scholarly journals Use of Ash from Sewage Sludge in the Preparation of Desulfurant Sorbents

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Josefa Fernández Ferreras ◽  
Hipolito García Posadas ◽  
Jose Luis Rico Gutierrez ◽  
Josefina Renedo Omaechevarría
Keyword(s):  
Wastewater Treatment ◽  
Sewage Sludge ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Municipal Wastewater ◽  
Fixed Bed Reactor ◽  
Municipal Wastewater Treatment ◽  
Bet Specific Surface Area ◽  
Two Temperatures

This work aims to develop new uses for sewage sludge, which is a byproduct of municipal wastewater treatment plants, by examining the calcination of this waste, the characterization of ashes is obtained, and its use to prepare desulfurant sorbents. Samples of sewage sludge were obtained from a local municipal wastewater treatment plant. This plant applies a pre-treatment followed by a biological treatment, where anaerobic digestion and centrifugation reduces the sludge. Three samples were characterized (in humidity, volatile and fixed solids content), dried, and ignited at two temperatures, 550 and 750°C. The composition of the ash obtained at both ignition temperatures was studied by x-ray fluorescent spectroscopy and the BET specific surface area of the two ashes and of the prepared sorbents was measured. Ash composition was similar for the two temperatures tested, where the components were Si, Ca, Al, Fe, P, S, Mg, K, Cl, Zn and Ti. BET specific surface area values indicate that the lower temperature of calcination produces ash with the highest SSA values (18 m2/g against near 10 m2/g). Preparation of desulfurant sorbents was carried out by mixing the ash with CaO or Ca(OH)2 at room temperature and different experimental conditions. The BET SSA of the prepared desulfurant sorbents showed higher values for the sorbents prepared with the ashes obtained at the lowest temperature. The behaviour of the ash and the prepared sorbents was tested in a fixed bed reactor at 58°C with a flue gas containing 5000 ppm of SO2 with a relative humidity of 55%. Results in the desulfurization process show that the calcium from the sludge seems more efficient than the calcium added as CaO or Ca(OH)2 to prepare the sorbents.

scholarly journals Sizes of particles formed during municipal wastewater treatment

2016 ◽  
Vol 75 (4) ◽  
pp. 971-977 ◽  
Author(s):  
Smoczynski Lech ◽  
Kosobucka Marta ◽  
Smoczynski Michal ◽  
Ratnaweera Harsha ◽  
Pieczulis-Smoczynska Krystyna
Keyword(s):  
Wastewater Treatment ◽  
Sewage Sludge ◽  
Specific Surface ◽  
Surface Area ◽  
Municipal Wastewater ◽  
Size Range ◽  
Theoretical Models ◽  
Municipal Wastewater Treatment ◽  
Uniform Particles ◽  
Higher Doses

Volumetric diameters Dv and specific surface area SpS of sludge particles formed during chemical coagulation and electrocoagulation of sewage were determined. The obtained aggregate-flocs differed substantially in both Dv and SpS values. The differences in Dv and SpS values of the analyzed particles were interpreted based on theoretical models for expanding aggregates. The most uniform particles were formed under exposure to: (a) optimal and maximal doses of PIX, (b) optimal doses of PAX, (c) maximal doses of the Al electro-coagulant. The lowest PIX dose produced the least uniform particles. Sludge aggregates-particles produced under exposure to minimal doses of PIX and the Al electro-coagulant were characterized by the lowest SpS values. Sludge particles coagulated by PAX and the particles formed at higher doses of PIX and the Al electro-coagulant had higher SpS values. The particles formed at all doses of the applied coagulants and electro-coagulants were generally classified into two size ranges: the main range and the secondary range. Most particles belonged to the main size range. An increase in the percentage of colloidal hydroxide particles in sewage sludge increased SpS.

