Nature-Based Solutions for Water Treatment
by Rami Elias Kremesti M.Sc., CSci, CEnv, CWEM
Introduction
The global demand for water has been increasing at a rate of about 1% per year over the past decades as a function of population growth, economic development and changing consumption patterns, among other factors, and it will continue to grow significantly over the foreseeable future. Industrial and domestic demand for water will increase much faster than agricultural demand, although agriculture will remain the largest user overall. The vast majority of the growth in demand for water will occur in countries with developing or emerging economies. At the same time, the global water cycle is intensifying due to climate change, with wetter regions generally becoming wetter and drier regions becoming even drier. Other global trends (e.x., urbanisation, de‐forestation, intensification of agriculture) add to these challenges.
UNDP NBS
The United Nations World Water Development Report, Nature-based Solutions for Water, launched 19 March 2018 during the 8th World Water Forum, and in conjunction to the World Water Day, demonstrates how nature‐based solutions (NBS) offer a vital means of moving beyond business‐as‐usual to address many of the world’s water challenges while simultaneously delivering additional benefits vital to all aspects of sustainable development.
NBS use or mimic natural processes to enhance water availability (e.g., soil moisture retention, groundwater recharge), improve water quality (e.g., natural and constructed wetlands, riparian buffer strips), and reduce risks associated with water‐related disasters and climate change (e.g., floodplain restoration, green roofs).
Current Water Treatment Engineering Practices
Currently, water management remains heavily dominated by traditional, human‐built (i.e. ‘grey’ concrete based) infrastructure and the enormous potential for NBS remains under‐utilized. NBS include green infrastructure that can substitute, augment or work in parallel with grey infrastructure in a cost‐effective manner. The goal is to find the most appropriate blend of green and grey investments to maximize benefits and system efficiency while minimizing costs and trade‐offs.
9 Different NBS
1. Sustainable drainage systems (SuDS)
SuDS are an actionable way to tick multiple sustainability boxes, and are more than a means to solve drainage issues or improve flood risk management alone.
Within the concept of ‘Sponge Cities’ and the development of blue-green infrastructure in urban areas, SuDS in simple terms collect water and filter it slowly, lowering and delaying flow rates, into the ground, rivers or the sewerage system. While doing so they can improve water quality, promote biodiversity, reduce urban heat island effect, and increase the resilience of the built environment, to name just some of the typical associated benefits.
A wide range of SuDS exist, for example attenuation basins, swales, permeable pavements, soakaways, rain gardens, filter strips, and green roofs; appropriate SuDS solutions need to reflect the local context and built environment, manage constraints and maximise opportunities.
In 2024, SuDS are expected to become mandatory for new developments in England. And the now looming implementation of Schedule 3 of the Flood and Water Management Act in England means that lead local flood authorities will need to approve and adopt SuDS for which they often have no skills or finances, which makes it an imperative to enrol the help of partners with a ‘systems thinking’ approach
2. River restoration and remediation
Unsuitable engineering solutions can negatively impact on flood risk and the morphological processes of a river. This in turn and unsurprisingly, might harm habitats and biodiversity, water quality and the riparian and aquatic environment.
Giving space back to water e.g. unculverting, re-meandering, protecting and enhancing floodplain storage capacity and wetlands etc – is essential if we are to meaningfully integrate climate adaptation and biodiversity enhancement within infrastructure and development planning – both in terms of engineering and management. Applying river restoration techniques and integrate natural banks protection where feasible should also be uppermost in design.
3. Natural flood management
Identifying and enhancing natural processes at catchment level to control flood waters and ‘slow the flow’ is the most sustainable solution to manage the effects of urbanisation and development, and provides a wide range of benefits beyond simple flood risk management.
For long-term resilience, we should aim for sustainable land management with permeability at its core, protecting and enhancing the space for water also through sustainable development planning (e.g. Sequential Test). Achieving this goal requires an integrated approach, informed by a wide range of specialists and stakeholders, in line with the various points discussed in these pages.
