Removal and Effects of Surfactants in Activated Sludge System

Abstract

The widespread use of detergents has raised concern with regard to the environmental pollution caused by their active substances, which are biorefractory, toxic or persistent. Even though anionic and non-ionic surfactants often used in commercial detergents composition are reasonably degradable under aerobic conditions and not particularly toxic at low concentrations, high concentration of surfactants influenced the activated sludge activity and are harmful for the aquatic environment. In the literature, data on the biodegradability and/or ecotoxicity of a certain type of surfactant (anionic, nonionic, cationic) are usually presented. Our study aimed to assess the biodegradability of a mixture of two types of surfactants (anionic mixed with non-ionic) and also, effects caused by their presence of elevated concentrations to the activated sludge micro-organisms, within a batch experiment. We performed a biodegradability test (according Zahn-Wellens method) on 2 synthetic solutions with high concentrations of anionic surfactant �methyl dodecylbenzene sulfonate (15-25 mg/L) and non-ionic surfactant -4-nonylphenyl-polyethylene glycol (10 mg/L). The study established different percent of biodegradability (measured by COD decrease and surfactants removal) depending on initial concentrations of anionic and nonionic surfactants in the tested solutions. High surfactants concentrations modulated the activity and morphology of activated sludge, so its degradation efficiency of the organic substrate has decreased. Surfactant solutions resulting from biodegradability experiment have been tested for toxicity to planktonic crustaceans (Daphnia magna).

Nanobioremediation: A sustainable approach towards the degradation of sodium dodecyl sulfate in the environment and simulated conditions

“…The extensive application of surfactants increases their presence in wastewater also making their way to the groundwater and raise ecological risks both for humans and aquatics due to their noxious nature [48]. A surfactant concentration of more than 3-12 mg/L in water can damage the life of aquatic organisms [49], whereas a further increase in the concentration may cause skin diseases in animals and humans. The surfactant has a tendency to attach with biomolecules like DNA, peptides, proteins, and so forth [50].…”

Toxicity and Benefits of Urban Stabilized Sludge Intended for Agriculture Use

“…However, there are some issues related to the content of toxic substances such as heavy metals (Cd, Ni, Cu, Pb, Zn), hazardous organic chemicals (aromatic hydrocarbons, amines, nitrosamines, pesticides, pharmaceuticals, detergents, hormone disruptors, biocide or surfactants), that can accumulate in the soil layer and can affect the soil organism's ecosystem, plant productivity, soil structure. Due to the bioaccumulation process, these compounds could have potential risk on human health [4,9,10]. Other concerns of land sludge reuse are related to the pathogenic microorganisms that could contaminate the vegetables and then be transmitted to humans [11].…”