OBJECTIVE
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 these nutrient and remove pollutants by developing a compact closed microalgae photo-bioreactor (PBR) system. Our treatment system will be able to produce nutrient poor water, which is safe for discharge or further reuse.
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Pre-treated drain water (project 2) contains, besides nutrients (nitrogen and phosphorus) also some contaminants. Direct discharge into water bodies has to be avoided because it will lead to excessive algae growth or eutrophication of water bodies due to the high nutrient concentrations. The nutrients, together with the still remaining pollutants (heavy metals, micropollutants and pathogens), make the receiving waters unsuitable for animal and human use.
The Indian climate is very suitable for microalgae as there is plenty of sun for these microscopic plants to grow. Because algae grow very fast, they take up nutrients from water very efficiently making them an excellent water treatment platform. When the nutrients and pollutants are removed, nutrient poor water is produced which is suitable for safe discharge or reuse. The produced water is suitable for reuse in various agricultural, industrial and domestic settings. With additional treatment (project 1B) this water becomes suitable as a potable source of water.
As algae take up nutrients, they grow and thereby form algae biomass. By recovering this biomass, added value can be created. The biomass is rich in nutrients and can be used as fertilizer, energy or as resource for industry (e.g. bioplastics). This ‘renewable resource’ aspect of microalgae technology fits with the principals of the bio based economy/circular economy.
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RESEARCH
Micro-algae are ideal to recover nutrients and remove pollutants from drain water, especially in climates where light is in abundance. Research will focus on photo bioreactor design and the recovery of nutrients from the algae biomass. Specifically, the separation of algae from the treated water by self-sedimentation is investigated. In addition, the removal of pollutants by using naturally occurring algae from the drain and altering process conditions will be studied. Finally, the quality of the algal biomass in respect to pollutants will be determined.
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Microalgae are unicellular photosynthetic microorganisms. They fix almost 50% of global carbon emission and produce about 80% of the oxygen we breathe every day. Microalgae absorb sunlight and fix CO2 in aquatic media to convert photon energy into chemical energy. Besides light and CO2, microalgae need nutrients for growth, such as nitrogen and phosphorus. Both these nutrients are available in excess in drain water.
Fig. Microscopic Pictures of different microalgae species
Microalgae technology is ideal for wastewater treatment in warm temperate climates were warmth and light are in abundance. Algae technology results in higher nutrients assimilation efficiencies than other technologies. Additionally, microalgae photobioreactors are also efficient at removing persistent pharmaceuticals, such as diclofenac and carbamazepine, human pathogens and heavy metals.
To make this technology possible research is needed. The current bottlenecks for using microalgae technology for water treatment are the technology’s footprint, the light intensity needs and the energy intensive separation step of biomass and treated liquid. In this project, the research will focus on these aspects.
We will compare the PBRs performance efficiency of suspended microalgae versus self-sedimenting algal-bacterial community. We will research how native species perform in relation to lab species in terms of nutrient recovery and pollutants removal. By using natural occurring microalgae species and a more oxidizing growing environment in the closed PBR we expect to enhance the degradation of persistent pollutants. We will also evaluate the level of contamination of the algae biomass and its limitations for field application.
Initial algae treatment systems will be able to handle up to 100 litres per day. This initial design will serve as a test case for a 1000 litres per day pilot photo bioreactor system that is efficient in removing nutrients and pollutants while making biomass harvesting affordable.
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TECHNOLOGY
Micro algae can be seen as microscopic plants: They need the nutrients from the drain water, CO2 and light energy to grow. In our project the algae are cultivated in illuminated systems: photo bioreactors. Due to the flexible design of photo bioreactors they can achieve a small structures making it a perfect technology for dense urban environments. To make the algae technology economically viable, especially a cost effective biomass separation, the self sedimenting algae technology is further developed.
SOCIETAL RELEVANCE
Water treatment using micro algae contributes to safe water discharge in to water bodies and increases the availability of water intended for industrial or domestic usages. This leads to less pressure on the available potable water resources. Besides reusable water, the algae biomass can serve as a source of income as it can be used for various purposes. By sharing our knowledge with stakeholders, algae technology can be further developed and help in the water management of urban systems.
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Safe reuse of effluent
The microalgae water treatment system can deliver water that is safe to discharge in rivers. This will have an immense positive impact on the overall water quality of the receiving rivers. Because the produced water does not contain nutrients, it is also suitable for reuse in various industrial and domestic purposes. With proper additional treatment, even drinking water becomes an option.
Source of income
The recovered algae biomass can be used as fertiliser and other algae based components as pre-cursor for industrial processes. Algae biomass trade could become a local source of income.
Knowledge creation & dissemination
The developed knowledge could be used by various stakeholders and partners to further develop and implement the technology. In turn, this will contribute to a safe water supply and clean water bodies.
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FEATURES
The developed microalgae technology will be able to provide a compact and modular water treatment system. Our technology has to fulfil following features:
- production of water safe for discharge or suitable for reuse in agriculture, industry and for domestic purposes
- Develop a closed PBR that can be integrated in the urban environment
- Highly efficient nutrient removal and recovery
- Cost efficient algae separation
- Flexible: stand alone or combined with other technologies
COLLABORATION & PARTNERS
This project is a collaboration between the Indian and Dutch research institutes including the Indian Institute of Technology Delhi (IITD), Wageningen University (WUR) and Research and Netherlands Institute of Ecology (NIOO-KNAW).
Our contributing partners are:
- Heineken who supports us because water and water treatment are part of their key priorities in their ‘Brew a Better World’ campaign.
- Scholte Holding B.V. is an architecture office, and is interested in exploring the inclusion of microalgae technology, as well as the other proposed technologies in urban architecture.
All our partners can be found here.
