Fouling control in membrane bioreactors with sewage-sludge based adsorbents

The potential application of powdered activated carbon (PAC) to mitigate membrane fouling has been tested in membrane bioreactors (MBRs) fed with cosmetic wastewater. Inexpensive powder activated carbon was prepared from sewage sludge biosolids (B-PAC) by pyrolysis (750 °C; 0.5 h) and air-activation (400 °C; 2 h). Adsorption capacities of 143 and 570 mg g −1 were reached for carbohydrates and proteins, respectively, quite similar to those of a commercial activated carbon (C-PAC). To check the effect of PAC addition on membrane fouling, three MBRs were simultaneously operated without (control-MBR) and with PAC (B-MBR and C-MBR) for 150 days in continuous mode at 8 L m −2  h −1 flux. Similar COD removal efficiencies were achieved in these three MBR systems. After 100 days of operation, the effect of the PACs on the sludge filterability was studied in the MBRs for 10 days. B-MBR showed stable transmembrane pressure (TMP) after 9 days of operation, unlike of control-MBR and C-MBR, where the TMP increased after the 2nd and 5th days, respectively. Therefore, operational cost saving can be achieved in the membrane cleaning due to decrease of fouling rate. Operating at stable state condition the addition of PAC gave rise to an increase of the critical flux of 25%. In an extra shear test, carried out at the end of the continuous experiment, a clear reduction in mean size of the flocs from 45 to 28 μm was observed in control-MBR. However, the extra shear led to a slight reduction of the mean size of flocs (less than 5%) in MBRs with PAC, with average sizes of 62 and 71 μm in C-MBR and B-MBR, respectively. The molecular weight fractionation of the MBR demonstrated a higher selectivity of B-PAC toward the adsorption of proteins smaller than 1 μm which prevents the irreversible fouling of the membranes. The membranes lifetime was increased because the B-PAC extended the filtration for a longer period than C-PAC, probably due to its easier in-situ regenerationThe authors greatly appreciatefinancial support by the SpanishMinisterio de Economia y Competitividad and Comunidad deMadrid through the projects CTM2013-43803-P and P2013/MAE-2716, respectivel

Effect of inoculum source and initial concentration on the anaerobic digestion of the liquid fraction from hydrothermal carbonisation of sewage sludge

Hydrothermal carbonisation (HTC) is a relatively new alternative for the management of sewage sludge that allows obtaining a HTC char (hydrochar) with a high heating value (≈22 MJ/kg). The aim of this work has been to study the anaerobic digestion of the liquid fraction generated as by-product during HTC (LFHTC) of dewatered sewage sludge, to get more value to the overall process. For this purpose, three different inocula: granular biomass from industrial reactors treating brewery and sugar beet wastewaters and a flocculent biomass from a full-scale digester of municipal sewage sludge, at two initial inoculum concentrations (IC) (10 and 25 g COD/L) were tested. ANOVA test was applied to evaluate the ultimate methane yield for each IC. The effect was different for each inoculum studied: an increase from 10 to 25 g COD/L increased the methane yield by 23% for brewery waste, achieving the highest value obtained (177 ± 5 mL STP CH4/g CODadded), while declining to 99 ± 2 mL STP CH4/g CODadded for sugar beet; it is not affected by the municipal sludge, yielding around 135 mL STP CH4/g CODadded. Therefore, among the inocula tested, brewery waste was the most appropriate for the anaerobic digestion of the LFHTC of dewatered sewage sludge at high ICThe authors wish to express their gratitude to the Spanish MINECO (CTM2016-76564-R) for providing financial support. M.A. de la Rubia acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (RYC-2013-12549

Mesophilic anaerobic co-digestion of the organic fraction of municipal solid waste with the liquid fraction from hydrothermal carbonization of sewage sludge

