Free nitrous acid pre-treatment of waste activated sludge enhances volatile solids destruction and improves sludge dewaterability in continuous anaerobic digestion

Wei, Wei; Wang, Qilin; Zhang, Liguo; Laloo, Andrew Elohim; Duan, Haoran; Batstone, Damien J.; Yuan, Zhiguo

doi:10.1016/j.watres.2017.11.050

Cited by 137 publications

(29 citation statements)

References 31 publications

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“…1) after the treatments reflect the cell walls and EPS disruption. Wang et al 25 and Wei et al 26 also attributed the higher Soluble Kjeldahl Nitrogen and VS in sludge after FNA treatment to the changed floc structure of the sludge. Mechanisms of solubilising organic matter in Fenton treatment were also shown in Eqs.…”

Section: Discussionmentioning

confidence: 97%

Synergy of combined free nitrous acid and Fenton technology in enhancing anaerobic digestion of actual sewage waste activated sludge

Karimi

Hallaji

Siami

et al. 2020

Sci Rep

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in this study, actual swage waste activated sludge in batch reactors was employed to assess the synergistic effect of free nitrous acid and Fenton pre-treatments on enhancing methane production in the anaerobic digestion process. in addition to methane enhancement, the mechanisms driving the enhancement were also investigated via measuring enzymes activity and solubilisation of organic matter. This study revealed that the combined pre-treatments solubilised organic matter significantly more than the bioreactors pre-treated with individual FNA and Fenton. For understanding the influence of pre-treatments on solubilisation of organic matter, soluble protein, soluble polysaccharide and soluble chemical oxygen demand (ScoD) were measured before and after the treatments and it was shown that they respectively increased by 973%, 33% and 353% after the treatments. Protease and cellulase activity, as the key constituents of the microbial community in activated sludge, decreased considerably after the combined pre-treatments 42% and 32% respectively, which resulted in considerable methane enhancement. the results corroborate the synergy of the combined fnA and Fenton pre-treatment in degrading the organic and microbial constituents in waste activated sludge, paving the way for the big-scale implementation of these technologies.

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Section: Discussionmentioning

confidence: 97%

Synergy of combined free nitrous acid and Fenton technology in enhancing anaerobic digestion of actual sewage waste activated sludge

Karimi

Hallaji

Siami

et al. 2020

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Therefore, effects of FNA pre-treatment conditions needed to be systematically evaluated in continuous AD reactor operations. Consequently, continuous AD reactors were operated with full-scale WAS to systematically assess the impacts of FNA pre-treatment on AD performances (Wei et al 2018. Two identical lab-scale AD reactors were operated in Wei et al (2018) study, receiving FNA pre-treated and untreated WAS, respectively.…”

Section: Enhancing Sludge Reduction and Energy Recovery In Sludge Manmentioning

confidence: 99%

“…Consequently, continuous AD reactors were operated with full-scale WAS to systematically assess the impacts of FNA pre-treatment on AD performances (Wei et al 2018. Two identical lab-scale AD reactors were operated in Wei et al (2018) study, receiving FNA pre-treated and untreated WAS, respectively. Due to the enhanced WAS biodegradability by the FNA pre-treatment (FNA = 1.8 mgN/L, treatment time = 24h), VS destruction of the experimental AD was enhanced by 17 ± 1% (from 29.2 ± 0.9% to 34.2 ± 1.1%) and the methane production increased accordingly, by 16 ± 1%.…”

Section: Enhancing Sludge Reduction and Energy Recovery In Sludge Manmentioning

confidence: 99%

“…In the case that the sidestream unit is not available, nitrite can be added externally for the FNA treatment, as illustrated in Option B (Figure 2). It should be noted the associated cost of chemical addition is relatively small, compared with the resulted economic benefits, and thus is cost-effective (Wei et al 2018). FNA pre-treatment of WAS benefits WWTPs by improving AD performance in the aspects of VS destruction, CH4 production, pathogen removal and sludge dewaterability.…”

Section: The Fna-based Applications Are Feasible and Economically Viamentioning

confidence: 99%

“…Economic analyses have been carried out for Options B, C, D & E (Duan et al 2018, Wang et al 2016a, Wang et al 2013a, Wei et al 2018. While the FNA approaches incur extra operational costs due to chemical addition (nitrite and acid for Options B, and acid for Options C-E) and capital costs for a sidestream nitritation unit (for WWTPs without sidestream treatment) and sludge treatment unit, the approaches are overall economically favourable due to significant savings in aeration energy, methanol addition and sludge handling.…”

Section: The Fna-based Applications Are Feasible and Economically Viamentioning

confidence: 99%

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