RESUMEN
GAC filtration of municipal wastewater was optimized and intensified, making its implementation and operation directly after secondary clarification possible and relevant. GAC was first selected based on laboratory tests. Performances on organic micropollutants were linked to the repartition of BET surface between micropores and meso/macropores. At pilot scale, in order to limit the impact of head loss, downflow declogging sequences (DCS) were implemented and upflow filtration tested. 6 to 12 DCS per day led to a 4.7-5.5-fold increase of particles retention capacity between backwashes (cycle duration of 20-120 h), and upflow operations improved head loss evolution profile with only a slight GAC (<15 %) expansion. DCS allows backwash frequency reduction, enabling significant water savings. Both adaptations maintained high organic micropollutants removals compared to a review of 16 GAC studies at pilot or full-scale, results being in the upper range. A specific dose of 2.0-2.5 g GAC/gC was necessary to obtain an average removal of pharmaceuticals and benzotriazole of 80 % at 20 min contact time, which is comparable to PAC and low granulometry GAC. Higher doses are needed for PFAS but >80 % removals are achievable. Particles, TKN, particulate phosphorus and organic matter are well removed by GAC filtration in both configurations. Biological activity is observed through nitrogen transformation in the GAC bed. Heavy metals are greatly removed in GAC filtration, in particular Cd, Cu, Ni and Pb, probably through biosorption onto the biofilm, developed within the GAC bed. For wastewater reuse applications, GAC filtration has an added value through physicochemical quality improvement and fecal contamination indicators removal of 1 log, facilitating the implementation and optimizing the design of a post-disinfection. Antibiotic resistant bacteria and antibiotic resistance genes are also partially retained in GAC filtration. Finally, biological wastewater treatments combined to GAC filtration is a good solution to effectively treat organic micropollutants together with heavy metals and preparing post-disinfection for reuse.
Asunto(s)
Carbón Orgánico , Filtración , Eliminación de Residuos Líquidos , Aguas Residuales , Contaminantes Químicos del Agua , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Eliminación de Residuos Líquidos/métodos , Filtración/métodos , Carbón Orgánico/química , Metales , Farmacorresistencia Microbiana , Purificación del Agua/métodosRESUMEN
An MBR treating filtrate from sludge ultra-dewatering (FSD) was studied to evaluate the real applicability to concentrated effluents. The MBR operation is comparable to conventional wastewater MBRs in terms of F/M and nitrogen to sludge ratios, SRT and MLSS in biological tanks. On the contrary, the volume treated is lower with a comparable pollution load, the effluent being concentrated in nitrogen and carbon. Very high and stable ammonium (97.7 ± 2.4%), total phosphorus (81.8 ± 11.9%), chemical (89.5 ± 2.3%) and biochemical oxygen demands (98.8 ± 0.7%) removals are observed despite a significant modification of the FSD composition. The MBR removal performances are whether comparable or greater than those reported at full-scale for Sharon or Anammox processes. The evolution of membranes properties, in particular, the decrease of permeability induced by the irreversible fouling, leads to a decrease of the daily permeate volume produced and an increase of the chemical cleaning need. The membrane lifespan was determined to be 5.5 years based on both the permeability loss and TSS in permeate. The permeability is directly correlated to the cumulated filtered flux of colloidal matter and a total of 350 kg O2/m2 of the membrane (COD in the supernatant) is needed to reach a permeability below 100 LMH/bar. The specific energy consumption is comparable to other wastewater MBRs in kWh/kgCOD removed but the intensive chemical cleanings need to be 2.5-4.5 times more frequent. Overall, it can be concluded that MBR is adapted to treat FSD efficiently.
