Group of Environmental Biotechnology

Universidade de Santiago de Compostela

Universidade de Santiago de Compostela Campus Vida Cretus

Group of Environmental Biotechnology

Universidade de Santiago de Compostela

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1.1.1 Removal of organic micropollutants (OMPs) from wastewater

Pharmaceutical and Personal Care Products (PPCPs) constitute a wide group of chemicals comprising human and veterinary medicines, hormones and cosmetic ingredients. Special attention should be paid to these biological active substances due to the possible adverse effects that these compounds could exert on aquatic organisms living in environmental compartments affected by their discharges (rivers, lakes, groundwater, etc.).

This research line arose mainly upon the participation of the group in the European Project POSEIDON, in the frame of which the first measurements of these compounds in a STP were performed, physico-chemical treatment units present in conventional STPs (flotation, coagulation-flocculation) were optimized, and the anaerobic digestion of sewage sludge from the primary and secondary settlers of these STP was evaluated. In the following projects (FARMEDAR 2004-2007; HOSPEDAR 2003-2005; CHUSEDAR 2005-2006; MICROFARM 2007-2010) more detailed studies on the occurrence of PPCPs in municipal and hospital wastewater were performed and diverse technologies for biological wastewater treatment (conventional activated sludge, membrane reactors, hybrid reactors) were evaluated, including also advanced postreatment technologies (ozonation, activated carbon). These works have been complemented with biomass characterization assays, including the determination of PPCP biodegradability under different ambient conditions (aerobic, anoxic, anaerobic).


Analysis of antibiotic resistance and antibiotic biotransformation in innovative plant layouts promoting recovery of carbon in the mainstream and sludge line (ANTARES)
Spanish Government. Co-funded by FEDER (UE). (PID2019-110346RB-C21). (October 2020 / October2023)

Joint PhD Laboratory for New Materials and Inventive Water Treatment Technologies (NOWELTIES)
European Commission. Horizon 2020 Programme. (EU project 812880, MSCA-ITN-EJD). (January 2019 / December 2022)

Completed Projects

(CO)METabolic biotransformations in low environmental footprint wastewater Treatment reactors, targeting organic micropollutants (COMETT)feder_color_2_0.png
Spanish Government. Co-funded by FEDER (UE). (CTQ2016-80847-R). (Dec 2016 / Dec 2019)

The proposal is focused on the development of low environmental footprint technologies, in terms of space, energy consumption and low sludge generation,for the treatment of municipal wastewaters in temperate regions, aiming at the minimization of Greenhouse Gases emissions (GHGs) such as CO2 , Methane and Nitrous Oxide, the removal of organic micropollutants (MPs), such as Pharmaceutical and personal care Products,and to determine the fate of nanopollutants(NPs) present in wastewaters, such as metal oxides, which are increasingly used by our society. An additional objective of the project will be to assess that effluents meet water quality requirements for reuse, in terms of chemical, physical and bacterial indicators.

The process to be studied includes an Anaerobic methanogenic reactor for the removal of a large fraction of the Biological Oxygen Demand (BOD) followed by a second moving bed Anoxic chamber in which dissolved methane, present in the effluent of the first methanogenic reactor, is used as the carbon source for denitrification, and a third Aerobic chamber for nitrification. For the third unit two options are considered: A Membrane Bioreactor Integrated System and an Activated Sludge Integrated System.

The proposal is based on the results obtained by the team in a previous project in which it has been proved the removal of 80 % of the dissolved methane and a denitrification of 15-20 mg/L, results still far from the expected from stoichiometric considerations.

Under the scientific point of view an important scientific issue of this project will be the use of dissolved methane as carbon source for denitrification, encouraging the growth of a newly discovered denitrifying methanotroph, Methylomirabilis oxifera, belonging to the NC10 phylum. Also the mechanisms for micropollutants removal, mainly the fate of co-metabolism, will be considered.

