Selection of indicator contaminants of emerging concern when reusing reclaimed water for irrigation — A proposed methodology

Organic and microbial contaminants of emerging concern (CECs), even though not yet regulated, are of great concern in reclaimed water reuse projects. Due to the large number of CECs and their different characteristics, it is useful to include only a limited number of them in monitoring programs. The selection of the most representative CECs is still a current and open question. This study presents a new methodology for this scope, in particular for the evaluation of the performance of a polishing treatment and the assessment of the risk for the environment and the irrigated crops. As to organic CECs, the methodology is based on four criteria (occurrence, persistence, bioaccumulation and toxicity) expressed in terms of surrogates (respectively, concentrations in the secondary effluent, removal achieved in conventional activated sludge systems, Log Kow and predicted-no-effect concentration). It consists of: (i) development of a dataset including the CECs found in the secondary effluent, together with the corresponding values of surrogates found in the literature or by in-field investigations; (ii) normalization step with the assignment of a score between 1 (low environmental impact) and 5 (high environmental impact) to the different criteria based on threshold values set according to the literature and experts' judgement; (iii) CEC ranking according to their final score obtained as the sum of the specific scores; and (iv) selection of the representative CECs for the different needs. Regarding microbial CECs, the selection is based on their occurrence and their highest detection frequency in the secondary effluent and in the receiving water, the antibiotic consumption patterns, and recommendations by national and international organisations. The methodology was applied within the ongoing reuse project SERPIC resulting in a list of 30 indicator CECs, including amoxicillin, bisphenol A, ciprofloxacin, diclofenac, erythromycin, ibuprofen, iopromide, perfluorooctane sulfonate (PFOS), sulfamethoxazole, tetracycline, Escherichia coli, faecal coliform, 16S rRNA, sul1, and sul2.publishedVersio

A review of nature-based solutions for urban water management in European circular cities: a critical assessment based on case studies and literature

Abstract Nature-based solutions (NBS) can protect, manage and restore natural or modified ecosystems. They are a multidisciplinary, integrated approach to address societal challenges and some natural hazards effectively and adaptively, simultaneously providing human well-being and biodiversity benefits. NBS applications can be easily noticed in circular cities, establishing an urban system that is regenerative and accessible. This paper aims to offer a review on NBS for urban water management from the literature and some relevant projects running within the COST Action 'Implementing nature-based solutions for creating a resourceful circular city'. The method used in the study is based on a detailed tracking of specific keywords in the literature using Google Scholar, ResearchGate, Academia.edu, ScienceDirect and Scopus. Based on this review, three main applications were identified: (i) flood and drought protection; (ii) the water-food-energy nexus; and (iii) water purification. The paper shows that NBS provide additional benefits, such as improving water quality, increasing biodiversity, obtaining social co-benefits, improving urban microclimate, and the reduction of energy consumption by improving indoor climate. The paper concludes that a systemic change to NBS should be given a higher priority and be preferred over conventional water infrastructure

Management of Urban Waters with Nature-Based Solutions in Circular Cities—Exemplified through Seven Urban Circularity Challenges

Nature-Based Solutions (NBS) have been proven to effectively mitigate and solve resource depletion and climate-related challenges in urban areas. The COST (Cooperation in Science and Technology) Action CA17133 entitled “Implementing nature-based solutions (NBS) for building a resourceful circular city” has established seven urban circularity challenges (UCC) that can be addressed effectively with NBS. This paper presents the outcomes of five elucidation workshops with more than 20 European experts from different backgrounds. These international workshops were used to examine the effectiveness of NBS to address UCC and foster NBS implementation towards circular urban water management. A major outcome was the identification of the two most relevant challenges for water resources in urban areas: ‘Restoring and maintaining the water cycle’ (UCC1) and ‘Water and waste treatment, recovery, and reuse’ (UCC2). s Moreover, significant synergies with ‘Nutrient recovery and reuse’, ‘Material recovery and reuse’, ‘Food and biomass production’, ‘Energy efficiency and recovery’, and ‘Building system recovery’ were identified. Additionally, the paper presents real-life case studies to demonstrate how different NBS and supporting units can contribute to the UCC. Finally, a case-based semi-quantitative assessment of the presented NBS was performed. Most notably, this paper identifies the most typically employed NBS that enable processes for UCC1 and UCC2. While current consensus is well established by experts in individual NBS, we presently highlight the potential to address UCC by combining different NBS and synergize enabling processes. This study presents a new paradigm and aims to enhance awareness on the ability of NBS to solve multiple urban circularity issues.publishedVersio

The potential of using E. coli as an indicator for the surveillance of antimicrobial resistance (AMR) in the environment

