Ettore Guerriero

Dioxins and furans formation in pilot incineration tests of sewage sludge spiked with organic chlorine

The factors affecting polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) formation were studied in sewage sludge incineration tests carried out on a demonstrative plant. The plant includes a circulating fluidised bed furnace (FBF) and a rotary kiln furnace (RKF), operating alternatively. During the tests sewage sludge was spiked with chlorinated hydrocarbons and the operating parameters of the afterburning chamber were varied. PCDD/F were sampled in each test before the bag filter, thus collecting the above contaminants before abatement systems. From the tests it appeared that PCDD/F were always produced in more abundance in the tests carried out by FBF than by RKF. The higher PCDD/F concentrations in the tests by FBF were reached when sewage sludge was spiked with a high dosage of a surrogate organic mixture of chlorinated hydrocarbons and when the afterburning chamber was used only as transit equipment with the burner off. The distribution of the different PCDD/F homologues was compared. P5CDFs were generally the prevalent fraction, with very few exceptions for the tests by RKF at high temperature of the afterburning chamber. As for FBF tests, it was found that the PCDD/F homologue profile depends on the afterburning chamber temperature.

Possible social relevance of illicit psychotropic substances present in the atmosphere

Although the worldwide presence of illicit psychotropic compounds in the environment is well known, the social impact of drug abuse on the community has yet to be determined. Besides, the possibility of deriving indicators of the prevalence of drug abuse from the content of illicit substances in the air remains unexplored. In this study, the atmospheric concentrations of psychotropic compounds recorded in Italy were plotted vs. a series of criminal statistics. Meaningful links were found between atmospheric cocaine and the amount of drugs seized, the number of drug related crimes and the demand for clinical treatment recorded in the Italian regions. Atmospheric cocaine and cannabinoids also seemed to be correlated with tumour insurgence and mental disease frequency, respectively. However, further investigations are necessary to elucidate/explain/clarify if the behaviours observed for cocaine vs. the parameters usually adopted to estimate drug abuse prevalence (correspond to an effective relationships)/are directly linked, and to understand why the same approach failed when applied to cannabinoids. Moreover, according to our study illicit drugs are suspected to promote long-term ill health effects even when present at low concentrations the air.

Polycyclic aromatic hydrocarbon emission profiles and removal efficiency by electrostatic precipitator and wetfine scrubber in an iron ore sintering plant.

Abstract A monitoring campaign of polychlorinated dibenzo-p-dioxins and dibenzofurans, polyaromatic hydrocarbons (PAHs), and polychlorinated biphenyl was carried out in an Italian iron ore sintering plant by sampling the combustion gases at the electrostatic precipitator (ESP) outlet, at the Wetfine scrubber (WS) outlet, and by collecting the ESP dust. Few data are available on these micropollutants produced in iron ore sintering plants, particularly from Italian plants. This study investigates the PAH emission profiles and the removal efficiency of ESPs and WS. PAHs were determined at the stack, ESP outlet flue gases, and in ESP dust to characterize the emission profiles and the performance of the ESP and the WS for reducing PAH emission. The 11 PAHs monitored are listed in the Italian legislative decree 152/2006. The mean total PAH sum concentration in the stack flue gases is 3.96 μg/N · m3, in ESP outlet flue gases is 9.73 μg/N · m3, and in ESP dust is 0.53 μg/g. Regarding the emission profiles, the most abundant compound is benzo(b)fluoranthene, which has a relative low BaP toxic equivalency factors (TEF) value, followed by dibenzo(a,l)pyrene, which has a very high BaP(TEF) value. The emission profiles in ESP dust and in the flue gases after the ESP show some changes, whereas the fingerprint in ESP and stack flue gases is very similar. The removal efficiency of the ESP and of WS on the total PAH concentration is 5.2 and 59.5%, respectively.

Biogas cleaning and upgrading with natural zeolites from tuffs.

