Improving response of sewer sediment floating to gravity sewage flow-caused erosion by plant ash-driven biopolymer hydrolysis: Lossless sewage transportation strategy

• Published in: Journal of water process engineering 2024-08, Vol.65, p.105798, Article 105798
• Main Authors: Pang, Heliang, Ding, Jiangbo, Li, Xingwang, Zhang, Zhiqiang, Lu, Jinsuo
• Format: Article
• Language: English
• Subjects: Adhesion sensitivity; Hydraulic shear stress; Plant ash; Sewage transportation; Sewer sediment
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2024.105798

Sediments presented strong resistance to gravity sewage flushing, leading to bottom adhesion and siltation with operation challenges in sewer. This study proposed an innovative plant ash treatment to improve response of sediment floating to gravity sewage-caused hydraulic shear stress. Plant ash-driven alkaline hydrolysis was capable of lysing cells and collapsing extracellular polymeric substances, driving sediment cohesion degeneration under hydraulic erosion. Endogenous biopolymers were deconstructed and outward migrated, including polysaccharides, humic acids and aromatic proteins. Particularly, the cell lysis and humic acid degeneration dominantly responded to plant ash-driven hydrolysis and hydraulic shear force, while the protein molecular loosening also contributed to turbulent sewage-triggered gelatinous breakage. Thereby, the sensitivity of sediment adhesion deterioration to hydraulic shear stress was improved, with the adhesion reduction by 73.4–74.8 %. Correspondingly, the electronegative repulsion was elevated to promote sediment floating by hydraulic shear erosion. Considerable organic and inorganic sediments of 20.32–27.01 g TS/L and 2.97–4.09 g VS/L were solubilized. The plant ash-driven hydrolysis remarkably improved response of sediment fluidity to hydraulic erosion and reduced critical shear force by 85.35 %, providing feasible pattern for in-situ sediment removal by sewage flow-caused flushing in gravity sewer. The findings proposed a promising organic lossless strategy for sewage transportation and treatment. [Display omitted] •Plant ash treatment improved sensitivity of sediment floating to sewage flushing.•Sediment EPS collapse disrupted gelatinous structure to promote hydraulic erosion.•Cell lysis and biopolymer deconstruction impaired adhesion in hydraulic resistance.•Response of sediment floating to hydraulic erosion in gravity sewer was revealed.•Reduced critical hydraulic shear force drove in-situ sediment removal by sewage flow.