Simultaneous removal of fluoride and phosphate from semiconductor wastewater via chemical precipitation of calcium fluoride and hydroxyapatite using byproduct of recycled aggregate.

Semiconductor wastewater with high concentrations of fluoride and phosphate is an environmental issue that cannot be ignored. Moreover, the byproduct of recycled aggregates, concrete fines, cannot be reused in concrete manufacturing, which is a key issue to address for the sustainable development of the concrete industry. The objective of this study was to tackle the crucial environmental issues of these two industries by developing concrete fines as an alternative material to treat semiconductor wastewater. The chemical precipitation of calcium fluoride and hydroxyapatite in the presence of concrete fines was determined as the mechanism underpinning the removal of fluoride and phosphate in wastewater. Owing to the wide range of contaminant concentration and solution pH and the possibility of multi-stage treatment, the effects of the initial contaminant concentration (F: 100-1000 mg/L; P: 20-200 mg/L) and solution pH (pH: 2-7) on the removal reactions were determined. The highest F and P removal percentages were more than 99%, and the final F and P concentrations met the effluent standard (F: 15 mg/L, P: 1.3 mg/L). The removal reactions of F and P are generally in competition, and the removal of F has priority over the removal of P. The pseudo-second-order model can describe the kinetics of the removal reactions well. The formation of fluorapatite can reduce the F concentration below the concentration achievable by CaF2 precipitation alone. Furthermore, using the byproduct of recycled aggregates instead of conventional chemicals to treat semiconductor wastewater is promising in terms of reducing CO2 emissions, and prospective applications are discussed. This study can lead to the development of a sustainable and clean process for semiconductor wastewater treatment using byproducts from the concrete industry.

Investigation of performance and mechanism of zinc removal from polluted water by concrete fines derived from aggregate recycling: From problematic byproducts to effective adsorbent.

Concrete fines are byproducts produced from aggregate recycling. Because of their properties, they cannot be directly recycled for use in concrete manufacturing, which is problematic to move the cement and concrete industry toward sustainable development goals and reduce its environmental impact. Taking advantage of concrete fines unique properties was regarded as a possible research direction. The hydrated cement fraction was expected to provide alkalinity to neutralize the acidic solutions, while calcium related compounds were expected to provide the function of heavy metals removal. In this research, concrete fines were used to remove Zn from acid mine drainage as an active treatment. The removal performance was comprehensively investigated. The maximum capacity of Zn-adsorption is 111.9 mg/g, and almost 100% Zn can be removed for an initial Zn concentration of 20 mg/L. The dominant reaction mechanism of Zn adsorption to concrete fines was determined to be ion-exchange reaction with surface complexation and precipitation. The Zn2+ ions in solution can exchange with the Ca2+ ions in calcium silicates and calcium silicate hydrates in concrete fines and replace the protons released by ionization of the silanol group for complexation, and thus Zn removal is not limited to an alkaline environment or high initial Zn concentration. The acidity was alkalized by hydration reaction, mainly consuming calcium hydroxide. Based on these mechanisms, concrete fines are effective adsorbent to remove Zn without the need for the synergistic reactions of other metals and for making the aqueous solution strongly alkaline, even in the strongly acidic environments and in effluents with high Zn concentration. Through evaluation and comparison of Zn adsorption capacity with other materials, concrete fines were regarded as promising alternative adsorbent for Zn removal.

Potential of major by-products from non-ferrous metal industries for CO2 emission reduction by mineral carbonation: a review.

By-products from the non-ferrous industry are an environmental problem; however, their economic value is high if utilized elsewhere. For example, by-products that contain alkaline compounds can potentially sequestrate CO2 through the mineral carbonation process. This review discusses the potential of these by-products for CO2 reduction through mineral carbonation. The main by-products that are discussed are red mud from the alumina/aluminum industry and metallurgical slag from the copper, zinc, lead, and ferronickel industries. This review summarizes the CO2 equivalent emissions generated by non-ferrous industries and various data about by-products from non-ferrous industries, such as their production quantities, mineralogy, and chemical composition. In terms of production quantities, by-products of non-ferrous industries are often more abundant than the main products (metals). In terms of mineralogy, by-products from the non-ferrous industry are silicate minerals. Nevertheless, non-ferrous industrial by-products have a relatively high content of alkaline compounds, which makes them potential feedstock for mineral carbonation. Theoretically, considering their maximum sequestration capacities (based on their oxide compositions and estimated masses), these by-products could be used in mineral carbonation to reduce CO2 emissions. In addition, this review attempts to identify the difficulties encountered during the use of by-products from non-ferrous industries for mineral carbonation. This review estimated that the total CO2 emissions from the non-ferrous industries could be reduced by up to 9-25%. This study will serve as an important reference, guiding future studies related to the mineral carbonation of by-products from non-ferrous industries.

