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

Published

Availability of nutrients from human excreta in Bolivia in 2018.

In our latest article in #Frontiers in Environmental Sciences, Luis Fernando Perez MercadoCesar 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

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.

How to evaluate the effectiveness of game-based interventions in decision-making process?

Published

In this latest publication on game-based approaches for planning and decision-making for sanitation, we have collaborated with researchers at EAWAG. The study aimed to answer the question: how effective are game-based interventions specifically designed to support decision-making processes? We used an illustrative case to reflect on this question. We simultaneously designed a card game to support sanitation decision-making and an evaluation procedure.

We found that it is possible to address the dual challenge of game-based interventions for participatory decision-making processes:

(1) designing an informative and engaging game-based intervention without telling participants what to think and

(2) designing a tailored evaluation procedure. Designing the game-based intervention and its evaluation simultaneously is valuable both to improve the quality of the game, but also the opportunity provided a structured assessment of the results.

We encourage others to follow this approach and use the evaluation framework proposed in this paper.

 

 

 

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

Published

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.

Ledare i tidskriften Insects as Food and Feed Vol. 8, No. 4, 2022

Published

Denna månad publicerar kretsloppstekniks Cecilia Lalander och Björn Vinnerås en ledare i tidskriften Journal of Insects as Food and Feed om de hinder som står i vägen för att förverkliga en insektsbaserat slutet cirkulärekonomiskt kretslopp i EU idag. Möjligheten att skriva en ledare i denna tidskrift kommer sig av att Cecilia är biträdande redaktörer för tidskriften. Läs ledaren om du är intresserad av att ta reda på mer om vad vi tror krävs för att möjliggöra ett cirkulärt insektsbaserad livsmedelssystem i EU.

Editorial in Journal of Insects as Food and Feed Vol. 8, No. 4, 2022

Published

This month Kretsloppsteknik’s Cecilia Lalander and Björn Vinnerås published an editorial in Journal of Insects as Food and Feed about the hindrances that exist in the EU that prevent a true insect based closed-loop circular economy in the EU. The opportunity to write an editorial in JIFF comes as of Cecilia being one of the associated editors of the journal. Please, read the full editorial if you want to find out what actions we believe are needed for achieving a circular insect food production system in the EU.

 

Omogen, men med stor potential – Läs vår review-artikel om BSF larver frass som organiskt gödningsmedel

Published

Lägligt med EU:s beslut att anta en förordning som reglerar produktion och användning av insektsfrass på EU-marknaden ((EU) 2021/1925) har vi publicerat en review-artikel  i Journal of Waste Management om kunskapsläget för användning fluglarvsfrass som organiskt gödningsmedel. Vi har beskrivit fördelarna med att använda fluglarvsfrass som organiskt gödningsmedel som har stöd i vetenskapliga studier, diskuterat ytterligare möjliga fördelar som ännu inte har påvisats, pekat på några av de utmaningar som kan mötas vid användning av detta gödningsmedel samt kartlagt kunskapsluckorna som för närvarande finns. Vill du veta mer, läs här.

Immature, but with great potential – Read our review on BSF larvae frass as an organic fertilizer

Published

Timely with the decision from the EU to adopt a regulation that governs the production and use of insect frass on the EU market ((EU) 2021/1925) we have compiled a review article published in the Journal of Waste Management on state of knowledge of using BSF larvae frass as an organic fertiliser. We have outlined the advantages of using BSF larvae frass as organic fertiliser that has been found so far, discussed possible additional benefits that have not yet been demonstrated, pointed to some of the challenges that could be faced using this fertiliser as well as elucidated the gaps in knowledge that currently exist. If you want to find out more, read here.

New publication from the urine dying group on the use of magnesium-doped alkaline substrates in the Chemical Engineering Journal

Published

In our latest paper, published in the Chemical Engineering Journal, we show how all the nitrogen in fresh human urine can be captured in the form of solid urine-based fertilisers.

Abstract: Recycling urine can reduce the flux of reactive nitrogen in the environment. This paper presents a novel approach to recover all N (Ntot) from urine, including ammonia (TAN; about 5% of Ntot), which is usually volatilised when alkalised urine is dehydrated. As analytical methods for measuring N have a standard deviation of at least 5%, real fresh urine was fortified with ammonia (urineN) or ammonia and phosphate (urineNP) so that TAN comprised 10% of Ntot. The urine was then added to different magnesium-based alkaline substrates (MgO, Mg(OH)2, MgCl2 + Mg(OH)2) and dried at 38 ˚C. Chemical speciation modelling suggested that, irrespective of the substrate, >98% of Ntot in urineNP was recovered and 86% of TAN was precipitated as struvite. Experimental results showed that < 90% of Ntot was recovered when urineNP was dried in MgO and Mg(OH)2, suggesting that no TAN was captured. However, all phosphorus and potassium and 93% (±5%) of Ntot and 30% of TAN were recovered when urineNP was dried in MgCl2 + Mg(OH)2, as the [Mg]:[NH4]:[PO4] molar ratio of 1.69:1.14:1.0 in urine favoured formation of struvite. Overall, this study demonstrated that all ammonia excreted in real fresh urine (unfortified, TAN < 5% Ntot) can be captured if urine is dried in substrates containing 3.7 g MgCl2·6H2O L−1 or 2.2 g MgSO4 L−1, but no calcium. Ammonia can also be captured if fresh urine is saturated with MgO or Mg(OH)2 with high reactivity (<60 s citric acid test). If the drying substrate has pH > 10 throughout the treatment, urease enzyme-catalysed degradation of urea to ammonia is prevented, resulting in complete recovery of all nutrients. The end-product is a solid fertiliser containing 10–11% nitrogen, 1–2% phosphorus and 2–3% potassium.

Poor awareness and attitudes to sanitation servicing can impede China’s Rural Toilet Revolution: Evidence from Western China

Published

Check out our new publication following up on China’s nationwide sanitation campaign, “the toilet revolution” in the journal, Science of the Total Environment.

Abstract: The ongoing Toilet Revolution in China offers an opportunity to improve sanitation in rural areas by introducing new approaches, such as urine source separation, that can contribute to achieving SDG6. However, few studies have systematically assessed the social acceptability of managing human excreta collected in new sanitation systems. Therefore, in this study we performed face-to-face interviews with 414 local residents from 13 villages across three provinces in western China, to analyze the current situation and attitudes to possible changes in the rural sanitation service chain. We found that the sanitation chain was predominantly pit latrine-based, with 86.2% of households surveyed collecting their excreta in a simple pit, 82% manually emptying their pits, and 80.2% reusing excreta in agriculture without adequate pre-treatment. A majority (72%) of the households had a generally positive attitude to production of human excreta-derived fertilizer, but only 24% agreed that urine and feces should be collected separately. Multivariate logistic regression indicated that three factors (level of education, number of permanent household residents, perceived social acceptability) significantly influenced respondents’ attitudes to reuse of excreta, although only perceived social acceptability had a high strength of association. Overall, our survey revealed that rural households often misuse toilet systems, fail to comply with government-specified sanitation guidelines, have low awareness of alternative solutions, and are over-reliant on the government to fix problems in the service chain. Thus while new sanitation technologies should be developed and implemented, information campaigns that encourage rural households to manage their excreta safely are also important.