Author: Prithvi Simha

The public defence of the doctoral thesis for Prithvi Simha, entitled “Alkaline Urine Dehydration. How to dry source-separated human urine and recover nutrients?” is scheduled –

When? 2nd of June at 13:00 Where? Room Framtiden at MVM-hus at SLU in Uppsala and via Zoom Click this URL to join via Zoom: https://slu-se.zoom.us/j/69422000884 with Passcode: 732271

External reviewer: Professor Nancy Love, Department of Civil and Environmental Engineering, The University of Michigan, Ann Arbor, USA.

Examining committee: Professor Annelie Hedström, Luleå University of Technology, Luleå, Sweden; Docent Sebastian Schwede, Mälardalen University, Västerås, Sweden; and PhD Surendra Pradhan, University of Eastern Finland, Kuopia, Finland

The thesis is openly available at: https://pub.epsilon.slu.se/23473/1/simha_p_210511.pdf

On 5th of March, Prithvi had his pre-dissertation seminar: Alklaine Urine Dehydration – how to dry urine and recover nutrients. David Gustavsson from VA SYD/Sweden Water Research was Prithvi’s opponent at the seminar and he quizzed Prithvi on his published papers as well as his preliminary thesis (or kappa). Overall, it was very interesting and long discussion ranging on topics like reactive nitrogen and ammonia capture, the use of different alkaline substrates, the use of IoT in sanitation and global sanitation outlook. With this successful seminar, Prithvi will now proceed further and have his PhD defence which is scheduled to be held on the 2nd of June in Uppsala and via zoom online. We thank David again for his thorough and insightful discussion on the topic!

We recently published a new paper on the use of Magnesium Oxide as an alkaline substrate for dehydrating urine in the journal Frontiers in Environmental Science.

https://www.frontiersin.org/articles/10.3389/fenvs.2020.619901/full

Abstract: Fresh human urine, after it is alkalized to prevent the enzymatic hydrolysis of urea, can be dehydrated to reduce its volume and to produce a solid fertilizer. In this study, we investigated the suitability of MgO to alkalize and dehydrate urine. We selected MgO due to its low solubility (<2 gL⁻¹) and relatively high saturation pH (9.9 ± 0.2) in urine. Using a laboratory-scale setup, we dehydrated urine added to pure MgO and MgO mixed with co-substrates (biochar, wheat bran, or calcium hydroxide) at a temperature of 50°C. We found that, dehydrating urine added to a mixture of MgO (25% w/w), biochar, and wheat bran resulted in a mass reduction of >90% and N recovery of 80%, and yielded products with high concentrations of macronutrients (7.8% N, 0.7% P and 3.9% K). By modeling the chemical speciation in urine, we also showed that ammonia stripping rather than urea hydrolysis limited the N recovery, since the urine used in our study was partially hydrolyzed. To maximize the recovery of N during alkaline urine dehydration using MgO, we recommend treating fresh/un-hydrolysed urine a temperature <40°C, tailoring the drying substrate to capture NH⁺⁴ as struvite, and using co-substrates to limit the molecular diffusion of ammonia. Treating fresh urine by alkaline dehydration requires only 3.6 kg MgO cap⁻¹y⁻¹ and a cost of US$ 1.1 cap⁻¹y⁻¹. Therefore, the use of sparingly soluble alkaline compounds like MgO in urine-diverting sanitation systems holds much promise.

Contact: Prithvi Simha

Last week, following our joint article on urine recycling in The Conversation Africa, Prof. Christopher Buckley from the University of KwZulu-Natal was interviewed by SAfm, South Africa’s national public radio station. In his interview with Stephen Groote, Prof. Buckley talked about our group’s pioneering urine treatment technology, alkaline dehydration, and how the technology holds promise for implementation across Africa. In the coming year, along with Prof Buckley’s research group and local stakeholders, we are hoping to implement our urine drying technology in Durban, South Africa. Listen to the interview below –

Jenna Senecal was interviewed by Popular Science, a widely distributed magazine in North America, about the potential to safely recover nutrients from human urine to help protect the environment. Scroll down to read the article –