Removal of fluoride ions from aqueous solution by metaettringite.

Fluoride contamination is a major problem in wastewater treatment. Metaettringite (which has previously shown enhanced anion adsorption) was investigated as a possible adsorbent to remove fluoride from low-concentration solution (25 mg-F/L). The fluoride removal properties of ettringite and metaettringite were first compared at pH 10, and metaettringite was found to be more effective. The dominant reaction mechanism for fluoride adsorption in metaettringite was found to be recrystallization of metaettringite by rehydration; this was accompanied by precipitation of calcium fluoride. The adsorption kinetics followed the pseudo-second order model. Metaettringite was also able to remove fluoride effectively in low pH environment (i.e., at pH 3.5). The influence of coexistence of sulfate ions in solution on the fluoride removal performance was investigated, and a small decrease in performance was noted. The residual fluoride concentrations obtained with higher doses of metaettringite were lower than those specified by the Japanese effluent standard (non-coastal areas: 8 mg-F/L; coastal areas: 15 mg-F/L). The fluoride removal capacity of metaettringite was compared with those of other solid materials. The observed maximum capacity was 174.7 mg-F/g-metaettringite. In the case of high fluoride concentration solution, the main removal mechanism will be changed to calcium fluoride precipitation. In general, metaettringite is regarded as promising material for fluoride removal in wastewater treatment.

Utilization of low-calcium fly ash via direct aqueous carbonation with a low-energy input: Determination of carbonation reaction and evaluation of the potential for CO2 sequestration and utilization.

Environmental impacts from coal-fired power generation that produces large amounts of CO2 and fly ash are of great interest. To reduce negative environmental impacts, fly ash utilization was investigated via a direct aqueous carbonation with a low-energy input in which the alkali calcium content in the fly ash reacted with CO2 to form carbonate. Raw fly ash was characterized to understand the potential for direct aqueous carbonation of fly ash. The performance of the fly ash as a calcium source for direct aqueous carbonation at atmospheric pressure was investigated for different solid-liquid ratios and introduced CO2 concentrations. Variations in fly ash elemental composition, reaction solution pH, CO2 concentration in the reactor outlet, CO2 uptake efficiency, CaCO3 content and degree of carbonation were used to illustrate this process reaction. The maximum CO2 uptake efficiency was ~0.016 g-CO2/g-fly ash. This value was compared with previous studies, and the CO2 uptake efficiency was comparable despite the use of a low-energy input method, i.e., direct aqueous carbonation with atmospheric pressure and unconcentrated CO2. The calculated maximum degree of carbonation was 31.0%, which corresponds to 0.0063 g-CO2/g-fly ash. Carbonated product characterization confirmed the carbonation reaction mechanism and safety for further utilization. A comparison of CO2 uptake efficiency in this work with previous work, and considering the energy input and reactive species content, is provided. An assessment of the CO2 reduction potential is provided.

Emission fluxes of styrene monomers and other chemicals for products containing expanded polystyrene beads.

Styrene in indoor air can adversely affect human health. In this study, styrene monomer and other chemical emission fluxes for products containing expanded polystyrene beads (pillows, cushions, and soft toys) were measured at various temperatures to simulate typical product use. The contributions of the products to styrene and other chemical concentrations in indoor air and human exposure to these chemicals were estimated, and health risk assessments were performed. The styrene monomer emission fluxes for the samples at 25°C were between 25.3 and 8.73×103 µg/(m2 h). The styrene emission fluxes for the product surfaces increased strongly as the temperature increased, from between 124 and 2.44×104 µg/(m2 h) at 36°C (simulating human body temperature) to between 474 and 4.59×104 µg/(m2 h) at 50°C (simulating inside an automobile in summer). The hexane, heptane, toluene, octane, ethylbenzene, m- and p-xylene, o-xylene, and dodecane emission fluxes at 25°C for the sample that emitted the analytes most readily were high. The maximum estimated styrene and xylene concentrations in indoor air caused by emissions from expanded polystyrene beads at 36°C in a bedroom and automobile were higher than the relevant guidelines. The maximum contribution of a product containing expanded polystyrene beads in a living room, bedroom, or automobile could cause the total volatile organic compound concentration in air to exceed the advisable value (400 µg/m3). The estimated maximum hazard quotients for styrene, toluene, and xylene emitted by a product containing expanded polystyrene beads at 36°C in a bedroom were 0.59, 0.30, and 0.37, respectively. These non-carcinogenic risk values for single products could contribute to the non-carcinogenic risk thresholds being exceeded when multiple products and other sources of chemicals are taken into consideration. The estimated styrene concentrations suggest that products containing expanded polystyrene beads are important sources of styrene to indoor air.