An especial attention will be paid to the environmental management including Life Cycle Assessment and Environmental Risk Assessmentin order to evaluate the environmental performance. Moreover, an economic evaluation of the developed technologies will be conducted through a Cost-Benefits Analysis methodology.

The proposal is presented by a team with a solid experience in all topics related with the proposal: anaerobic processes, membrane bioreactors,micropollutants removal, environmental, risk and economic assessment. Stakeholders (a Water Authority and a Company) support the project.

The proposals fits well with the objectives of the Spanish Program of Research, Development and Innovation Oriented to the Societal Challenges, focussing on the solution of problems outlined in challenge 5 about actions on climate change and efficiency in the use of resources and raw materials, as the sustainable use of hydric resources (promoting its reuse) and the minimization of persistant organic pollutants (MPs and NPs) and GHGs emissions.

Legislation establishes that all urban agglomerations, regardless of their size, must efficiently treat their wastewaters, which will result in a rapid increase in the volume of sludge produced. The sustainable management of this waste sludge should meet the requirements of efficient recycling of resources, without posing a danger to the environment and humans. The anaerobic digestion and agricultural use are the most applied models of sewage sludge treatment and management, respectively, in Spain and Galicia. In the last decade, there is a growing concern derived from the presence of organic micropollutants (MCOs) such as pharmaceutical compounds, personal care products, hormones and other endocrine disruptors in the environment including surface water, groundwater, sediments, soils, etc. Although there is still no conclusive information about the ecotoxicological impact of these substances, it is known that the conventional technologies installed in Sewage Treatment Plants (STPs) are not effective enough to complete their removal. Therefore, the main objective of this project is to improve the removal efficiency of MCOs during the treatment of sewage sludge by anaerobic (co-)digestion in order to reduce their emission into the environment through the application of treated sludge in agriculture. For this purpose, a more detailed knowledge about the mechanisms responsible for the removal of MCOs in this process and the factors affecting this removal is required. So, the first part of this project (2 years) focuses on the detailed study of the degradation of MCOs in anaerobic conditions at different temperatures and with different co-substrates, determining the degradation kinetic constants in the different stages of the anaerobic process (hydrolysis-acidogenesis, acetogenesis and methanogenesis) and identifying which enzyme(s) produced by anaerobic biomass are responsible of MCOs removal. In the second part of the project (last year), all the knowledge acquired in the first stage to improve the removal of MCOs during the anaerobic (co-)digestion of sewage sludge will be applied by assessing two sequences of operation in pilot reactors. The conclusions derived from this project are very important to have a complete picture of MCOs fate in STPs, as the sludge line is usually not taken too much into account, and they will also anticipate the stricter requirements of the regulations about the quality of treated sludge for later use in agriculture.

Wastewater treatment is considered as an economic burden on an industrialist, especially for small and medium scale enterprises (SMEs) rather than as a business opportunity. This proposal aims to develop energy efficient, cost effective and natural effluent treatment process package for industrial effluents from SMEs and domestic sewage, which would make this operation a profitable venture through recovery of resources and reclaiming renovated water for reuse. The approach is based on biogas recovery through high rate anaerobic digestion system that is applicable in both hot and cold climates. Targeting treatment and recovery of resources from low strength effluent is challenging. Hence an integrated approach for anaerobic treatment would be taken up through combination of various modules/options of treating post digested effluents.

The treatment of digested effluent would be evaluated through three different options, namely, a natural wetlands system for removal of residual COD, nutrients, solids and pathogens, a co-culture system of methane oxidizing bacteria and microalgae (‘Methalgae’) for utilization of dissolved methane and a biological filtration/adsorption system for removal of micropollutants. The treatment of post digested effluents would be carried out for recovering biomass and renovated water through removal of nutrients, recalcitrant compounds, micropollutants and pathogens.