ABSTRACT CO2 adsorption on synthetic zeolites has become a consolidated approach for biogas upgrading to biomethane. As an alternative to synthetic zeolites, tuff waste from building industry was investigated in this study: indeed, this material is available at a low price and contains a high fraction of natural zeolites. A selective adsorption of CO2 and H2S towards CH4 was confirmed, allowing to obtain a high-purity biomethane (CO2 <2 g m−3, i.e. 0.1%; H2S <1.5 mg m−3), suitable for injection in national grids or as vehicle fuel. The loading capacity was found to be 45 g kg−1 and 40 mg kg−1, for CO2 and H2S, respectively. Synthetic gas mixtures and real biogas samples were used, and no significant effects due to biogas impurities (e.g. humidity, dust, moisture, etc.) were observed. Thermal and vacuum regenerations were also optimized and confirmed to be possible, without significant variations in efficiency. Hence, natural zeolites from tuffs may successfully be used in a pressure/vacuum swing adsorption process.

Assessment of nitrous oxide emission from cement plants: Real data measured with both Fourier transform infrared and nondispersive infrared techniques

Nitrous oxide (N2O) is the third most important greenhouse gas after carbon dioxide and methane, and contributes about 6% to the greenhouse effect. Nitrous oxide is a minor component of the atmosphere, and it is a thousand times less than carbon dioxide (CO2). Nevertheless, it is much more potent than CO2 and methane, owing to its long stay in the atmosphere of approximately 120 yr and the high global warming potential (GWP) of 298 times that of CO2. Although greenhouse gases are natural in the atmosphere, human activities have changed the atmospheric concentrations. Most of the values of emission of nitrous oxide are still obtained by means of emission factors and not actually measured; the lack of real data may result in an underestimation of current emissions. The emission factors used for the calculation of N2O can be obtained from the “Guidelines for the implementation of the national inventory of emissions” of the Intergovernmental Panel on Climate Change, which refer to all nations for the realization of their inventory. This study will present real data, measured in several Italian cement plants with different characteristics. The work also shows a comparison between N2O concentration measured with in situ Fourier transform IR (FTIR) and the reference method EN ISO 21258 based on nondispersive IR (NDIR), in order to investigate the interfering compounds in the measurement with NDIR. Implications: N2O may arise as an unwanted by-product of nitrogen oxide (NOx) abatement systems, in particular selective noncatalytic reduction (SNCR). Since it is applied in the cement plants, N2O emission from cement industry is evaluated, with both FTIR and NDIR instrument. Several considerations emerged from the results. First of all, the emission from this industrial sector is not negligible, and for that reason N2O concentration should be regulated; another observation is that the reference method based on the NDIR technique is not as selective as FTIR could be.

Evaluation of a simultaneous sampling method of PAHs, PCDD/Fs and dl-PCBs in ambient air

The Stockholm Convention on Persistent Organic Pollutants (POPs) was signed in May 2001 by 127 countries. Currently, 12 substances are regulated by the convention, and the work on finding new candidate chemicals to the convention has started. Among these 12 substances, dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) are the objects of this study. There are no European standard methods for the simultaneous determination of these microorganic compounds, together with polycyclic aromatic hydrocarbons (PAHs) in ambient air--they must be referred to three different methods developed by the U.S. Environmental Protection Agency (EPA). The quali-quantitative analysis of these microorganic pollutants is an important challenge due to the low concentrations at which they may be present. In this study, the development of a simplified, alternative, fast and affordable sampling method for the determination of PAHs, PCDDs, PCDFs and PCBs in ambient air was performed. The sampling time was extended from 24 h to 7 d in order to enrich the sample, to fall within the instrumental limits of detection and to reduce the number of samples to be processed and, therefore, errors that may arise. First of all, experiments with labelled standards were conducted in the research area of Montelibretti (rural station, which is sited about 20 km northeast of Rome), with the purpose of optimizing sampling efficiency. Finally, the method was applied to the analysis of these compounds in the air of a suburban area with small industrial plants in order to evaluate the feasibility of the proposed sampling method system, by comparing concentrations of native compounds acquired during simultaneous daily and weekly sampling.

