Principles and potential of thermal hydrolysis of sewage sludge to enhance anaerobic digestion

Gahlot, Pallavi; Tyagi, Vinay Kumar; Balasundaram, Gowtham; Atabani, A.E.; Suthar, Surinder; Kazmi, A.A.; Štěpanec, Libor; Juchelková, Dagmar; Kumar, Arvind

doi:10.1016/j.envres.2022.113856

Cited by 63 publications

(13 citation statements)

References 124 publications

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“…For example, after thermal pretreatment for 24 h at 60, 70, 80, and 90 °C, SCOD/TCOD increased from 4.5% to 29.6%, 30.3%, 34.8%, and 41.1%, respectively, while biogas production only increased only by 11.3%, 9.3%, 12.3%, and 8.8%, respectively 36 . Additionally, high temperature pretreatment (> 100 °C) requires high quality heat and results in higher operating costs 37 . In comparison, TPAcD has a better performance in enhancing methane production (increased by 50.3% and 32.7% compared to MAcD and TAcD, respectively) with acceptable operating costs.…”

Section: Resultsmentioning

confidence: 99%

Thermophilic-mesophilic temperature phase anaerobic co-digestion compared with single phase co-digestion of sewage sludge and food waste

Hu,

Shen

2024

Sci Rep

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Anaerobic co-digestion is an effective method for addressing the issue of a single substrate not being able to achieve optimal conditions for anaerobic digestion. By adjusting the mixture ratio of sewage sludge and food waste to achieve the optimal carbon to nitrogen ratio, the effectiveness of thermophilic–mesophilic temperature phase anaerobic co-digestion (TPAcD) was evaluated in comparison to single phase mesophilic anaerobic co-digestion (MAcD) and thermophilic anaerobic co-digestion (TAcD). The results indicated that TPAcD increased methane yield by 50.3% and 32.7% compared to MAcD and TAcD, respectively. The variation in VFA, pH, and ammonia nitrogen levels demonstrated that TPAcD combines the advantages of both MAcD and TAcD, with a higher hydrolysis rate in the early stage under thermophilic conditions (55 °C) and a suitable environment in the later stage under mesophilic conditions (35 °C). The kinetic parameters of anaerobic co-digestions also demonstrated that TPAcD performs better. Therefore, further research on TPAcD of sewage sludge and food waste is warranted due to its significant improvements in methane production rate, total methane yield, and system stability. Additionally, TPAcD contributes to reducing carbon emissions and supports the realization of “carbon neutrality”.

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Section: Resultsmentioning

confidence: 99%

Thermophilic-mesophilic temperature phase anaerobic co-digestion compared with single phase co-digestion of sewage sludge and food waste

Hu,

Shen

2024

Sci Rep

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“…However, it is of industrial interest to know whether the process is energetically and economically feasible. The references to self-sufficiency and energy improvement by applying thermal pretreatment for subsequent AD of sewage sludge from sewage treatment are extensive (Barber, 2016; Devos et al, 2021; Gahlot et al, 2022). Nowadays, it is reported that by using cogeneration processes in conjunction with AD and pretreatment, it is possible to meet the energy needs of the system with less than a 10% increase in biogas production from the treated waste (Gahlot et al, 2022; Kor-Bicakci and Eskicioglu, 2019).…”

Section: Resultsmentioning

confidence: 99%

“…The references to self-sufficiency and energy improvement by applying thermal pretreatment for subsequent AD of sewage sludge from sewage treatment are extensive (Barber, 2016; Devos et al, 2021; Gahlot et al, 2022). Nowadays, it is reported that by using cogeneration processes in conjunction with AD and pretreatment, it is possible to meet the energy needs of the system with less than a 10% increase in biogas production from the treated waste (Gahlot et al, 2022; Kor-Bicakci and Eskicioglu, 2019). Furthermore, thermal sewage sludge pretreatments are not only energy self-sufficient but are also reported to be economically feasible with interesting payback (Cano et al, 2014; Fernandez-Polanco et al, 2021).…”

