Transformation and Mobility of Cu, Zn, and Cr in Sewage Sludge during Anaerobic Digestion with Pre- or Interstage Hydrothermal Treatment

Wang, Qian; Zhang, Chiqian; Jung, Haesung; Liu, Pan; Patel, Daxesh P.; Pavlostathis, Spyros G.; Tang, Yuanzhi

doi:10.1021/acs.est.0c05164

Cited by 28 publications

(7 citation statements)

References 67 publications

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“…Secondary wastewater effluent was then added to reach a total liquid volume of 400 ml. As mentioned above, instead of pre‐reduced medium, secondary wastewater effluent was used to avoid any interference from the medium as the digestates at the end of the incubation for the BMP tests I and II were used in a companion, parallel study which assessed the speciation of several elements (nutrients and metals) (Wang et al, 2021; Wang, Zhang, Liu, et al, 2020; Wang, Zhang, Patel, et al, 2020). Preliminary experiments showed that substituting secondary wastewater effluent for medium in BMP tests did not significantly affect the rate and extent of methane production (data not shown).…”

Section: Methodsmentioning

confidence: 99%

“…For the AD-HT-AD configuration, in order to obtain predigested sludge, the first batch AD was carried out in a 9-L glass reactor with a liquid volume of 6 L, which contained (initial values): sludge mixture (see Table 1), 10 g volatile solids (VS)/L; anaerobic inoculum, 1 g VS/L; secondary wastewater effluent, 4.15 L; and NaHCO 3 , 1.4 g/L. It should be noted that instead of pre-reduced medium, secondary wastewater effluent was used because the digestates at the end of the incubation were used to assess the speciation of several elements (nutrients and metals) in a companion, parallel study without any interference from the medium Wang, Zhang, Jung, et al, 2021). For the same reason, a low VS-based inoculum-to-substrate ratio (ISR) of 1:10 was chosen to avoid over diluting the sludge mixture.…”

Section: Preparation Of Pre-digested Sludgementioning

confidence: 99%

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Comparative assessment of pre‐ and inter‐stage hydrothermal treatment of municipal sludge for increased methane production

Zhang

Liu

Wang

et al. 2021

Water Environment Research

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Hydrothermal treatment (HT) is a promising technology to enhance anaerobic digestion (AD) of municipal sludge. However, the capacity of pre-and inter-stage HT (i.e., HT-AD and AD-HT-AD, respectively) to enhance the digestibility of municipal sludge has not been sufficiently explored. This study compared the efficacy of pre-and inter-stage HT performed from 90 to 185°C to enhance methane production from a mixture of primary sludge and waste activated sludge using mesophilic (35°C) biochemical methane potential tests. In both configurations, sludge solubilization increased with HT temperature. HT-AD, and to a greater extent AD-HT-AD, increased the release of ammonium nitrogen. Even though HT at 185°C dramatically increased sludge solubilization, the overall specific methane yield with HT at 185°C was lower than or comparable to that at lower HT temperatures in the HT-AD and AD-HT-AD configurations, respectively. Up to 155°C HT, the overall specific methane yield with the HT-AD configuration was higher by 4.9%-8.3% compared to the AD-HT-AD configuration. However, when the HT energy was considered, compared to the control (i.e., AD of sludge without HT), the net energy gain (ΔE) decreased as the HT temperature increased, becoming negative at an HT of 185°C. The AD-HT-AD configuration resulted in a higher overall volatile solids destruction (by 8.1 to 20.1%). In conclusion, for municipal sludge with a relatively high ultimate digestibility, as was the case in this study, HT-AD is preferable as it has a smaller footprint and is easier to operate than the AD-HT-AD configuration. However, given the significantly higher volatile solids destruction in the AD-HT-AD configuration, compared to the HT-AD configuration, AD-HT-AD may be more beneficial considering post-AD sludge handling processes. © 2021 Water Environment Federation • Practitioner points• Hydrothermal treatment (HT) increased the rate and extent of methane production from municipal sludge mixture. • 155°C was the optimal temperature for either pre-or inter-stage HT to increase biogas production. • Pre-and inter-stage HT resulted in comparable ultimate methane production.• Pre-stage HT is preferable to inter-stage HT (smaller footprint, easier to operate).• AD-HT-AD resulted in significantly higher volatile solids destruction compared to the HT-AD configuration.

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Section: Methodsmentioning

confidence: 99%

Section: Preparation Of Pre-digested Sludgementioning

confidence: 99%

Comparative assessment of pre‐ and inter‐stage hydrothermal treatment of municipal sludge for increased methane production

