Production of cement clinkers from municipal solid waste incineration (MSWI) fly ash

This communication reports the laboratory scale study on the production of cement clinkers from two types of municipal solid waste incineration fly ash (MSW ash) samples. XRD technique was used to monitor the phase formation during the burning of the raw mixes. The amount of trace elements volatilized during clinkerization and hydration, as well as leaching behaviours of the clinkers obtained from optimum compositions, were also evaluated. From the results it is observed that all of the major components of ordinary Portland cement (OPC) clinkers are present in the produced clinkers. Results also show the volatilization of considerable amounts of Na, K, Pb, Zn and Cd during the production of clinkers. However, major parts of the toxic elements remaining in the clinkers appear to be immobilized in the clinkers phases. Hydration studies of the clinkers obtained from optimum compositions show that the clinkers prepared from raw MSW ash are more reactive than the washed MSW ash based clinkers. TG/DTA analyses of the hydrated pastes show the formation of hydration products, which are generally found in OPC and OPC derived cements. The initial study, therefore, shows that more than 44% of MSW ash with the addition of very small amounts of silica and iron oxide can be used to produce cement clinkers. The amount of CaCO3 necessary to produce clinkers (approximately 50%) is also smaller than the same required for the conventional process (more than 70%).     

Characterization of char derived from various types of solid wastes from the standpoint of fuel recovery and pretreatment before landfilling

Carbonization is a kind of pyrolysis process to produce char from organic materials under an inert atmosphere. In this work, chars derived from various solid wastes were characterized from the standpoint of fuel recovery and pretreatment of waste before landfilling. Sixteen kinds of municipal and industrial solid wastes such as residential combustible wastes, non-combustible wastes, bulky wastes, construction and demolition wastes, auto shredder residue, and sludges were carbonized at 500 degrees C for 1h under nitrogen atmosphere. In order to evaluate the quality of char as fuel, proximate analysis and heating value were examined. The composition of raw waste had a significant influence on the quality of produced char. The higher the ratio of woody biomass in waste, the higher heating value of char produced. Moreover, an equation to estimate heating value of char was developed by using the weight fraction of fixed carbon and volatile matter in char. De-ashing and chlorine removal were performed to improve the quality of char. The pulverization and sieving method seems to be effective for separation of incombustibles such as metal rather than ash. Most char met a 0.5 wt% chlorine criterion for utilization as fuel in a shaft blast furnace after it was subjected to repeated water-washing. Carbonization could remove a considerable amount of organic matter from raw waste. In addition, the leaching of heavy metals such as chrome, cadmium, and lead appears to be significantly suppressed by carbonization regardless of the type of raw waste. From these results, carbonization could be considered as a pretreatment method for waste before landfilling, as well as for fuel recovery.     

Mass balance of anti-influenza drugs discharged into the Yodo River system,Japan, under an influenza outbreak

In February 2011, at the peak of an influenza outbreak, we performed a comprehensive analysis of the mass balances of four anti-influenza drugs—oseltamivir (OS), oseltamivir carboxylate (OC), amantadine (AMN), and zanamivir (ZAN)—in the urban area of the Yodo River system. This area includes three main river catchments (the Katsura, Uji, and Kidzu Rivers) and is home to 12 million people, about 10% of Japan’s population. Water was sampled at six main rivers and 13 tributary sites and eight sewage treatment plants (STPs). We concluded that the STP effluents were the major sources of the anti-influenza drug load in the Yodo River system (68–94% of total mass fluxes). Extended measurement throughout the Yodo River system further showed only small fluctuations of the ratio of OS to OC from 0.2 to 0.3, suggesting that OS and its metabolite are environmentally stable. The results also clearly showed the importance of reducing the levels of anti-influenza drugs in the water environment by reducing their emission at STPs.     

Estimation of the respiratory ventilation rate of preschool children in daily life using accelerometers

