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The research on emerging pollutants in wastewater has become a worldwide issue of increasing environmental concern, especially considering the growing interest in wastewater reuse. However, the latter implies additional post-treatment after the conventional activated sludge processes, in order to produce a safer effluent. Our work aimed at determining the efficiency of reducing the toxicity associated with organic micropollutants (OMPs) in secondary wastewater effluents, using 3 different post-treatment technologies (granular activated carbon (GAC), sand biofiltration and UV irradiation): in particular, target chemical analysis of the OMPs most commonly founded in wastewater was coupled with effect-based assays (estrogenicity and mutagenicity). While chemical analysis assessed satisfactory performances for all 3 technologies in the abatement of selected OMPs, biological assays evidenced another perspective: both GAC and sand biofilters were significantly able to make the estrogenic load plummet; however, the UV system was ineffective in estrogenicity abatement, and its effluent exhibited also a slight mutagenicity, likely due to photo-transformation by-products. These results indicate that a synergistic combination of chemical analysis and biological assays can drive to a proper gauging of post-treatment technologies, taking into account not only the removal of OMPs, but also their overall toxicity This work was conceived within a Short Term Scientific Mission (STSM) of the Water2020 Cost Action ES1202: Conceiving Wastewater Treatment in 2020 | Energetic, environmental and economic challenges. Authors from Universidade de Santiago de Compostela belong to the Galician Competitive Research Group GRC 2013-032 and to the CRETUS Strategic Partnership (AGRUP2015/02). All these programmes are co-funded by FEDER (UE) SI

The phototransformation of 18 organic micropollutants (OMPs) commonly detected in wastewater treatment plant (WWTP) effluents was examined attempting to explain their fate during UV disinfection in WWTPs. For this purpose, a lab-scale UV reactor (lamp emitting at 254 nm) was used to study the influence of the operational conditions (UV dose, temperature and water matrix) on OMPs abatement and disinfection efficiency. Chemical properties of OMPs and the quality of treated effluent were identified as key factors affecting the phototransformation rate of these compounds. Sampling campaigns were carried out at the inlet and outlet of UV systems of three WWTPs, and the results evidenced that only the most photosensitive compounds, such as sulfamethoxazole and diclofenac, are eliminated. Therefore, despite UV treatment is an effective technology to phototransform OMPs, the UV doses typically applied for disinfection (10–50 mJ/cm 2 ) are not sufficient to remove them. Consequently, small modifications (increase of UV dose, use of catalysts) should be applied in WWTPs to enhance the abatement of OMPs in UV systems.

Sewage sludge reuse will become crucial for the sustainability of agriculture, given the increasing population and the lack of essential nutrients for crop growth. Nevertheless, this practice raises some concerns, due to the large amounts of contaminants of emerging concern (CECs) present in sewage sludge, including pharmaceuticals and personal care products (PPCPs), microplastics (MPs), engineered nanomaterials (ENMs), per- and polyfluoroalkyl substances (PFASs), flame retardants, plasticizers, metals, antibiotic resistance bacteria (ARB) and resistance genes (ARGs). These CECs may adversely affect the environment and, ultimately, human health through the consumption of crops grown under sludge-amended soils. This chapter reviews the potential environmental and human health risks associated with sewage sludge reuse in agriculture, by focusing on relevant classes of CECs, such as PPCPs, MPs, carbon-based ENMs and considering ARBs and ARGs, a topic so far poorly addressed. The risks discussed focus on the contamination of aquatic and terrestrial ecosystems and on CECs uptake by crops intended for human consumption. Finally, technological strategies to improve sludge treatment, and thus minimize such risks, are briefly discussed.

Granular activated carbon (GAC) is applied as post-treatment technology in wastewater treatment plants (WWTPs) in order to increase the elimination of organic micropollutants (OMPs). However, the efficiency and life-time of GAC depend on several parameters, such as the quality of the effluent to be treated or the type of GAC. In the present paper, two types of GAC, based on bituminous carbon (BC-GAC) and coconut shell (CS-GAC), were assessed from a technical, economic and environmental point of view to further remove OMPs present in two secondary effluents, coming from integrated biological systems with a membrane or a settler, respectively. Although all GAC filters were efficient in removing selected OMPs, the quality of the secondary effluent had a strong influence on the lifespan of adsorbent material and the technical operability of the filtration systems. While GAC filters treating membrane effluent were highly effective to remove recalcitrant compounds, such as carbamazepine and diazepam (>80%), even after 430 d of operation (>30,800 BV), the efficiency of GAC filters treating settler effluent quickly lowered to 50% after 100 d of operation (

Novel wastewater treatment plants (WWTPs) are designed to be more energy efficient than conventional plants. One approach to becoming more energy efficient is the pre-concentration of organic carbon through chemically enhanced primary treatment (CEPT) or high-rate activated sludge (HRAS). This study compares these approaches in terms of energy demand, operational costs, organic micropollutants (OMP), and virus removal efficiency. A CEPT pilot-scale plant was operated at a hydraulic retention time (HRT) of 30 min, and a lab-scale HRAS reactor was operated at an HRT of 2 h and a solid retention time (SRT) of 1 d in continuous mode. A minimum dose of 150 mg/L ferric chloride (FeCl3) was required to achieve a threshold chemical oxygen demand (COD)-to-ammonium ratio below 2 g COD to 1 g of NH4+ –N (fulfilling the requirement for a partial nitritation-anammox reactor), reaching high phosphate (PO43−)-removal efficiency (>99%). A slightly lower COD recovery was attained in the HRAS reactor, due to the partial oxidation of the influent COD (15%). The lower PO43− removal efficiency achieved in the HRAS configuration (13%) was enhanced to a comparable value of that achieved in CEPT by the addition of 30 mg/L FeCl3 at the clarifier. The CEPT configuration was less energy-intensive (0.07 vs 0.13 kWh/m3 of wastewater) but had significantly higher operational costs than the HRAS-based configuration (6.0 vs 3.8 c€/m3 of wastewater). For OMPs with kbiol > 10 L/gVSS·d, considerably higher removal efficiencies were achieved in HRAS (80–90%) than in CEPT (4–55%). For the remaining OMPs, the biotransformation efficiencies were generally higher in HRAS than in CEPT but were below 55% in both configurations. Finally, CEPT was less efficient than HRAS for virus removal. HRAS followed by FeCl3 post-treatment appeared to be a more effective alternative than CEPT for COD pre-concentration in novel WWTPs.

Sergio Ponsá talks about the valorization of the wastes generated by the dairy industry to recover phosphorous, a relevant macronutrient for plant growth that currently depends on a critical raw material. REFLOW, an interdisciplinary cross-sectoral H2020 European Training Network project, will develop and provide a solid economic and environmental alternative to inorganic fertilizers by delivering cost-effective, nutritive and safe standardised Bio Based Fertilizers (BBF) products. In accordance with the circular economy framework, new fertilizer products will increase, or at least maintain, actual production yields while avoiding environmental impacts in the dairy processing industry.