Zhang

Liu

Wang

et al. 2021

Water Environment Research

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“…With the recent development of an atomic-resolution transmission electron microscope (AC-TEM) and X-ray absorption fine structure (XAFS), direct visualization of single atoms has become feasible and regular. − More adsorption dynamic details, which might be ignored with traditional empirical adsorption models, could be directly visible now. These advancements, together with other techniques, provide an excellent opportunity to directly visualize the adsorption behavior on a material surface and open a new era to study the adsorption dynamics on the material interface.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Beyond the Monolayer Adsorption as Derived from Langmuir Curve Fitting

et al. 2022

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Langmuir adsorption model is a classic physical–chemical adsorption model and is widely used to describe the monolayer adsorption behavior at the material interface in environmental chemistry. Traditional adsorption dynamic modeling solely considered the surface physiochemical interaction between the adsorbent and adsorbate. The surface reaction dynamics resulting from the heterogeneous surface and intrinsic electronic structure of absorbents were rarely considered within the reported adsorption experiments. Herein, by employing the chlorine hybrid graphene oxide (GO-Cl) to adsorb Ag+ in an aqueous solution, complicated molecular dynamics significantly deviated from the monolayer adsorption mechanism, as suggested by Langmuir adsorption curve fitting, has been elucidated down to atomic scale. In the time-dependent Ag adsorption experiments, both Ag single atoms and Ag/AgCl nanoparticle heterostructures are observed to be formed sequentially on GO-Cl. These observations indicate that for the surface adsorption dynamics, not only the surface chemical adsorption process involved but also photoreduction and the C–Cl bond cleavage reaction has been heavily engaged within the GO-Cl interface, suggesting a much more complicated vision rather than the monolayered adsorption algorithm as derived from curve fitting. This study uses GO-Cl as a simple example to disclose the complicated adsorption dynamic process underneath Langmuir adsorption curve fitting. It advocates the necessity of imaging the interfacial atomic-scale dynamic structure with high-resolution microscopy techniques in modern adsorption studies, rather than simply explaining the adsorption dynamics relying on the curve fitting results due to the complicated physiochemical reactivity of the adsorbents.

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“…More than 10 million dry tons of sewage sludge are generated annually as a byproduct of publicly owned municipal wastewater treatment works in the United States. Sewage sludge generally consists of a significant portion of organic matter (OM), phosphorus (P), and nitrogen (N), − providing great opportunities for energy recovery via biomethane production and recycling/reclamation of nutrients. ,− However, sewage sludge also contains toxic metals (e.g., Cu, Zn, and Cr) and organic pollutants (e.g., polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzofurans (PCDFs)), along with pathogenic bacteria. − Thus, the management of sewage sludge must integrate resource recovery and safe disposal to achieve societal and environmental sustainability.…”

Section: Introductionmentioning

confidence: 99%

Effect of Prestage Hydrothermal Treatment on the Formation of Struvite vs Vivianite during Semicontinuous Anaerobic Digestion of Sewage Sludge

Wang

Liu

Jung

et al. 2021

ACS Sustainable Chem. Eng.

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Anaerobic digestion (AD) with prestage hydrothermal treatment (HT) is an emerging strategy for the sustainable management of sewage sludge and recovery of valuable resources. Both struvite and vivianite can be precipitated during AD process and serve as two important phases for phosphorus (P) and/or nitrogen (N) recovery. Yet the effect of HT conditions on the phase selection and precipitation of struvite vs vivianite in the subsequent AD process remains unclear. This study investigated the evolution and mineralization of P and N in sewage sludge during AD with prestage HT using complementary chemical extraction and X-ray spectroscopy characterizations. Influencing factors such as sludge type and HT temperature were explored. For raw sludge with high molar ratio of Mg/Fe (5.9), HT did not induce the formation of struvite in the HT-derived hydrochars, because the acidic pH of HT slurries was similar to that in the raw sludge. Struvite was observed during the AD of low temperature (90 and 125 °C) HT slurries due to the reaction of Mg-phosphate phases with high concentration of NH 4 + at pH > 7. For HT slurries prepared at 155 °C, the pH was always below 7 during the subsequent AD process, preventing struvite precipitation in the AD solids. For raw sludge with low molar ratio of Mg/Fe (1.1), HT at 90 and 125 °C induced the formation of vivianite in the hydrochars, as compared to the formation of strengite at 155 °C HT. In comparison with the corresponding hydrochars, more vivianite was precipitated during the subsequent AD via microbial reduction of Fe(III) species. Results from this study suggest that the formation of struvite or vivianite in the final AD solids is highly dependent on the Mg/Fe molar ratio and/or the pH of AD suspensions. Meanwhile, both HT and AD also strongly affected N speciation evolution in sewage sludge. Along with the release of large amounts of ammonia, HT favored the accumulation of quaternary-and pyrrole-N in the hydrochars, while only pyrrole-N was enriched in the AD solids. This study sheds light on the recycling and reclamation of P and N during HT-AD of sewage sludge.

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Transformation and Mobility of Cu, Zn, and Cr in Sewage Sludge during Anaerobic Digestion with Pre- or Interstage Hydrothermal Treatment

Cited by 28 publications

References 67 publications

Comparative assessment of pre‐ and inter‐stage hydrothermal treatment of municipal sludge for increased methane production

Comparative assessment of pre‐ and inter‐stage hydrothermal treatment of municipal sludge for increased methane production

Molecular Dynamics Beyond the Monolayer Adsorption as Derived from Langmuir Curve Fitting

Effect of Prestage Hydrothermal Treatment on the Formation of Struvite vs Vivianite during Semicontinuous Anaerobic Digestion of Sewage Sludge

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