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.

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 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.

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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