Providing adequate water supply and sanitation, particularly in urban areas, is a challenging task for governments throughout the world. This task is made even more difficult due to predicted dramatic global changes. Population growth, urbanisation, increasing industrialisation, climate change and a steep increase in water consumption are putting pressure on urban water resources.
In order to cope with water shortages in urban areas, there is a need for a paradigm shift from conventional end-of-pipe water management to an integrated approach. This integrated approach should include several actions such as: (i) interventions over the entire urban water cycle (considering wastewater and freshwater both as integrated part of water resources in general); (ii) optimisation of water use by reusing wastewater and preventing pollution of freshwater source; (iii) prioritisation of small-scale natural and technical systems, which are flexible, cost-effective and require low operation and maintenance.
Natural water systems, such as manmade wetlands and sub-soil filtration and storage via soil aquifer treatment and bank filtration, are such systems. In addition, compact technical systems such as SBRs and MBRs have made a great development step in the last years. Moreover, they can absorb highly and widely varying pollution loads; buffer seasonal fluctuations in the availability of water; and they can be integrated into the urban planning as green infrastructures providing additional socio-economic benefits such as amenity.
In Europe, those systems have been developed for many years and their potential for the application in developing and newly-industrialised countries is widely accepted. However, the location of India and many developing and newly industrialised countries in warmer climatic zones sets different environmental conditions.
Taking these facts into account the project NaWaTech aims at maximising the exploitation of natural and compact technical systems and processes for the effective management of municipal water resources, of water supply and sanitation services, and of the municipal water cycle as a whole in urbanised areas of India. On the basis of a detailed inventory of natural and technical treatment systems, the European and India consortia have identified several promising axes:
· Wastewater and storm water treatment and reuse for the managed aquifer recharge (MAR) (constructed wetland; SBRs & MBRs, soil aquifer treatment and aquifer storage and recovery);
· Stimulation of water retention and self-purification capacity of water resource via in-stream remediation using eco-hydrology principles
·Improvement of surface water quality via bank filtration (lake or river bank filtration) for the generation (indirect) potable water
· Secondary treatments for drinking water (sand filtration; membrane filtration; UV disinfection)
Strategic objectives of NaWaTech:
1. To assess the technical, financial and environmental potential of natural water treatment technologies to cope with water shortages in urbanized areas in India.
2. To enhance the natural water treatment systems for the production of recycled water to supplement water sources considering extreme climatic conditions and highly & widely varying pollutions loads (e.g. monsoon floods).
3. To disseminate, exploit, and ensure the take-up in practice and mainstreaming of NaWaTech activities and output by key stakeholders (e.g. end-users, SMEs and service providers, decision makers). Develop technical guidelines, tools, and manuals for design, implementation and operation and maintenance as well as policy briefs.
4. To ensure the interest and potential benefit to SMEs by supporting the development of a local market of natural water treatment and storage technologies, and facilitating the local SMEs by organizing training and capacity building workshops. Ensure the participation of local SMEs in the implementation phase of the project itself (learning by doing).
5. To create an enabling institutional environment in order to allow the take-up in practice and mainstreaming of the results (e.g. align NaWaTech initiatives with existing urban water plans, strategies and policies).
6. To establish foundations of a long-term cooperation between EU and India in water technologies as part of the Strategic Forum for International Science and Technology Cooperation (SFIC) and establishing bridgeheads among research institutions and ensure the take up of the NaWaTech approach in educational curricula).
The scientific objectives are:
(A)Pre-treatments of high-strength wastewaters (i.e. blackwater) prior to constructed wetlands (e.g. UASB):
-To achieve suspended solid removals by applying low rate anaerobic digestors.
-To couple constructed wetlands with sludge digesters in a compact design, with simple O&M requirements and increased lifespan.
(B) Constructed wetlands (CW) to improve the quality of different urban water sources (i.e. blackwater, greywater, rainwater and stormwater); potential coupling with soil aquifer treatment (e.g. infiltration ponds); the potential of root zone treatment for the improvement of surface water quality prior to bank filtration.
-To improve the performance of CWs, by predicting, preventing and delaying the clogging process.
-To optimize space requirements of constructed wetlands for the Indian context.
-To study and control the effects on salinity raise due to high evapotranspiration.
-To understand the influence of shading of wetland plants on treatment performance of the CW and to propose innovative methods to control the breeding of mosquitoes and other vectors of human diseases.
-To define the potential of producing high-value energy crops in constructed wetlands, considering the treatment performance, the environmental, social and economic implications.
-To couple constructed wetlands and managed aquifer recharge technologies, minimizing the risk for pollution through a multibarrier system.
(C)Soil filtration capacity via soil aquifer treatment (SAT) or Bank Filtration (BF) for the generation of (indirect) water sources; potential combination for the coupling with other natural water treatment systems for the improvement of the overall quality.
For soil aquifer treatment (SAT):
-To identify the Indian-specific physical, chemical, biological parameters controlling the removal performance, to better understand the process, facilitating the design and implementation.
-To study the removal of trace organic compounds.
-To measure and control the risk of microbiological contamination, relevant for drinking water production.
-To predict hydraulic retention times and removal efficiencies, as well as distance from treatment facility to point of abstraction (and flow velocity) through numerical modeling.
For Bank filtration (BF):
-To assess the effect of temperature and oxygen conditions in the soil (removal performance for suspended solids, microbial contamination, trace organic substances such herbicides or drugs and geogenic heavy metals).
- To predict hydraulic retention times and removal efficiencies, as well as distance from treatment facility to point of abstraction (and flow velocity) through numerical modeling.
(D)Compact technical treatment solutions adapted to high loads especially in urban areas such as MBR and SBR systems.
-To develop a system for simplified control for SBR.
-To develop a low energy aeration system for aerobic SBR and MBR adapted to the Indian conditions.
-To test anaerobic MBR systems under the Indian conditions.
-To optimize the combination of SBR and MBR (SMBR) into a robust system to cope with the needs of the Indian urban population.
(E)Potential post-treatment units (e.g. sand filtration, membrane filtration or UV-disinfection).
-To develop and test a simplified sand filtration system (slow/rapid filtration), requiring low-energy input and low operation and maintenance.
-To test the applicability of low pressure membrane filtration systems in the Indian context, particularly the operation and maintenance.
-To optimize an UV-disinfection or chlorination process for further polishing of the water.
Further scientific objectives to be achieved during the field research step at the NaWaTech in India are:
-To determine the economic, social, financial and environmental sustainability of the NaWaTech sites.
-To develop an operation and monitoring scheme that is technically viable and cost-effective for the application of NaWaTech approaches in urbanized areas of India.
-To ensure the sustainability of the NaWatech sites beyond the project duration, considering technical, financial, environmental and institutional aspects.
It is anticipated that these projects will produce knowledge, technologies, guidelines and tools for implementation and operation, skilled service providers and SMEs, research partnerships and enabled institutional environments for the application of natural water treatment systems to cope with water shortages in urban areas of India. Besides the scientific enhancement, an important component of the projects is that it brings together all the involved or stakeholders in urban water management. These multi-stakeholder learning alliances will be institutionalised in the NaWaTech community of practice (CoP) in order to achieve an impact beyond the project on the implementation of research and dissemination activities, by taking account of local problems and needs. Clearly, this will substantially contribute to a reduction in the vulnerability of Indian cities and their capacity to cope with water shortages.