CO2 Utilization via Direct Aqueous Carbonation of Synthesized Concrete Fines under Atmospheric Pressure.

Mineral carbonation using alkaline wastes is an attractive approach to CO2 utilization. Owing to the difference between waste CO2 and feedstock CO2, developing CO2 utilization technologies without CO2 purification and pressurization is a promising concept. This study investigated a potential method for CO2 utilization via direct aqueous carbonation of synthesized concrete fines under atmospheric pressure and low CO2 concentration. The carbonation reaction with different solid-liquid ratios and different concentrations of introduced CO2 was examined in detail. Under basic conditions, a CO2 uptake of 0.19 g-CO2/g-concrete fines demonstrated that direct aqueous carbonation of concrete fines under atmospheric pressure and low CO2 concentration is effective. The CaCO3 concentration, degree of carbonation, and reaction mechanism were clarified. Furthermore, characterization of the carbonated products was used to evaluate ways of utilizing the carbonated products.

Non-electrolytic synthesis of copper oxide/carbon nanocomposite by surface plasma in super-dehydrated ethanol.

Electrolytic processes are widely used to synthesize different nanomaterials and it does not depend on what kind of the method has been applied (wet-chemistry, sonochemistry, plasma chemistry, electrolysis and so on). Generally, the reactions in the electrolyte are considered to be reduction/oxidation (REDOX) reactions between chemical reagents or the deposition of matter on the electrodes, in line with Faraday's law. Due to the presence of electroconductive additives in any electrolyte, the polarization effect of polar molecules conducting an electrical current disappears, when external high-strength electric field is induced. Because initially of the charge transfer always belongs of electroconductive additive and it does not depend on applied voltage. The polarization of ethanol molecules has been applied to conduct an electric current by surface plasma interaction for the synthesis of a copper oxide/carbon nanocomposite material.

Optimized arrangement of constant ambient air monitoring stations in the Kanto region of Japan.

Continuous ambient air monitoring systems have been introduced worldwide. However, such monitoring forces autonomous communities to bear a significant financial burden. Thus, it is important to identify pollutant-monitoring stations that are less efficient, while minimizing loss of data quality and mitigating effects on the determination of spatiotemporal trends of pollutants. This study describes a procedure for optimizing a constant ambient air monitoring system in the Kanto region of Japan. Constant ambient air monitoring stations in the area were topologically classified into four groups by cluster analysis and principle component analysis. Then, air pollution characteristics in each area were reviewed using concentration contour maps and average pollution concentrations. We then introduced three simple criteria to reduce the number of monitoring stations: (1) retain the monitoring station if there were similarities between its data and average data of the group to which it belongs; (2) retain the station if its data showed higher concentrations; and (3) retain the station if the monitored concentration levels had an increasing trend. With this procedure, the total number of air monitoring stations in suburban and urban areas was reduced by 36.5%. The introduction of three new types of monitoring stations is proposed, namely, mobile, for local non-methane hydrocarbon pollution, and Ox-prioritized.

A cluster analysis of constant ambient air monitoring data from the Kanto region of Japan.

This study demonstrates an application of cluster analysis to constant ambient air monitoring data of four pollutants in the Kanto region: NOx, photochemical oxidant (Ox), suspended particulate matter, and non-methane hydrocarbons. Constant ambient air monitoring can provide important information about the surrounding atmospheric pollution. However, at the same time, ambient air monitoring can place a significant financial burden on some autonomous communities. Thus, it has been necessary to reduce both the number of monitoring stations and the number of chemicals monitored. To achieve this, it is necessary to identify those monitoring stations and pollutants that are least significant, while minimizing the loss of data quality and mitigating the effects on the determination of any spatial and temporal trends of the pollutants. Through employing cluster analysis, it was established that the ambient monitoring stations in the Kanto region could be clustered topologically for NOx and Ox into eight groups. From the results of this analysis, it was possible to identify the similarities in site characteristics and pollutant behaviors.

