Assessment of cross-media effects deriving from the application of lower emission standards for acid pollutants in waste-to-energy plants.

The recent release of the new European Commission reference document on the Best Available Techniques (BAT) for waste incineration has set ambitious targets for the control of the emission of pollutants. However, an improved performance of the existing flue gas treatment systems in waste-to-energy (WtE) facilities is usually associated to an increase of cross-media effects, i.e., additional indirect environmental impacts related to the increased consumption of reactants and to the increased generation of process residues/wastewater in flue gas treatment. The present study introduces an innovative approach to assess cross-media effects deriving from more stringent acid gas emission standards in the WtE sector. By coupling simplified process modelling and life cycle analysis, the proposed methodology links the higher removal efficiency required for flue gas treatment to the impacts related to the reactants supply and waste disposal chain. An application to the Italian WtE sector exemplifies the potential of the method. The results evidence that, in case of HCl emission setpoints lower than 1 mg/Nm3, the reduction of acidifying emissions at the WtE stacks can be offset by the increase of global warming and smog formation impacts in the supply chain of flue gas cleaning reactants. In case of setpoints lower than 0.5 mg/Nm3, even within the acidification category the increase of indirect impacts more than compensates the decrease of WtE emissions. The net environmental benefit is strongly affected by the type of acid gas removal technology adopted, with dry systems typically associated with a larger increase of cross-media burdens when required to perform at higher removal efficiencies.

Techno-economic impact of lower emission standards for waste-to-energy acid gas emissions.

Acid gas removal is one of the main drivers of operating costs in the flue gas cleaning lines of waste-to-energy (WtE) plants. In the light of updated technical and normative references, such as the revised Best Available Technology reference document for waste incineration in the EU, plants are required to comply with increasingly lower emission limit values (ELV). In the case of existing WtE plants, this requires selecting the appropriate option among three alternatives: intensification of current operations, installation of additional equipment (retrofitting) or substitution of equipment (revamping). The identification of the most cost-effective solution to meet the new ELVs is thus paramount. In the present study, a comparative techno-economic assessment is performed with reference to the relevant options available to WtE plants equipped with a dry acid gas treatment system, explicitly taking into account the influence of several technical and economic variables by a sensitivity analysis. The results show that retrofitting based on furnace sorbent injection is a competitive option especially in the presence of high acid gas loads in the flue gas. Despite the high investment cost, revamping based on conversion to wet scrubbing can also reduce the overall cost of treatment compared to intensification, but only if no constraints are present on flue gas temperature downstream of the acid gas treatment. If flue gas reheating is needed, e.g., for the compatibility with a downstream DeNOx treatment or to avoid plume visibility at stack, the associated costs make revamping not competitive with retrofitting or intensification. Sensitivity analysis confirms that these findings are robust even in presence of relevant variations in cost entries.

Probing the Local Structure of Na in NaNO3-Promoted, MgO-Based CO2 Sorbents via X-ray Absorption Spectroscopy.

This work provides insight into the local structure of Na in MgO-based CO2 sorbents that are promoted with NaNO3. To this end, we use X-ray absorption spectroscopy (XAS) at the Na K-edge to interrogate the local structure of Na during the CO2 capture (MgO + CO2 ↔ MgCO3). The analysis of Na K-edge XAS data shows that the local environment of Na is altered upon MgO carbonation when compared to that of NaNO3 in the as-prepared sorbent. We attribute the changes observed in the carbonated sorbent to an alteration in the local structure of Na at the NaNO3/MgCO3 interfaces and/or in the vicinity of [Mg2+···CO32-] ionic pairs that are trapped in the cooled NaNO3 melt. The changes observed are reversible, i.e., the local environment of NaNO3 was restored after a regeneration treatment to decompose MgCO3 to MgO. The ex situ Na K-edge XAS experiments were complemented by ex situ magic-angle spinning 23Na nuclear magnetic resonance (MAS 23Na NMR), Mg K-edge XAS and X-ray powder diffraction (XRD). These additional experiments support our interpretation of the Na K-edge XAS data. Furthermore, we develop in situ Na (and Mg) K-edge XAS experiments during the carbonation of the sorbent (NaNO3 is molten under the conditions of the in situ experiments). These in situ Na K-edge XANES spectra of molten NaNO3 open new opportunities to investigate the atomic scale structure of CO2 sorbents modified with Na-based molten salts by using XAS.

