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Background: Epidemiology frequently relies on surrogates of long-term exposures, often either individual-level short-term measurements or group-level based on long-term characteristics of subjects and their environment. Whereas individual-level measures are often imprecise due to within-subject variability, group-level measures tend to be inaccurate due to residual between-subject variability within groups. Rather than choose between these error-prone estimates, we borrow strength from each by use of mixed-model prediction and we compare the predictive validity. Methods: We compared alternative measures of long-term exposure to carbon monoxide (CO) among children in the RESPIRE wood-stove randomized control trial during years 2003 and 2004. The main study included 1932 repeated 48-hour-average personal CO measures among 509 children from 0–18 months of age. We used a validation study with additional CO measures among a random subsample of 70 of the children to compare the predictive validity of individual-level estimates (based on observed short-term exposures), group-level estimates (based on stove type and other residential characteristics), and mixed-model predictions that combine these 2 sources of information. Results: The estimated error variance for mixed-model prediction was 63% lower than the individual-level measure based on the exposure data and 58% lower than the corresponding group-level measure. Conclusions: When both individual- and group-level estimates are available but imperfect, mixed-model prediction may provide substantially better measures of long-term exposure, potentially increasing the sensitivity of epidemiologic studies to underlying causal relations.

Municipal solid waste incineration (MSWI) generates bottom ash, fly ash (FA), and air pollution control (APC) residues as by-products. FA and APC residues are considered hazardous due to the presence of soluble salts and a high concentration of heavy metals, and they should be appropriately treated before disposal. Physicochemical characterization using inductively coupled plasma mass spectroscopy (ICP-MS), X-ray diffraction (XRD), and X-ray fluorescence (XRF) have shown that FA and APC have potential for reuse after treatment as these contain CaO, SiO 2 , and Al 2 O 3 . Studies conducted on treatment of FA and APC are categorized into three groups: (i) separation processes, (ii) solidification/stabilization (S/S) processes, and (iii) thermal processes. Separation processes such as washing, leaching, and electrochemical treatment improve the quality and homogeneity of the ash. S/S processes such as chemical stabilization, accelerate carbonation, and cement solidification modify hazardous species into less toxic constituents. Thermal processes such as sintering, vitrification, and melting are effective at reducing volume and producing a more stable product. In this review paper, the treatment processes are analyzed in relation to ash characteristics. Issues concerning mixing FA and APC residues before treatment, true treatment costs, and challenges are also discussed to provide further insights on the implications and possibilities of utilizing FA and APC as secondary materials.

Waste incineration is increasingly used to reduce waste volume and produce electricity. Several incinerators have recently been proposed in Australia and community groups are concerned about health impacts. An overview of the evidence on health effects has been needed. A systematic review of English language literature for waste incinerators and health using PRISMA methodology. A range of adverse health effects were identified, including significant associations with some neoplasia, congenital anomalies, infant deaths and miscarriage, but not for other diseases. Ingestion was the dominant exposure pathway for the public. Newer incinerator technologies may reduce exposure. Despite these findings, diverse chemicals, poor study methodologies and inconsistent reporting of incinerator technology specifications precludes firmer conclusions about safety. Older incinerator technology and infrequent maintenance schedules have been strongly linked with adverse health effects. More recent incinerators have fewer reported ill effects, perhaps because of inadequate time for adverse effects to emerge. A precautionary approach is required. Waste minimisation is essential. Public health practitioners can offer clearer advice about adverse health effects from incinerators. We suggest improved research design and methods to make future studies more robust and comparable. We offer ideas for better policy and regulation.

The solidification/stabilization (S/S) through geopolymer is regarded as the ideal approach for the disposal of municipal waste incineration fly ashes (MSWI FA). This work aims to investigate the S/S behaviors of MSWI FA (up to 20 wt.% incorporations) in metakaolin-based geopolymer (MKG), with a focus on the effect of MSWI FA dosage on the performance of geopolymer. Results show that MSWI FA participates in the geopolymerization and alters the reaction products of geopolymer. MSWI FA imposes a dual effect on the performance of geopolymers. A dosage of MSWI FA lower than 5 wt.% can enhance the strength development of geopolymer, mainly due to the formation of C-A-S–H gels in the framework. However, an MSWI FA addition higher than 5 wt.% significantly decreases the strength of geopolymer. The efficiency of immobilization increases with the ionic radius of heavy metals, following the order of Pb > Zn > Cr > Cu. Heavy metals are immobilized in geopolymer framework through ions exchange and coordination to the nonbridging Si–O − and Al-O − . These results help to further understand the use of metakaolin-based geopolymer as an MSWI FA S/S binder. Graphical abstract

