Prithvi Simha – Page 8 – Kretsloppsteknik

Nutrient stocks, flows and balances for the Bolivian agri-food system: Can recycling human excreta close the nutrient circularity gap?

Published 25 July, 2022
By Prithvi Simha

Availability of nutrients from human excreta in Bolivia in 2018.

In our latest article in #Frontiers in Environmental Sciences, Luis Fernando Perez Mercado, Cesar Ariel Perez Mercado, Bjorn Vinneras and Prithvi Simha analyse the current state of nutrient stocks, flows, and balances of the agri-food system in #bolivia. Their findings show that there is sufficient stock of #nitrogen and #phosphorus in human excreta to meet the deficit of nutrients in the food system, as well as regional nutrient surpluses that are not recirculated today. Today, Bolivia recirculates 44% of nitrogen and 74% of phosphorus used in agriculture. But we believe that circularity is going to decrease considerably over the coming years, as the national strategy to address nutrient deficits has been to increase the domestic production of synthetic fertilisers (See shorturl.at/abNQV).

Calculating mass balances always seems simple on paper. But it is difficult in practice, especially when you perform it at national, regional, and municipal levels, as we have done in this article. They usually don’t add up. Here, they also suggest how deforestation and depletion of forest nutrient stocks could be a reason why our national-level balance does not add up.

The full artile is available here: https://lnkd.in/d5dt42Qf

Prithvi co-authored a paper on degumming of Ramie Fiber with group from ICT India

Published 19 July, 2022
By Prithvi Simha

In a new study that was published in the journal Environmental Technology and Innovation, Prithvi along with his co-authors describe a novel process to degum ramie (Boehmeria nivea L.) is one of the oldest known fiber crops and one of the strongest natural fibers. For textile processing industry, the fiber needs to be degummed to a gum content below 6%. Conventionally, ramie is degummed by using chemicals like hot alkali solutions (sodium sulfate, sodium hydroxide or combination of both) followed by hydrogen peroxide treatment for bleaching or by water retting, both of which generate significant amount of effluent.

Gratulationer till Dr Alice Isibika!

Published 28 June, 2022
By Prithvi Simha

Den 8 juni försvarade Alice Isibika framgångsrikt sin avhandling Förbehandling och substratblandning för ökad processeffektivitet vid fluglarvskompostering av livsmedelsindustriavfall. Extern opponent var Professor Sven Gjedde Sommer från Aarhus Universitet (Danmark). Betygskommittén bestod av Docent Lara Maistrello från University of Modena och Reggio Emilia Area San Lazzaro (Italien), Dr Chrysantus Tanga från International Centre of Insect Physiology and Ecology (Kenya) och Docent Maria Westerholm från SLU här i Uppsala. Reserv var docent Åke Nordberg från vår egen institution. Alice fick många frågor från både opponenten och betygskommittén och försvaret pågick från 13 till 16:30. Vi tycker att Alice gjorde ett mycket bra jobb och gratulerar henne till denna prestation. Vi önskar Alice lycka till i framtiden och hoppas att hon kommer att kunna tillämpa det hon lärt sig under sin doktorandtid när hon nu återvänder till Tanzania.

Congratulations to Dr Alice Isibika!

Published 28 June, 2022
By Prithvi Simha

On the 8^th of June, Alice Isibika successfully defended her thesis Use of pre-treatments and substrate blending to enhance process efficiency in black soldier fly larvae composting of food industry waste. External reviewer was Professor Sven Gjedde Sommer from Aarhus University (Denmark). The evaluation committee was Associate Professor Lara Maistrello from University of Modena and Reggio Emilia Area San Lazzaro (Italy), Dr Chrysantus Tanga from International Centre of Insect Physiology and Ecology (Kenya) and Docent Maria Westerholm from SLU here in Uppsala. The reserve in the committee was Docent Åke Nordberg from our own department. Alice got a lot of questions from both the opponent and the committee members, and the defense lasted from 1 pm till 4:30 pm. We think Alice did a great job and congratulate her on this achievement. We wish Alice the best of luck in her future endeavors, and hope that she will be able to apply what she studied in her thesis work also in practice when she returns home to Tanzania.

SLU’s Urine Drying in Deutsche Welle (DW)

Published 13 May, 2022
By Prithvi Simha

Beatrice Christofaro captures the argument quite well as to why source-separated fractions like #urine should be recycled in this #DeutscheWelle (DW) article.