Assessing the externalities of a waste management system via life cycle costing: The case study of the Emilia-Romagna Region (Italy).

Effective and efficient urban waste management systems (WMSs) are a cornerstone for a sustainable society. Life cycle costing (LCC) provides a useful framework for the joint analysis of economic and environmental impacts of a WMS, by considering both financial and external costs. The present study applies the methodology of societal LCC to the WMS of the Italian region of Emilia-Romagna to provide a case study on how the available information on waste flows and budget costs of a real WMS can be used to obtain an estimate of the total cost of waste management, including externalities. The results evidence that the main source of negative externality in the analyzed WMS is the transportation of waste, with only a minor role of external burdens due to incinerators and landfills. However, the positive externality resulting from recycling more than compensates those impacts, leading to a net external benefit associated to the WMS. The contribution of both uncertain unit external costs and environmental benefits imputable to recycled materials to the overall uncertainty of the result is systematically investigated by parametric uncertainty analysis. The most critical parameters in determining the sensitivity of the result are the monetary values attributed to primary energy consumption and CO2 emissions, together with assumptions on energy savings related to recycling. Eventually, it is shown how the developed LCC model can be used as decision-support tool to preliminarily investigate the implications of alternative management options on the financial and external costs of the WMS.

Economic and environmental benefits by improved process control strategies in HCl removal from waste-to-energy flue gas.

The control of HCl emission in waste-to-energy (WtE) facilities is a challenging flue gas treatment problem: the release of HCl from waste combustion is highly variable in time and the HCl emission standards are typically far lower in WtE than in any other industry. Traditional process control approaches in dry HCl removal processes are generally based on feeding a large excess of solid reactants to the system, to ensure robustness and a wide safety margin in the compliance to environmental regulations. This results in the production of a high amount of unreacted sorbents, strongly increasing the generation of solid wastes that need to be disposed. In the present study, an approach was developed to allow the implementation of improved control strategies for dry HCl abatement systems in operating full-scale facilities. Its objective is the reduction of the reactant feed and the waste production, while still providing an adequate safety margin for emission compliance. The approach was based on the reproduction of the behaviour of the real system in a virtual console that allows the extensive testing of alternative control strategies, limiting the need of demanding test-runs at the real plant. A test case on an Italian WtE facility demonstrated the capability of a control logic tuned in the virtual console to achieve a 13% reduction in the consumption of reactants and generation of process residues, with unchanged HCl removal efficiency. The results evidence the wide opportunities for optimisation of dry acid gas removal systems, in particular when multistage systems are implemented.

Techno-economic performance of HCl and SO2 removal in waste-to-energy plants by furnace direct sorbent injection.

With the impending release of Best Available Techniques (BAT) conclusions on waste incineration, existing European waste-to-energy (WtE) plants will be required to achieve a higher efficiency in the removal of several target pollutants, such as acid gases (above all, HCl and SO2). The direct injection of a sorbent in the furnace as a primary deacidification stage may be a cost-effective option to achieve the required performances. The present study investigated the furnace injection of a specific dolomitic sorbent, with the aim of identifying the techno-economic optimum for the sorbent feed rate considering different scenarios of flue gas composition. A full-scale test run campaign was carried out on two WtE plants and a phenomenological model linking HCl and SO2 conversion to reactant feed rate was developed. The model allowed assessing the cost-effectiveness of dolomitic sorbent furnace injection for WtE plants equipped with either a single or a two-stage acid gas treatment system. The addition of dolomitic sorbent resulted particularly suitable for WtE plants equipped with a single stage treatment coping with a high SO2 concentration in the flue gas, where the injection of dolomitic sorbent can increase the redundancy of flue gas treatment with a reduction of the total operating costs.

Effect of molten sodium nitrate on the decomposition pathways of hydrated magnesium hydroxycarbonate to magnesium oxide probed by in situ total scattering.

