete products from construction wastes. With these efforts, the cement industry is attempting to become more eco-friendly and reduce environmental load. This study analyzed the possibility of using inorganic construction wastes to produce environmentally friendly recycled cement using the process of proportioning. To this end, the types and production trends of recyclable construction wastes and previous studies on the development of recycled cement using such construction wastes were analyzed. Based on this analysis, recyclable inorganic construction wastes were selected, and real waste was collected. The chemical composition of each inorganic construction waste was analyzed using X-ray fluorescence, and the composition of ordinary commercial cement was used as the baseline. After the collected inorganic construction wastes were mixed, they were fired using the Bogue formula. The mineral components of clinker, which was generated from the firing process, were predicted and analyzed. Waste gypsum board and ceiling materials were shown to contain large amounts of CaO, which could substitute limestone—a key component of cement. These results suggested that if the limestone content was greater than 85 wt %, mixing inorganic construction wastes in appropriate proportions could be used to develop various types of Portland cement.

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 2. Fixed Bed

This paper is the second of two describing the use of shredded waste gypsum board (SWGB) as an additive during combustion of biomass. The focus of this paper is to determine whether SWGB can be use ...

Synthesis of Calcium Ferrite from Waste Gypsum Board

Synthesis of Calcium Ferrite from Waste Gypsum Board

廃石こうボードを有効利用した晶析型脱リン材の作製

廃石こうボードを有効利用した晶析型脱リン材の作製

Waste Gypsum Board and Ash-Related Problems during Combustion of Biomass. 1. Fluidized Bed

This paper is the first in a series of two describing the use of waste gypsum boards as an additive during combustion of biomass. This paper focuses on experiments performed in a bench-scale bubbling fluidized-bed reactor (5 kW). Three biomass fuels were used, i.e., wheat straw (WS), reed canary grass (RC), and spruce bark (SB), with and without addition of shredded waste gypsum board (SWGB). The objective of this work was to determine the effect of SWGB addition on biomass ash transformation reactions during fluidized bed combustion. The combustion was carried out in a bed of quartz sand at 800 or 700 °C for 8 h. After the combustion stage, a controlled fluidized–bed agglomeration test was carried out to determine the defluidization temperature. During combustion experiments, outlet gas composition was continuously measured by means of Fourier transform infrared spectroscopy. At the same place in the flue gas channel, particulate matter was collected with a 13-stage Dekati low-pressure impactor. Bottom and cyclone fly ash samples were collected after the combustion tests. In addition, during the combustion tests a 6-h deposit sample was collected with an air-cooled (430 °C) probe. All ash samples were analyzed by means of scanning electron microscopy combined with energy dispersive X-ray spectrometry for elemental composition and with X-ray powder diffraction for the detection of crystalline phases. Decomposition of CaSO4 originating from SWGB was mainly observed during combustion of reed canary grass at 800 °C. The decomposition was observed as doubled SO2 emissions. No significant increase of SO2 during combustion of SB and WS was observed. However, the interaction of SWGB particles with WS and SB ash forming matter, mainly potassium containing compounds, led to the formation of K2Ca2(SO4)3.

廃石膏ボードを利用したカルシウムフェライトの製造

廃石膏ボードを利用したカルシウムフェライトの製造

Hydrogen Sulfide Generation Suppression by Nitrate Addition �C Application to Solid Waste Landfill Site

In Japan, three deaths were reported at an inert solid waste landfill site after exposure to hydrogen sulfide (H2S) generated at the site. H2S gas is produced when sulfate-reducing bacteria (SRB) convert sulfate derived from waste gypsum board under anaerobic conditions. The recommended countermeasure is to supply oxygen by installing gas venting pipes. However, a large cost is necessary for pipe installation and the pipes are not applicable to coastal landfill sites. On the other hand, H2S generation suppression by nitrate (NO3) addition has been reported in sewage systems. In this study, in order to develop a method to suppress H2S generation by NO3 addition at a landfill site, the extent of suppression was quantitatively estimated. When NO3 reagent was added at the rate of 0.46 mmol-NO3/(L•d) into a liquid from which H2S gas was generated at the rate of 0.21 ± 0.05 mmol-H2S/(L•d), H2S generation rate was decreased to approximately 1/4 of the original rate. Although it was difficult to maintain the concentration of NO3 because it tended to disappear rapidly, the frequent addition of NO3 reagent to maintain the concentration of approximately 430 mg-NO3/L enabled us to control H2S concentration to below 1000 ppmv for one month and H2S generation rate to below 1/20 of the original rate.

Utilization of calcium sulfide derived from waste gypsum board for metal-containing wastewater treatment

To achieve recycling of waste gypsum boards (CaSO4), production of calcium sulfide by reductive decomposition of CaSO4 was investigated and the decomposition product of CaS was used as a sulfuration agent in the treatment of nickel-containing simulated wastewater. At the end of the experiment, residual nickel concentration and filtration characteristics of the slurry formed by adding CaS to the nickel-containing wastewater were investigated. Regarding the reductive decomposition of CaSO4, it was found that CaS could be effectively generated by CaSO4 reductive decomposition with graphite and the CaS content in the final product was greater than 80% when the reductive decomposition was carried out for one hour at a temperature of 1273 K, under N2 atmosphere. Then, in the sulfuration treatment of nickel-containing wastewater with CaS, the applicability of CaS as a sulfuration agent was confirmed and the nickel concentration in the simulated wastewater was reduced from 100 mg-Ni l-1 to a value below 1.0 mg l-1, when the CaS was added to the simulated wastewater at CaS to Ni molar ratio of 1.3. Moreover, sulfide slurry obtained by adding CaS was characterized by lower average specific filtration resistance and compressibility coefficient, compared to hydroxide slurry formed by the conventional precipitation treatment.

Salt-Affected Soil Amelioration with Flue Gas Desulfurization By-Products and Waste Gypsum Board in Tianjin, China

Soil salinization has progressed rapidly in northeastern and western China. In addition, air pollution is one of the most serious environmental problems. To alleviate the problems of soil salinization, food shortages, and air pollution, we have studied the amelioration of salt-affected soil using the by-products of flue gas desulfurization (FGD). Moreover, the recycling of waste gypsum produced at both new construction sites and demolition work sites has become a serious challenge in Japan. FGD gypsum in China and gypsum separated from waste gypsum board (WGB) in Japan were added to salt-affected soil as soil amendments. The effects of lignite and peat, which contains humic substances, were also investigated. With treatment, the soil's chemical parameters were restored, and agricultural production increased in all fields. Therefore, we have confirmed the effectiveness of amelioration of salt-affected soil by both FGD and WGB gypsum. Moreover, the use of lignite and peat with gypsum accelerated the effect of soil amelioration. This result suggests that the application rates of both types of gypsum could be reduced. Thus, we can propose a new salt-affected soil reclamation method using WGB, lignite, and peat in China.

Treatment of Fluoride in Wastewater and Waste Gypsum Board Based on Nano-Surface Reaction of Calcium Phosphate

Treatment of Fluoride in Wastewater and Waste Gypsum Board Based on Nano-Surface Reaction of Calcium Phosphate