Skip to main content

Demonstrating synergies in combined natural and engineered processes for water treatment systems

Periodic Reporting for period 2 - AquaNES (Demonstrating synergies in combined natural and engineered processes for water treatment systems)

Période du rapport: 2017-12-01 au 2019-05-31

The water sector is under increasing pressure to deliver improved and affordable water services whilst reducing the amount of energy used, lowering the environmental footprint of their activities and coping with climate change impacts. These challenges have prompted water professionals to revisit the role of catchment landscape features such as riverbanks, aquifers and wetlands in providing treatment and storage capacity.
AquaNES pursued the concept of integrating these nature-based elements into solutions for water management challenges, such as organic micropollutant (OMP) removal, microbial safety of drinking water, or water resources protection and augmentation. The established combined natural and engineered processes (cNES) included managed aquifer recharge (MAR), constructed wetlands (CW) and bank filtration (BF), and their combinations with engineered pre- or post-treatments to produce water for various purposes from a range of water sources (Fig. 1.)
The overall project objective was to catalyse innovations in water treatment and management and to increase the confidence with which utilities may chose cNES. In particular we aspired
–to demonstrate the feasibility and benefits of post-treatment options such as membranes, activated carbon and ozonation after BF for the production of safe drinking water
–to validate the treatment and storage capacity of soil-aquifer systems in combination with oxidative pre-treatments
–to demonstrate the combination of CW with different technical post- or pre-treatment options (ozone or bioreactor systems) as a wastewater treatment option
–to evidence reductions in operating costs and energy use
–to test a risk assessment (RA) framework
–to deliver design guidance
–to identify market opportunities
The project delivered a series of comprehensively field-tested cNES. We demonstrated their technical and environmental performance. Most of the tested combinations achieved quality targets for the envisaged treatment purpose. We found them suitable to future-prove long-existing bank filtration sites and to contribute to OMP removal in a more extensive way, with lower impacts than benchmark technologies.
AquaNES demonstrated and assessed various cNES in 13 sites in Europe, India and Israel. The technical set-ups (Fig. 2) were operated and monitored for 12 to 24 months. The involved companies and utilities gained comprehensive datasets and insights into long-term operation and cost implications. They collected valuable experiences and consolidated the basis for considering and promoting cNES as options in their product portfolio or investment programs.
Towards a more resilient drinking water production by BF we found bank filtrate a suitable feed for membranes with reduced cost compared to surface water use (lower energy and chemicals use). Nanofiltration of anoxic bank filtrate proved feasible and can be recommended for partial flow treatment containing specific contamination, e.g. sulfate or certain OMPs. The use of ultrafiltration for full-stream treatment seems a viable option for bank filtrate with short travel times or in case of space limitations. Recommendations for operators (D1.6) summarise these experiences and are complemented by a structured approach for RA and decision support for BF design & operation (D1.4). An Excel-based tool supports the design of energy-saving siphon wells (D1.3&D1.5). A guide towards their application is provided in the AquaNES DSS (D6.4).
The effectiveness and robustness of a solar-powered in-situ electro-chlorination system for disinfection of bank filtrate was demonstrated in two Indian sites. The SME concerned will promote and commercialise this concept worldwide with first replication cases already realised in Africa.
On OMP abatement, the oxidative processes were effective when treating surface water and WWTP effluent respectively before soil infiltration. In wastewater treatment, CW performed similar to technical filtration systems in post-treating ozonated effluent. Knowledge derived from these sites enabled the concerned utilities and companies
–to optimise ozonation using a closed-loop control
–to specify the design of a full-scale ozonation plant to be built in the next 3 years
–to develop new treatment trains for drinking water production or indirect potable reuse in the European and U.S. market, with e.g. the UV/H2O2 process as barrier against OMP with no bromate formation issues
The Retention Soil Filterplus to flexibly treat combined sewer overflow or WWTP effluent was implemented in full-scale supported by the project results on OMP, nutrient and microbial removal. The utility will further promote the treatment concept within the German and international water sector with future results from long-term testing.
For another demosite we developed a tailored ICT tool for optimised operation of a MAR scheme. It facilitates the integrated monitoring, modelling and control of the system in dependence of environmental factors: groundwater levels, groundwater quality, infiltration rate. (D2.3&D2.4). The exploiting company will further collaborate with the local stakeholders towards a long-term implementation, and acquisition of follow-up projects.
Next to treatment solutions, AquaNES developed tools and methods to assist planners, utilities and authorities in assessing cNES more comprehensively.
AquaNES results were shared with the scientific and end-user community on conferences and workshops. Consortium partners presented project output in 42 talks at 27 different events and exhibited 17 posters at 9 events. 19 peer-reviewed publications emerged from the work. We organised two stakeholder workshops and a final dissemination event to discuss the project results with practitioners, policy and the public.
Reliable and sustainable water services are vital for human and societal well-being. Nature-based solutions have been recognised as sustainable measures meeting environmental and socio-economic objectives as well as increasing the flexibility of water services. Our demonstration activities increased the Technology Readiness Level of several process combinations, typically from 5/6 to 7/8. This allows commercial partners to exploit the cases as reference systems for further market uptake.
AquaNES demonstrated efficient solutions supporting water policy objectives and water legislation implementation.
On the debate on OMP removal in both, drinking water and wastewater treatment, we found viable options to optimise and complement technical processes (D3.2 D2.1) with natural treatment steps.
The project highlighted the potential of nature-based solutions or cNES to close the implementation gap of wastewater treatment solutions for agglomerations <2000 pe. Additionally, it revealed the need for expertise on design and operation, to which the adapted design guidelines for CW based systems in combination with engineered treatment steps (D3.3) contribute.
We further informed the EU strategy on water reuse by comparing the performance of the demonstrated constructed wetlands with limit values of national/EU reuse legislation (D3.1). This demonstrated the impact of chosen monitoring parameters and procedures on compliance with set standards, which is relevant when implementing minimum quality requirements for water reuse. An online quantitative microbial risk assessment tool (D4.4) is at hand to support the development and implementation of Water Reuse Safety Plans
Figure 1 Concept and scope of the AquaNES project
Figure 2 AquaNES technology portfolio