The effect of NaNO3 and its physical state on the thermal decomposition pathways of hydrated magnesium hydroxycarbonate (hydromagnesite, HM) towards MgO was examined by in situ total scattering. Pair distribution function (PDF) analysis of these data allowed us to probe the structural evolution of pristine and NaNO3-promoted HM. A multivariate curve resolution alternating least squares (MCR-ALS) analysis identified the intermediate phases and their evolution upon the decomposition of both precursors to MgO. The total scattering results are discussed in relation with thermogravimetric measurements coupled with off-gas analysis. MgO is obtained from pristine HM (N2, 10 °C min-1) through an amorphous magnesium carbonate intermediate (AMC), formed after the partial removal of water of crystallization from HM. The decomposition continues via a gradual release of water (due to dehydration and dehydroxylation) and, in the last step, via decarbonation, leading to crystalline MgO. The presence of molten NaNO3 alters the decomposition pathways of HM, proceeding now through AMC and crystalline MgCO3. These results demonstrate that molten NaNO3 facilitates the release of water (from both water of crystallization and through dehydroxylation) and decarbonation, and promotes the crystallization of MgCO3 and MgO in comparison to pristine HM. MgO formed from the pristine HM precursor shows a smaller average crystallite size than NaNO3-promoted HM and preserves the initial nano-plate-like morphology of HM. NaNO3-promoted HM was decomposed to MgO that is characterized by a larger average crystallite size and irregular morphology. Additionally, in situ SEM allowed visualization of the morphological evolution of HM promoted with NaNO3 at a micrometre scale.

Complicated colorectal cancer in nonagenarian patients: is it better not to perform anastomosis in emergency?

BACKGROUND: Colorectal cancer (CRC) is predominantly a disease of elderly people. Cancer in nonagenarian patients presents an ethical dilemma for surgeons and oncologists, and management of this group of patients in emergency for complicated CRC is debated. Presently described is retrospective study reporting experience of 6 departments of emergency surgery with management of nonagenarian patients sent to emergency surgery for CRC complications. METHODS: Data concerning patients aged over 90 years hospitalized from January 2011 to June 2015 in 6 departments of emergency surgery for complicated CRC were retrospectively analyzed. Data were collected in a dedicated database. Statistical analysis was conducted using IBM software SPSS 22 (IBM Corp., Armonk, NY, USA); statistical significance was set at p=0.05. RESULTS: In the period of study, 19 patients aged over 90 underwent surgery in emergency department for complicated CRC. Of the total, 52.63% were female, with sex ratio F:M of 1.11:1. Mean age was 92.52 years (range: 90-97 years; SD 1.49). Preoperative assessment of surgical risk was made using American Society of Anesthesiologists (ASA) score. There was no statistically significant difference in terms of in-hospital mortality between patients with ASA score ≤ 3 and patients with an ASA score >3. Primary anastomosis was performed in 6 of 19 patients (31.57%), all of whom had right-side colon cancer. Diverting stoma was created for 12 of 19 patients (63.15%). There was a statistically significant difference in incidence of postoperative complications between patients with right-side colon cancer and patients with left-side colon cancer (p=0.0498). Mean length of hospital stay was 12.78 days (range: 2-31 days; SD 6.31). In-hospital mortality rate was 21.05% (n=4). At follow up, overall survival was 47.36% (n=9). CONCLUSION: Elective surgery is the best way to manage CRC in all patients affected. Emergency surgery for CRC complications in patients over 90 is feasible with careful preoperative selection and evaluation of the patient. One-stage surgery is the best choice, in selected patients. Two- and three-stage surgery is indicated in case of peritonitis, for frail patients, for hemodynamically unstable patients. If there is high risk of anastomotic leakage, decompressive stoma is suggested as bridge to elective surgery, and in advanced neoplastic disease, as palliative procedure. In emergency setting, diverting stoma is a good surgical option in nonagenarian patients to decrease surgical risk, morbidity, and mortality; however, clinical randomized controlled trials are necessary to confirm this.

Comparison of alternative flue gas dry treatment technologies in waste-to-energy processes.

Acid gases such as HCl and SO2 are harmful both for human health and ecosystem integrity, hence their removal is a key step of the flue gas treatment of Waste-to-Energy (WtE) plants. Methods based on the injection of dry sorbents are among the Best Available Techniques for acid gas removal. In particular, systems based on double reaction and filtration stages represent nowadays an effective technology for emission control. The aim of the present study is the simulation of a reference two-stage (2S) dry treatment system performance and its comparison to three benchmarking alternatives based on single stage sodium bicarbonate injection. A modelling procedure was applied in order to identify the optimal operating configuration of the 2S system for different reference waste compositions, and to determine the total annual cost of operation. Taking into account both operating and capital costs, the 2S system appears the most cost-effective solution for medium to high chlorine content wastes. A Monte Carlo sensitivity analysis was carried out to assess the robustness of the results.