Asunto(s)
Aguas del Alcantarillado , Aguas Residuales , Aguas del Alcantarillado/química , Eliminación de Residuos Líquidos , Longevidad , Reactores Biológicos , Membranas Artificiales , NitrógenoRESUMEN
This paper analyzes the fate of 71 priority and emerging organic contaminants all along the treatment trains of sewage sludge treatment facilities in Paris including dewatering by centrifugation, thermal drying and anaerobic digestion. It aimed at proposing and applying a mass balances calculation methodology to each process and pollutant. This data validation strategy demonstrated the complexity to perform representative inlet/outlet sampling and analysis campaigns at industrial scales regarding organic compounds and to propose options to overcome this issue. Centrifugation and drying processes only implied physical mechanisms as phase separation and water elimination. Hence, correct mass balance were expected observed for organic contaminants if sampling and analysis campaigns were representative. This was the case for hydrophobic and neutral compounds. For the other more hydrophilic and charged compounds, the mass balances were scarcely correct. Thus, the conventional sampling and analytical practices used with sludge should be questioned and adapted to better take into account the high heterogeneity of sludge and the evolution of matrix effect within sludge treatment processes on micropollutant determination. For the biological anaerobic digestion process where degradations can occur and removals can be observed, the mass balances were deeply interpreted for 60 contaminants. This process contributed to the elimination above 70% of 21 detected compounds including 16 pharmaceuticals, 2 phthalates, 2 hormones and 1 perfluorinated compound. Removals of domperidone, propranolol, escitalopram, lidocaine, verapamil and cefoperazone under this condition were reported for the first time.
Asunto(s)
Contaminantes Ambientales , Aguas del Alcantarillado , Desecación , Paris , Eliminación de Residuos LíquidosRESUMEN
The fate of pathogen indicators (Escherichia coli - EC, intestinal enterococci - IE, RNA-F bacteriophages and spores of sulfite reducing bacteria - SSR) was extensively studied in Parisian large-scale wastewater treatment plants (WWTPs), based on conventional activated sludge, biofiltration or membrane bioreactor (MBR) processes. Between 14 and 87 campaigns were performed between 2014 and 2018 in five WWTPs. High removals of 3 log for both EC and IE, and lower removals of 1-2 log for SSR and RNA-F bacteriophages, were observed in conventional activated sludge and biofiltration WWTPs. The MBR WWTP achieves notably greater removals of 4.5-5.5 log for faecal bacteria and 3-4 log for SSR and RNA-F bacteriophages. This WWTP is the only one already in compliance with reuse standards, the other ones being non-compliant because of SSR and RNA-F bacteriophages. The implementation of a micro-grain activated carbon process would increase the WWTP removals of 0.8 log for faecal bacteria, due to particles retention, with no significant effect on both other pathogens. Ozonation (0.9-1.3 g O3/g dissolved organic carbon) or performic acid (0.8-1.2 ppm) would have greater benefits with additional removals of 1.5-2.5 log for EC, 1-2 log for IE and 0.5-1 log for SSR and RNA-F bacteriophages. Correlations between pathogen indicator removals and initial concentrations were found, as well as a significant decrease of RNA-F bacteriophage concentrations in Parisian raw wastewater, below 2 log. Thus, RNA-F bacteriophages could be a real issue to evaluate the compliance of Parisian wastewater with reuse. The time evolution of removals demonstrated that SSR is the most problematic parameter regarding reuse in conventional activated sludge and biofiltration WWTPs, as its initial concentration is high (5 log) but removals insufficient (<2 log). In contrast, removals of RNA-F bacteriophages greater than 2 log can be obtained within WWTPs completed or not with a tertiary treatment when the initial concentration in raw wastewater is sufficient. Correlations were also found between the removals of pathogen indicators and the removals of physico-chemical parameters, but they are not good enough to allow performance predictions.
Asunto(s)
Aguas Residuales , Purificación del Agua , Paris , Aguas del Alcantarillado , Eliminación de Residuos Líquidos , Microbiología del AguaRESUMEN
Centrifuge are common machines used for sludge thickening and dewatering in wastewater treatment plant but performances and optimal setting parameters are often difficult to predict and optimize, owing to complex mechanisms occurring during separation and high shear stresses undergone by flocs. Laboratory tests are necessary to assess performances and to screen chemicals and dosage in order to decrease optimization time at full scale. They include volatile matters characterization, drainage and CST tests vs mixing time, basket spin tests with shearing, limit dryness determination. The ability of these tests, to assess sludge dehydration and/or to select polymer and dosage, is discussed and is compared with performances obtained in a screw centrifuge decanter at lab and full scale.