Behaviour and adsorptive removal of siloxanes in sewage sludge biogas

2010 ◽  
Vol 61 (8) ◽  
pp. 2003-2012 ◽  
Author(s):  
K. Oshita ◽  
Y. Ishihara ◽  
M. Takaoka ◽  
N. Takeda ◽  
T. Matsumoto ◽  
...  
Keyword(s):  
Sewage Sludge ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
External Surface ◽  
Large Diameter ◽  
Surface Areas ◽  
Bet Specific Surface Area ◽  
Cyclic Siloxanes ◽  
Biogas Engines

We investigated the behaviour of siloxanes, which adversely affect biogas engines, as well as their concentration levels in sewage sludge biogas in Japan. We also performed experiments on the absorptive removal of siloxanes using various adsorbents and determined the main adsorbent characteristics required for the removal of siloxanes. The results of our study on the concentration and composition of siloxanes in biogas were similar to previous reports. Moreover, we found that the concentration of siloxanes changes in relation to the outside air temperature based on real-time measurements of siloxanes using a continuous analyser. We further speculated that the continuous analyser would accurately indicate the siloxane concentration in model biogas but overestimate the siloxane concentration in actual biogas because of positive interference by VOCs and other biogas components. In the siloxane adsorption experiment, the equilibrium uptake of both cyclic siloxanes, D4 and D5, was positively related to the BET-specific surface area of the adsorbents and the fraction of the external surface area taken up by relatively large diameter pores. We attributed the adsorption results to the fact that the siloxane molecules are generally larger than micropores; therefore, they are less susceptible to adsorption to micropores. Based on these results, we concluded that adsorbents with large BET-specific surface areas, especially those with a high external specific surface area and pores of relatively large diameters, are desired for the removal of siloxanes.

scholarly journals Study of Sludge Particles Formed during Coagulation of Synthetic and Municipal Wastewater for Increasing the Sludge Dewatering Efficiency

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 101
Author(s):  
Lech Smoczynski ◽  
Slawomir Kalinowski ◽  
Igor Cretescu ◽  
Michal Smoczynski ◽  
Harsha Ratnaweera ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Specific Surface ◽  
Size Distribution ◽  
Surface Area ◽  
Specific Surface Area ◽  
Municipal Wastewater ◽  
Wastewater Sludge ◽  
Synthetic Wastewater ◽  
Dye Molecules ◽  
Sludge Dewatering

Municipal wastewater sludge was produced by chemical coagulation of synthetic wastewater (sww) based on Synthene Scarlet P3GL disperse dye and real municipal wastewater (nww), coagulated by commercial coagulants PAX (prepolymerised aluminum coagulant) and PIX (a ferric coagulant based on Fe2(SO4)3). An attempt was made to correlate the sludge’s dewatering capacity (in terms of capillary suction time—CST) with operation parameters for wastewater treatment, size distribution and specific surface area of the sludge particles. It was found that the presence of phosphate ions in the system facilitates the removal efficiency of the above-mentioned dye (L) due to the interaction between the dye molecules and H2PO4− ions. Unlike sww, negatively charged organic substances (sorg) in nww are directly adsorbed on the surface of colloidal particles {Fe(OH)3} and {Al(OH)3} (prtc). It was also discovered that an increase in the dose of a coagulant led to an increase of CST for sww sludge and to a decrease of CST for nww sludge. It has been suggested that flocs composed of spherical {Al(OH)3} units possessed more internal space for water than aggregates consisting of rod-shaped {Fe(OH)3} units and, consequently, it is more difficult to remove water from Al-sww sludge than from Fe-sww. The results obtained showed that smaller particles dominate in sww sludge, while larger particles are prevalent in nww sludge. To explain this distinct difference in the size distribution of particles in sludge obtained with the use of Al3+ and Fe3+, simple models of aggregation and agglomeration-flocculation processes (aaf) of treated wastewater have been proposed. Except for PIX in nww, the analyzed particles of the investigated types of sludge were characterized by similar specific surface area (Sps), regardless of the kind of sludge or the applied coagulant. Slightly larger, negatively-charged sorg bridges, anchored directly on the surface of positive prtc are more effective in closing the structure of nww sludge than small L bridges of the dye molecules anchored on the surface of prtc via H2PO4−. All the discovered aspects could lead to improved performance of wastewater treatment plants (WWTP) by increasing the efficiency of sludge dewatering.

scholarly journals Samarium Promoted Ni/Al2O3 Catalysts for Syngas Production from Glycerol Pyrolys