Preparation and performance of arsenate (V) adsorbents derived from concrete wastes.

Solid adsorbent materials, prepared from waste cement powder and concrete sludge were assessed for removal of arsenic in the form of arsenic (As(V)) from water. All the materials exhibited arsenic removal capacity when added to distilled water containing 10-700 mg/L arsenic. The arsenic removal isotherms were expressed by the Langmuir type equations, and the highest removal capacity was observed for the adsorbent prepared from concrete sludge with heat treatment at 105°C, the maximum removal capacity being 175 mg-As(V)/g. Based on changes in arsenic and calcium ion concentrations, and solution pH, the removal mechanism for arsenic was considered to involve the precipitation of calcium arsenate, Ca3(AsO4)2. The enhanced removal of arsenic for the adsorbent prepared from concrete sludge with heat treatment was thought to reflect ion exchange by ettringite. The prepared adsorbents, derived from waste cement and concrete using simple procedures, may offer a cost effective approach for arsenic removal and clean-up of contaminated waters, especially in developing countries.

Development of a combined real time monitoring and integration analysis system for volatile organic compounds (VOCs).

A combined integration analysis and real time monitoring (Peak Capture System) system was developed for volatile organic compounds (VOCs). Individual integration analysis and real time monitoring can be used to qualitatively and quantitatively analyze VOCs in the atmosphere and in indoor environments and determine the variation in total VOC (TVOC) concentration with time, respectively. In the Peak Capture System, real time monitoring was used to predict future elevations in the TVOC concentration (peak), and this was used an indicator of when to collect (capture) ambient air samples for integration analysis. This enabled qualitative and quantitative analysis of VOCs when the TVOC concentration was high. We developed an algorithm to predict variation in the TVOC concentration, and constructed an automatic system to initiate air sampling for integration analysis. With the system, auto-sampling and analysis of VOCs in a conventional house were conducted. In comparison with background concentrations, the results of peak analysis enabled identification of compounds whose concentration rose. This also enabled an evaluation of possible VOC emission sources.

Estimation of uncertainty in tracer gas measurement of air change rates.

Simple and economical measurement of air change rates can be achieved with a passive-type tracer gas doser and sampler. However, this is made more complex by the fact many buildings are not a single fully mixed zone. This means many measurements are required to obtain information on ventilation conditions. In this study, we evaluated the uncertainty of tracer gas measurement of air change rate in n completely mixed zones. A single measurement with one tracer gas could be used to simply estimate the air change rate when n = 2. Accurate air change rates could not be obtained for n ≥ 2 due to a lack of information. However, the proposed method can be used to estimate an air change rate with an accuracy of <33%. Using this method, overestimation of air change rate can be avoided. The proposed estimation method will be useful in practical ventilation measurements.

Severe degenerative change of multiple organs mediated by chronic active Epstein-Barr virus infection with infected T-cell expansion.

We here report the case of a young Japanese woman diagnosed with chronic active Epstein-Barr virus (EBV) infection. Intensive therapy with the CHOP regimen was partially able to control virus expansion, but various central nervous system symptoms appeared and gradually progressed. EBV-encoded RNA, detected using in situ hybridization, disclosed the presence of EBV in liver and bone marrow tissue, and real-time PCR revealed the presence of EBV in the cerebrospinal fluid (CSF) and serum. CD3+CD4+CD8-CD56- T-cell expansion in the peripheral blood (PB) and CSF was also observed. Atrophic brain changes were progressive, and the patient died of central nervous system disturbance and pulmonary hemorrhage a year after diagnosis. Autopsy revealed that EBV-infected T lymphocytes with a phenotype similar to those seen in PB and CSF had infiltrated multiple organs: the lymph nodes, bone marrow, endocardium, pericardium, myocardium, spleen, liver, and spinal cord. There have been few previous reports of severe degenerative changes in the myocardium, liver, and spinal cord in patients with EBV infection. Although EBV occasionally infiltrates the central nervous system and brain, atrophic changes mediated by EBV are rare. The autopsy results of this case suggest the possibility of EBV-mediated, severe degenerative changes in multiple organs.

Lymphomatoid granulomatosis and diffuse alveolar damage associated with methotrexate therapy in a patient with rheumatoid arthritis.

