Antibiotic resistance in European wastewater treatment plants mirrors the pattern of clinical antibiotic resistance prevalence.

Integrated antibiotic resistance (AR) surveillance is one of the objectives of the World Health Organization global action plan on antimicrobial resistance. Urban wastewater treatment plants (UWTPs) are among the most important receptors and sources of environmental AR. On the basis of the consistent observation of an increasing north-to-south clinical AR prevalence in Europe, this study compared the influent and final effluent of 12 UWTPs located in seven countries (Portugal, Spain, Ireland, Cyprus, Germany, Finland, and Norway). Using highly parallel quantitative polymerase chain reaction, we analyzed 229 resistance genes and 25 mobile genetic elements. This first trans-Europe surveillance showed that UWTP AR profiles mirror the AR gradient observed in clinics. Antibiotic use, environmental temperature, and UWTP size were important factors related with resistance persistence and spread in the environment. These results highlight the need to implement regular surveillance and control measures, which may need to be appropriate for the geographic regions.

Sewers as potential reservoirs of antibiotic resistance.

Wastewater transport along sewers favors the colonization of inner pipe surfaces by wastewater-derived microorganisms that grow forming biofilms. These biofilms are composed of rich and diverse microbial communities that are continuously exposed to antibiotic residues and antibiotic resistant bacteria (ARB) from urban wastewater. Sewer biofilms thus appear as an optimal habitat for the dispersal and accumulation of antibiotic resistance genes (ARGs). In this study, the concentration of antibiotics, integron (intI1) and antibiotic resistance genes (qnrS, sul1, sul2, blaTEM, blaKPC, ermB, tetM and tetW), and potential bacterial pathogens were analyzed in wastewater and biofilm samples collected at the inlet and outlet sections of a pressurized sewer pipe. The most abundant ARGs detected in both wastewater and biofilm samples were sul1 and sul2 with roughly 1 resistance gene for each 10 copies of 16s RNA gene. Significant differences in the relative abundance of gene intI1 and genes conferring resistance to fluoroquinolones (qnrS), sulfonamides (sul1 and sul2) and betalactams (blaTEM) were only measured between inlet and outlet biofilm samples. Composition of bacterial communities also showed spatial differences in biofilms and a higher prevalence of Operational Taxonomic Units (OTUs) with high sequence identity (>98%) to well-known human pathogens was observed in biofilms collected at the inlet pipe section. Our study highlights the role of sewer biofilms as source and sink of ARB and ARGs and supports the idea that community composition rather than antibiotic concentration is the main factor driving the diversity of the sewage resistome.

Remoção de matéria orgânica e sólidos suspensos por nova configuração de biofiltro aeróbio submerso no pós-tratamento de efluente de reator UASB / Removal of organic matter and suspended solids by a new configuration of biological aerated filter in the post-treatment of UASB reactor effluent

O pós-tratamento de efluentes de reatores anaeróbios é um processo necessário para o atendimento dos padrões de emissão. Os resultados aqui apresentados mostram a viabilidade de uso de uma nova configuração de biofiltro aeróbio submerso (BAS) no pós-tratamento desses efluentes. Os BAS multiestágio apresentam uma câmara anaeróbia (V=12,6L), seguido de uma câmara aeróbia (V=30L) e uma câmara anóxica (V=26,4L), todas em série (V total=70L). Neste estudo, foi analisada a remoção de sólidos suspensos (SS), DQO e DBO5. Foram utilizados três BAS multi-estágio preenchidos com três diferentes materiais-suporte: tampas e gargalos PET (165m²/m³), pedra britada n. 4 (50m²/m³) e anéis Pall 1,5'' (135m²/m³). Os reatores foram operados com valores de tempos de detenção hidráulicas (TDH) de 4,1, 8,2 e 12,3 horas, e três taxas de aplicação superficial (TAS) (21, 12 e 8m³/m².d). A associação dos reatores UASB+BAS possibilitou remoções de DQO total superiores a 90 por cento para os BAS 1 e 3, e 85 por cento para o BAS 2, sendo independente do TDH aplicado. A remoção de SS foi maior no BAS contendo anéis Pall, provavelmente devido ao maior índice de vazios desse material.

The post-treatment of effluents from anaerobic reactors is normally a mandatory step to meet the emission standards. The results presented here show the feasibility of using a new configuration of biological aerated filter (BAF) in the post-treatment of UASB reactors. The multi-stage BAF presents an anaerobic chamber (V=12.6L), followed by an aerobic chamber (V=30L) and an anoxic chamber (V=26.4L), all in series (total V=70L). This study examined the removal of suspended solids (SS), COD and BOD5. Three multi-stage BAF filled with three different packing materials were used: lids and bottlenecks of PET bottles (165m²/m³), gravel n. 4 (50m²/m³) and Pall rings 1.5'' (135m²/m³). The reactors were operated with the values of hydraulic detention time (HDT) of 4.1, 8.2 and 12.3 hours, and three superficial application rates (21, 12 and 8m³/m².d). COD removal efficiencies of 90 percent for BAF 1 and 3, and 85 percent for BAF 2 were obtained, being the removal independent of the HDT applied to BAF. The removal of SS was higher in BAF containing Pall rings, probably due to the higher voidage of this material.

Otimização de uma estação de tratamento de efluentes de uma indústria de embalagens de papel / Optimization of a cardboard paper factory wastewater treatment plant

Este trabalho versa sobre a utilização de uma estratégia de otimização de uma estação de tratamento de efluentes de uma indústria de embalagens de papel, com problemas de "foaming". Os resultados do diagnóstico inicial mostraram que o tratamento primário alcançou uma eficiência superior a 70 por cento na remoção de sólidos suspensos. As modificações operacionais realizadas foram limpezas das caixas de gordura, redução da geração de óleos e graxas nos pontos de geração. As modificações no processo na ETE foram à implementação da equalização da vazão de alimentação do tanque de aeração, adição de hipoclorito de sódio na entrada do sedimentador secundário, adição de ácido fosfórico para equilibrar a relação entre nutrientes e DBO5 e a manutenção de uma concentração e idade do lodo constante durante o processo.

This paper describes the strategies used to optimize a cardboard paper factory wastewater treatment plant regarding operational problems caused by the occurrence of foaming and filamentous organisms. The operational modifications involved the use of an equalization tank, the reduction of oil and grease from the industrial process, the addition of sodium hypochlorite at the inlet of the secondary settler to control filamentous organisms and phosphoric acid to correct the nutrients balance and BOD. A correct value of biomass concentration and sludge age were maintained constant all the time. The first results showed that the TSS removal efficiency in the primary settler was higher than 70 percent, followed by an improved performance of the biological reactor due to the control of filamentous organisms and better performance of the secondary settler.