4. Biodiversity net gain (BNG)
BNG is becoming a critical as part of any meaningful EIA, with a view to promoting rivers, streams, deltas amongst other, habitats – and there is a requirement for all developments to achieve +10% net gain in biodiversity compared to their pre-development baseline. It is therefore critical to enlist the support of hydrologists, geo-morphologists and ecologists to carry out River Condition Assessments, and more critically, to inform the design of river habitat improvements.
5. Water neutrality
The idea of water neutrality is to ensure developments and operations do not increase pressure on water resources. Last year – ultimately recognising the importance of their water footprint, Natural England put a moratorium to new developments in the Sussex North Water Resource Zone, with a challenge to prove that it would not cause increased pressure on water resources. This has stopped several local plans and raised concern about potential solutions amongst developers – a situation likely to be mirrored elsewhere as the importance of water resilience becomes more of a key issue.
Water neutrality requires water efficiency, reuse (rainwater harvesting, grey water recycling, seawater flushing, dry urinals) and offsetting and at KEC we see a great opportunity for an holistic approach which promotes water quality protection (e.g. wetlands, groundwater recharge) and re-use, where feasible, integrating surface water flood risk management and storage (e.g. basin full when needed for consumption, empty when needed for flood storage).
6. Improve land management
How land is managed will have a major impact on water design, and with the right monitoring, reporting and verification of solutions also offers an opportunity for biodiversity net gain.
Improved land management practices might include choosing sustainable methods of farming versus industrial approaches (for example agroecology or agroforestry) using cover crops to increase soil carbon content and promoting soil health by lessening the amount of chemical fertilisers applied.
7. Eco coastal and marine design
Using natural solutions for flood and coastal management specifically can support localised economic growth through safeguarding fishing, tourism and raw materials industries. Natural flood protection, wave dampening and storm water runoff reduction can also mitigate the risk of erosion, pollution and natural habitat loss which in turn protects biodiversity as well as infrastructure.
8. Reed Beds and Wetlands
Reed Beds and Wetlands are wonderful NBS that can help filter SS, heavy metals, remove N and P and increase BNG. Plants love N and P as do soil bacteria.
9. Using Fish to Control Algae
The olympic rowing canal in Plovdiv, Bulgaria where I spend my summer vacations is used by professional rowers and canoe enthusiasts. The canal, which is 2 Km long is filled from the Maritsa river and empties back into it. In order to control algae, certain algae eating fish species are kept in the canal and they do a wonderful job at keeping algae under control.
10. Using Phyto-Plankton Iron Seeding to Capture CO2 in the Oceans
I digress from the subject of water treatment here, but I cannot help mentioning another potential NBS for CO2 capture to fight climate change:
Ocean Iron Fertilization is one of the ocean engineering solutions being researched to capture atmospheric CO2. The great Southern Ocean has expanses that have N and P but iron is a limiting nutrient for phytoplankton. Researchers are looking into seeding the southern ocean with Iron to boost algae/phytoplankton to capture atmospheric CO2. If Zooplankton are also boosted then, fish stocks will boom and we all know that large fish like whales, capture CO2 in their bodies when they die and sink to the bottom of the ocean.
Click here to read our article on OIF in CIWEM.
Conclusion
New developers need to design modern cities and villages as embedded in nature. Nature preservation must become part of the circular economy and the fabric of modern living.
References
https://www.undp.org/publications/nature-based-solutions-water
9 Nature-based solutions that could transform the water sector landscape
Integrating nature-based solutions into wastewater treatment
About the Author
Rami Elias Kremesti is a passionate environmentalist and water treatment specialist. He holds an M.Sc. degree in chemistry from the USA and has worked in the water treatment field for over 20 years. He enjoys his line of work and is constantly learning new things about nature, water and human beings.
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