Elsevier

Journal of Cleaner Production

Volume 214, 20 March 2019, Pages 514-523
Journal of Cleaner Production

Removal of emerging contaminants from wastewater using nanofiltration for its subsequent reuse: Full–scale pilot plant

https://doi.org/10.1016/j.jclepro.2018.12.297Get rights and content

Highlights

  • The study was performed using real wastewater from a wastewater treatment plant.

  • Stimulants and antibiotics were detected in the wastewater from Medina Sidonia.

  • Advanced wastewater treatment pilot full-scale installations are considered.

  • Nanofiltration is recommended to remove successfully caffeine, theobromine, theophylline, amoxicillin and penicillin.

  • The treated effluent met reuse criteria.

Abstract

Effluents from wastewater treatment plants (WWTPs) are widely recognized as the main source of emerging contaminants (including stimulants and antibiotics) in natural water courses. The problem is aggravated in those regions where water is scarce and its reuse is necessary. With the aim of avoiding these problems, the present paper reports the results obtained by installing a nanofiltration membrane at the outlet of the secondary decanter at the WWTP situated in the municipality of Medina Sidonia (SW Spain). Permeate samples were taken over a period of 72 h while the membranes were operating. Contaminants belonging to the aforementioned families (caffeine, theobromine, theophylline, amoxicillin and penicillin G) were analysed by means of liquid chromatography with mass spectrometry (UPLC-MS). The results indicate that nanofiltration removed these contaminants from the wastewater turning the treated water as suitable to be reused for all the uses included in the Spanish Royal Decree 1620/2007 on water regeneration and reuse.

Introduction

Earth is continually being polluted with numerous chemical substances of natural and anthropogenic origin. The exponential growth of the population and the rise in the use of these substances has led to an increase in their concentrations in wastewater, hence in the environment (Sarkar et al., 2018).

Many of these pollutants have not been subjected to a suitable assessment of the potential environmental risks and impacts that they may have on ecosystems and living beings, including their effects on human health (Riva et al., 2018a).

Among the substances detected in WWTP effluents it is possible to detect antibiotics (amoxicillin and penicillin G). Antibiotics may have a considerable environmental impact even at low concentrations, as they can cause resistance in bacteria and other microorganisms (Lu et al., 2016), including Streptococcus pneumoniae, which is classified as “penicillin-non-susceptible” in the World Health Organization (WHO) list of priority pathogens for R&D (WHO, 2017). Caffeine, theobromine and theophylline, which belong to the family of stimulants, have also been detected in quite significant concentrations in both wastewater and receiving waters (Buchberger, 2011, Senta et al., 2015), especially in some Mediterranean river basins where WWTP effluents (Rabiet et al, 2006) constitute a high percentage of the total river flow, especially in periods of drought (Köck-Schulmeyer et al., 2011).

Different types of treatments are currently being tested to effectively remove these emerging contaminants (EC) from wastewater, with the lowest possible economic cost, before being discharged into ecosystems. The technologies that are currently being used include membrane processes, in particular, nanofiltration and reverse osmosis. Both technologies have been very effective in the removal of different organic compounds (Kim et al., 2018), as they even permit the respective separation of divalent and monovalent ions from wastewater.

Besides, the scarcity of water in certain areas of the world (Mediterranean countries among them) leads to the need to regenerate and reuse water from secondary effluents. European landfill regulations (Directive 91/271/EEC) regulate the organic load that WWTP effluents must have, but guides about their possible reuse are missing. There is no specific legislation in Europe on the reuse of treated water. In Spain, the quality of reclaimed water is regulated by Royal Decree 1620/2007, of 7 December, establishing the legal framework for the reuse of treated water. In order to reuse reclaimed water, Spanish legislation requires that quality water obtained at the WWTP have to be in accordance with its intended use. However, the legislation on discharges and reuse do not takes into consideration emerging contaminants, as they are not among the priority substances in the field of water policy (Directive, 2013/39/EU). These substances will be probably included in the pertinent legislation in the future. For all these reasons, to avoid the problems that they may cause in the meantime and taking into account the effectiveness and relative low cost of nanofiltration membranes, they were chosen. Previous studies demonstrated that nanofiltration as tertiary treatment is a viable method for removing trace pharmaceutically (García-Ivars et al., 2017), but it is necessary to know at higher concentrations of emerging contaminants, real wastewater in pilot plant and more time than those studied. The present study shows an open circuit (72 h) with high concentrations of the chosen contaminants. The removal of emerging contaminants belonging to the family of stimulants (caffeine, theobromine and theophylline) and the family of antibiotics (amoxicillin and penicillin G) present in municipal wastewater via the use of nanofiltration as a tertiary treatment at a WWTP was studied in this work, in order to test the effectiveness of this technology for the reuse of the effluent.

Section snippets

Equipment used

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    Medina Sidonia WWTP

The plant chosen to carry out the experiments was located in the town of Medina Sidonia, a municipality in Southern Spain, in the centre of the province of Cádiz, Andalusia. It currently has a population of 11.741 inhabitants. Its WWTP is equipped to treat the wastewater from a population centre of 17.599 hab-eq and can achieve a flow rate of 2.223 mday−1.

There are two treatment lines: water and sludge. As at the majority of the existing WWTPs in Spain, the water line of

Characterization of the influent and effluent at Medina Sidonia WWTP

The influent and effluent at Medina Sidonia WWTP were characterized between January 2017 and January 2018. Table 3 shows the average, minimum and maximum values of the different parameters for the 12 samplings performed, as well as their standard deviations. In general, the characterization of the influent wastewater reaching the plant indicates that it is comparable to medium-polluted municipal wastewater (Egea-Corbacho, 2019).

Some parameters (Chemical Oxygen Demand (COD), turbidity,

Conclusions

The study of tertiary treatment by nanofiltration for the removal of stimulants and antibiotics in a pilot plant was found to be both satisfactory and highly promising, achieving complete removal of the contaminants under study. Likewise, the viability of the nanofiltration in obtaining a permeate water with suitable quality to be put to all possible reuses has been demonstrated. These reuses may vary from residential or urban irrigation (e.g. irrigation of green areas or street cleaning),

Acknowledgments

We thank WWTP's technician of Medina Sidonia, Juan Carlos, for all his work and we also thank the Global Medina company for the facilities.

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