Sustainable disposal of excess sludge: Post-thermal hydrolysis for anaerobically digested sludge

Cai, Chen; Hu, Chongliang; Yang, Wan; Yu, Hua; Li, Lei; Yang, Dongyuan; Dai, Xiaohu

doi:10.1016/j.jclepro.2021.128893

Cited by 25 publications

(4 citation statements)

References 54 publications

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“…It is worth noting that the abundance of various ARGs was within the range of absolute abundance of ARGs about 10 4 to 10 10 copies per gram of sludge reported for digestate from full-scale sludge mesophilic AD in the literature. 52,53 Overall, the total copies of ARGs for the microaeration and iron-dosed reactors were 8.8 × 10 4 and 9.1 × 10 4 per gram of sludge which was significantly lower (p-value = <0.001) than the control (1.2 × 10 5 gene copies/g sludge) (Figure 5). Analogous to ARGs, MGEs (intl1 and intl2) also showed similar patterns, i.e., substantially higher levels (p-value = <0.001) in the control than in test reactors.…”

Section: ■ Materials and Methodsmentioning

confidence: 93%

Bench-Scale Liquid-Phase Microaeration and Iron Dosing Comparison for In Situ Biogas Desulfurization and Antibiotic Resistance Management in Mesophilic Anaerobic Digestion

Mirsoleimani Azizi,

Zakaria,

Haffiez

et al. 2023

ACS EST Water

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Microaeration and iron dosing are promising in situ desulfurization methods for anaerobic digestion (AD). However, limited reports exist on their systematic comparison. Consequently, this study investigated liquid-phase microaeration (60–106 mL air/Lreactor/d) and ferric chloride (250–650 mg FeCl3/L) dosages in mesophilic AD of sewage sludge operated at a solid residence time of 20 days. Both methods provided up to 88% H2S removal and moderate siloxane removal (30–37%) but had no apparent impact on mercaptan removal from biogas. However, the control and test reactors demonstrated equivalent AD performance in terms of biomethane yields, chemical oxygen demand, and total/volatile solids degradation efficiencies, indicating that air and iron dosages were primarily utilized for biogas desulfurization. Still, both methods resulted in substantial changes in microbial community composition. Notably, the indication of syntrophy between facultative microbes and hydrogenotrophic methanogens was intensified by both methods. For both methods, antibiotic resistance gene (ARG) and mobile genetic element (MGE) abundances in digestate decreased considerably due to the decrease in the abundance of potential ARG hosts. Compared to iron dosing, MGE removal was slightly higher in the microaeration reactor. These findings provide valuable insights into the efficacy of these two approaches in desulfurization and the reduction of antibiotic resistance in AD.

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Section: ■ Materials and Methodsmentioning

confidence: 93%

Bench-Scale Liquid-Phase Microaeration and Iron Dosing Comparison for In Situ Biogas Desulfurization and Antibiotic Resistance Management in Mesophilic Anaerobic Digestion

Mirsoleimani Azizi,

Zakaria,

Haffiez

et al. 2023

ACS EST Water

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“…This process involves a microbial-mediated conversion of biodegradable organic and nutrient pollutants into gaseous and solids with a residual pollution in the effluent suitable with the environmental requirements for discharge into the receiving water bodies (Wang et al, 2015). Given the large application of the activated sludge process in wastewater treatment, several researches were carried out with the aim to improve its efficiency while minimizing the drawbacks (Cai et al, 2021;Collivignarelli et al, 2019). Among these, the excess sludge management, including its treatment and disposal operation, is arising as one of the most concern topic of the last decade (Collivignarelli et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Insights on mechanisms of excess sludge minimization in an oxic-settling-anaerobic process under different operating conditions and plant configurations

et al. 2023

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“…Among the EAS treatment methods, composting and anaerobic digestion for methane production are effective ways to utilize the carbon present in EAS [4,5]. However, to improve the efficiency of composting and anaerobic digestion, pretreatment of EAS using thermal hydrolysis (TH) and alkali hydrolysis, which can promote the dissolution of nitrogen, organic matter, and other nutrients from sludge, are generally required [6,7]. Thermal hydrolysis can disintegrate the floc structure of sludge and break up sludge cells, to release and hydrolyze the organic matter [8].…”

Section: Introductionmentioning

confidence: 99%

Preliminary Study on the Treatment Efficiency of Pasteurized Lime Thermal Alkaline Hydrolysis for Excess Activated Sludge and Reduction of Tetracycline Resistance Genes

Chen¹,

Zhou²,

Zhang³

et al. 2023

Journal of Renewable Materials

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Thermal alkaline hydrolysis is a common pretreatment method for the utilization of excess activated sludge (EAS). Owing to strict environment laws and need for better energy utilization, new methods were developed in this study to improve the efficiency of pretreatment method. Direct thermal hydrolysis (TH), pasteurized thermal hydrolysis (PTH), and alkaline pasteurized thermal hydrolysis (PTH + CaO and PTH + NaOH) methods were used to treat EAS. Each method was compared and analyzed in terms of dissolution in ammonium nitrogen (NH 4 + -N) and soluble COD (SCOD) in EAS. Furthermore, the removal of tetracycline resistance genes (TRGs)and class 1 transposon gene intI1 from EAS was investigated. The NH 4 + -N and SCOD concentrations in EAS treated by PTH were 1.24 and 2.58 times higher than those of TH. However, the removal efficiency of total TRGs and intI1 between the groups was comparable. The SCOD concentration of the PTH + NaOH group was 4.37 times higher than that of the PTH group, and the removal efficiency of total TRGs was increased by 9.52% compared with that by PTH. The NH 4 + -N and SCOD concentrations of the PTH + CaO group could reach 85.04% and 92.14% of the PTH + NaOH group, but the removal efficiency of total TRGs by PTH + CaO was 19.78% lower than that by PTH + NaOH. Thus, to reduce the financial cost in actual operation, lime (CaO) can be used instead of a strong alkali (NaOH), and pasteurized steam at 70°C instead of conventional high-temperature heating to treat EAS. This study provides a reference for the development of alkaline hydrolysis under moderate temperatures along with the removal of TRGs in EAS.

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Sustainable disposal of excess sludge: Post-thermal hydrolysis for anaerobically digested sludge

Cited by 25 publications

References 54 publications

Bench-Scale Liquid-Phase Microaeration and Iron Dosing Comparison for In Situ Biogas Desulfurization and Antibiotic Resistance Management in Mesophilic Anaerobic Digestion

Bench-Scale Liquid-Phase Microaeration and Iron Dosing Comparison for In Situ Biogas Desulfurization and Antibiotic Resistance Management in Mesophilic Anaerobic Digestion

Insights on mechanisms of excess sludge minimization in an oxic-settling-anaerobic process under different operating conditions and plant configurations

Preliminary Study on the Treatment Efficiency of Pasteurized Lime Thermal Alkaline Hydrolysis for Excess Activated Sludge and Reduction of Tetracycline Resistance Genes

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