Effect of potassium ferrate treatment on adhesive gelatinous biopolymer structure and erosion resistance of sewer sediments: Promotion or inhibition?

Abstract

Massive presence of sediments not only results in decreasing drainage capacity but also causes a series of severe environmental problems. Gelatinous biopolymer adhesive properties in sediments will probably affect the flushing and pipeline self-cleansing efficiency. Therefore, exploring the molecular mechanism of biopolymer enhancing anti-erosion from the seldom-concerned perspective of reducing adhesion is an important approach to subvert the traditional method of controlling sediments. Through the gradient disintegration of continuous flow sewer reactors cultivated sediments with environmentally-friendly oxidant potassium ferrate (PF) in short-term treatment, this study evaluated its potential applications and explored the molecular structure mechanisms mentioned above. The results showed that the sediments erosion capability was improved to 4 to 20 times than untreated sediments after different PF dosage treatment. The corresponding critical erosion shear stress of sediments also decreased though PF treatment. Gelatinous biopolymer did contribute adhesion of inorganic particles through the first atomic force microscope (AFM) application in sediments, and such adhesion promoted anti-erosion. Furthermore, the average adhesion could be weakened by up to 93.5 % under PF treatment. HA (humic acid), protein-like tyrosine and protein-like tryptophan exhibited strong correlation with adhesion. –CH3/–CH2, COO−, O–H, N–H and other functional groups were inextricably related to the adhesion properties through two-dimensional correlation spectroscopy (2D-COS) analysis. Aggregated strands, α-Helix and β-Turn exhibited significant correlation with adhesion. However, PF could destroy these structures and transfer small and medium molecules to external, enhancing electronegativity to cripple gelatinous agglomeration. The destruction of the gelatinous biopolymer structure led to weaken adhesion and further deteriorate anti-erosion of sediments. Application of PF contributed to enhance drainage pipeline self-cleansing capacity or improve flushing device efficiency to substantially decrease the controlling cost by at least 51%.