The way we manage nutrients in our wastewater and produce food globally is not sustainable. Countries are vulnerable changes in supply of fertilizers, as they’re produced using non-renewable feedstock such as natural gas, coal, and phosphate rock. Majority of the fertilisers used globally are also produced by a handful of countries. So its not a big suprise to us that fertiliser prices have soared recently and food price inflation has increased.
But we can make food production more resilient. Read the article and see how the #SLU and #Sanitation360 solution could increase local food security.

Read Full Article here: https://www.dw.com/en/are-we-flushing-away-the-answer-to-our-fertilizer-shortages/a-61737037

Artikel om urintorkning i ATL Magazine

Published 13 May, 2022
By Prithvi Simha

Läs artikeln om urintorkning i ATL Magazine: https://www.atl.nu/slu-torkar-urin-till-godsel

New publication digs deep into dissolution behaviour of Magnesium Hydroxide in Human Urine

Published 27 April, 2022
By Prithvi Simha

Here’s a new paper we published in Frontiers in Environmental Science: https://www.frontiersin.org/articles/10.3389/fenvs.2022.889119/full

In the study, we systematically analysed the kinetics and thermodynamics of how magnesium hydroxide dissolves in different types of human urine (fresh urine and fresh urine concentrated by evaporation). We showed that Mg hydroxide has a unique dissolution behaviour which is unlike that of other alkaline earth hydroxides, especially when water is removed from urine. We detail conditions and design criteria for alkalising and for dehydrating urine, which is useful when developing source-separating sanitation systems.

A cool aspect of the study was that we found a smart way to simulate the kinetics of how fast Mg hydroxide dissolves, how fast various precipitates form (e.g. struvite, apatite), and how fast urine is alkalised and saturated. We did this by matching the experimentally measured pH of urine with its thermodynamically simulated pH. This approach could be applied to any system as long as the parameter we measure is something we can also simulate thermodynamically.

Can urine help save food production under crises?

Published 21 March, 2022
By Prithvi Simha

Field with crops. Two persons in the background.

Prithvi spoke with Agnes Bondesson, SLU Global’s International Scientific Communications Officer about the ongoing food and fertiliser price inflation. Check out the article here: https://internt.slu.se/en/news-originals/2022/3/can-urine-help-save-food-production-under-crises/ or read below –

With the current state in the world, seen to conflicts and climate change, the question about food production in case of short-term or long-term crises has been emphasised. Sweden has a solid food production, but it is a production vulnerable for disruptions of imported products such as fertilisers, diesel, pesticides, seeds and protein feed as well as electricity. One of the main components in conventional plant production is the use of imported fertilisers. When the climate crisis, higher prices and insecurity in import forces us to rethink our ways to use artificial fertilisers there is a need to see other solutions.

Studyvisit to VAFAB in Västerås

Published 14 December, 2021
By Prithvi Simha

We went on a study trip to the waste management company VAFAB in Västerås with students from our two courses about waste management, ”Safe nutrient recycling 15HP” and ”Waste management 5HP”. A very interesting tour that gave insights about the volumes of waste that we all generate, among the things we visited we had a bus tour over the 45 hectar old landfill. Additionally we had a nice tour of the newly re-built biogas plant and hear about the challenges they had with sediments in the reactors from egg shells, sand and dirt that consumes reactor volumes. The produced biogas is used for the local buses and the bio-fertiliser is collected by local farmers for free.

Food waste bags that have been collected in the Västerås region are stored before they are feed to the anaerobic digester.

Studiebesök på VAFAB i Västerås

Published 14 December, 2021
By Prithvi Simha

Vi åkte förra veckan på studiebesök till avfallsbolaget VAFAB i Västerås med studenterna från våra två kurser som hanterar avfallshantering, ”Säker näring i kretslopp, 15HP” och ”Avfallshantering 5HP”. Det var en väldigt givande tur som gav tydlig insikt i mängderna avfall vi alla genererar, då vi bland annat åkte med bussen över den gamla deponin som är 45 hektar stor. Dessutom fick vi se den nyligen ombyggda biogasanläggningen och höra om problemen i biogasreaktorerna som orsakas av sediment från äggskal, jord och sand som tar upp en stor del av reaktorvolymen. Den producerade biogasen används till drivmedel, främst för stadens bussar, samt biogödseln som hämtas gratis av lokala bönder.

Matavfallspåsar som samlats in i Västerås regionen och väntar på att rötas.