A comparison assessment of landfill waste incineration and methane capture in the central region of Mexico.

This article aims to conduct a techno-economic feasibility assessment of producing energy by waste incineration and methane capture in the central region of Mexico. Three scenarios at different efficiency rates were considered: 50, 80 and 100%. For the methane project, yields and power capacity were determined using the potential generation rate and the degradable organic carbon content through the LandGEM model. For incineration, the waste calorific potential and the average moisture content were used to estimate the achievable electrical performance. The estimated annual energy was 35,018 GWh for methane, compared to 537.71 GWh for incineration. Both projects reported financial economic feasibilities when evaluated at a discount rate of 12%. Incineration reported an net present value of US$49,942,534 and an internal rate of return of 26% in contrast to US$4,054,109 and 17% for the methane project. Although the payback period for incineration was lower than for methane, its levelized cost of energy was significantly higher. These results are intended to assist the decision-making process when planning and developing waste management strategies under principles of circular economy in Mexico and similar regions worldwide.

Carbon footprint associated with four disposal scenarios for urban pruning waste.

The inadequate disposal of urban pruning residues can cause significant environmental impacts. The objective of the study presented herein was to quantify the carbon footprint and analyze four disposal scenarios for the urban pruning waste of the city of Joao Pessoa (Northeast Brazil). Software SimaPro was utilized for the quantification of the carbon footprint, with the IPCC 2013 GWP 100y impact evaluation method. The end-of-life treatments considered were sanitary landfilling (with and without collection of methane), simple municipal incineration, and reutilization of wood (transformation into briquettes). The results indicated that simple disposal in sanitary landfill generated 136.34 kg CO2/t urban pruning waste collected (highest carbon footprint), sanitary landfill with methane collection emitted 113.43 kg CO2/t waste, municipal incineration generated 71.31 kg CO2/t waste, and reutilization of woody residues was the scenario with the lowest carbon footprint, with 27.82 kg CO2/t waste. This study demonstrated that reutilization of biomass, besides being environmentally viable, presents the potential to contribute to the city's environmental quality, including the possibility of being used to obtain carbon credits.

Black carbon emission reduction strategies in healthcare industry for effective global climate change management.

Climate change remains one of the biggest threats to life on earth to date with black carbon (BC) emissions or smoke being the strongest cause after carbon dioxide (CO2). Surprisingly, scientific evidence about black carbon emissions reduction in healthcare settings is sparse. This paper presents new research findings on the reduction of black carbon emissions from an observational study conducted at the UN Peacekeeping Operations (MINUSTAH) in Haiti in 2014. Researchers observed 20 incineration cycles, 30 minutes for each cycle of plastic and cardboard sharps healthcare waste (HCW) containers ranged from 3 to 14.6 kg. The primary aim was to determine if black carbon emissions from healthcare waste incineration can be lowered by mainstreaming the use of cardboard sharps healthcare waste containers instead of plastic sharps healthcare waste containers. Similarly, the study looks into whether burning temperature was associated with the smoke levels for each case or not. Independent samples t-tests demonstrated significantly lower black carbon emissions during the incineration of cardboard sharps containers (6.81 ± 4.79% smoke) than in plastic containers (17.77 ± 8.38% smoke); a statistically significant increase of 10.96% smoke (95% Confidence Interval ( CI) [4.4 to 17.5% smoke], p = 0.003). Correspondingly, lower bottom burner temperatures occurred during the incineration of cardboard sharps containers than in plastic (95% Cl [16 to 126°C], p = 0.014). Finally, we expect the application of the new quantitative evidence to form the basis for policy formulation, mainstream the use of cardboard sharps containers and opt for non-incineration disposal technologies as urgent steps for going green in healthcare waste management.

Análise morfoestrutural de biomateriais para auxílio no processo de identificação humana / Morphostructural analysis of biomaterials for assistance in the human identification process

O objetivo do estudo foi avaliar as alterações de biomateriais restauradores e protéticos submetidos a temperaturas elevadas para o estabelecimento de parâmetros físicos que auxiliem nos casos de identificação humana em corpos carbonizados. A amostra do estudo experimental in vitro foi composta por 40 corpos de prova dividida em quatro grupos: GI (corpos de prova de cimentos de iônomero de vidro químico), GII (amálgamade prata), GIII (resina composta híbrida) e GIV (liga de cobre alumínio). Os corpos de prova foram submetidosa temperaturas de 300°C, 500°C, 700°C e 900°C. Após a incineração, os biomateriais foram submetidos a análises macroscópicas sobre as modificações de estrutura, coloração, forma e estabilidade dimensional e os dados analisados pela Análise de Variância e teste de Dunn (p<0,05). Os dados obtidos demonstraram em relação à radiopacidade uma diferença estatisticamente significante para as médias de densidade radiográfica no GI entre as temperaturas 700°C e 900°C; GIV entre as temperaturas 300°C e 900°C; 500° e 900°C. O GII atingiu seu ponto de fusão à 700ºC com aspecto pulverulento e lojas isoladas de mercúrio a 900°C. O GIII apresentou mudança estrutural nas temperaturas à 700°C e 900°C. No GIV não se constatou modificações relevantes. Assim, pode-se coligir que a resina composta micro hibrida e o amálgama apresentam severas alterações morfoestruturais enquanto o ionômero de vidro e o cobre alumínio não sofrem mudanças significativas em suas características originais. As alterações sofridas pelos materiais fornecem dados relevantes para o auxilio no processo de identificação humana de corpos carbonizados.

