Tire materials disturb transformations of nitrogen compounds and affect the structure of biomass in aerobic granular sludge reactors.

Tire materials (TMs) present a notable hazard due to their potential to release harmful chemicals and microplastics into the environment. They can infiltrate wastewater treatment plants, where their effects remain inadequately understood, raising concerns regarding their influence on treatment procedures. Thus, this study investigated the impact of TMs in wastewater (10, 25, 50 mg/L) on wastewater treatment efficiency, biomass morphology, and microbial composition in aerobic granular sludge (AGS) reactors. TM dosage negatively correlated with nitrification and denitrification efficiencies, reducing overall nitrogen removal, but did not affect the efficiency of chemical-oxygen-demand removal. The presence of TMs increased the diameter of the granules due to TM incorporation into the biomass. The most frequently leached additives from TMs were N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine, benzothiazole (BTH), and 2-hydroxybenzothiazole. In the treated wastewater, only BTH and aniline were detected in higher concentrations, which indicates that tire additives were biodegraded by AGS. The microbial community within the AGS adapted to TMs and their chemicals, highlighting the potential for efficient degradation of tire additives by bacteria belonging to the genera Rubrivivax, Ferruginibacter, and Xanthomonas. Additionally, our research underscores AGS's ability to incorporate TMs into biomass and effectively biodegrade tire additives, offering a promising solution for addressing environmental concerns related to TMs.

The challenges in the identification of Escherichia coli from environmental samples and their genetic characterization.

Escherichia coli bacteria are an essential indicator in evaluations of environmental pollution, which is why they must be correctly identified. This study aimed to determine the applicability of various methods for identifying E. coli strains in environmental samples. Bacterial strains preliminary selected on mFc and Chromocult media as E. coli were identified using MALDI Biotyper techniques, based on the presence of genes characteristic of E. coli (uidA, uspA, yaiO), as well as by 16S rRNA gene sequencing. The virulence and antibiotic resistance genes pattern of bacterial strains were also analyzed to investigate the prevalence of factors that may indicate adaptation to unsupportive environmental conditions and could have any significance in further identification of E. coli. Of the strains that had been initially identified as E. coli with culture-based methods, 36-81% were classified as E. coli with the use of selected techniques. The value of Cohen's kappa revealed the highest degree of agreement between the results of 16S rRNA gene sequencing, the results obtained in the MALDI Biotyper system, and the results of the analysis based on the presence of the yaiO gene. The results of this study could help in the selection of more accurate and reliable methods which can be used in a preliminary screening and more precise identification of E. coli isolated from environmental samples.

Coagulation and Flocculation before Primary Clarification as Efficient Solutions for Low-Density Microplastic Removal from Wastewater.

Microplastic (MP) removal from wastewater was investigated using various types and doses of commercial coagulants (PIX, PAX) and flocculants (FPM, PEL, FCT) before primary clarification in a wastewater treatment plant (WWTP). Dosing with FPM, PIX, and PEL caused small MPs (180-212 µm) to be transferred mainly to the settled sludge (up to 86.4% of MP at a dose of 5 mL FMP/m3), while dosing of FCT and PAX caused these MPs to be transferred to the floated sludge (up to 64% MP at a dose of 5 mL PAX/m3). The efficiency of MP removal from wastewater was the highest (90%) with 2.5 mL PAX/m3; the generated primary sludge had a low MP content and could be safely managed in subsequent stages of sludge treatment. At the highest doses, PIX significantly increased the removal of P-PO4 (up to 94%) and COD (up to 73%). FPM and FCT resulted in over 40% efficiency of ammonium removal-such disturbance in wastewater composition may negatively affect further biological treatment. Effective removal of MP in the mechanical part of WWTP resulting from coagulation and flocculation enables the safe use of the excess sludge for agricultural purposes.

Polyethylene microplastics increase extracellular polymeric substances production in aerobic granular sludge.

Wastewater treatment plants act as microplastic (MPs) sinks and secondary MP pollution sources. Little is known about the effect of MPs on biomass and the efficiency of biological wastewater treatment. This study assessed the impact of polyethylene (PE) MPs concentrations (1, 10, 50 mg/L) in wastewater on biological conversions and extracellular polymeric substances (EPS) production (including alginate) in aerobic granular sludge (AGS). PE MPs did not worsen the efficiency of biological treatment but stimulated the production of EPS and alginate in AGS. The alginate content increased from 238.7 ± 4.4 mg/g MLSS in control to 441.6 ± 13.8 mg/g MLSS at the highest PE load in wastewater. The presence of MP changed AGS morphology and worsened the settling properties of biomass, causing biomass washout from the reactors. At the highest PE load in wastewater, the biomass concentration in the reactor effluent was over 2.8 times higher than in the control.

