Abstract
In this study, we evaluated the impact of the successive bioaugmentation of the activated sludge (AS) with the defined bacterial consortium on the activity and functional capacity of the AS microorganisms. In parallel, the removal of low concentrations of the selected non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, diclofenac) and analgesic paracetamol was studied. We found that the addition of the bacterial consortium consisting of three pharmaceuticals-degrading strains Bacillus thuringiensis B1 (2015b), Stenotrophomonas maltophilia KB2, and Pseudomonas moorei KB4 into the AS did not cause any significant changes in the biomass abundance and metabolic activity of the AS microorganisms. Although, the successive bioaugmentation of the AS caused a slight increase in the metabolic diversity, the intensity of carbohydrates usage, and metabolic richness. Microorganisms in the bioaugmented and non-bioaugmented AS were able to degrade the mixture of the analyzed drugs with similar efficiency, however, diclofenac was removed more effectively in the bioaugmented AS. Several metabolites were identified and efficiently utilized, with the exception of 4-OH diclofenac. Two new diclofenac-degrading strains assigned as Serratia proteamaculans AS4 and Rahnella bruchi AS7 were isolated from the diclofenac-treated AS.
Highlights
A wide range of contaminants of emerging concerns (CEC), including pharmaceuticals and personal care products are continuously introduced into various environmental matrices
It was indicated that the high activity of the bacterial consortium in the control AS3 assay was inhibited by the autochthonous microorganisms which was reflected in the lowest microbial activity in the assay AS4
The relatively high bacterial activity observed in the control AS3 was probably connected with the high accessibility of nutrients released from the activated sludge (AS) flocs
Summary
A wide range of contaminants of emerging concerns (CEC), including pharmaceuticals and personal care products are continuously introduced into various environmental matrices. Organic pollutants are usually characterized by highly diversified structure, low water solubility, poor biodegradability, and environmental persistence [1,2]. Pharmaceuticals used within this study, ibuprofen (IBU), naproxen (NPX), diclofenac (DCF), and paracetamol (APAP) have been detected in several natural matrices, e.g., surface water [3,4], wastewater [5], soil and sludge [6,7,8] at a concentration range from ng L−1 to μg L−1. Drugs remain active even at low concentrations, their presence may lead to successive deterioration of water quality and have an adverse impact on the ecosystem and human health [9]. The main sources of pharmaceuticals in the environment include domestic and industrial wastewater from pharmaceuticals production, hospital effluents, landfill leachate, Water 2020, 12, 1133; doi:10.3390/w12041133 www.mdpi.com/journal/water
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