The presence of a wide group of organic micropollutants in different water bodies has been evidenced by an important number of recent publications, being the potential adverse effects on the biota exposed to them outlined in several studies. Most efforts carried out when studying the fate and behaviour of such compounds during wastewater treatment have focussed on the determination of the overall removal efficiencies achieved in activated sludge and to a less extend in membrane bioreactors working under different operational conditions. An overview of these works evidences that some compounds are very persistent (e.g. carbamazepine), others are removed to a high degree (e.g. ibuprofen) and for a wide number of substances the removal efficiencies reported vary in a wide range (e.g. diclofenac). In order to understand the different efficiencies achieved depending on the research considered, a deeper knowledge on the factors affecting their removal, including the main operational parameters and mechanistic aspects, as well as the different removal mechanisms involved (sorption, volatilization, biodegradation, etc.), is required. The aim of this proposal is to study the removal of micropollutants when innovative technologies are implemented for sewage treatment, that have not been considered previously. All experiments will be carried out at pilot-scale including a Membrane Modified UCT process, an Anaerobic Hybrid Membrane Biological Reactor, a Granular biomass based Sequencing Batch Reactor, a Sharon-Anammox reactor and a Nitrifying Membrane Biological Reactor. The effect of the different types of biomass responsible for the biodegradation of micropollutants in these reactors, which differ in its conformation, bacterial population, sludge age and environmental conditions (redox and temperature), will be assessed in specifically designed lab-scale experiments. In order to have complete information on the operation of these systems, conventional parameters (organic matter, nutrients, pH, etc.), micropollutant concentrations, biomass characteristics (physic-chemical, metabolic, enzymatic, microbiological) and sorption constants will be regularly followed in both, pilot and lab scale reactors. Since the final goal of this project is to propose an optimal treatment strategy for the removal of micropollutants, which is a decision that should not only be based on the minimal discharge of such compounds, a task about environmental impact has been included in the proposal. The objective of it is to perform ecotoxicology assays on the effluents from the different reactors and to determine the overall environmental impact associated to the discharge of these compounds on the basis of Life Cycle Analysis. A multi-criteria understanding task will allow to integrate and analyse the whole set of data (technological, mechanistic and environmental) to identify the best available treatment option.

Sewage treatment plants were conceived for the reduction of organic matter and nutrients, being the removal of PPCPs not considered in the design. Due to this fact, a vast number of these compounds are not completely removed, being a significant fraction of them continuously discharged to the environment. The main aim of this project is the establishment of a strategy that allows and improved removal of PPCPs in STPs, by determining the optimal operational conditions of existing plants or by modifying the current technologies. The project is supported by Administrations and companies (Augas de Galicia, Adantia, Aguas del Norte, Aquagest, Aqualia Galicia, Asturagua, Espina & Delfin, Gestión de Aguas de Aragón and Labaqua), which allows an effective transfer of results.

The objective of this proposal is the study of the removal of Pharmaceutical and Personal Care Products (PPCPs) present in urban wastewaters by using two pilot plants based on Membrane Biological Reactors (MBR): a) a sequential aerobic-anoxic reactor (SMBR) and b) a hybrid reactor (HMBR). Both plants will be operated with municipal wastewaters maintaining a level of PPCPs around 10 μg/l (ppb) (except for hormones, that will be around 10 ng/l). A group of 16 PPCPs considered as representative has been selected. The selection of these substances has been based on three items: i) social perception of its potential risk; ii) they belong to different therapeutic groups widely used and, iii) there is reliable analytical methodology to perform their determination. Thus, selected PPCPs correspond to the following groups: fragrances, antiinflammatories, antibiotics, antiepileptics, tranquilizers, antidepressants, antiseptics and hormones. The removal efficiency for each substance will be assessed in each pilot plant, as a function of the operating conditions (type of membrane, hydraulic and cellular residence time, time distribution of aerobic and anoxic phases, etc.). The sludges developed in each stage of operation will be used to perform biodegradability tests in continuous lab-scale reactors to determine the elimination of each PPCP under different environments (aerobic and anoxic). Moreover, postreatment of the effluents obtained in each membrane pilot plant will be carried out by using pilot-scale ozonation and activated carbon units.