Energy and exergy analyses of sewage sludge thermochemical treatment

The aim of this research was to provide a methodology for calculating the energy and exergy balances for the thermochemical treatment of sewage sludge. The results of the balances were assessed and compared for three different scenarios (torrefaction, pyrolysis and pyrolysis combined with catalytic post-treatment of the vapors). The balances were calculated based on previously published experimental data and evaluated under different conditions. The results indicated that the endothermicity decreased with the severity of the process. The energy recovery from the products favored the exothermicity of the processes. The three-step process (pyrolysis of torrefied sewage sludge combined with catalytic post-treatment of the hot vapors) was the least exergy efficient scenario

Pyrolysis of cashew nutshells: Characterization of products and energy balance

Cashew cultivation leads to the generation of large amounts of nutshells. In order to determine whether pyrolysis could be a suitable method for the valorization of this agricultural residue, cashew nutshells (CNS) from Burkina Faso were pyrolyzed in the temperature range between 400 and 600 °C in a laboratory-scale fixed bed reactor. The solid, liquid and gaseous fractions were quantified and characterized, with special focus on the solid product. Recovery of the cashew nutshell liquid (CNSL) was accomplished during pyrolysis separately from the pyrolysis liquid. Results suggest that, except for the aqueous fraction, all the products obtained from pyrolysis are suitable for fuel purposes, and that part of the CNSL can be recovered below 200 °C during the heating process. A preliminary energy balance of the process shows that burning the gases can provide the energy necessary for the process at a pyrolysis temperature of 500 °C

Combustion characteristics of hydrochar and pyrochar derived from digested sewage sludge

In this paper, hydrochars and pyrochars were produced at 260 ºC under different residence times (2 and 4 h) using anaerobic digested sewage sludge (SSL) as initial feedstock. The effect of reaction time on the fuel properties of hydrochars and pyrochars was evaluated. Moreover, the combustion kinetics of raw SSL and the derived pyrochars and hydrochars without coal blending were determined at two different air flows (20 and 90 mL/min) and compared. In the same conditions, the yield of hydrochar was significantly lower than that of pyrochar, confirming the different reaction pathways followed in each process. The results showed hydrochars have lower carbon recovery and energy yield than pyrochars, making the latter more suitable for energy purposes. The thermogravimetric combustion study showed that both thermochemical treatments increased the ignition temperature but decreased the burnout temperature, which results in higher stability during handling and storage. However, raw SSL is better for combustion than hydrochar according to the combustibility index. In addition, the kinetic study showed that the activation energy of the combustion of biochars, especially pyrochar, is lower than that of raw SSL, which is advantageous for their combustion

Bibliometric Study of Technology and Occupational Health in Healthcare Sector: A Worldwide Trend to the Future

Since the eighties, technological tools have modified how people interact in their environment. At the same time, occupational safety and health measures have been widely applied. The European Agency for Safety and Health at Work considers that information and communication technologies are the main methods to achieve the goals proposed to improve working life and the dissemination of good practices. The principal objective was to determine the trends of publications focused on these technologies and occupational safety in the healthcare sector during the last 30 years. A bibliometric study was carried out. The 1021 documents showed an increased trend per country, especially for the United States (p < 0.001) and year (p < 0.001). The citations per year showed significant differences between citations of articles published before 2007 (p < 0.001). The year was also linked to the increase or decrease of articles (72.2%) and reviews (14.9%) (p < 0.001). The analysis of journal co-citations also showed that the main journals (such as Infection Control and Hospital Epidemiology) were linked to other important journals and had a major part in the clusters formed. All these findings were discussed in the manuscript and conclusions were drawn

Occupational Safety and Health Training for Undergraduates Nursing Students: A Spanish Pilot

Most of blood borne and airborne pathogens are highly contagious, harmful and have prevalence among healthcare workers. In this group, healthcare students, especially nursing undergraduates, have even higher risk to be exposed and suffered a contagious accident. One of the main pillars to prevent exposure to such pathogens and decrease accidents seems to be through education. A prospective observational educational research focused on quantifying the students’ knowledge, and prevention culture was carried out. The educational approach based on the development of a technological tool, its integration in the students’ education, and posterior assessment. The Chi-square, ANOVA, Kruskal–Wallis, Man–Whitney U, and Spearman correlations were used to determine the effect of such educational methodology. The results, previous to the integration of the educational approach, showed differences between the elementary and proficient knowledge and correct procedure in each academic year (p < 0.05), being the best year the third academic year. The mean of elementary knowledge among second year students after the inclusion of the educational methodology improved for 2017/2018 with a mean of 7.5 (1.11) and in 2018/2019 with 7.87 (1.34). This study argued that the educational approach proposed could improve the prevention culture and knowledge among students and future healthcare professionals