The aim of this study was to evaluate the changes of restorative and prosthetic biomaterials subjected to high temperatures for the establishment of physical parameters that assist in cases of charred bodies in human identification. The sample of the experimental in vitro study was composed by 40 specimens divided into 4 groups: GI (specimens of cements of ionomer of chemical glass), GII(silver amalgam), GIII (hybrid composite resin) and GIV (copper alloy aluminum). The specimens were subjected to temperatures of 300°C, 500°C, 700°C and 900°C. After incineration the biomaterials were submitted macroscopic analysis on changes of structure, color, shape and dimensional stability and all data were analyzed by ANOVA and Dunn’s test (p <0.05). Regarding the radiopacity there was statistically significant difference for the mean radiographic density in GI temperatures within 700°C and 900°C; GIV temperatures within 300°C and 900°C, 500°C and 900°C. The GII has reached its melting point at 700ºC with powdery appearance and isolated stores of mercury at 900°C. The GIIIhad structural change at 700°C and 900°C. In GIV it not observed significant changes. Thus, one cangather that the micro hybrid composite resin and amalgam exhibit severe morpho structural changes while the glass ionomer aluminum and copper does not undergo significant changes in their original characteristics. The changes undergone by materials provide relevant data to aid in the identification process of human bodies charred.

Determination of activation energy of pyrolysis of carton packaging wastes and its pure components using thermogravimetry.

Many processes have been used for recycling of carton packaging wastes. The pyrolysis highlights as a promising technology to be used for recovering the aluminum from polyethylene and generating products with high heating value. In this paper, a study on pyrolysis reactions of carton packaging wastes and its pure components was performed in order to estimate the kinetic parameters of these reactions. For this, dynamic thermogravimetric analyses were carried out and two different kinds of kinetic models were used: the isoconversional and Independent Parallel Reactions. Isoconversional models allowed to calculate the overall activation energy of the pyrolysis reaction, in according to their conversions. The IPR model, in turn, allowed the calculation of kinetic parameters of each one of the carton packaging and paperboard subcomponents. The carton packaging pyrolysis follows three separated stages of devolatilization. The first step is moisture loss. The second stage is perfectly correlated to devolatilization of cardboard. The third step is correlated to devolatilization of polyethylene.

Enhanced diesel fuel fraction from waste high-density polyethylene and heavy gas oil pyrolysis using factorial design methodology.

Factorial Design Methodology (FDM) was developed to enhance diesel fuel fraction (C9-C23) from waste high-density polyethylene (HDPE) and Heavy Gas Oil (HGO) through co-pyrolysis. FDM was used for optimization of the following reaction parameters: temperature, catalyst and HDPE amounts. The HGO amount was constant (2.00 g) in all experiments. The model optimum conditions were determined to be temperature of 550 °C, HDPE = 0.20 g and no FCC catalyst. Under such conditions, 94% of pyrolytic oil was recovered, of which diesel fuel fraction was 93% (87% diesel fuel fraction yield), no residue was produced and 6% of noncondensable gaseous/volatile fraction was obtained. Seeking to reduce the cost due to high process temperatures, the impact of using higher catalyst content (25%) with a lower temperature (500 °C) was investigated. Under these conditions, 88% of pyrolytic oil was recovered (diesel fuel fraction yield was also 87%) as well as 12% of the noncondensable gaseous/volatile fraction. No waste was produced in these conditions, being an environmentally friendly approach for recycling the waste plastic. This paper demonstrated the usefulness of using FDM to predict and to optimize diesel fuel fraction yield with a great reduction in the number of experiments.

Electrochemical incineration of omeprazole in neutral aqueous medium using a platinum or boron-doped diamond anode: degradation kinetics and oxidation products.

