PROJECT DESCRIPTION
BACKGROUND
Anthropogenic pressures and climate change are responsible for severe variations in water availability and quality, and for the degradation of water sources by emerging contaminants that are of environmental-health concern because of their toxicity, mutagenicity and/or endocrine-disrupting behaviour. These include personal care products and pharmaceuticals; pesticides from agriculture; and cyanotoxins produced by toxic cyanobacterial (blue-green algal) blooms. Such emerging pollutants are dissolved organics, of intermediate-to-low molar mass, and commonly present in very low concentrations. As such, conventional wastewater treatment plants and processes do little to remove them.
OBJECTIVES
The objective of the LIFE Hymemb project was to demonstrate the feasibility and sustainability of advanced membrane processes for the treatment of drinking water, to provide a safer and more resilient barrier against emerging contaminants, with lower environmental impacts.
Specific objectives included developing an innovative hybrid process, using powdered activated carbon (PAC) and a low-pressure ceramic membrane (microfiltration - MF); conducting a two-year field test of a PAC/MF prototype; drafting guidelines on PAC/MF application based on several drinking water scenarios for safer water with a reduced carbon footprint (e.g. decreased chemical consumption and reduced sludge production); and carrying out a cost-benefit analysis of the process. LIFE Hymemb aimed to identify potential opportunities for using PAC/MF technology in drinking water treatment. The project was implemented under real-life conditions at Alcantarilha wastewater treatment plant (WTP) in Portugal.
RESULTS
The LIFE HyMemb project demonstrated an innovative, cost-efficient and highly transferrable powdered activated carbon (PAC)/microfiltration (MF) technology for treating drinking water. The prototype demonstration presented good operational results (high fluxes, high water recovery and long filtration time) and high water quality (in microbiological and physical-chemical parameters, including removed nearly all pharmaceuticals and pesticides), thus showing the huge potential of this technology for controlling emerging contaminants in drinking water.
To begin, the project team selected a representative list of 39 target contaminants (including 22 pharmaceuticals, 10 pesticides, 4 cyanotoxins, aerobic endospores, cyanotoxins, bacteriophages and natural organic matter). Then, the project selected activated carbons and prototype conditions through laboratory studies: 9 PACs were pre-selected for testing (4 for PAC/CFS (Coagulation/Flocculation/Sedimentation) and 5 for PAC/MF), while one PAC was selected for each application at pilot scale. This led to the design and assembly of the PAC/MF prototype which was tested for over 1.5 years at the Alcantarilha WTP, using water from four points of the WTP sequence (raw water, ozonated water, decanted water, and filtered water). The advanced PAC/MF process was benchmarked against the conventional treatment process, showing higher effectiveness and reliability for emerging contaminants (20% higher removal), turbidity, endospores (used as surrogates of chemically-resistant biological forms) and fine PAC particles, using similar doses of activated carbon.
In particular, the technology managed to remove up to 98% of pharmaceuticals, pesticides and microcystins (all spiked in the feed water, 1-20 ug/L), full removal of endospores and long-term stability in perme, full removal of protozoan cysts and long-term stability in permeate concentration. For low turbidity waters (≤ 5 NTU) of low and hydrophilic organic content (≤ 3 mgC/L Total Organic Carbon), Capital (CAPEX) and operating (OPEX) expenditures of 0.08 to 0.12 €/m3 were estimated for producing 100 000 m3/day of water by PAC/MF. These treatment costs were similar to the current state of the art technologies (conventional treatment with ozone pre-oxidation). PAC/MF energy consumption proved similar to the status-quo and significantly lower than when using nanofiltration.
Environmental benefits derive from improved water treatment plants contributing to consumer protection (drinking water quality), and to climate change adaptation (where poor raw water quality or fast and severe variations might be a reality). The new technology enables water treatment with lower environmental impacts (reduced carbon footprint, sludge production, lower reagent and energy consumption), and provides a sustainable solution for emerging contaminant control.
The project is associated with a range of socio-economic benefits. For instance, business opportunities may arise (e.g. the development of ceramic membranes), and the technology enables decentralised water treatment solutions with smaller distribution networks and cost savings. The project also raised public awareness about water consumption, water saving, water quality and treatment technologies.
In terms of policy and legislation, the project filled gaps in knowledge on the occurrence of pharmaceuticals and helped implement the Water Framework Directive (WFD, 2000/60/EC) and the Drinking Water Directive (98/83/EC) in the Algarve region of Portugal. Project results have also contributed to the implementation of the Environmental Quality Standards Directive (2013/39/EU) for the update of the “List of priority substances” and the “Watch List” monitoring mechanisms for emerging water pollutants. The project team produced Technical Guidelines for the use of PAC/MF to support water professionals, water and environment authorities, public administration and other stakeholders during technology transfer. The guidelines are particularly helpful in Portugal, where treatment membrane technology is quite insipient.
Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).