Volatilization and oxidative artifacts of PM bound PAHs collected at low volume sampling (1): Laboratory and field evaluation

Laboratory and field studies were carried out to assess the effects of oxidative degradation and volatilization on PM10 bound polycyclic aromatic hydrocarbons (PAHs), collected at low volume condition according to the EU sampling reference method EN12341:2014 (flow rate 2.3 m3 h-1), on 47 mm quartz filters. For the laboratory experiments, pairs of twin samples were collected in field and, after treatments favoring decomposition or/and volatilization of PAHs on one sample, the PAH amount was compared with that of the corresponding untreated sample. Ozone exposure caused a general PAHs decay with more marked effects on benzo [a]pyrene, perylene and benz [a]anthracene; these compounds showed, similarly to benzo [ghi]perylene, correlations between ozone dose and losses. Treatments with zero air exhibited losses due to volatilization even for 5-ring PAHs up to benzo [a]pyrene, whereas a linear dependence was observed between filter PAH load and losses for benzo [a]anthracene, chrysene and benzofluoranthenes. Concentrations on samples collected simultaneously over 48, 24, 12 and 6 h were compared. Results confirmed a lack of temporal auto-consistency in the PAHs sampling methodology here adopted. In particular higher atmospheric PAH concentrations were ascertained on samples constituted by cumulative filters exposed over shorter sampling times. When 24-h and 2 × 12-h samples were compared, comparable losses were evaluated in the hot and cold seasons. This finding shows that, although in summer meteorology conditions favor sampling artifacts, the effectiveness of these phenomena continue in the winter, probably due to the larger amount of PAH available on the sampling filter (total PAHs ∼ 10 vs 0.5 ng m-3).

Emission of submicron aerosol particles in cement kilns: Total concentration and size distribution

Cement plants are responsible for particle and gaseous emissions into the atmosphere. With respect to particle emission, the greater part of is in the range from 0.05 to 5.0 µm in diameter. In the last years attention was paid to submicron particles, but there is a lack of available data on the emission from stationary sources. In this paper, concentration and size distribution of particles emitted from four cement kilns, in relationship to operational conditions (especially the use of alternative fuel to coal) of the clinker process are reported. Experimental campaigns were carried out by measuring particles concentration and size distribution at the stack of four cement plants through condensation particle counter (CPC) and scanning mobility particle sizer spectrometer (SMPS). Average total particle number concentrations were between 2000 and 4000 particles/cm3, about 8–10 times lower that those found in the corresponding surrounding areas. As for size distribution, for all the investigated plants it is stable with a unimodal distribution (120–150 nm), independent from the fuel used. Implications: The study provides information on submicron particles emitted from cement kilns in different driving conditions. In particular, the total particle number is modest and considerably lower than that measured in ambient air, whereas the particle size distribution could be influenced by the operational conditions.

Behavior of Organic and Inorganic Micropollutants in Chlorine Spiked Sludge Incineration by a Circulating Fluidized Bed Furnace

The effects of combustion and feeding conditions on Polycyclic Aromatic Hydrocarbons (PAH) and PCDD/F formation and appearance in the emissions at the stack during sludge incineration are discussed in this paper. Partitioning in the solid streams of Cd, Cr, Cu, Mn, Ni, Pb and Zn is also analyzed. Tests were performed on a demonstrative plant equipped with a fluidized bed furnace (FBF) using sewage sludge either as is or spiked with chlorinated organic compounds (tetrachloroethylene or a mixture of tetrachloroethylene, chlorobenzene and toluene) to study the chlorine effect on the presence of micropollutants in the different streams. Exhaust gases were sampled both before and after the treatment system (bag house and wet scrubber). In the untreated flue gas the highest values of PCDD/F and PAH were detected when the afterburning chamber was not in use or operating at low temperatures. Operation of the afterburning chamber at temperature higher than 850–900 °C was sufficient to keep organic micropollutants concentrations in the untreated flue gas at reasonably low levels. No significant correlation of the operating conditions with emissions at the stack was found. High copper concentration in the feed enhanced PCDD/F formation, with exception of tests carried out with high afterburning temperature. The homologue profile of PCDD/F and PAH depended on test conditions. Preferential accumulation of heavy metals in the filter ash with respect to cyclone ash was quantified in terms of an enrichment factor. Out of the seven metals considered, only Cd and Pb undergo significant enrichment in the filter ash. The enrichment increased with increasing chlorine content of the feed. In contrast, Cu, Cr, Mn, Ni, and Zn behaved as refractory (non-volatile) elements even at high chlorine dosage. In accordance with the widely accepted hypothesis that metal enrichment is due to metal vaporization in the combustion chamber and subsequent condensation onto the filter ash particles, a thermodynamic model of the combustion process was able to satisfactorily predict the different metal behavior and the effect of chlorine dosage on metal enrichment.Copyright