Section: Resultsmentioning

confidence: 99%

“…Devos et al (2021) mention an optimal temperature range for TH of sewage sludge between 140 °C and 160 °C. On the other hand, the value of 165 °C is recurrently used as the optimum temperature in already established commercial-scale technologies for sewage biosludge, as in the case of Exelys and well reported in the work of Gahlot et al (2022) recently. In addition, it was reported that 140 °C is generally the lower limit for currently developed sewage sludge technologies.…”

Section: Introductionmentioning

confidence: 98%

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Improvements in the anaerobic digestion of biological sludge from pulp and paper mills using thermal pretreatment

et al. 2023

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The current disposal of biosludge generated in wastewater treatment has high costs and causes environmental problems, anaerobic digestion (AD) of solid waste is a promising alternative. Thermal hydrolysis (TH) is an accepted technology to enhance anaerobic biodegradability of sewage sludge, but this technology has not been developed to be used with biological sludge from industrial wastewater treatment. In this work, the improvements to the AD of biological sludge from cellulose industry when thermal pretreatment is carried out were experimentally determined. The experimental conditions for TH were 140 °C and 165 °C for 45 minutes. Batch tests were carried out to quantify methane production evaluated as biomethane potential (BMP), anaerobic biodegradability according to volatile solids (VS) consumption and kinetic adjustments. An innovative kinetic model based on the serial mechanism of fast and slow biodegradation fractions was tested for untreated waste, and parallel mechanism was also evaluated. Increases in BMP and biodegradability values according to VS consumption were determined with increasing TH temperature. The results of 241 NmL CH4 gVS substrate−1 for BMP and 65% biodegradability are reported for the 165 °C treatment. AD rate increased for the TH waste compared to the untreated biosludge. Improvements of up to 159% for BMP and 260% for biodegradability according to VS consumption were quantified for TH biosludge compared to untreated biosludge.

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“…The aim of these digestion processes is to break down organic matter and to raise the temperature of the biosolid to eliminate pathogenic organisms that may have been present in the wastewater (Mello Leite Moretti et al 2015 ; Al-Gheethi et al 2018 ). Additionally, pretreatment steps can be included prior to digestion, such as thermal hydrolysis which uses high temperatures and pressure to improve organic matter breakdown and pathogen control (Gahlot et al 2022 ). In the UK 73% of biosolids are produced using AD (Assured Biosolids Limited 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Response of soil bacterial populations to application of biosolids under short-term flooding

Humphries

Thornton

Chen

et al. 2023

Environ Sci Pollut Res

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Biosolids are applied to agricultural land as a soil conditioner and source of crop nutrients. However, there is concern that bacteria from biosolids may become established in soils, particularly if that soil becomes water-logged. This study examined the microbial community of arable soils cultivated with barley under different applications of biosolids (0, 24t/ha, 48t/ha) in laboratory mesocosms which simulated a 10-day flood. Nutrients (P and N) and organic matter in the soil increased with application rate, but plant growth was not affected by biosolid application. The biosolids contained 10× more genetic material than the soil, with much lower bacterial diversity, yet application did not significantly change the taxonomy of the soil microbiome, with minor changes related to increased nutrients and SOM. Anaerobic conditions developed rapidly during flooding, causing shifts in the native soil microbiome. Some bacterial taxa that were highly abundant in biosolids had slightly increased relative abundance in amended soils during the flood. After flooding, soil bacterial populations returned to their pre-flood profiles, implying that the native microbial community is resilient to transient changes. The short-term changes in the microbiome of biosolid-amended soils during flooding do not appear to increase the environmental risk posed by biosolid application.

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Principles and potential of thermal hydrolysis of sewage sludge to enhance anaerobic digestion

Cited by 63 publications

References 124 publications

Thermophilic-mesophilic temperature phase anaerobic co-digestion compared with single phase co-digestion of sewage sludge and food waste

Thermophilic-mesophilic temperature phase anaerobic co-digestion compared with single phase co-digestion of sewage sludge and food waste

Improvements in the anaerobic digestion of biological sludge from pulp and paper mills using thermal pretreatment

Response of soil bacterial populations to application of biosolids under short-term flooding

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