The electrochemical incineration of omeprazole, a widely prescribed gastrointestinal drug which is detected in natural waters, has been studied in a phosphate buffer of pH 7.0 by anodic oxidation with electrogenerated H(2)O(2) (AO-H(2)O(2)) operating at constant current density (j). The experiments were carried out in a cell equipped with either a Pt or a boron-doped diamond (BDD) anode and an air-diffusion cathode to continuously produce H(2)O(2). In these systems, organics are mainly oxidized by hydroxyl radicals formed at the Pt or BDD surface from water oxidation. A partial total organic carbon (TOC) abatement close to 78% for omeprazole was achieved by AO-H(2)O(2) with a BDD anode after consumption of 18 Ah L(-1) at 100 mA cm(-2), whereas the alternative use of Pt did not allow mineralizing the drug. However, the drug was totally removed using both anodes, although it decayed more rapidly using BDD. In this latter system, increasing j accelerated the degradation process, but lowering the mineralization current efficiency. Greater drug content also enhanced the degradation rate with higher mineralization degree and current efficiency. The kinetics for omeprazole decay always followed a pseudo-first-order reaction and its rate constant increased with increasing j and with decreasing its concentration. Seven heteroaromatic intermediates and four hydroxylated derivatives were detected by LC-MS, while nine short-linear carboxylic acids were identified and quantified by ion-exclusion HPLC. These acids were largely accumulated using Pt and rapidly removed using BDD, thus explaining the partial mineralization of omeprazole achieved by AO-H(2)O(2) with the latter anode. The release of inorganic ions such as NO(3)(-), NH(4)(+) and SO(4)(2-) was followed by ionic chromatography. A plausible reaction sequence for omeprazole mineralization involving all intermediates detected is proposed.

Open burning of household waste: Effect of experimental condition on combustion quality and emission of PCDD, PCDF and PCB.

Open burning for waste disposal is, in many countries, the dominant source of polychlorinated dibenzodioxins, dibenzofurans and biphenyls (PCDD/PCDF/PCB) release to the environment. To generate emission factors for open burning, experimental pile burns of about 100 kg of household waste were conducted with emissions sampling. From these experiments and others conducted by the same authors it is found that less compaction of waste or active mixing during the fire--"stirring"--promotes better combustion (as evidenced by lower CO/CO(2) ratio) and reduces emissions of PCDD/PCDF/PCB; an intuitive but previously undemonstrated result. These experiments also support previous results suggesting PCDD/PCDF/PCB generation in open burning - while still highly variable - tends to be greater in the later (smoldering) phases of burning when the CO/CO(2) ratio increases.

Determination of total organic halogen (TOX) in humic acids after microwave-induced combustion.

Chemically chlorinated organic matter as well as natural background humic acids contain significant amounts of organically bound halogens that must be determined for assessment of environmental pollution. In this work the use of ion chromatography (IC) and inductively coupled plasma mass spectrometry (ICP-MS) is proposed for the determination of total organic Cl, Br and I concentration in humic acids extracted from various forest soil horizons after a single digestion by microwave-induced combustion (MIC). Samples were pressed as pellets and combusted using 20 bar of oxygen and ammonium nitrate solution as igniter. Analytes were absorbed in diluted alkaline solution (50mM (NH(4))(2)CO(3)) and a reflux step was applied after combustion to improve analyte recoveries (5 min, microwave power of 1400W). The accuracy was evaluated using certified reference materials (CRM) and spiked samples. Using MIC the agreement with CRM values and spike recoveries was higher than 97% for all analytes. As an advantage over conventional procedures, using MIC it was possible to digest up to eight samples in only 25 min, obtaining a single solution suitable for all halogens determination in humic acids samples by different techniques (IC and ICP-MS). The limit of detection (3σ) for Cl, Br and I obtained by IC was 1.2, 2.5 and 4.3µgg(-1) and by ICP-MS it was 1.4, 0.03 and 0.002µgg(-1), respectively.

Stack emissions tests in a brick manufacturing Hoffmann kiln: firing of municipal solid waste.

This article reviews the results obtained from stack emissions analysis during the co-firing process of municipal solid waste (MSW) from the municipality of Tabio, Colombia, in a Hoffmann-type brick kiln. MSW (2 tonne) was incinerated and about 18.5 tonnes of clay were processed into brick using one and four kiln chambers, respectively. During the process, the following emissions were investigated: particulate emissions, emissions of SO(2), SO(3), NO( X), metals (Sb, As, Cd, Co, Sn, Cr, Cu, Mn, Ni, Hg), hydrofluoric and hydrochloric acid, hydrocarbons (such as methane) and emission of polychlorinated dioxins and furans. Also, CO emissions were monitored during each test to evaluate the influence of MSW co-firing on that parameter. The observed emissions concentrations proved to be below the threshold values issued by MAVDT, the environmental authority in Colombia, indicating that the emissions were under control during the proposed process. In addition, statistical analysis showed that the emissions were 10-40% below the regulation limit with a confidence of 95%.

Occupational airborne contamination in South Brazil: 2. Oxidative stress detected in the blood of workers of incineration of hospital residues.

