Fecal contamination of wastewater treatment plants in Portugal

Abstract

Reutilization of effluents from wastewater treatment plants (WWTP) for non-potable applications is increasing due to the reduction of sustainable water resources. These products mostly come from municipal WWTP and also from slaughterhouses effluents. The microbiological certification of these products is mandatory before their discharge into the environment. This study evaluates if the treatment applied in WWTP to municipal waters or to poultry slaughterhouse effluents distributed over the Portuguese continental territory is efficient in reducing the microbiological risk associated with the reutilization of those wastewaters and sludges. Fecal indicators Escherichia coli and enterococci were evaluated in 42 and 24 wastewater samples from 14 municipal WWTP and 8 poultry slaughterhouse treatment plants, respectively, by the conventional culture method and a rapid Fluorescent in situ hybridization (FISH) technique. Bacterial enumeration in inflow water from most WWTP was rather high (generally >10(5) cells/ml), for both E. coli and Enterococcus spp., and the bacterial quantification by FISH was generally higher than enumeration by the conventional culture method. In both types of treatment plants studied, bacterial load from effluents and sludges was not statistically different from the inflows, indicating that the treatment applied seems to be equally unable to reduce the microbiological load of the effluents. These findings may jeopardize the safe reuse of treated wastewaters in agriculture and the quality of the water environment. Therefore, products like water, sewage sludge, and biosolids originated from the municipal and slaughterhouse WWTP studied should not be reutilized, and effluents treatment should be urgently reviewed.

Surveillance of human enteric viruses in coastal waters using concentration with methacrylate monolithic supports prior to detection by RT-qPCR

“…The observed variability among sites might be, not only because of the distance to sewage outputs, but due to a higher dispersion and dilution effects ( Wyn-Jones et al, 2011 ). The observed variability among sampling sites was also observed in other studies in fresh and sea water ( Marti et al, 2013 ; M. Oliveira et al, 2016 ; Sun et al, 2016 ).

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Impact of type of wastewater treatment process on the antibiotic resistance of bacterial populations

“…The percentage of bacteria resistant to cefotaxime and doxycycline, which are antibiotics from new generation groups, in the total number of E. coli has been increased. Some researchers [28,33] suggest that WWTPs are effective in removal of bacteria, including indicator bacteria like E. coli. However, there are also studies which suggest that the number of bacteria did not decrease after the wastewater treatment processes, regardless of the type of treatment [34].…”

The Resistome of ESKAPEE Pathogens in Untreated and Treated Wastewater: A Polish Case Study

“…In other studies, biological and mechanical wastewater treatment systems led to a similar reduction in microbial levels (80–99%) [ 33 , 50 ]. According to the literature, the effectiveness of wastewater treatment can be significantly affected by the type of wastewater inflow and fluctuations in a plant’s performance [ 51 , 52 , 53 ]. There is evidence to indicate that the activated sludge process can both decrease and increase the size of the bacterial population in wastewater.…”