Prospective evaluation of ultrasonography plus MIBI scintigraphy in selecting patients with primary hyperparathyroidism for unilateral neck exploration under local anaesthesia.

BACKGROUND: Unilateral neck exploration (UNE) is currently replacing conventional bilateral neck exploration with cervicotomy for the surgical treatment of primary hyperparathyroidism (PHPT). However, many concerns still exist about the indications and the effectiveness of this minimally invasive approach. METHODS: Prospective evaluation of operative results in consecutive patients having indications for UNE on the basis of strict selection criteria consisting of ultrasound-MIBI agreement in adenoma localization, absence of thyroid disease, and psychological suitability for undergoing a procedure under local anesthesia. No intraoperative confirmation study was adopted. RESULTS: Among 149 consecutive PHPT patients, 45 (30.2%) had indications for UNE. No operative morbidity or mortality was observed. Mean operative time for the UNE procedure was 42 minutes (range 25 to 57). Conversion to general anesthesia was chosen for 5 patients (11.1%), whereas conversion to bilateral neck exploration was chosen for 3 patients (6.6%). For the UNE procedure, the success rate was as high as 91.7%. When the only factor indicated UNE, ultrasound-MIBI localization agreement had low sensibility (44.1%) and specificity (55.6%) but a high positive predictive value (91.1%). CONCLUSIONS: We concluded that UNE performed under local anesthesia, without intraoperative confirmation studies, could be considered a safe and effective approach to treating patients with PHPT, but we regret the low rate of patients selected for this procedure because of the low sensitivity of the imaging-inclusion criterion.

A primary pancreatic carcinoid tumour with unusual clinical complaints: A case report.

BACKGROUND: Unless metastatic or compressing the pancreatic duct, carcinoid of the pancreas are asymptomatic showing normal levels of serotonine and its metabolites in plasma and urine, thus resulting in delayed diagnosis and a consequent poor prognosis. However, if resection is timely accomplished, no local recurrence might be encountered and a normal survival might be expected in the absence of metastatic disease. CASE PRESENTATION: The reported case of pancreatic carcinoid tumour in a 62-year-old woman reporting only atypical symptoms consisting of intermittent epigastric pain and nausea. Urinary 5-hydroxyindolacetic acid levels were within normal limits and only a slight elevation of serum serotonine level was detected on admission. After tumour localisation with endoscopic ultrasonography, left splenopancreasectomy with splenic, celiac and hepatic lymphadenectomy was carried out. CONCLUSION: The role of endoscopic ultrasonography in early detection and precise localisation of pancreatic carcinoids, as well as the role of somatostatin-receptor scintigraphy with 111Indium labelled pentreotide in excluding distant metastases, are confirmed. The radical resection with lymphadenectomy is recommended in order to have a precise histological examination and detect occult lymph node metastases.

[Solitary fibrous liver tumor: clinical, radiological and pathological characteristics]. / Tumeur fibreuse solitaire du foie: caractéristiques cliniques, radiologiques et anatomo-pathologiques.

A solitary fibrous liver tumor is a rare disease which is difficult to diagnose. Radiological findings are not specific, and cannot confirm benignity or malignancy. Treatment most often involves a major hepatic resection. A precise diagnosis is made by pathological examination, mainly immunohistochemistry with positive results for anti CD34 and anti vimentin antibodies. Prognosis is directly correlated to the presence of malignant histoprognostic features, i.e. the number of mitoses. We report a case of a benign solitary fibrous liver tumor, which presented as a voluminous hepatic mass with few symptoms and was treated successfully by radical hepatic resection.

[Gastric interdigitating reticulum cell sarcoma: unusual presentation of a histiocytic tumor]. / Sarcome gastrique à cellules interdigitées: présentation inhabituelle d'une tumeur histiocytaire rare.

Histiocytic sarcoma, proliferation arising from immunoregulatory effector system cells, is a very rare and recently recognized tumor. Diagnosis is based on immunohistochemical and molecular genetic study, which allows to distinguish histiocytic sarcoma from lymphocytic proliferation, such as non-Hodgkin's lymphoma. We report the case of a gastric interdigitating reticulum cell sarcoma, treated by resection and chemotherapy. We review here clinical, histological, immunohistochemical and genotypic features of histiocytic tumors of the digestive tract.