Our dedication to continuous research and development

Water is our most precious resource and yet scarce and polluted in a lot of places around the world. We believe that urban wastewater streams can be used as a resource. The lotus project aims to develop a universal water management and risk assessment plan that is applicable for megacities all around the world.



Recycling and reuse of water is important for managing water resources sustainably. Our aim is to develop socially acceptable water reuse framework and implementation strategies. To fulfil our aim, it is important to understand water reuse perceptions of key stakeholders and institutional boundaries, as these influence acceptability and uptake of water reuse and new technologies associated with it.

Scientific background

In our research, we use the Ajzen’s Theory of Planned Behaviour and the Analytic Hierarchy Process to assess major factors influencing people’s decision to accept or reject water reuse. Primary information for this analysis will be collected through interviews with local stakeholders such as governmental agencies, local businesses and a sample of the residents of New Delhi within a vicinity of the project treatment plant.



The quality of the in LOTUSHR produced waters is the key aspect: it dictates the purpose for which the water can be reused safely. Our aim is to develop quality guidelines and advanced water treatment steps for the healthy reuse of the water produced within the LOTUSHR project. By relating the health risks of the produced water qualities to the quality needed for different reuse purposes, a treatment scheme can be formulated that ensures safe reusable water. 

Scientific background

The urban waste streams contain different contaminants such as organics, nutrients, heavy metals, pathogens and micro pollutants (antibiotics, hormones, pesticides etc.). In our research we use different target contaminants to monitor their survival and behaviour in LOTUSHR technologies. This information on how water is reused, will be used in Health Impact Assessments. The development of additional treatments steps will ensure that water quality matches with its intended use. These steps are based on advanced oxidation, membrane technology or UV based systems.



For reliable water reuse, organic material has to be removed from the wastewater. Our aim is to develop a stable and robust process for the removal of organic material and its conversion into biogas. This system will ensure superior effluent quality which is suitable for additional treatment. Anaerobic treatment would be used. Solids separation from the treated wastewater will be done either by membrane filtration (as part of Anaerobic Membrane Bio Reactor (AnMBR) technology) or by dissolved air flotation (DAF).        

Scientific background

For the removal of organic material, the basis is formed by anaerobic technology. In these systems bacteria grow on in the absence of oxygen and break down the organic material from the incoming wastewater and convert parts of it into biogas. By filtering the bacterial slurry, or sludge using the membrane modules, the slurry can be separated from the water. The anaerobic system can also be combined with dissolved air flotation (DAF) technology. This system uses gas bubbles to separate water and particles. Particles stick to the bubbles and rise up, effectively separating them from the now clear water.

The anaerobic treatment produces sludge and biogas. Both these products can be used as resources. The energy in and heat from biogas can be recovered with high efficiency using solid oxide fuel cells (SOFC). The sludge can be utilised to manufacture activated carbon and as a partial replacement for clay in bricks and tiles suitable for construction purposes. 



To be able to produce safe reusable water, pollutants have to be removed from the pre-treated drain water. Our aim is to develop the compact, robust and nature-based Vital Urban Filters (VUFs). This water treatment system is able to produce safe reusable, nutrient rich water for agricultural purposes while having an added social and economic value through the growing of plants.

Scientific background

The Vital Urban Filters are based on the principle of conventional vertical flow constructed wetland that are commonly used in decentralised wastewater management. The filter consists of a flat bed of hydroponic filter material planted with ornamental plants. The filter materials are highly porous providing a high surface area for biomass. As the influent percolates through the filter, heavy metals, pathogens and micropollutants are removed through the interaction of the plants, filter materials and bacteria.



Before pre-treated drain water can be discharged in rivers or used for more quality demanding usages, nutrients and pollutants have to be removed. Our aim is to recover the nutrient and remove pollutants by developing a compact microalgae photo bioreactor (PBR) system. Our treatment system will be able to produce nutrient poor water which is safe for discharge or further reuse.

Scientific background: technology

Microalgae are unicellular photosynthetic microorganisms that use light energy, CO2 and nutrients, mainly nitrogen and phosphate, to grow. Algae treatment is a straightforward process, by growing algae on the drain water, the nutrients are taken up and effectively removed from the water by the algae. Algae are grown in photo bioreactors that offers optimal process conditions. The main drawback of algae technology is the lack of a cost effective method of algae biomass separation. By steering process conditions to grow algae in small granules (agglomeration of algae in to a small clumps), the algae can separate themselves from the water simply by using gravity. The biomass can be used as fertiliser or as precursor for various industrial processes.

Illustrations: Projekt C| Text: Steef de Valk & Maaike Spuij | Logo: Annemarie van Aken
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