Comparative characterization of surface sludge deposits from fourteen French Vertical Flow Constructed Wetlands sewage treatment plants using biological, chemical and thermal indices

Abstract

Due to their design and mode of operation, French Vertical Flow Constructed Wetlands (VFCWs) accumulate suspended solids from the inflow wastewater in the form of a sludge layer at the surface of the first filter. In order to maintain the treatment performance over the long term, the characteristics of the sludge deposits and their evolution have to be well described. In this objective, a panel of sludge deposit samples taken from 14 French VFCW sewage treatment plants was investigated. Elemental composition and organic matter content, nature and reactivity were analyzed. Results clearly revealed two categories of sludge deposits, namely the "young-age plants" type (1 year of operation and less) and the "mature plants" type (3 years of operation and more). Sludge deposits from the "mature plants" exhibited same biological, physical and chemical properties. Their organic matter was globally less abundant, more humified and less biodegradable than in the young-age plants type. Their overall contents in trace metals were also higher, although in a limited manner. The effect of additional treatments, particularly FeCl injection for phosphorus precipitation, was observable in the "young-age plants" group. Finally, the sludge deposits sampled from one particular plant with specific operating conditions were found to exhibit very different characteristics from those of either groups identified. This observation underlined the influence of local conditions on the typology of the sludge deposits.

[Retracted] Migration and Deposition Law of Pollutants in Urban Sewage Confluence Pipe Network from the Perspective of Ecology

“…Ozone, chlorine, UV radiation, and sodium hypochlorite are often used disinfectants. Due to its durability, monochloramine, which is employed to cleanse groundwater, is not utilized to treat wastewater [26][27][28]. (3) Determine the location of monitoring points.…”

Leaching behavior of major and trace elements from sludge deposits of a French vertical flow constructed wetland

“…The physical properties and organic matter composition of the selected sample was previously shown to be representative of a typology of surface deposits from French VFCW of more than 2-3 years of age (Kania et al, 2019;Kania et al 2018 a and b). The results obtained here firstly showed that only marginal proportions of the total contents in major elements and trace metals were leached from the surface deposits into the aqueous solution when the sample was contacted with water at the close-to-neutral pH obtained at thermodynamic equilibrium (pH 6.4).…”

Residuals, sludge, and biosolids: Advancements in the field

“…The highlight this year for innovative technologies is on constructed wetlands for treatment of municipal sludge. In France, Kania, Gautier, Imig, Gautier, Imig, Michel, and Gourdon (2019) described a vertical flow constructed wetlands in 14 plants across the country to determine the impacts of aging on the sludge deposits within the wetland. The study showed those wetlands in operation one year or less had more abundant organic matter, less humified, and more biodegradable than more established wetlands (three years of operation or more) (Kania, Gautier, Imig, et al, 2019).…”

“…In France, Kania, Gautier, Imig, Gautier, Imig, Michel, and Gourdon (2019) described a vertical flow constructed wetlands in 14 plants across the country to determine the impacts of aging on the sludge deposits within the wetland. The study showed those wetlands in operation one year or less had more abundant organic matter, less humified, and more biodegradable than more established wetlands (three years of operation or more) (Kania, Gautier, Imig, et al, 2019). To assess the ability of the sludge to retain specific elements including trace metals under both normal operating conditions and extreme pH conditions, samples from the wetlands noted above were examined for leaching (Kania, Gautier, Blanc, et al, 2019).…”