Adsorption of nonylphenol on activated sludge biomass under aseptic conditions

Summarization: This work examined the relative distribution of nonylphenol (NP), a known endocrine disrupting compound, between the water phase and biosolids (sludge) under aseptic conditions, as well as the conditions under which NP could be released from the biosolids back into the water phase. The experimental work involved adsorption and desorption studies on activated sludge biomass with the water phase being both pure water and treated municipal wastewater (secondary effluent). NP adsorption on biomass was very fast: about 90% of NP was removed from the water phase in 1 h, while in 5 h the equivalent degree of removal was around 99%. There was no significant difference in adsorptive behavior of active and inactive biomass. Adsorption of NP under equilibrium showed that NP accumulates in the biosolids reaching levels up to two orders of magnitude higher than the equilibrium water phase concentration. This was due to the hydrophobic nature of both NP and the biosolids. The adsorption isotherm was modeled by means of the Freundlich model. Desorption of NP from biosolids was possible to a significant extent at pH 12 and above. This may have an implication on lime stabilized sludge, where under high pH conditions, NP may leach out from dewatered sludge.Presented on: CLEAN - Soil, Air, Wate