Inhalation rate is an essential factor for determining the inhaled dose of air pollutants. Here, accelerometers were used to develop regression equations for predicting the minute ventilation rate (V(E)) to estimate the daily inhalation rate in young children. Body acceleration and heart rate were measured in 29 Japanese preschool children (6 yr of age) during nine different levels of activities (lying down, sitting, standing, playing with plastic bricks, walking, building with blocks, climbing stairs, ball tossing, and running) using the Actical omnidirectional accelerometer, the ActivTracer triaxial accelerometer, and a heart rate monitor. Measurements were calibrated against the V(E) measured by the Douglas bag method. ActivTracer accelerometer measurements gave a strong correlation with V(E) (Pearson's r = 0.913), which was marginally stronger than that for the Actical counts (r = 0.886) and comparable to the correlation between heart rate and logarithmic V(E) (r = 0.909). According to the linear regression equation, the V(E) for lying down, sitting, standing, playing with plastic bricks, walking, and running was overestimated by 14-60% by the Actical and by 14-37% by the ActivTracer. By comparison, for building with blocks, climbing stairs, and ball tossing, the V(E) was underestimated by 19-23% by the Actical and by 13-18% by the ActivTracer. When these three activities were excluded, a stronger correlation was found between the V(E) and ActivTracer measurements (r = 0.949); this correlation was 0.761 for the three excluded activities. Discriminant analysis showed that the ratio between vertical and horizontal acceleration obtained by the ActivTracer could discriminate walking from building with blocks, climbing stairs, and ball tossing with a sensitivity of 75%. The error in estimating V(E) was considerably improved for the ActivTracer measurements by the use of two regression equations developed for each type of activity.     

Organochlorine concentrations in breast milk and prevalence of allergic disorders in Japanese women

Persistent organic pollutants have been shown to have immunomodulating effects in humans. However, epidemiological evidence regarding the relationships between organochlorine compound exposure and allergic disorders coming from studies of children has been limited and inconsistent. The current cross-sectional study examined the associations between the concentrations of β-hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), p,p'-dichlorodiphenyldichloroethylene (DDE), and trans-nonachlordane in breast milk and the prevalence of allergic disorders in 124 adult Japanese women. The definition of wheeze and asthma was based on criteria from the European Community Respiratory Health Survey whereas that of eczema and rhinoconjunctivitis was based on criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for age, smoking, family history of allergic disorders, and education. The prevalence values of wheeze, asthma, eczema, and rhinoconjunctivitis in the past 12 months were 9.7%, 4.8%, 13.7%, and 29.8%, respectively. The median concentrations of β-HCH, HCB, p,p'-DDE, and trans-nonachlordane in breast milk were 28.3, 7.0, 71.6, and 23.9 ng g(-1) lipid, respectively (range, 4.5-253, 2.1-14.5, 7.5-362, and 1.8-130 ng g(-1) lipid, respectively). When the exposures were treated as continuous variables, no significant associations were found between concentrations of HCB, β-HCH, p,p'-DDE, or trans-nonachlordane and the prevalence of wheeze, asthma, eczema, or rhinoconjunctivitis. Our results suggest that concentrations of β-HCH, HCB, p,p'-DDE, and trans-nonachlordane in breast milk are not evidently associated with the prevalence of wheeze, asthma, eczema, or rhinoconjunctivitis in young female Japanese adults.     

Trends in hazardous trace metal concentrations in aerosols collected in Beijing, China from 2001 to 2006

Daily observations of hazardous trace metal concentrations in aerosols in Beijing, China were made in the period from 2001 to 2006. We considered coal combustion as a major source of some anthropogenic metals by achieving a correlation analysis and by investigating enrichment factors and relative composition of metals. A possible extra source of some specific metals, such as Cu and Sb, was brake abrasion particles, however, we did not think the transport-related particle was a major source for the hazardous anthropogenic metals even though they could originate from vehicle exhaust and brake/tire abrasion particles. A time-trend model was used to describe temporal variations of chemical constituent concentrations during the five-year period. Several crustal elements, such as Al, Ti, V, Cr, Mn, Fe, and Co, did not show clear increases, with annual rates of change of -15.2% to 3.6%. On the other hand, serious increasing trends were noted from several hazardous trace metals. Cu, Zn, As, Cd, and Pb, which are derived mainly from anthropogenic sources, such as coal combustion, showed higher annual rate of change (4.9-19.8%, p<0.001) according to the regression model. In particular, the Cd and Pb concentrations increased remarkably. We hypothesize that the trend towards increasing concentrations of metals in the air reflects a change that has occurred in the process of burning coal, whereby the use of higher temperatures for coal combustion has resulted in increased emissions of these metals. The increasing use of low-rank coal may also explain the observed trends. In addition, nonferrous metal smelters are considered as a potential, albeit minor, reason for the increasing atmospheric concentrations of anthropogenic hazardous metals in Beijing city.     

How ICT can contribute to realize a sustainable society in the future: a CGE approach

Environment, Development and Sustainability - Many information and communications technology (ICT) services have become commonplace worldwide and are certain to continue to spread faster than...