One of the most useful methods for elimination of solid residues of health services (SRHS) is incineration. However, it also provokes the emission of several hazardous air pollutants such as heavy metals, furans and dioxins, which produce reactive oxygen species and oxidative stress. The present study, which is parallel to an accompanied paper (Avila Jr. et al., this issue), investigated several enzymatic and non-enzymatic biomarkers of oxidative stress in the blood (contents of vitamin E, lipoperoxidation = TBARS, reduced glutathione = GSH, oxidized glutathione = GSSG, and activities of glutathione S-transferase = GST, glutathione reductase = GR, glutathione peroxidase = GPx, catalase = CAT and superoxide dismutase = SOD), in three different groups (n = 20 each) exposed to airborne contamination associated with incineration of SRHS: workers directly (ca. 100 m from the incinerator) and indirectly exposed (residents living ca. 5 km the incineration site), and controls (non-exposed subjects). TBARS and GSSG levels were increased whilst GSH, TG and alpha-tocopherol contents were decreased in workers and residents compared to controls. Increased GST and CAT activities and decreased GPx activities were detected in exposed subjects compared to controls, while GR did not show any difference among the groups. In conclusion, subjects directly or indirectly exposed to SRHS are facing an oxidative insult and health risk regarding fly ashes contamination from SRHS incineration.

Combining individual- and group-level exposure information: child carbon monoxide in the Guatemala woodstove randomized control trial.

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 woodstove 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.

[Sugar cane burning in Brazil: respiratory health effects]. / Queimadas de cana-de-açúcar no Brasil: efeitos à saúde respiratória.

The article aimed to update scientific literature information about respiratory health effects caused by sugarcane burning, considering the expansion of sugarcane plantations in Brazil and in the state of São Paulo. Articles published between 1996 and 2006, which deal with the health effects of sugarcane burning and/or air pollutants originating from this burning, were discussed. These studies suggest that part of the population--especially the elderly, children and asthmatics--suffers health effects of sugarcane burning. As a result, these people require health care, thus affecting health services and their families.

Performance of a semi-industrial scale gasification process for the destruction of polychlorinated biphenyls.

A semi-industrial scale test was conducted to thermally treat mixtures of spent oil and askarels at a concentration of 50,000 ppm and 100,000 ppm of polychlorinated biphenyls (PCBs) under a reductive atmosphere. In average, the dry-basis composition of the synthesis gas (syngas) obtained from the gasification process was: hydrogen 46%, CO 34%, CO2 18%, and CH4 0.8%. PCBs, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans (PCDDs/PCDFs) in the gas stream were analyzed by high-resolution gas chromatography (GC)-mass spectrometry. The coplanar PCBs congeners 77, 105, 118, 156/ 157, and 167 were detected in the syngas at concentrations < 2 x 10(-7) mg/m3 (at 298 K, 1 atm, dry basis, 7% O2). The chlorine released in the destruction of the PCBs was transformed to hydrogen chloride and separated from the gas by an alkaline wet scrubber. The concentration of PCBs in the water leaving the scrubber was below the detection limit of 0.002 mg/L, whereas the destruction and removal efficiency was > 99.9999% for both tests conducted. The concentration of PCDDs/PCDFs in the syngas were 8.1 x 10(-6) ng-toxic equivalent (TEQ)/m3 and 7.1 x 10(-6) ng-TEQ/m3 (at 298 K, 1 atm, dry basis, 7% O2) for the tests at 50,000 ppm and 100,000 ppm PCBs, respectively. The only PCDD/F congener detected in the gas was the octachloro-dibenzo-p-dioxin, which has a toxic equivalent factor of 0.001. The results obtained for other pollutants (e.g., metals and particulate matter) meet the maximum allowed emission limits according to Mexican, U.S., and European regulations for the thermal treatment of hazardous waste (excluding CO, which is a major component of the syngas, and total hydrocarbons, which mainly represent the presence of CH4).

NO2 emissions from agricultural burning in São Paulo, Brazil.

We report here on the application of a compact ultraviolet spectrometer to measurement of NO2 emissions from sugar cane field burns in São Paulo, Brazil. The time-resolved NO2 emission from a 10 ha plot peaked at about 240 g (NO2) s(-1), and amounted to a total yield of approximately 50 kg of N, or about 0.5 g (N) m(-2). Emission of N as NOx (i.e., NO + NO2) was estimated at 2.5 g (N) m(-2), equivalent to 30% of applied fertilizer nitrogen. The corresponding annual emission of NOx nitrogen from São Paulo State sugar cane burning was >45 Gg N. In contrast to mechanized harvesting, which does not require prior burning of the crop, manual harvesting with burning acts to recycle nitrogen into surface soils and ecosystems.