In the present study, the influence of substrate pre-treatment (grinding and sieving) on batch anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) was first assessed, then followed by co-digestion experiments with the liquid fraction from hydrothermal carbonization (LFHTC) of dewatered sewage sludge (DSS). The methane yield of batch anaerobic digestion after grinding and sieving (20 mm diameter) the OFMSW was considerably higher (453 mL CH4 STP g−1 VSadded) than that of untreated OFMSW (285 mL CH4 STP g−1 VSadded). The modified Gompertz model adequately predicted process performance. The maximum methane production rate, Rm, for ground and sieved OFMSW was 2.4 times higher than that of untreated OFMSW. The anaerobic co-digestion of different mixtures of OFMSW and LFHTC of DSS did not increase the methane yield above that of the anaerobic digestion of OFMSW alone, and no synergistic effects were observed. However, the co-digestion of both wastes at a ratio of 75% OFMSW-25% LFHTC provides a practical waste management option. The experimental results were adequately fitted to a first-order kinetic model showing a kinetic constant virtually independent of the percentage of LFHTC (0.52–0.56 d−1) and decreasing slightly for 100% LFHTC (0.44 d−1)The authors wish to express their gratitude to the Spanish MINECO (CTM2016-76564-R) for providing financial support. M. A. de la Rubia received financial support from the Spanish Ministry of Economy and Competitiveness (RYC-2013-12549

Valorisation of the liquid fraction from hydrothermal carbonisation of sewage sludge by anaerobic digestion

This is the peer reviewed version of the following article: Journal of Chemical Technology and Biotechnology 93.2 (2018): 450-456, which has been published in final form at https://doi.org/10.1002/jctb.5375. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsBACKGROUND: The mesophilic anaerobic digestion of the liquid fraction from hydrothermal carbonisation (208°C, 1 h) of dehydrated sewage sludge has been studied. Two initial inoculum concentrations (IC) (10 and 25 g COD L-1) and four inoculum to substrate ratios (ISR) (2, 1, 0.5 and 0.4 on a COD basis) have been selected to analyse their influence on the evolution of the anaerobic digestion process. RESULTS: The substrate is characterised by a high COD (95.5 g L-1) and TKN (8.7 g N L-1) values. High inoculum concentration (25 g COD L-1) and/or low ISR (≤ 0.5) inhibited methanogenesis due to the high ammonia nitrogen (1.4 g TAN L-1) and VFA (>4 g COD L-1) released. For the inhibited samples final COD removals lower than 15% and IA/TA ratios higher than 0.3 were found. The greatest methane yield (177±5 mL CH4 STP g-1 CODadded) was achieved at 25 g COD L-1 of IC and at an ISR of 2. CONCLUSION: During anaerobic digestion of the liquid fraction from the hydrothermal carbonisation of sewage sludge, the IC and ISR must be adequately selected for proper operation of the process and successful valorisation. According to the results, working at an ISR ≥ 1 is recommendedThe authors wish to express their gratitude to the UAM-Santander (Project CEAL-AL/2015-29) and Spanish MINECO (CTM2016-76564-R) for providing financial support. MA de la Rubia acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (RYC-2013-12549

Anaerobic co-digestion of the process water from waste activated sludge hydrothermally treated with primary sewage sludge. A new approach for sewage sludge management

Hydrothermal carbonization (HTC) is a suitable technology for managing wastes with a high moisture content, providing a carbon-rich and high energy density material called hydrochar and a process water (PW) with significant organic matter content. The aim of this work was to develop a new approach to sewage sludge management involving anaerobic digestion (AD) of the PW of dewatered waste activated sludge (DWAS) with primary sewage sludge (PSS). The process was optimized by performing semi-continuous experiments with different feed mixture compositions (10% PW/90% PSS and 5% PW/95% PSS, on a COD basis), organic loading rates (OLR; 1.5 and 2.5 g COD L−1 d−1), and temperature regimes (mesophilic and thermophilic). The combination of mesophilic conditions, a 10% PW/90% PSS feed mixture and OLR of 1.5 g COD L−1 d−1 provided concentrations of volatile fatty acids <400 mg COD L−1 in addition to a methane yield (172 ± 11 mL CH4 g−1 CODadded), 1.15 times the value for the control test (100% PSS). Therefore, the energy content of hydrochar from HTC of DWAS followed by AD of the process water with primary sewage sludge enhances the valorization of this renewable residueThe authors greatly appreciate funding from Spain's MINECO (Project CTM2016-76564-R; project RYC-2013-12549), Madrid Regional Government (Project P2018/EMT-4344) and UAMSantander (Project 2017/EEUU/07

