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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.

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.