2016 ◽  
Vol 11 (2) ◽  
pp. 238 ◽  
Author(s):  
Mohd Nasir Nor Shahirah ◽  
Bamidele V. Ayodele ◽  
Jolius Gimbun ◽  
Chin Kui Cheng
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Fixed Bed Reactor ◽  
Ni Catalyst ◽  
Impregnation Method ◽  
Glycerol Conversion ◽  
Product Ratio ◽  
Syngas Production ◽  
Bet Specific Surface Area

<p>The current paper reports on the kinetics of glycerol reforming over the alumina-supported Ni catalyst that was promoted with rare earth elements. The catalysts were synthesized via wet impregnation method with formulations of 3 wt% Sm-20 wt% Ni/77 wt% Al<sub>2</sub>O<sub>3</sub>. The characterizations of all the as-synthesized catalysts were carried out, viz.  BET specific surface area measurements, thermogravimetri analysis for temperature-programmed calcination studies, FESEM for surface imaging, XRD to obtain diffraction patterns, XRF for elemental analysis, etc.. Reaction studies were performed in a stainless steel fixed bed reactor with reaction temperatures set at 973, 1023 and 1073 K employing weight hourly space velocity (WHSV) of 4.5×10<sup>4</sup> mL g<sup>-1</sup> h<sup>-1</sup>. Agilent GC with TCD capillary column was used to analyze gas compositions. Results gathered showed that the BET specific surface area was 2.09 m<sup>2</sup>.g<sup>-1</sup> for the unpromoted Ni catalyst while for the promoted catalysts, was 2.68 m<sup>2</sup>.g<sup>-1</sup>. Significantly, the BET results were supported by the FESEM images which showed promoted catalysts exhibit smaller particle size compared to the unpromoted catalyst. It can be deduced that the promoter can increase metal dispersion on alumina support, hence decreasing the size of particles. The TGA analysis consistently showed four peaks which represent water removal at temperature 373-463 K, followed by decomposition of nickel nitrate to produce nickel oxide. From reaction results for Sm promotion showed glycerol conversion, X<sub>G</sub> of 27% which was 7% higher than unpromoted catalyst. The syngas productions were produced from glycerol decomposition and created H<sub>2</sub>:CO product ratio which always lower than 2.0. The H<sub>2</sub>:CO product ratio of 3 wt% Sm promoted Ni/Al<sub>2</sub>O<sub>3</sub> catalyst was 1.70 at reaction temperature of 973 K and glycerol partial pressure of 18 kPa and suitable enough for Fischer-Tropsch synthesis.  Copyright © 2016 BCREC GROUP. All rights reserved</p><p><em>Received: 22<sup>nd</sup> January 2016; Revised: 1<sup>st</sup> February 2016; Accepted: 17<sup>th</sup> February 2016</em></p><strong>How to Cite:</strong> Shahirah, M.N.N., Ayodele, B.V., Gimbun, J., Cheng, C.K. (2016). Samarium Promoted Ni/Al<sub>2</sub>O<sub>3</sub> Catalysts for Syngas Production from Glycerol Pyrolysis. <em>Bulletin of Chemical Reaction Engineering &amp; Catalysis</em>, 11 (2): 238-244 (doi:10.9767/bcrec.11.2.555.238-244)<p><strong>Permalink/DOI:</strong> http://dx.doi.org/10.9767/bcrec.11.2.555.238-244</p>

scholarly journals Modelling the bioenergy potential of municipal wastewater treatment plants

2018 ◽  
Vol 77 (11) ◽  
pp. 2613-2623 ◽  
Author(s):  
Kerstin Schopf ◽  
Johannes Judex ◽  
Bernhard Schmid ◽  
Thomas Kienberger
Keyword(s):  
Wastewater Treatment ◽  
Sewage Sludge ◽  
Energy Recovery ◽  
Municipal Wastewater ◽  
Energy Content ◽  
Treatment Plant ◽  
High Energy ◽  
Recovery Efficiency ◽  
Municipal Wastewater Treatment ◽  
Self Sufficiency

