Abstract
The increased production and commercial use of nanoparticles (NPs), combined with a lack of regulation regarding their disposal, may result in the unwanted introduction of NPs to wastewater. Wastewater nutrient removal depends on the metabolisms of activated sludge bacteria and their related key enzymes. Therefore, the aim of this work was to determine the effect of aluminium oxide nanoparticles concentrations on the activated sludge enzymatic activity of microorganisms. Tested nanoparticles inhibition cellular respiration in TTC method in the four highest tested concentrations. Moreover, in most samples observed increase dehydrogenase activity. In this study, nano-Al2O3 also caused a clear stimulation of the activity of hydrolytic enzymes microorganisms of activate sludge. Effects of aluminum oxide (compound in bulk forms) on enzymatic activity were different than in the case of the nano from of Al2O3.
Highlights
Wastewater may contain wide variety chemical substances, which can inhibit microorganism’s growth and cause various problems during biological treatment
Enzymatic activity of the microorganisms in the presence of tested compounds was determined by means of the triphenyl tetrazolium chloride (TTC) test for dehydrogenases activity and test for hydrolytic activity – fluorescein diacetate (FDA) determination
The TTC test was performed in accordance with the Polish Standard PN-C-04616-8 2008
Summary
Wastewater may contain wide variety chemical substances, which can inhibit microorganism’s growth and cause various problems during biological treatment. Many harmful substances, depending on their physical and chemical properties, can be not readily biodegradable and remain toxic during the entire wastewater treatment process [1]. Examples of such compounds are nanoparticles, which are used in agriculture, industrial products and in medicine [2]. Investments for their production in 2005 amounted to about 10 billion dollars, and in the years 2011–2015 they were to reach USD 1.000 billion [3]. Literature data showed, that predicted concentrations in sludge, for engineered nanoparticles (nano-TiO2, nano-Ag, nano-SiO2, nano-Au) that are being used or could be used in cosmetics and personal care products and coatings, they ranged from 0.01 to 40.7 mg/kg [5]
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