To understand the dynamics of antimicrobial resistance (AMR), in a One-Health perspective, surveillance play an important role. Monitoring systems already exist in the human health and livestock sectors, but there are no environmental monitoring programs. Therefore there is an urgent need to initiate environmental AMR monitoring programs nationally and globally, which will complement existing systems in different sectors. However, environmental programs should not only identify anthropogenic influences and levels of AMR, but they should also allow for identification of transmissions to and from human and animal populations. In the current review we therefore propose using antimicrobial resistant Escherichia coli as indicators for monitoring occurrence and levels of AMR in the environment, including wildlife.publishedVersio

A global multinational survey of cefotaxime-resistant coliforms in urban wastewater treatment plants

The World Health Organization Global Action Plan recommends integrated surveillance programs as crucial strategies for monitoring antibiotic resistance. Although several national surveillance programs are in place for clinical and veterinary settings, no such schemes exist for monitoring antibiotic-resistant bacteria in the environment. In this transnational study, we developed, validated, and tested a low-cost surveillance and easy to implement approach to evaluate antibiotic resistance in wastewater treatment plants (WWTPs) by targeting cefotaxime-resistant (CTX-R) coliforms as indicators. The rationale for this approach was: i) coliform quantification methods are internationally accepted as indicators of fecal contamination in recreational waters and are therefore routinely applied in analytical labs; ii) CTX-R coliforms are clinically relevant, associated with extended-spectrum ?-lactamases (ESBLs), and are rare in pristine environments. We analyzed 57 WWTPs in 22 countries across Europe, Asia, Africa, Australia, and North America. CTX-R coliforms were ubiquitous in raw sewage and their relative abundance varied significantly (< 0.1% to 38.3%), being positively correlated (p < 0.001) with regional atmospheric temperatures. Although most WWTPs removed large proportions of CTX-R coliforms, loads over 103 colony-forming units per mL were occasionally observed in final effluents. We demonstrate that CTX-R coliform monitoring is a feasible and affordable approach to assess wastewater antibiotic resistance status

Membrane bioreactors (MBRs): Activated sludge filterability and full-scale MBR functioning

Despite continuous developments in the field of MBR technology, membrane fouling together with the associated energy demand and related costs issues remain major challenges. The efficiency of the filtration process in an MBR is governed by the activated sludge filterability, which is still limitedly understood and is determined by the interactions between the biomass, the wastewater and the applied process conditions. This paper provides better understanding of membrane fouling propensity based on activated sludge filterability assessment. Furthermore, it provide important insights on full-scale MBR overall functioning, i.e., design options, operation, performance and energy efficiency, in order to provide a step forward towards optimum performance conditions and efficient operation of the MBR technology. The paper is based on the Ph.D. dissertation: Krzeminski, P. (2013). Activated sludge filterability and full-scale membrane bioreactor operation. Delft University of Technology, the Netherlands, ISBN: 978-94- 6186-092-7. ---- Membran-bioreaktorer (MBRs): Aktivslammets filtrerbarhet og fullskala MBR-funksjon. Til tross for at det har vært en kontinuerlig forbedring av MBR-teknologien, er det fortsatt store utfordringer knyttet til membrangjentetting (fouling) og medfølgende høyt energiforbruk og kostnadsnivå. Effektiviteten til filtreringsprosessen i en MBR er styrt av aktivslammets filtrerbarhet, som fortsatt er lite klarlagt men bestemt av samspillet mellom biomassen, avløpsvannets sammensetning og prosessforhold. Denne artikkelen bidrar til å styrke koblingen mellom membranens tilbøyelighet til å tettes igjen og aktivslammets filtrerbarhet. Videre framkommer viktig innsikt knyttet til funksjonen av MBR i fullskala, dvs. designmuligheter, drift, stabilitet, effektivitet og energibetraktninger, for å komme et skritt nærmere optimale driftsbetingelser og effektiv styring av MBR-teknologien. Artikkelen er basert på doktorgradsavhandlingen til Pawel Krzeminski (2013): Activated sludge filterability and full-scale membrane bioreactor operation. Delft University of Technology, the Netherlands, ISBN: 978-94-6186- 092-7.publishedVersio

Abundance of antibiotic resistance genes and removal of antibiotic resistant E. coli in to Norwegian wastewater treatment plants

