Search

Pharmaceutical residues and other emerging substances commonly summarised as micropollutants pass through wastewater treatment plants (WWTPs) and end up in the receiving waters and sludge. Many studies have investigated the removal efficiency of various techniques but a holistic evaluation of various relevant treatment alternatives regarding both the removal efficiency for various micropollutants, investment and operating costs, environmental impacts and future comprehensiveness is still lacking. This paper provides the results from a large 3-year project about the evaluation of sustainable treatment systems for removal of various micropollutants or disruptive effects at Swedish WWTPs and their environmental, economic and future sustainability. The presented results are based on our own pilot tests and related assessment and modelling efforts and provide a holistic view on advanced treatment of wastewater for removal of micropollutants.

Micropollutants such as pharmaceuticals, hormones and phenolic utility chemicals in sewage water are considered to be an emerging problem because of increased use and observed adverse effects in the environment. The study provides knowledge on the removal efficiency of micropollutants with a range of physical and chemical properties in three commercially available onsite wastewater treatment facilities (OWTFs), tested on influent wastewater collected from 2500 person equivalents in Bildchen, Germany. A longer hydraulic retention time would in theory be expected to have a positive effect, and this study presents results for three different OWTFs in full-scale comparable tests under natural conditions. A range of 24 different pharmaceuticals, five phenols and three hormones were analyzed. Flow-proportional consecutive sampling was performed in order to determine the removal efficiency. Twenty-eight substances were detected in the effluent wastewater out of 32 substances included. Average effluent concentrations of Simvastatin, Estrone, Estradiol and Ethinylestradiol were above the indicative critical-effect concentration of pharmacological effect on fish in all facilities. Average effluent concentrations of both Diclofenac and Estradiol were higher than the Environmental Quality Standards applied in Sweden (190–240 times and 9–35 times respectively). The removal efficiency of micropollutants was high for substances with high logKow, which enhance the adsorption and removal with sludge. Low removal was observed for substances with low logKow and acidic characteristics, and for substances with stabilizing elements of the chemical structure. Facilities that use activated sludge processes removed hormones more efficiently than facilities using trickling filter treatment technique. Moreover, longer hydraulic retention time increased the removal of pharmaceuticals, hormones, turbidity and total nitrogen. Removal of Caffeine, Ibuprofen, Estrone, Naproxen and Estradiol, was strongly correlated to the sludge and particles removal. Thus, the efficiency of the tested OWTFs could be improved by adjusting the technical methods and increasing the hydraulic retention time.

The aim of the present study was to determine some properties of antibiotic-resistant bacterial strains isolated from onsite wastewater technology in relation to biofilm formation, e.g., autoaggregation and motility. Additionally, biosurfactant production by the isolates was also evaluated. The ability of selected strains to develop a biofilm was assessed by using the crystal violet method, which allows to indirectly quantify the attached bacterial biomass (live, dead cells, and polysaccharides as well). Obtained results showed that 19 of the analyzed strains were able to produce biofilm after 72 h of incubation. The low values of surface tension in the range between 28 and 36 mN/m were observed in the bacteria, which are not able to produce biofilm or be classified as weak biofilm producers. Among biofilm-forming strains the highest autoaggregation index was observed for Mycobacterium brumae and Bacillus alcalophilus. Noteworthy, that some strains capable of biofilm formation showed no aggregation abilities or were characterized by low autoaggregative properties. The results of visual autoaggregation assay showed no visible flocs after given time of incubation. The results from motility test demonstrated that most of the analyzed strains were motile. Noteworthy, that up to now literature data about physiology, biofilm formation, and autoaggregative capabilities of bacteria isolated from onsite wastewater technology are very limited and this paper gives the information on the antibiotic-resistant bacteria with ability to form biofilm. Thus, the present study points to develop novel bioinocula in antibiotic degradation and to reach novel biofilm-dispersing agents produced by various bacteria that can be used as disinfectants or surface-coating agents to prevent microbial surface colonization and biofilm development.

Folia microbiologica 62(6), 453-461 (2017). doi:10.1007/s12223-017-0516-9, Published by Springer, [S.l.]

The scope of this study was to apply the Biolog system to identify and characterize a Serratia strain isolated from the surface of black plastic pieces which constitute the fluidized bed filter (onsite wastewater technology, OSWT). The preliminary isolation of the strain was done in the medium with tetracycline at a 16 mg/l concentration. To characterize the isolated strain, the following Biolog methods were applied: (1) EcoPlates microplates for evaluation of physiological profiling, (2) GEN III OmniLog® ID System for identification of the isolate, and (3) phenotypic microarrays (PM) technology for evaluation of sensitivity to antibiotics (PM11 and PM12). Results were recorded using the original OmniLog® software. The Serratia strain was identified as Serratia marcescens ss marcescens with similarity index 0.569. The same identification was obtained by the 16S rDNA analysis. PM analysis showed an enhancement of phenotype (resistance or growth) of this strain to 35 antibiotics. The loss of phenotype (sensitivity or non-growth) was observed only for 5 antibiotics: lomefloxacin (0.4 µg/ml), enoxacin (0.9 µg/ml), nalidixic acid (18.0 µg/ml), paromomycin (25.0 µg/ml) and novobiocin (1100 µg/ml). This study acknowledges that the methods proposed by the Biolog system allow correct and complete identification and characterization of the microbes isolated from different environments. Phenotypic microarrays could be successfully used as a new tool for identification of the multi-antibiotic resistance of bacteria and for determination of the minimal inhibition concentrations (MIC).

PLoS one 11(1), e0147725 (2016). doi:10.1371/journal.pone.0147725, Published by PLoS, Lawrence, Kan.