Asunto(s)
Aguas del Alcantarillado , Eliminación de Residuos Líquidos , Tornillos Óseos , Centrifugación , Polímeros , AguaRESUMEN
Among the release solutions for reducing the discharge of organic and persistent contaminants in the aquatic environment, the use of a tertiary treatment in addition to existing conventional wastewater treatment processes is considered. The use of micro-grain activated carbon in a fluidized bed is a promising technique investigated in this study. The effluents from a large-scale pilot system were analyzed by liquid chromatography coupled with high-resolution mass spectrometry (QToF). Several strategies were deployed, namely molecular fingerprint comparison, suspected and non-target analyses, identification of refractory compounds to treatment, and finally, quantification of identified compounds. The evaluation of the molecular fingerprints provided evidence of the overall effect of the tertiary treatment on the treated wastewater quality. The suspected approach highlighted the presence of 83 pharmaceuticals and pesticides as well as transformation products in the effluents. The non-target approaches also highlighted compounds refractory to tertiary treatment, such as illicit drugs or some pharmaceuticals. The identification and quantification of identified compounds underscored the suitability of micro-grain activated carbon in eliminating many classes of pharmaceuticals with various physicochemical properties, such as anti-hypertensive, analgesic, anti-viral, antidepressant and even various pesticides.
Asunto(s)
Carbón Orgánico/análisis , Espectrometría de Masas/métodos , Aguas Residuales/química , Purificación del Agua/métodos , Analgésicos , Antidepresivos , Antihipertensivos , Antivirales , Carbón Orgánico/química , Plaguicidas/análisis , Plaguicidas/aislamiento & purificación , Preparaciones Farmacéuticas/aislamiento & purificación , Contaminantes Químicos del Agua/análisisRESUMEN
This article provides data on the contamination of different kinds of sludge (raw, centrifuged, digested, thermally dried sludge and sludge cake) from Paris conurbation by 71 various pollutants including pharmaceutical products (PHPs), hormones, perfluorinated acids (PFAs), linear alkylbenzene sulfonate (LAS), alkylphenols (APs), phthalates (PAEs), polycyclic aromatic hydrocarbons (PAHs) and polychlorobiphenyls (PCBs). Very high contents of LAS (0.1-10g/kg dry matter - DM) compared to other compounds were found in all types of sludge followed by DEHP (10-100mg/kg DM) and fluoroquinolones (1-100mg/kg DM). APs were measured at intermediary contents in Parisian sludge, lying in the 2-20mg/kg DM range. Finally, hormones, PAHs, PCBs, PAEs, PFAs and the remaining PHPs were all found at contents lower than 1mg/kg DM. For most compounds (PHPs, PFOS, DEHP, PAHs), no significant differences in the micropollutant contents were found for similar types of sludge from different WWTP in Paris, highlighting the homogeneity of sludge contamination in downstream Paris catchment. The variability of concentration is rather high (coefficient of variation >100%) for several PHPs, PFAs or PCBs while it is moderate (<100%) or low (<50%) for fluoroquinolones, hormones, PAHs, APs or LAS. In addition, digestion seems to have a buffer effect as variabilities are lower in digested sludge for PHPs, PFAs, APs and PCBs. During sludge treatment (centrifugation, digestion, thermal drying, sludge conditioning+press filtration), the hormones, LAS, APs, PAHs, DEHP and PCBs concentrations increased, while those of PHPs and PFAs decreased. In the case of digestion, the increase of content can be explained by no pollutant removal or a lower removal than DM removal (concentration phenomenon) whereas the decrease underlines that the compound is more removed than the DM. In any case, these concentration variations presuppose the mechanisms of dissipation that could be attributed to volatilization, biotic or abiotic transformation (complete or with metabolites production), bound residues formation. In addition, data on sludge liquors - centrifuged (CW) and condensed (TDW) waters - from respectively centrifugation and thermal drying were collected. Several hormones, PHPs, PFAs, LAS, PAEs, APs, PCBs and PAHs were quantified in CW and TDW, displaying a transfer through the water removal. The concentrations observed are rather comparable to those found in wastewater.