Currently, China is facing severe pressure of environmental emission reduction. As a kind of clean energy, waste-to-energy technology has the advantages of renewability, low pollution, and stable supply. To establish an affordable, effective, and sustainable waste disposable method is critical for the low carbon society transition. Therefore, the innovation diffusion of waste incineration power technology is a problem worth studying. Based on this, in order to answer this question scientifically, this paper constructs a system dynamics model of innovative diffusion, and analyzes the internal mechanism of innovation diffusion. The results show that firstly, the government support policies have a positive influence on the innovation and diffusion of waste incineration power technology; secondly, compared with the R&D policy, feed-in tariffs policy is more efficient to expand the installed capacity of waste incineration power; At last, technological innovation caused by government support policies is the main driving force of waste incineration power industry investment cost reduction.

Biochars are increasingly used as soil amendment and for C sequestration in soils. The influence of feedstock differences and pyrolysis temperature on biochar characteristics has been widely studied. However, there is a lack of knowledge about the formation of potentially toxic compounds that remain in the biochars after pyrolysis. We investigated biochars from three feedstocks (wheat straw, poplar wood, and spruce wood) that were slowly pyrolyzed at 400, 460, and 525°C for 5 h (straw) and 10 h (woodchips), respectively. We characterized the biochars’ pH, electrical conductivity, elemental composition (by dry combustion and X‐ray fluorescence), surface area (by N2 adsorption), water‐extractable major elements, and cation exchange capacity (CEC). We further conducted differential scanning calorimetry (DSC), Fourier‐transform infrared spectroscopy (FTIR), and X‐ray diffractometry to obtain information on the biochars’ molecular characteristics and mineralogical composition. We investigated trace metal content, total polycyclic aromatic hydrocarbon (PAH) content, and PAH composition in the biochars. The highest salt (4.92 mS cm−1) and ash (12.7%) contents were found in straw‐derived biochars. The H/C ratios of biochars with highest treatment temperature (HTT) 525°C were 0.46 to 0.40. Surface areas were low but increased (1.8–56 m2 g−1) with increasing HTT, whereas CEC decreased (162–52 mmolc kg−1) with increasing HTT. The results of DSC and FTIR suggested a loss of labile, aliphatic compounds during pyrolysis and the formation of more recalcitrant, aromatic constituents. X‐ray diffractometry patterns indicated a mineralogical restructuring of biochars with increasing HTT. Water‐extractable major and trace elements varied considerably with feedstock composition, with trace elements also affected by HTT. Total PAH contents (sum of EPA 16 PAHs) were highly variable with values up to 33.7 mg kg−1; irrespective of feedstock type, the composition of PAHs showed increasing dominance of naphthalene with increasing HTT. The results demonstrate that biochars are highly heterogeneous materials that, depending on feedstock and HTT, may be suitable for soil application by contributing to the nutrient status and adding recalcitrant C to the soil but also potentially pose ecotoxicological challenges.

The main aim of this study was to develop a decision support system for sustainable municipal solid waste management (MSWM) in Hoi An city (HAC), Vietnam. A face-to-face interview was conducted with local experts including authorities, citizens, waste collection contractors and recyclers to identify main objectives of waste management system and appropriate treatment methods. A multi-objective optimization model was proposed using non-linear programming approach. An interactive method known as reference point method (RPM) was applied for solving the problem with three objectives including cost minimization, landfill minimization and emission minimization. As a result, the efficient waste-flow-allocation and the optimal capacity of disposal facilities were determined by intense discussion and agreement among decision-makers. Waste incineration, anaerobic digestion, sanitary landfill and current recycling activities should be applied with a cost of about 2300 US$ daily. Also, the daily emission of various pollutants was about 35 metric tons, and the greenhouse gas (GHG) is 313 tons CO 2-eq .