Anaerobic co-digestion of the aqueous phase from hydrothermally treated waste activated sludge with primary sewage sludge. A kinetic study

The mesophilic anaerobic co-digestion of the liquid fraction from hydrothermal carbonization (LFHTC) of dewatered waste activated sludge with primary sewage sludge (PSS) has been studied. Mixtures of different composition (25, 50 and 75% of LFHTC on a chemical oxygen demand (COD) basis), as well as the individual substrates, have been tested using two inocula (flocculent (FS) and granular (GS) sludges). Methane production decreased as the LFHTC/PSS ratio increased, which can be related to the presence of recalcitrant compounds in the LFHTC, such as alkenes, phenolics, and other oxygen- and nitrogen-bearing aromatics hard-to-degrade through anaerobic digestion. Methane yield reached 248 ± 11 mL CH4 STP/g CODadded with the GS inoculum and 25% LFHTC. A 74 and a 30% increase of methane production was achieved in the 25% LFHTC runs respect to the obtained in the similar experiments with 100% LFHTC, using the FS and GS inocula, respectively. In those late runs, the COD was reduced more than 86%, with a negligible concentration of total volatile fatty acids. With both inocula, total Kjeldahl nitrogen hydrolysis increased as the LFHTC to PSS mixture ratio decreased, reaching values higher than 79% at the end of the experiments. Methane yield values fitted well the first-order, Cone and Weibull kinetic models for both inocula. Significant differences in the kinetic constant values, ranging from 0.100 to 0.168 d−1 and 0.059–0.068 d−1, were found with the FS and GS inocula, respectively. The results obtained support the potential integration of HTC of dewatered waste activated sludge in wastewater treatment plantsThe authors greatly appreciate financial support from the SpanishMINECO (Project CTM2016-76564-R) and the Community of Madrid(Project P2013/MAE-2716). M.A. de la Rubia acknowledges financialsupport from the Spanish MINECO (RYC-2013-12549). The valuablecontribution of

Valorization of microalgal biomass by hydrothermal carbonization and anaerobic digestion

The potential of hydrothermal carbonization (HTC) as a novel choice for treating microalgal biomass (MAB) was assessed. The hydrochar obtained at 210 °C had a carbon content and a higher heating value (HHV) 1.09 and 1.1 times greater, respectively, than that of the feedstock. Also, washing the hydrochar with HCl efficiently removed ash and increased its carbon content 1.40-fold. Energy recovery in the liquid fraction from the hydrothermal treatment (LF) by anaerobic digestion (AD) allowed methane yields of 188–356 mL STP CH4 g−1 VSadded, to be obtained. As a result, the amount of energy recovered from MAB was increased from about 4 MJ kg−1 (20% in terms of HHV) to 15.4, 12.1 and 10.4 MJ kg−1 by combining HTC at 180, 210 and 240 °C, respectively, with AD. Therefore, HTC at 180 °C in combination with AD seemingly provides an effective method for valorizing MABThe authors wish to express their gratitude to Spain’s MINECO (CTM2016-76564-R and 449 RYC-2013-12549) for funding this wor

Mangrove forest mapping through remote sensing imagery: study case for Buenaventura, Colombia

