Details

Category: 
Student subject
Function: 
Student (University)
Department: 
Aquatic Ecology
METS
Contact: 
Tania Fernandes
Closing date: 
Monday 31 December 2018

Welcome to the world where waste no longer exists. In this new world, waste is converted into resources that can be reused. This is the world where we have learned from Nature how to live in a cyclic natural balance, just like all other species: the waste of one is the resource of the other.

In this new world we have realized that current wastewater treatment systems do not fulfil the ideology of waste being a resource, as they aim at removal not recovery. We therefore need to rethink the toilet, stop flushing our toilets with drinking water and provide the right technologies to recover all the riches present in our wastewater.

Introduction


Fig 1. Black water treatment scheme proposed by
NIOO-KNAW (Vasconcelos Fernandes et al., 2015)

New sanitation concepts where black water (BW - toilet wastewater) and grey water (GW - shower/washing wastewater) are separated at source, conserve organic and inorganic compounds in a smaller volume which makes them easier to recover (Zeeman et al., 2008). The Netherlands Institute of Ecology (NIOO-KNAW) in the Netherlands, has implemented such source separated system in its new building. The BW is vacuum collected using only 1L of water per flush and then treated in a UASB (upflow anaerobic  sludge blanket), where the carbon is converted into biogas – a green energy source. The remaining effluent, known as anaerobically treated black water (AnBW), contains the major part of the nutrients. One of these nutrients is phosphorus. The world’s main source of phosphorus is phosphate rock which, at current extraction rate, will be depleted in the coming century (Cordell et al., 2011). Of all domestic wastewater produced in a household, urine has 40% of phosphorus and 69% of nitrogen, while faeces has 28% of phosphorus and 13% of nitrogen (Kujawa-Roeleveld & Zeeman, 2006).  When able to recover that phosphorus, human excreta could supply 22% of the world phosphorus demand (Mihelcic et al., 2011).

A very promising alternative to recover phosphorus, and nitrogen at the same time, is by microalgae growth. Microalgae are becoming increasingly interesting as renewable energy sources due to their fast growth and non-competitive nature with regard to food production (Wijffels & Barbosa, 2010). When sufficient light and carbon dioxide are supplied, microalgae biomass production and nutrient uptake are high. The algae biomass could be directly used as a fertilizer, therefore returning the nutrients back to the soil to grow crops and therefore closing the nutrient cycle. The algae biomass could also be used as a resource for a diversity of added-value products.

Objectives

The general goals are:

  • Develop the best microalgae photobioreactor (PBR) for wastewater treatment;
  • Recovery of all nitrogen and phosphorus present in the wastewater with microalgae;
  • Select the best microalgae-bacteria consortium for nutrients recovery;
  • Develop the best harvesting method for the produced algal biomass;
  • Test the value of the harvested microalgae for use as a raw material (fertilizer, etc).

Approach


Fig 2. Lab scale (flasks), bench scale (flat panel PBR) and
pilot scale (tubular PBR) experiments at NIOO

We perform experiments in lab, bench and pilot scale to reply to fundamental and applied research questions. We accept BSc and MSc students for periods no shorter than 5 months.

In the experiments we look at:

  • Microalgae growth – quantification and composition of biomass (also on species level);
  • Nitrogen and phosphorus uptake for full nutrients recovery from wastewater;
  • Efficiency and robustness of the microalgae cultivation process;
  • Best method for harvesting (to be started);
  • Value of microalgae (to be started).

References

Cordell, D., Rosemarin, A., Schröder, J.J., Smit, A.L. 2011. Towards global phosphorus security: A systems framework for phosphorus recovery and reuse options. Chemosphere, 84(6), 747-758.

Kujawa-Roeleveld, K., Zeeman, G. 2006. Anaerobic Treatment in Decentralised and Source-Separation-Based Sanitation Concepts. Reviews in Environmental Science and Biotechnology, 5(1), 115-139.

Mihelcic, J.R., Fry, L.M., Shaw, R. 2011. Global potential of phosphorus recovery from human urine and feces. Chemosphere, 84(6), 832-839.

Vasconcelos Fernandes, T., Shrestha, R., Sui, Y., Papini, G., Zeeman, G., Vet, L.E.M., Wijffels, R.H., Lamers, P. 2015. Closing Domestic Nutrient Cycles Using Microalgae. Environmental Science & Technology, 49(20), 12450-12456.

Wijffels, R.H., Barbosa, M.J. 2010. An Outlook on Microalgal Biofuels. Science, 329(5993), 796-799.

Zeeman, G., Kujawa, K., de mes, T., Hernandez Leal, L., De Graaff, M.S., Abu-Ghunmi, L.N.A.H., Mels, A.R., Meulman, B., Temmink, H., Buisman, C.J.N., Van Lier, J.B., Lettinga, G. 2008. Anaerobic treatment as a core technology for energy, nutrients and water recovery from source-separated domestic waste (water). Water Science and Technology, 57(8), 1207 - 1212.