Abstract A municipal wastewater treatment plant accounts for a large portion of the total energy consumption of a municipality. Besides their high energy demand, the plants also display a significant bioenergy potential. This is due to the utilisation of the energy content of digester gas and sewage sludge if there exist suitable units. To maximise the energy recovery efficiency of wastewater treatment systems (WWTS), it is important to analyse the amount of digester gas and sludge produced in different types of plants. Therefore, the present paper deals with designing a tool to answer the following research questions: Which bioenergy potentials occur in different plant types? Which mass and energy flows are related to the specific potentials? Which utilisation processes for the potentials can lead to a high energy recovery efficiency of WWTS? Preliminary analyses with the designed tool were focused on estimating the level of electric and thermal energy self-sufficiency of different plant configuration scenarios including or excluding digester gas and/or sludge utilisation units. First results based on the level of self-sufficiency and associated energy and disposal costs show that a digester gas and sewage sludge utilisation should be considered when designing future WWTS.

Microstructural and porosimetry analysis of Ag-TiO2intercalated kaolin and diatomite as nanocomposite ceramic materials

Clay Minerals ◽  
2018 ◽  
Vol 53 (4) ◽  
pp. 665-674 ◽  
Author(s):  
Emmanuel Ajenifuja ◽  
Abimbola P.I. Popoola ◽  
Kabir O. Oyedotun ◽  
Olawale Popoola
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ceramic Materials ◽  
Mineral Particle ◽  
Scanning Calorimetry ◽  
Sintered Ceramic ◽  
Morphological Studies ◽  
Bet Specific Surface Area ◽  
Bet Analysis

ABSTRACTKaolin and diatomite are abundant and widely available geological materials that may immobilize or stabilize functional chemical species on their surfaces for various applications. Acid-treated kaolin and diatomite were intercalated with photocatalyst Ag-TiO2nanoparticles using the sol–gel technique to prepare nanocomposite ceramic materials. The nanocomposites were sintered between 900°C and 1000°C to induce thermal reactions and to enhance nanoparticle–substrate attachment. Chemical and thermal characterizations of the acid-treated materials and intercalated nanocomposites were performed with energy-dispersive X-ray (EDX) analysis and differential scanning calorimetry (DSC), respectively. The Brunauer–Emmett–Teller (BET)-specific surface area and scanning electron microscopy (SEM) were employed for physical and microstructural characterization of the nanocomposites, respectively. Morphological studies revealed a uniform distribution of Ag-TiO2nanocrystallites in pores and on mineral particle surfaces. The BET analysis showed remarkable surface and grain modification by sintering. Decreases in the BET-specific surface area were observed for the sintered ceramic nanocomposite, Ag-TiO2-kaolin (20.244 to 5.446 m2/g) and Ag-TiO2-diatomite (19.582 to 10.148 m2/g).

Evaluating the stabilisation degree of digested sewage sludge: investigations at four municipal wastewater treatment plants

2006 ◽  
Vol 53 (8) ◽  
pp. 81-90 ◽  
Author(s):  
V. Parravicini ◽  
E. Smidt ◽  
K. Svardal ◽  
H. Kroiss
Keyword(s):  
Wastewater Treatment ◽  
Sewage Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Municipal Wastewater Treatment ◽  
Digested Sludge ◽  
Aerobic Conditions ◽  
Specific Oxygen Uptake Rate ◽  
Municipal Wastewater Treatment Plants ◽  
Digested Sewage Sludge

Further reduction of volatile suspended solids (VSS) during a post-stabilisation step was applied to evaluate the stabilisation degree of digested sewage sludge. For this purpose digested sludge was collected at four municipal wastewater treatment plants (WWTPs) and further stabilised in lab-scale chemostat reactors either under anaerobic or aerobic conditions. Experimental results showed that even in adequately digested sludge a consistent amount of VSS was degraded during aerobic post-stabilisation. It seems that aerobic conditions play a significant role during degradation of residual VSS. Additionally, specific VSS production (gVSS/peCOD110.d) as well as specific oxygen uptake rate were shown to be suitable parameters to assess the degree of sludge stabilisation at WWTPs. Fourier transform infrared spectroscopy was used to reveal changes in the sludge composition. Spectra of treated and untreated sludge samples indicated that the major component of residual VSS in stabilised sludge for instance consisted of biomass, while cellulose was absent.

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