Asunto(s)
Bifenilos Policlorados/análisis , Hidrocarburos Policíclicos Aromáticos/química , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Ácidos Alcanesulfónicos/química , Desecación , Hormonas/análisis , Paris , Preparaciones Farmacéuticas/análisis , Aguas del Alcantarillado/química , Temperatura , Purificación del Agua/métodosRESUMEN
Among the solutions to reduce micropollutant discharges into the aquatic environment, activated carbon adsorption is a promising technique and a large scale pilot has been tested at the Seine Centre (240,000 m(3)/d - Paris, France) wastewater treatment plant (WWTP). While most of available works studied fixed bed or contact reactors with a separated separation step, this study assesses a new type of tertiary treatment based on a fluidized bed containing a high mass of activated carbon, continuously renewed. For the first time in the literature, micro-grain activated carbon (µGAC) was studied. The aims were (1) to determine the performances of fluidized bed operating with µCAG on both emerging micropollutants and conventional wastewater quality parameters, and (2) to compare its efficiency and applicability to wastewater to former results obtained with PAC. Thus, conventional wastewater quality parameters (n=11), pharmaceuticals and hormones (PPHs; n=62) and other emerging pollutants (n=57) have been monitored in µGAC configuration during 13 campaigns. A significant correlation has been established between dissolved organic carbon (DOC), PPHs and UV absorbance at 254 nm (UV-254) removals. This confirms that UV-254 could be used as a tertiary treatment performance indicator to monitor the process. This parameter allowed identifying that the removals of UV-254 and DOC reach a plateau from a µGAC retention time (SRT) of 90-100 days. The µGAC configuration substantially improves the overall quality of the WWTP discharges by reducing biological (38-45%) and chemical oxygen demands (21-48%), DOC (13-44%) and UV-254 (22-48%). In addition, total suspended solids (TSS) are retained by the µGAC bed and a biological activity (nitratation) leads to a total elimination of NO2(-). For micropollutants, PPHs have a good affinity for µGAC and high (>60%) or very high (>80%) removals are observed for most of the quantified compounds (n=22/32), i.e. atenolol (92-97%), carbamazepine (80-94%), ciprofloxacin (75-95%), diclofenac (71-97%), oxazepam (74-91%) or sulfamethoxazole (56-83%). In addition, alkylphenols, artificial sweeteners, benzotriazole, bisphenol A, personal care products (triclocarban and parabens) and pesticides have removals lying in the 50 ->90% range. Overall, the fluidized bed of µGAC allows obtaining performances comparable to PAC at the same activated carbon dose. Indeed, the average removal of the 13 PPHs found at a high occurrence (>75%) in WWTP discharges is similar at 20 g/m(3) of µGAC (78-89%) and PAC (85-93%). In addition, this recycled µGAC operation leads to several operational advantages (no FeCl3, reactivable, higher SRT, higher treated flow) and has a stronger impact on the overall wastewater quality compared to PAC.
Asunto(s)
Carbón Orgánico/química , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/química , Contaminantes Químicos del Agua/análisis , Adsorción , Análisis de la Demanda Biológica de Oxígeno , ParisRESUMEN
The efficacy of a fluidized powdered activated carbon (PAC) pilot (CarboPlus(®)) was studied in both nominal (total nitrification + post denitrification) and degraded (partial nitrification + no denitrification) configuration of the Seine Centre WWTP (Colombes, France). In addition to conventional wastewater parameters 54 pharmaceuticals and hormones (PhPHs) and 59 other emerging pollutants were monitored in influents and effluents of the pilot. Thus, the impacts of the WWTP configuration, the process operation and the physico-chemical properties of the studied compounds were assessed in this article. Among the 26 PhPHs quantified in nominal WWTP configuration influents, 8 have high dissolved concentrations (>100 ng/L), 11 have an intermediary concentration (10-100 ng/L) and 7 are quantified below 10 ng/L. Sulfamethoxazole is predominant (about 30% of the sum of the PhPHs). Overall, 6 PhPHs are poorly to moderately removed (<60%), such as ibuprofen, paracetamol or estrone, while 9 are very well removed (>80%), i.e. beta blockers, carbamazepine or trimethoprim, and 11 are well eliminated (60-80%), i.e. diclofenac, naproxen or sulfamethoxazole. In degraded WWTP configuration, higher levels of organic matter and higher concentrations of most pollutants are observed. Consequently, most PhPHs are substantially less removed in percentages but the removed flux is higher. Thus, the PAC dose required to achieve a given removal percentage is higher in degraded WWTP configuration. For the other micropollutants (34 quantified), artificial sweeteners and phthalates are found at particularly high concentrations in degraded WWTP configuration influents, up to µg/L range. Only pesticides, bisphenol A and parabens are largely eliminated (50-95%), while perfluorinated acids, PAHs, triclosan and sweeteners are not or weakly removed (<50%). The remaining compounds exhibit a very variable fate from campaign to campaign. The fresh PAC dose was identified as the most influencing operation parameter and is strongly correlated to performances. Charge and hydrophobicity of compounds have been recognized as crucial for the micropollutant adsorption on PAC, as well as the molecular weight. Finally, a PAC dose of 10 mg/L allows an average removal of 72-80% of the sum of the PhPHs in nominal WWTP configuration. The comparaison of the results with those from the scarce other studies tends to indicate that an extrapolation of them to different PAC processes and to other WWTPs could be possible and relevant, taking into account the differences of water quality from WWTP to WWTP.