Effektiviteten av de ulike behandlingstrinnene for fjerning av antibiotikaresistente E. coli i avløpsvann fra to store avløpsrenseanlegg i Oslo ble undersøkt. Renseanleggene reduserer den totale mengden kultiverbare E. coli fra avløpsvannet effektivt, men fjerningen av disse bakteriene var ufullstendig i begge anleggene. Bakteriene var delvis resistente mot ampicillin og cotrimoxazole, og i mindre grad tetracyclin og ciprofloxacin. Med hensyn til fjerning av resistente E. coli viste anleggene forskjellige mønstre utover i behandlingsprosessen. Analysen av et utvalg markørgener i utslippsvannet viser forekomst av resistens mot antibiotika som brukes hyppig i Norge, men også svært sjelden brukte og kritisk viktige antibiotika, inkludert karbapenemer, colistin og cefalosporiner. Gjennom ultra- og nanofiltrering på laboratorieskala av utslippsvannet fra avløpsrenseanleggene, ble alle kultiverbare E. coli, inkludert resistente E. coli, fullstendig fjernet.publishedVersio

Removal of antibiotic resistant E. coli in two Norwegian wastewater treatment plants and by nano- and ultra-filtration processes

The effectivity of different treatment stages at two large wastewater treatment plants (WWTPs) located in Oslo, Norway, to remove antibiotic resistant Escherichia coli from municipal wastewater was investigated. The WWTPs were effective in reducing the total cultivable E. coli. The E. coli in WWTP samples were mainly resistant to ampicillin (6–27%) and trimethoprim-sulfamethoxazole (5–24%), and, to a lesser extent, tetracycline (3–14%) and ciprofloxacin (0–7%). In the first WWTP, a clear decrease in the percentage of E. coli resistant to these antibiotics was found, with the main removal occurring during physical/chemical treatment. In the second WWTP, the percentage of cultivable resistant E. coli did not display a considerable change. During laboratory-scale membrane filtration of WWTP effluents using ultrafiltration (UF) and nanofiltration (NF) membranes, all E. coli, including those resistant to antibiotics, were removed completely. The results imply that UF and NF processes are potent measures to remove antibiotic resistant bacteria (ARB) during post-treatment of WWTP effluents, thus reducing the potential spread of antibiotic resistance in the receiving aquatic environment.acceptedVersio

Forekomst av antibiotikaresistensgener og fjerning av antibiotikaresistente E. coli i to norske avløpsrenseanlegg

Effektiviteten av de ulike behandlingstrinnene for fjerning av antibiotikaresistente E. coli i avløpsvann fra to store avløpsrenseanlegg i Oslo ble undersøkt. Renseanleggene reduserer den totale mengden kultiverbare E. coli fra avløpsvannet effektivt, men fjerningen av disse bakteriene var ufullstendig i begge anleggene. Bakteriene var delvis resistente mot ampicillin og cotrimoxazole, og i mindre grad tetracyclin og ciprofloxacin. Med hensyn til fjerning av resistente E. coli viste anleggene forskjellige mønstre utover i behandlingsprosessen. Analysen av et utvalg markørgener i utslippsvannet viser forekomst av resistens mot antibiotika som brukes hyppig i Norge, men også svært sjelden brukte og kritisk viktige antibiotika, inkludert karbapenemer, colistin og cefalosporiner. Gjennom ultra- og nanofiltrering på laboratorieskala av utslippsvannet fra avløpsrenseanleggene, ble alle kultiverbare E. coli, inkludert resistente E. coli, fullstendig fjernet

Natural organic matter fractions and their removal in full-scale drinking water treatment under cold climate conditions in Nordic capitals

Drinking water treatment plants (DWTPs) designed to remove natural organic matter (NOM) are challenged as concentrations of NOM in raw waters are increasing. Here, we assess seasonal differences in NOM quality and quantity, from raw waters to the distribution network, at three large DWTPs in Oslo, Stockholm and Helsinki. Samples, collected during stable stratification in both winter and summer and during the autumnal turnover, were analysed for NOM concentrations and composition. The NOM was characterized by common routine parameters, size and content (TFF, LC-OCD, fluorescence) and biodegradability. The NOM concentration decreased to 2.5 mg/L (55%), 4.0 mg/L (48%) and 5.7 mg/L (76%) at the respective DWTPs in Oslo, Stockholm and Helsinki. The NOM in raw waters were predominantly in the largest size fraction (>50 kDa), in particular from Oslo. High MW fractions >50 kDa and humics remained the largest fractions with minimum 30% and maximum 80% of the total NOM. The BDOC in treated water <0.3 mg/L and the conditions in the distribution network imply low probability for bacteria regrowth. The multi-step treatment consisting of coagulation/flocculation, sedimentation, rapid sand filtration, ozonation and biological activated carbon filtration (BAC) was most effective in removing NOM. Coagulation/flocculation followed by sedimentation and sand filtration were critical, especially for the removal of biopolymers and humics, and somewhat for building blocks. The sand filtration provided up to 25% additional removal of biopolymers and below 7% removal of other fractions. The ozonation and BAC was more effective and removed 11% of biopolymers, and about 35% of building blocks and LMW neutrals.publishedVersio