We report on a patient of rheumatoid arthritis (RA) who sequentially developed an axillary mass and a fatal interstitial pneumonia during a 2-year course of methotrexate (MTX) therapy. Autopsy revealed a systemic lymph node involvement and the diagnosis of Epstein-Barr virus (EBV)-related lymphoproliferative disease (LPD) with the features of lymphomatoid granulomatosis was made. The lung tissue specimens revealed a typical diffuse alveolar damage (DAD), and small nodules consisting of atypical B lymphocytes showing positive staining for EBV were sparsely recognized only in basal lungs. This is the first report of a RA patient receiving MTX therapy sequentially developing MTX-associated lymphomatoid granulomatosis and DAD.

De novo CD5+ diffuse large B cell lymphoma with basophilia in the peripheral blood: successful treatment with autologous peripheral blood stem cell transplantation.

Basophils play an important role in allergic inflammation and are pathologically related to hematological disturbances, such as iron deficiency anemia and myeloproliferative disorders; however, they are only rarely encountered in lymphoid malignancies. Here, we report the case of a 33-year-old man with a bulky mass of the small intestine, multiple paraaortic lymphoadenopathy, pleural effusion, and ascites, who was diagnosed as a case of de novo CD5+ diffuse large B cell lymphoma (DLBCL). This patient showed a marked elevation of the basophil count in the peripheral blood, which appeared to run in parallel with the tumor burden. High dose chemotherapy followed by autologous peripheral blood cell transplantation yielded complete remission, and the patient has remained disease free for 5 years. To the best of our knowledge, this is the first report of a case of de novo CD5+ DLBCL showing marked elevation of the PB basophil count.

Lymphoproliferative disorders in rheumatoid arthritis: clinicopathological analysis of 76 cases in relation to methotrexate medication.

OBJECTIVE: Individuals with rheumatoid arthritis (RA) with or without methotrexate (MTX) medication occasionally develop lymphoproliferative disorders (MTX-LPD and non-MTX-LPD, respectively). The hyperimmune state of RA itself or the immunosuppressive state induced by MTX administration might contribute to development of LPD. Our objective was to characterize MTX-LPD in comparison to non-MTX-LPD and sporadic LPD in patients with RA. METHODS: We compared MTX-LPD to non-MTX-LPD and sporadic LPD by evaluating 48 cases of MTX-LPD, 28 non-MTX-LPD, and 150 sporadic LPD. RESULTS: Later onset age of LPD and female predominance were evident in patients with RA-LPD compared to sporadic LPD. The interval between the diagnosis of RA and LPD in MTX-LPD (median 132 mo) was significantly shorter than that in non-MTX-LPD (240 mo). The frequency of diffuse large B cell lymphoma (DLBCL) and positive rate of Epstein-Barr virus (EBV) in RA-LPD was significantly higher than in sporadic LPD (57.9% vs 42.7%, 27.6% vs 9.9%, respectively). After withdrawal of MTX, 11 of the MTX-LPD cases showed a spontaneous regression of tumors. The 5-year survival rate in RA-LPD (59.2%) was significantly worse than that in sporadic LPD (74.6%). CONCLUSION: The majority of cases of RA-LPD show similar clinicopathological characteristics irrespective of MTX medication, except for spontaneous regression of LPD after withdrawal of MTX in MTX-LPD, and a shorter interval between the diagnosis of RA and LPD in MTX-LPD than in non-MTX-LPD. RA-LPD cases showed younger age of onset, female predominance, unfavorable prognosis, and higher frequencies of DLBCL and EBV positivity compared to sporadic LPD.

Incidence of cytomegalovirus reactivation in patients with inflammatory connective tissue diseases who are under immunosuppressive therapy.

OBJECTIVE: To evaluate the incidence and effect of cytomegalovirus (CMV) reactivation in patients with inflammatory connective tissue diseases (CTD) undergoing immunosuppressive therapy. METHODS: A total of 18 consecutive CMV seropositive patients undergoing immunosuppressive therapy for inflammatory CTD were enrolled. CMV reactivation was determined by detection of CMV-DNA in peripheral blood leukocytes (PBL) or plasma using quantitative real-time polymerase chain reaction. RESULTS: CMV reactivation was detected in PBL in 7 of 17 evaluable patients (41%), and in plasma in 5 of 17 patients (29%). Patients with detectable CMV-DNA in plasma were exclusively positive for CMV-DNA in PBL. Conclusion. Patients with inflammatory CTD under immunosuppressive therapy are at high risk for CMV reactivation. The clinical significance of such an event and indications for antiviral therapy should be examined further.