Asunto(s)
Carbón Orgánico/química , Eliminación de Residuos Líquidos , Aguas Residuales/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua , Hormonas/aislamiento & purificación , Preparaciones Farmacéuticas/aislamiento & purificación , Proyectos Piloto , Polvos , Calidad del AguaRESUMEN
This paper aims at characterizing the quality of different treated sludges from Paris conurbation in terms of micropollutants and assessing their fate during different sludge treatment processes (STP). To achieve this, a large panel of priority and emerging pollutants (n=117) have been monitored in different STPs from Parisian wastewater treatment plants including anaerobic digestion, thermal drying, centrifugation and a sludge cake production unit. Considering the quality of treated sludges, comparable micropollutant patterns are found for the different sludges investigated (in mg/kg DM - dry matter). 35 compounds were detected in treated sludges. Some compounds (metals, organotins, alkylphenols, DEHP) are found in every kinds of sludge while pesticides or VOCs are never detected. Sludge cake is the most contaminated sludge, resulting from concentration phenomenon during different treatments. As regards treatments, both centrifugation and thermal drying have broadly no important impact on sludge contamination for metals and organic compounds, even if a slight removal seems to be possible with thermal drying for several compounds by abiotic transfers. Three different behaviors can be highlighted in anaerobic digestion: (i) no removal (metals), (ii) removal following dry matter (DM) elimination (organotins and NP) and iii) removal higher than DM (alkylphenols - except NP - BDE 209 and DEHP). Thus, this process allows a clear removal of biodegradable micropollutants which could be potentially significantly improved by increasing DM removal through operational parameters modifications (retention time, temperature, pre-treatment, etc.).
Asunto(s)
Aguas del Alcantarillado/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/análisis , Contaminación Química del Agua/análisis , Contaminación Química del Agua/prevención & control , Anaerobiosis , Centrifugación , Desecación , Cromatografía de Gases y Espectrometría de Masas , Paris , Aguas del Alcantarillado/análisis , Espectrofotometría Atómica , Espectrometría de Masas en Tándem , Contaminantes Químicos del Agua/químicaRESUMEN
This paper compares the removal performances of two complete wastewater treatment plants (WWTPs) for all priority substances listed in the Water Framework Directive and additional compounds of interest including flame retardants, surfactants, pesticides, and personal care products (PCPs) (n = 104). First, primary treatments such as physicochemical lamellar settling (PCLS) and primary settling (PS) are compared. Similarly, biofiltration (BF) and conventional activated sludge (CAS) are then examined. Finally, the removal efficiency per unit of nitrogen removed of both WWTPs for micropollutants is discussed, as nitrogenous pollution treatment results in a special design of processes and operational conditions. For primary treatments, hydrophobic pollutants (log K ow > 4) are well removed (>70 %) for both systems despite high variations of removal. PCLS allows an obvious gain of about 20 % regarding pollutant removals, as a result of better suspended solids elimination and possible coagulant impact on soluble compounds. For biological treatments, variations of removal are much weaker, and the majority of pollutants are comparably removed within both systems. Hydrophobic and volatile compounds are well (>60 %) or very well removed (>80 %) by sorption and volatilization. Some readily biodegradable molecules are better removed by CAS, indicating a better biodegradation. A better sorption of pollutants on activated sludge could be also expected considering the differences of characteristics between a biofilm and flocs. Finally, comparison of global processes efficiency using removals of micropollutants load normalized to nitrogen shows that PCLS + BF is as efficient as PS + CAS despite a higher compactness and a shorter hydraulic retention time (HRT). Only some groups of pollutants seem better removed by PS + CAS like alkylphenols, flame retardants, or di-2-ethylhexyl phthalate (DEHP), thanks to better biodegradation and sorption resulting from HRT and biomass characteristics. For both processes, and out of the 68 molecules found in raw water, only half of them are still detected in the water discharged, most of the time close to their detection limit. However, some of them are detected at higher concentrations (>1 µg/L and/or lower than environmental quality standards), which is problematic as they represent a threat for aquatic environment.