Removal of pharmaceuticals from a WWTP secondary effluent by ultrafiltration/reverse osmosis followed by electrochemical oxidation of the RO concentrate
Introduction
The focus of environmental research has expanded to include both “classic” environmental pollutants and so-called “emerging contaminants”, which comprise pharmaceuticals and personal care products (PPCPs) [1], [2], [3], [4]. Concern about their presence in aquatic environments has been increasing because their presence in small concentrations has been associated with chronic toxicity, endocrine disruption and the development of pathogen resistance [5], [6], [7], [8], [9].
Because of the observed concentrations of emerging pollutants in raw wastewaters and the limited effectiveness of secondary treatments, municipal wastewater treatment plant (WWTP) effluents are the main disposal pathway for pharmaceuticals and personal care products into the environment [10], [11], [12]. In general, the total concentration of emerging contaminants in WWTP effluents ranges from ng/L to μg/L [13]. The technologies for removing emerging contaminants from WWTP effluents include ultra-violet (UV) radiation, granulated activated carbon, ion-exchange, membrane filtration and advanced oxidation processes such as ozonation, photocatalysis and the Fenton reaction [1], [5], [14], [15], [16], [17], [18], [19], [20], [21], [22].
Membrane processes are being increasingly implemented in water treatment because these technologies combine process stability with an excellent effluent quality [23], [24], [25], [26]. However, widely used microfiltration and ultrafiltration technologies have been found to filter out only a few emerging organic contaminants [27], [28], [29]. In contrast, it has been shown that nanofiltration and reverse osmosis can separate out many of these compounds [5], [21], [30], [31], [32].
While the permeate water obtained from NF/RO treatments of WWTP effluents can be employed for industrial uses that demand high quality water [24], [33], [34], [35], [36], [37], the pollutants are accumulated in a concentrate stream and an additional step is required to treat it [38], [39], [40]. In addition to conventional technologies, such as coagulation and activated carbon adsorption [41], advanced oxidation technologies, including ozonation, photocatalysis, sonolysis, and electrochemical oxidation have been proposed for eliminating contaminants from the concentrate stream [42], [43], [44], [45], [46], [47], [48]. Electrochemical oxidation, in particular has several advantages. For example, it can be used to treat RO concentrate streams with moderate to high salinity [49], which ensures excellent electric conductivity and reduces the energy consumption, and with moderate chloride concentrations, which promote indirect oxidation and disinfection pathways [39], [44], [46], [47], [48], [49], [50], [51], [52]. A few studies have shown that electrochemical oxidation with boron-doped diamond (BDD) electrodes is effective at eliminating emerging contaminants with removal percentages higher than 90% for most compounds [53], [54], [55].
In this work, an advanced tertiary treatment that includes membrane technologies and electrooxidation was proposed to treat a secondary WWTP effluent and eliminate the removed pollutants to prevent their discharge into the environment. The occurrence of numerous emerging contaminants in the WWTP influent and effluent was assessed, and the removal efficiency of some of the most prevalent pharmaceuticals and stimulants was determined by using an on-site pilot-scale integrated membrane system (UF-RO). The electrooxidation of the RO concentrate stream with boron-doped diamond electrodes was proposed for the mineralization of the retained pharmaceuticals.
Section snippets
Description of the applied tertiary treatment
The experimental work was performed on-site using the secondary effluent of the WWTP located in Vuelta Ostrera (Cantabria, Spain) as the feed water. This WWTP currently operates at 85% capacity, treating an average flow-rate of 110,000 m3/day, and utilizes a secondary treatment based on activated sludge. In this work, the applied tertiary treatment consisted of pilot-scale ultrafiltration (UF) and reverse osmosis (RO) units combined with laboratory-scale electrooxidation (ELOX). A process
Physicochemical characterization
The physicochemical characteristics of the macro-contaminants and main ionic components of the WWTP effluent and tertiary unit effluents have been included in the supplementary material (see Table S3 of the supplementary data). Because the WWTP effluent exhibited a high variability, the minimum and maximum values are given for each parameter, and the mean value of all the analyzed samples is given in brackets.
Fig. 2 shows the results expressed as removal percentages of the main
Conclusions
A wastewater treatment scheme that integrates activated sludge, ultrafiltration, reverse osmosis and electrooxidation was used to remove emerging contaminants from municipal wastewaters. The concentrations of 77 pharmaceuticals, stimulants, personal care products and metabolites were monitored in the raw municipal wastewater and secondary treatment effluent at a WWTP in the northern Spain over a period of two years. The amount of micropollutants removed during the secondary treatment varied
Acknowledgments
Support from the CTQ2008-0690, 062/SGTB/2007/3.1, and CONSOLIDER CSD2006-44 projects and Greentech (New Indigo ERANet Programme) is gratefully acknowledged. Special thanks are given to Prof. Amadeo Fernandez–Alba and his research team (Universidad de Almeria) for the analysis of the emerging contaminants.
References (76)
- et al.