Tuberculosis and Other Airborne Microbes in Occupational Health and Safety

Airborne pathogens and non-malignant infectious diseases such as tuberculosis are highly contagious and can have severe effects on healthcare workers. The symptoms of these diseases take time to manifest, which can prevent workers from noticing that they have been exposed until symptoms appear. The current paper sought to assess the occupational safety and preventative measures taken in laboratories in Spain, and to compare these measures with those reported by other studies worldwide. A cross-sectional study of workers (35–50 years old) was conducted using a web survey (N = 30), and a bibliometric analysis was carried out in the Scopus database (92 documents were selected). The occupational safety and health measures were inadequate, according to the opinions of the workers. The training (p < 0.01), the amount of work (p < 0.05), and how the workers followed their protocols (p < 0.001) were linked to incidents and exposure to airborne pathogens. The most significant previous publication was a report (848 citations) stating that the previous variables linked to exposure are vital for prevention. Most works focused on countries like the U.S.A. (p = 0.009) were reviews, with a limited number of studies focused on occupational safety

Co-pyrolysis of sewage sludge and manure

The management and valorization of residual organic matter, such as sewage sludge and manure, is gaining interest because of the increasing volume of these residues, their localized generation and the related problems. The anaerobic digestion of mixtures of sewage sludge and manure could be performed due to the similarities between both residues. The purpose of this study is to evaluate the feasibility of the co-pyrolysis of sewage sludge (SS) and digested manure (DM) as a potential management technology for these residues. Pyrolysis of a sewage sludge/manure blend (50:50%) was performed at 525 °C in a stirred batch reactor under N2 atmosphere. The product yields and some characteristics of the product were analyzed and compared to the results obtained in the pyrolysis of pure residues. Potential synergetic and antagonist effects during the co-pyrolysis process were evaluated. Although sewage sludge and manure seem similar in nature, there are differences in their pyrolysis product properties and distribution due to their distinct ash and organic matter composition. For the co-pyrolysis of SS and DM, the product yields did not show noticeable synergistic effects with the exception of the yields of organic compounds, being slightly higher than the predicted average, and the H2 yield, being lower than expected. Co-pyrolysis of SS and DM could be a feasible management alternative for these residues in locations where both residues are generated, since the benefits and the drawbacks of the co-pyrolysis are similar to those of the pyrolysis of each residue

Phytotoxicity of sewage sludge biochars prepared at different pyrolysis conditions

6 Pags.- 8 Figs.- 3 Tabls. Creative Commons License Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0).Pyrolysis of sewage sludge was carried out at three different lab-scale reactors and conditions: an Auger reactor for sewage sludge pyrolysis at low temperature (300ºC), a stirred batch reactor (530ºC) and a fluidised bed reactor (530ºC). The starting material is anaerobically digested and thermally dried sewage sludge from a wastewater treatment plant located in Spain. A preliminary study to assess the feasibility of application to soil of the three biochars was performed using two germination tests and a greenhouse experiment. Water soluble compounds from biochar did not affect seed germination, but volatile compounds reduced germination of more sensitive seeds. Biochar applied to soil at agricultural rates (20 t/ha) reduced growth and development of a corn crop. No differential effects of the three pyrolysis conditions were found.The Authors are grateful to the Spanish Ministry of Economy and Competitiveness (MINECO) for the Project CTQ2013-47260-R.Peer reviewe

Functionalization of sewage sludge char by partial oxidation with molecular oxygen to enhance its adsorptive properties

This study investigates the activation of sewage sludge char through partial oxidation with molecular oxygen with the goal to increase the concentration of oxygen-containing surface functional groups and to enhance its ammonium adsorption capacity. The effects of oxidation temperature (200–350 °C), oxygen concentration (5–21 vol %) and oxidation time (30–120 min) on the degree of char oxidation are analyzed. The results obtained by thermogravimetric and elemental analysis, and Fourier Transform Infrared and X-ray Photoelectron spectroscopy corroborate the incorporation of oxygenated functional groups on the surface of sewage sludge char either at low temperature (200 °C) using air or at higher temperature (350 °C) using 5% O2 for 30 min. The oxidation of sewage sludge char hardly increases its specific surface area. The operating conditions during oxidation must be carefully controlled to avoid runaway reactions that lead to total oxidation of char. The evolution of CO and CO2 during oxidation is a good indicator of the advance of the oxidation/burn-off reactions. The ammonium adsorption capacity of sewage sludge char increases after oxidation under mild operating conditions, providing support to the idea of onsite utilization of sewage sludge as ammonium adsorbent in waste water treatment plants. This would provide a step forward towards the implementation of a circular economy

Proceso combinado de tratamiento con ácido y pirólisis para la recuperación de fósforo y la obtención de sólidos adsorbentes a partir de digestato

En el presente trabajo se pretende valorizar digestato de pur&iacute;n de vacuno y otros residuos org&aacute;nicos mediante un proceso combinado de tratamiento con &aacute;cido y pir&oacute;lisis con el fin de recuperar el f&oacute;sforo (P) presente y obtener un s&oacute;lido que pueda emplearse como material adsorbente