Bernard Quant

Antimicrobial resistance of fecal indicators in disinfected wastewater

The main objective of the study was to assess the potential of three systems (UV irradiation, ozonation, and micro/ultrafiltration) operated in a pilot scale in removal of antimicrobial-resistant fecal bacteria from secondary effluent of the local wastewater treatment plant (700,000 population equivalent). The effectiveness of the processes was analysed using the removal ratio of fecal indicators (Escherichia coli and Enterococcus spp.). The susceptibility of fecal indicators to antimicrobial agents important in human therapy was examined. Resistance to nitrofurantoin and erythromycin was common among enterococci and followed by resistance to fluoroquinolones and tetracycline. Resistance to high-level aminoglycosides and glycopeptides was also observed. E. coli isolates were most frequently resistant to penicillins and tetracycline. The extended-spectrum beta-lactamase-producing E. coli was detected once, after ozonation. Substantial attention should be paid to the E. coli and enterococci resistant to three or more chemical classes of antimicrobials (MAR), which in general constituted up to 15 and 49% of the tested isolates, respectively. Although the applied methods were effective in elimination of fecal indicators (removal efficiency up to 99.99%), special attention has to be paid to the application of sufficient disinfection and operation conditions to avoid selection of antimicrobial resistant bacteria.

Diversity of fecal coliforms and their antimicrobial resistance patterns in wastewater treatment model plant.

The occurrence of resistance patterns among wastewater fecal coliforms was determined in the study. Susceptibility of the isolates was tested against 19 antimicrobial agents: aminoglycosides, aztreonam, carbapenems, cephalosporines, beta-lactam/beta-lactamase inhibitors, penicillines, tetracycline, trimethoprim/sulfamethoxazole, and fluoroquinolones. Additionally the removal of resistant isolates was evaluated in the laboratory-scale wastewater treatment model plant (M-WWTP), continuously supplied with the wastewater obtained from the full-scale WWTP. Number of fecal coliforms in raw (after mechanical treatment) and treated wastewater, as well as in aerobic chamber effluent was determined using selective medium. The selected strains were identified and examined for antibiotic resistance using Phoenix Automated Microbiology System (BD Biosciences, USA). The strains were identified as Escherichia coli (n=222), Klebsiella pneumoniae ssp. ozaenae (n=9), and Pantoea agglomerans (n=1). The isolate of P. agglomerans as well as 48% of E. coli isolates were sensitive to all antimicrobials tested. The most frequent resistance patterns were found for ampicillin: 100% of K. pneumoniae ssp. ozaenae and 41% of E. coli isolates. Among E. coli isolates 12% was regarded as multiple antimicrobial resistant (MAR). In the studied M-WWTP, the applied activated sludge processes reduced considerably the number of fecal coliforms, but increased the ratio of antimicrobial-resistant E. coli isolates to sensitive ones, especially among strains with MAR patterns.

SILICATIZATION OF FLY ASHES - A HARMLESS WAY OF THE WASTES UTILIZATION

The achievements in the field of fly-ashes utilization in the forming of the FlyAsh Composites are described in the paper. The Fly-Ash Composites are the mixtures of fly ashes, soluble silicates (water-glass solutions) and/or lime (more often waste lime). There are presented two principal composites: the Fly-Ash Composite and the Liquid Fly-Ash Composite. The theoretical principle of the composites creation, their basic physico-mechanical properties, their way of formation and mainly the directions of their application are shortly presented. The influence of fly ashes on the environment is also taken into account.

Elimination of the Chemical and Microbiological Pollutants in the Modernized Wastewater Treatment Plant “WschóD” in Gdańsk

In the article the results of investigations concerning the performance of modernised wastewater treatment plant “Wschod” are presented. The MUCT reactors were introduced in the biological treatment stage. WWTP is equipped with a unit for volatile fatty acids generation from primary sludge. The results of 2-years investigations of the removal of chemical and microbiological pollutants and parasites are discussed. The basic technological problems during the operation of the WWTP are identified. The removal of bacteria and parasites at subsequent stages of sewage treatment is analysed.