COVID-19 greatly challenges the human health sector, and has resulted in a large amount of medical waste that poses various potential threats to the environment. In this study, we compiled relevant data released by official agencies and the media, and conducted data supplementation based on earlier studies to calculate the net value of medical waste produced in the Hubei Province due to COVID-19 with the help of a neural network model. Next, we reviewed the data related to the environmental impact of medical waste per unit and designed four scenarios to estimate the environmental impact of new medical waste generated during the pandemic. The results showed that a medical waste generation rate of 0.5 kg/bed/day due to COVID-19 resulted in a net increase of medical waste volume by about 3366.99 tons in the Hubei Province. In the four scenario assumptions, i.e., if the medical waste resulting from COVID-19 is completely incinerated, it will have a large impact on the air quality. If it is disposed by distillation sterilization, it will produce a large amount of wastewater and waste residue. Based on the results of the study, we propose three policy recommendations: strict control of medical wastewater discharge, reduction and transformation of the emitted acidic gases, and attention to the emission of metallic nickel in exhaust gas and chloride in soil. These policy recommendations provide a scientific basis for controlling medical waste pollution.

Leachate sludge is generated from the biochemical treatment sludge tank for disposing the leachate from landfill municipal solid waste (MSW). It has the characteristics of high water content and high organic matter content. Sulfoaluminate cement (SAC) is used as the main curing agent, and municipal solid waste incineration (MSWI) by-products are used as auxiliary curing agents to solidify/stabilize the leachate sludge. The influences of SAC content and MSWI by-products content on the strength and solidification mechanism of the leachate sludge are investigated by unconfined compressive strength (UCS) test and micro-observation tests. Moreover, the leaching concentration of heavy metals of the solidified samples is analyzed by leaching toxicity test. The results show that the UCS of the solidified samples increases with an increase in cement content. When the cement content is larger than 20%, the UCS of the solidified samples satisfies the strength requirement of landfill. The enhancing effect of bottom ash on the cement-solidified samples is slight. The fly ash is a good auxiliary curing agent for improving the UCS of cement-solidified samples, and the optimal dosage of fly ash is 5% and 15% for the solidified samples with 10 ~ 30% and 40 ~ 50% cement content, respectively. Ten percent fly ash can replace 10% cement to achieve better solidification effect for the solidified samples. The leaching concentration of heavy metals in the solidified sample with 30%/40% cement and 15% fly ash/bottom ash can satisfy the strength and leaching toxicity requirements of landfill. The immobilization of heavy metal of the cement and MSWI by-products solidified samples is mainly achieved through physical adsorption, physical encapsulation, ion exchange, and chemical precipitation.

Solidification/stabilization (S/S) is a typical technique to immobilize toxic heavy metals in Municipal solid waste incineration fly ash (MSWI FA). This study utilized blast furnace slag, steel slag, desulfurization gypsum, and phosphoric acid sludge to develop a novel metallurgical slag based cementing material (MSCM). Its S/S effects of MSWI FA and long-term S/S effectiveness under dry–wet circulations (DWC) were evaluated and compared with ordinary Portland cement (OPC). The MSCM-FA block with 25 wt.% MSCM content achieved 28-day compressive strength of 9.38 MPa, indicating its high hydration reactivity. The leaching concentrations of Pb, Zn and Cd were just 51.4, 1895.8 and 36.1 μg/L, respectively, well below the limit standard of Municipal solid wastes in China (GB 16889–2008). After 30 times’ DWC, leaching concentrations of Pb, Zn and Cd for MSCM-FA blocks increased up to 130.7, 9107.4 and 156.8 μg/L, respectively, but considerably lower than those for OPC-FA blocks (689, 11,870.6 and 185.2 μg/L, respectively). The XRD and chemical speciation analysis revealed the desorption of Pb, Zn and Cd attached to surface of C-S–H crystalline structure during the DWC. The XPS and SEM–EDS analysis confirmed the formation of Pb–O-Si and Zn–O-Si bonds via isomorphous replacement of C-A-S–H in binder-FA blocks. Ettringite crystalline structure in OPC-FA block was severely destructed during the DWC, resulting in the reduced contents of PbSO 4 and CaZn 2 Si 2 O 7 ·H 2 O and the higher leachability of Pb 2+ and Zn 2+ .