[EN] Mangroves are plant communities of high ecological and economic importance for coastal regions. This investigation provides a methodology for mapping Mangrove forests through remote sensing images in a semidetail scale (1:25,000) in a sector of the municipality of Buenaventura, Colombia. A Sentinel 2 image and 2017 highresolution ortophotomosaic of the municipality were used for the mangrove cartography, using QGIS software, spectral analysis was performed and supervised classification was established using Maximum Likelihood algorithm. Results shown that mangrove is the most representative cover in the study area whit 7,264.21 ha in total extension (59.21% of total area), the development classification got a thematic accuracy of 80% and 0.70 in Kappa index. The used methodology can be used as an academic and research reference for mangrove semi-detail mapping in the world.[ES] Los manglares son comunidades vegetales de alta importancia ecología y económica para las regiones costeras. La presente investigación proporciona un método para determinar la cartografía de bosques manglar mediante imágenes de sensores remotos a escala 1:25.000 en un sector del municipio de Buenaventura, Colombia; para la cartografía de bosques de manglar se empleó una imagen satelital Sentinel 2 y una ortofotografía de alta resolución del año 2017; usando el software libre QGIS, se realizó los análisis espectrales, se estableció una clasificación supervisada mediante el algoritmo de máxima verosimilitud. Los resultados obtenidos muestran que la cobertura de manglar es la de mayor representatividad en el área de estudio con una extensión total de 7.264,21 ha (59,21% del área total), la clasificación desarrollada presentó una exactitud temática global de 80% e índice de Kappa de 0,70. El método empleado sirve como un referente sobre la cartografía de bosques de manglar en el mundo.Perea-Ardila, MA.; Oviedo-Barrero, F.; Leal-Villamil, J. (2019). Cartografía de bosques de manglar mediante imágenes de sensores remotos: estudio de caso Buenaventura, Colombia. Revista de Teledetección. (53):73-86. https://doi.org/10.4995/raet.2019.11684SWORD73865

Synthesis of a Novel Boronic Acid Transition State Inhibitor, MB076: A Heterocyclic Triazole Effectively Inhibits Acinetobacter-Derived Cephalosporinase Variants with an Expanded-Substrate Spectrum

Class C Acinetobacter-derived cephalosporinases(ADCs) represent an important target for inhibition in the multidrug-resistantpathogen Acinetobacter baumannii. ManyADC variants have emerged, and characterization of their structuraland functional differences is essential. Equally as important is thedevelopment of compounds that inhibit all prevalent ADCs despite thesedifferences. The boronic acid transition state inhibitor, MB076, a novel heterocyclic triazole with improved plasma stability, wassynthesized and inhibits seven different ADC &amp; beta;-lactamase variantswith K (i) values MB076 acted synergistically in combination with multiple cephalosporinsto restore susceptibility. ADC variants containing an alanine duplicationin the &amp; omega;-loop, specifically ADC-33, exhibited increased activityfor larger cephalosporins, such as ceftazidime, cefiderocol, and ceftolozane.X-ray crystal structures of ADC variants in this study provide a structuralcontext for substrate profile differences and show that the inhibitoradopts a similar conformation in all ADC variants, despite small changesnear their active sites

Rational design of benzobisheterocycle metallo-β-lactamase inhibitors:a tricyclic scaffold enhances potency against target enzymes

Antimicrobial resistance is a global public health threat. Metallo-β-lactamases (MBLs) inactivate β-lactam antibiotics, including carbapenems, are disseminating among Gram-negative bacteria, and lack clinically useful inhibitors. The evolving bisthiazolidine (BTZ) scaffold inhibits all three MBL subclasses (B1 - B3). We report design, synthesis and evaluation of BTZ analogs. Structure-activity relationships identified the BTZ thiol as essential, while the carboxylate is replaceable, with its removal enhancing potency by facilitating hydrophobic interactions within the MBL active site. While the introduction of a flexible aromatic ring is neutral or detrimental for inhibition, a rigid (fused) ring generated nM benzobisheterocycle (BBH) inhibitors that potentiated carbapenems against MBL-producing strains. Crystallography of BBH:MBL complexes identified hydrophobic interactions as the basis of potency towards B1 MBLs. These data underscore BTZs as versatile, potent broad spectrum MBL inhibitors (with activity extending to enzymes refractory to other inhibitors), and provide a rational approach to further improve the tricyclic BBH scaffold