Fate of Benzalkonium Chloride in a Sewage Sludge Low Temperature Conversion Process Investigated by LC‐LC/ESI‐MS/MS

Abstract

Thermocatalytic low temperature conversion (LTC) is a new method for the disposal of sewage sludge. Using this method, sludge is converted into a residual solid (coal) along with reaction water, oil, and non-condensable gases. The oil can be used as an energy source and the coal as a substitute for charcoal. To this end, it is important to determine whether there are any easily available contaminants present in the coal generated by the process. Contaminants that can be strongly sorbed by sewage sludge solids are, e. g., pharmaceuticals and disinfectants. As an example the fate of the persistent and strong adsorbing disinfectant benzalkonium chloride (BAC) has been investigated within the LTC process. The sewage sludge was spiked with BAC and then subjected to the LTC process. The resulting coal was extracted and analyzed using LC-LC/ESI-MS/MS (ion trap). BAC could not be detected in the LTC coal, although it could be extracted from the spiked sludge before the LTC treatment. It can thus be concluded that the investigated compound is not easily available in the coal, and hence that its use does not present a risk.

Unlocking the Fertilizer Potential of Waste-Derived Biochar

“…18,42,60 Importantly, pyrolysis destroys a whole suite of organic contaminants present in sewage sludge resulting in markedly increased safety. [12][13][14][15][16][17] To further optimise (sewage sludge) biochar as a fertiliser, refinement of the method presented here is possible, e.g. through change in biochar pH, feedstock K/P ratio, concentration and form of K minerals and K distribution in the feedstock (soaking time).…”

“…hormones) and other microconstituents (plastics, surfactants). [12][13][14][15][16][17] It also immobilises potentially toxic elements (PTE) present in the feedstock, such as copper (Cu), cadmium (Cd) and chromium (Cr), reducing risk of leaching and plant uptake. 18,19 In contrast to incineration, pyrolysis retains most of the carbon present in sewage sludge and even converts it into a recalcitrant form.…”

“…Pyrolysis is a thermochemical conversion process under oxygen-limited conditions. It sterilizes the material and reduces the concentration of organic toxins (e.g., polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and dioxins), pharmaceuticals (e.g., hormones), and other microconstituents (plastics, surfactants). − It also immobilizes potentially toxic elements (PTE) present in the feedstock, such as copper (Cu), cadmium (Cd), and chromium (Cr), reducing the risk of leaching and plant uptake. , In contrast to incineration, pyrolysis retains most of the carbon present in sewage sludge and even converts it into a recalcitrant form. Therefore, if pyrolysis vapors and liquids are used to fuel the process or renewable energies, pyrolysis can be considered the most sustainable treatment for sewage sludge from the perspective of atmospheric carbon removal and storage, and environmental impacts.…”

Pyrolysis Solves the Issue of Organic Contaminants in Sewage Sludge while Retaining Carbon—Making the Case for Sewage Sludge Treatment via Pyrolysis

“…9,26 Temperatures of 400 °C also reduced the extractable content of the disinfectant benzalkonium chloride (BAC) to levels below the detection limit (not shown in Table 1 as the extractable and not total levels were measured in the given study). 34 The presence of microplastics in cosmetics and toothpaste elevates respective concentrations in wastewater and subsequently also in wastewater solids. 35 Yet, at pyrolysis temperatures of 500 °C, the concentration of microplastics in two different sewage sludge samples were reduced by >99.7% with no microplastics detectable in biochar demonstrating effective removal.…”

“…Release of antibiotics and antimicrobial pharmaceuticals into the environment can both adversely affect microbial communities and foster the development of antibiotic resistance. , In a study by Tian et al, the concentrations of 7 antibiotics were reduced by >99% during pyrolysis at 500 °C . Antimicrobial pharmaceuticals (triclosan and triclocarban) were measured at levels of 2–5 μg g –1 in sewage sludge and after exposure to pyrolysis conditions of ≥400 °C, the compounds could not be detected in the resulting biochar. , Temperatures of 400 °C also reduced the extractable content of the disinfectant benzalkonium chloride (BAC) to levels below the detection limit (not shown in Table as the extractable and not total levels were measured in the given study) …”