Occurrence and removal of pharmaceuticals, caffeine and DEET in wastewater treatment plants of Beijing, China
Water Res.
(2010) - et al.
Priority organic micropollutants in water sources in Flanders and the Netherlands and assessment of removal possibilities with nanofiltration
Environ. Pollut.
(2007) - et al.
Removal of selected pharmaceuticals, frangances and endocrine disrupting compounds in a membrane bioreactor and conventional wastewater treatment plants
Water Res.
(2005) - et al.
Behaviour of pharmaceuticals, cosmetics and hormones in a sewage treatment plant
Water Res.
(2004) - et al.
A review of the effects of emerging contaminants in wastewater and options for their removal
Desalination
(2009) - et al.
Pilot survey monitoring pharmaceuticals and related compounds in a sewage treatment plant located on the Mediterranean coast
Chemosphere
(2007) - et al.
Removal of pharmaceuticals and fragrances in biological wastewater treatment
Water Res.
(2005) - et al.
Fate and removal of typical pharmaceuticals and personal care products by three different treatment processes
Sci. Total Environ.
(2013) - et al.
Consumption and occurrence of pharmaceutical and personal care products in the aquatic environment in Spain
Sci. Total Environ.
(2013) - et al.
Evaluation of a model for the removal of pharmaceuticals, personal care products, and hormones from wastewater
Sci. Total Environ.
(2013)
Contribution of hospital effluents to the load of pharmaceuticals in urban wastewaters: identification of ecologically relevant pharmaceuticals
Sci. Total Environ.
Photocatalytic ozonation to remove pharmaceutical diclofenac from water: influence of variables
Chem. Eng. J.
Solar photo-Fenton at mild conditions to treat a mixture of six emerging pollutants
Chem. Eng. J.
Treatment of emerging contaminants in wastewater treatment plants (WWTP) effluents by solar photocatalysis using low TiO2 concentrations
J. Hazard. Mater.
Suspended TiO2-assisted photocatytic degradation of emerging contaminants in a municipal WWTP effluent using a solar pilot plant with CPCs
Chem. Eng. J.
Review of photochemical reaction constants of organic micropollutants required for UV advanced oxidation processes in water
Water Res.
Improved removal of estrogenic and pharmaceutical compounds in sewage effluent by full scale granular activated carbon: impact on receiving river water
J. Hazard. Mater.
Pharmaceucials, hormones and bisphenol A in untreated source and finished drinking water in Ontario, Canada – Occurrence and treatment efficiency
Sci. Total Environ.
Role of membranes and activated carbon in the removal of endocrine disruptors and pharmaceuticals
Desalination
Dead-end ultrafiltration for pretreatment of RO in reclamation of municipal wastewater effluent
J. Membr. Sci.
On the feasibility of urban wastewater tertiary treatment by membranes: a comparative assessment
Desalination
Membranes enabling the affordable and cost effective reuse of wastewater as an alternative water source
Desalination
The use of RO to remove emerging micropollutants following CAS/UF or MBR treatment of municipal wastewater
Desalination
Nanofiltration and ultrafiltration of endocrine disrupting compounds, pharmaceuticals and personal care products
J. Membr. Sci.
Removal of pesticides from water by NF and RO membranes — a review
Desalination
Removal of pesticides and other micropollutants by nanofiltration
Desalination
Membrane technology for advanced wastewater reclamation for sustainable agriculture production
Desalination
A two stage membrane treatment of secondary effluent for unrestricted reuse and sustainable agricultural production
Desalination
Feasibility study for reclamation of a secondary treated sewage effluent mainly from industrial sources using a dual membrane process
Sep. Purif. Technol.
Pilot study for reclamation of secondary treated sewage effluent
Desalination
Non-conventional treatment of treated municipal wastewater for reverse osmosis
Desalination
State of the art and review on the treatment technologies of water reverse osmosis concentrates
Water Res.
Electro-oxidative abatement of low-salinity reverse osmosis membrane concentrates
Water Res.
Removal of pollutants from surface water and groundwater by nanofiltration: overview of possible applications in the drinking water industry
Environ. Pollut.
Characterisation and removal of recalcitrants in reverse osmosis concentrates from water reclamation plants
Water Res.
Electrochemical oxidation of reverse osmosis concentrate on mixed metal oxide (MMO) titanium coated electrodes
Water Res.
Treatment of high-salinity reverse osmosis concentrate by electrochemical oxidation on BDD and DSA electrodes
Desalination
Ozone-biological activated carbon as a pretreatment process for reverse osmosis brine treatment and recovery
Water Res.
Cited by (193)
Process design for removal of pharmaceuticals in wastewater treatment plants based on predicted no effect concentration (PNEC)
2023, Chemical Engineering JournalEnvironmental occurrence, risk, and removal strategies of pyrazolones: A critical review
2023, Journal of Hazardous MaterialsA critical review on latest innovations and future challenges of electrochemical technology for the abatement of organics in water
2023, Applied Catalysis B: Environmental