The fate of microplastic in sludge management systems.

Sewage sludge (SS) from wastewater treatment plants (WWTPs) is commonly used as a soil amendment on agricultural land; however, this sludge contains microplastics (MPs) which harm soil ecosystems and can leach into aquatic environments. This review aims to assess the fate of MPs in SS systems and, in the context of a changing agricultural scene, present alternatives for sustainable SS disposal that are consistent with the practices of a clean, circular economy. Anaerobic digestion and composting, which are commonly used to stabilize SS before land application, were not reported to substantially affect MP removal, although process efficiency and the microbiome were affected by MPs. Alternatively, MPs can be destroyed or removed by mono-incineration or combustion, but unfortunately, some MPs may remain in the ash after these processes. Therefore, the most desirable solutions would prevent MPs from entering the environment and remove them before they enter the biological part of a WWTP, where they build up in SS. Additionally, the management of MP-containing sludge must be adapted to the geographical context and the local economy, and it should begin with legislation addressing MPs in SS. The information presented here will help to develop good practices in waste management for preventing or decreasing the transfer of MPs into the environment.

Chemical and microbiological changes on the surface of microplastic after long term exposition to different concentrations of ammonium in the environment.

The increasing production of plastic in the world has resulted in the widespread pollution of the environment with microplastics (MP). MP enter facilities such as wastewater treatment plants or landfills characterized by various ammonium concentrations. The aim of this study was to determine the structure of the microbial community on MP surfaces at various concentrations of ammonium nitrogen, and in particular, to identify microorganisms capable of polyethylene terephthalate (PET) degradation. Moreover, changes in the chemical characteristics of the MP surface resulting from microbial activity were also investigated, and the potential of MP to serve as a vector for pollutants was determined. The tests were carried out in a reactor filled with PET for a period of 260 days. The experiment was carried out in 3 phases: in I and III phase, the concentration of N-NH4 was about 70 mg/L, while in II phase, it was about 430 mg/L. On the MP surface, biofilm-forming microorganisms from the genera Rhodococcus, Pseudomonas and Xantomonas were identified at the lower ammonium concentration. At this concentration, MP-degraders belonging to genera Acidovorax, Gordonia, Pseudomonas, Sphingomonas, and Sphingopyxis were identified in the biofilm. At the higher N-NH4 concentration, the biomass was enriched with bacteria from genera Nitrosospira, Nitrosomonas and Terrimonas, and the number of microorganisms with the potential to degrade MP decreased. Analysis of the MP surface during the experiment has showed the loss of carbonyl groups and formation of carboxyl and hydroxyl groups, which indicated the degradation of MP. Independent of the ammonium concentration in the environment, MP was a carrier of pathogenic microorganisms from the genera Mycobacterium, Enterobacter and Brevundimonas.

Small-scale wastewater treatment plants as a source of the dissemination of antibiotic resistance genes in the aquatic environment.

Wastewater treatment plants (WWTPs) are significant source of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), which can spread further in the environment by reaching rivers together with effluents discharged from WWTPs. In this study untreated and treated wastewater (UWW, TWW), upstream and downstream river water (URW, DRW) were collected from 4 WWTPs, in the winter and autumn seasons. The occurrence of ARB resistant to beta-lactams and tetracyclines as well as the presence of antibiotics from these classes were analysed in water and wastewater samples. Additionally, the amounts of 12 ARGs, 2 genes of mobile genetic elements (MGEs), gene uidA identifying E. coli and 16S rRNA were also determined. Resistance to beta-lactams prevailed among ARB in water and wastewater samples (constituting 82-88% of total counts of bacteria). The dominant genes in water and wastewater samples were blaTEM, tetA, sul1. The gene blaOXA demonstrated high variability of its concentration in samples collected in both seasons. Despite the high per cent reduction of ARB and ARGs concentration observed during the wastewater treatment processes, their large quantities are still transmitted into the environment. The research focuses on WWTPs' role in the dissemination of ARGs and MGEs in the aquatic environment.