Phosphorus flow analysis for Malawi: Identifying potential sources of renewable phosphorus recovery

Mnthambala, Frank; Tilley, Elizabeth; Tyrrel, Sean; Sakrabani, Ruben

doi:10.1016/j.resconrec.2021.105744

Cited by 19 publications

(3 citation statements)

References 32 publications

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“…This approach is supported by the analysis of 12 case studies, which accounted for 9.6% of the total research conducted in this area [121,122,101] . Similarly, the integration of MFA with Life Cycle Assessment (LCA), employed in 8 case studies (6.4%), is used to evaluate agricultural waste utilization and greenhouse gas mitigation [123][124][125] . LCA, used independently in 7 studies (5.6%), is instrumental for analyzing sustainable urban agriculture and phosphorus management [126][127][128] .…”

Section: Type Of Um Methods Used In the Literaturementioning

confidence: 99%

Role of Urban Metabolism Assessments in Addressing Food Security through Urban Agriculture in Informal Settlements: A Critical Review

Acevedo-De-los-Ríos,

Perrotti

2024

IOP Conf. Ser.: Earth Environ. Sci.

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This literature review explores the role of urban metabolism (UM) assessments in addressing food security through urban agriculture in informal settlements, particularly in lower-income countries. It addresses the challenges of food security in urban areas and aims to unravel existing urban dynamics and networks to generate agro-food resources in these settings. The review included a comprehensive search using the Scopus and Web of Science (WOS) databases to identify relevant studies. A total of 381 articles published between 2000 and 2023 were retrieved. Additionally, a systematic review of grey literature was performed using Google Scholar, focusing on publications in the Spanish language from the years 2000 to 2023 to address food security dynamics in Latin America as a key case study area. After screening titles, keywords, and abstracts, 127 journal articles from the Scopus and WOS databases and 51 results from the grey literature were considered for further analysis. Bibliometric coupling techniques, including co-citation analysis, co-occurrence analysis, and keyword analysis, were employed using VOSviewer software to visualize the scholarly landscape and identify major themes. The analysis of white literature facilitated the identification of six major themes: (1) UM and Sustainability; (2) Phosphorus Management and Recycling; (3) Food Security and Waste Management; (4) Material Flow Analysis and Environmental Impact; (5) Human Impacts on the Environment; and (6) Food Systems and Sustainability. The main findings pointed to the environmental and social sustainability impacts of food flows in UM studies, emphasizing the pertinence of UM as a conceptual framework to address urban sustainability and justice challenges, particularly in informal settlements. Additionally, the grey literature provided insights into community strategies, urban resilience, and social inequality, enriching the understanding of local realities and socio-economic dimensions related to UM and food security in informal settlements. The review showed that by incorporating UM approaches and circular economy strategies, it is possible to optimize flows and stocks within the agro-food systems, leading to improved food security, sustainable development, and enhanced resilience in urban environments.

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Section: Type Of Um Methods Used In the Literaturementioning

confidence: 99%

Role of Urban Metabolism Assessments in Addressing Food Security through Urban Agriculture in Informal Settlements: A Critical Review

Acevedo-De-los-Ríos,

Perrotti

2024

IOP Conf. Ser.: Earth Environ. Sci.

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“…However, the percentage weight of silica in the beach sand xerogel and aerogel is 56 % and 57 %, respectively, with both showing a lesser level of purity when compared to the gels from the rice husk. Another remarkable observation is the complete absence of phosphoric oxide in both the gels from the beach sand source, which is likely because the sand is not obtained from a farmland where fertilizer could have been used to improve crop yield [13]. The rice husk -based gels have an associated oxide of minute phosphorus possibly taken up by the rice from the soil during paddy growth.…”

Section: Elemental Composition Of the Xerogels And Aerogelsmentioning

confidence: 99%

Synthesis and characterization of silica xerogel and aerogel from rice husk ash and pulverized beach sand via sol-gel route

Omatolaa,

Onojah,

Amah

et al. 2023

J. Nig. Soc. Phys. Sci.

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The high cost and toxicity associated with the use of orthosilicates as silica precursors drive growing interest in an environmentally friendly and cost - efficient natural silica source. Rice husk (a biomass) and beach sand are both natural and non - toxic and the extraction of silica from each using sodium hydroxide makes the process green for the production of nanosilica gels (xerogel and aerogel) via the sol – gel route. The gels from the ash of rice husk and pulverized beach sand were dried by the use of a laboratory oven and supercritical extraction methods. The structures of the gels were studied through X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning electron microscopy (SEM), X - ray fluorescence (XRF) spectroscopy and Fourier transform infrared (FTIR) spectroscopic analyses. XRF spectroscopy revealed silicon in its oxide form as the prominent element with low levels of trace elements concentrations. XRD results showed the crystalline nature of the prepared silica. TEM images confirmed the crystalline and nanometric structures of the streak - free xerogel and aerogel. SAED confirmed that the gels were polycrystalline with no streaks. SEM monographs showed varied globes of fine surfaces indicating the high level of purity of the gels. FTIR showed the absorption peaks of the silanol-OH bond and Si-O-Si vibration, confirming the gels as nanometric structures. The high yield, crystalline nature, purity and crystallographic features of the produced silica suggest rice husk ash and pulverized beach sand as alternative silica sources for the production of silica gels nanoparticles with potential applications in biomedical field, nanofiltration and as additive for improving the strength of materials.

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“…As in other developing countries that aim to increase food production, the agricultural strategy in Bolivia has focused on improving the access of farmers to synthetic fertilisers (INIAF, ANAPO, CIAB, (2019); Mnthambala et al, 2021). In 2017, a state-owned petrochemical plant was inaugurated in Bolivia to produce urea and ammonia.…”

Section: Nutrient Recycling and Circularity In The Bolivian Agri-food...mentioning

confidence: 99%

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

Perez-Mercado

Perez-Mercado²,

Vinnerås

et al. 2022

Front. Environ. Sci.

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Analysis of the current state of nutrient stocks, flows, and balances of a territory is necessary to inform strategies that can transition the agri-food sector to a circular economy model. In this study, we quantified the nitrogen and phosphorus budgets for the Bolivian agri-food system at national and regional scales by way of agro-ecological zoning. We performed nutrient balances to calculate indicators for sufficiency (extent of nutrient deficit/surplus) and circularity (proportion of nutrients recirculated). We also evaluated the potential of renewable stocks (human excreta and livestock manure) to meet nutrient deficits in the system. Our results showed that there are apparent deficits of 32 kt N and 8 kt P in the system that cannot be accounted for using available data. We estimate the real deficits required to bring yields of 45 crops grown in Bolivia to parity with those of neighbouring countries to be 110 kt N and 33 kt P. About 44% of nitrogen and 74% of phosphorus is currently recirculated in the system, with the major nutrient inputs being biological nitrogen fixation, livestock manure, and crop residues. However, nutrient recycling is likely to decrease in the future because the national strategy to address nutrient deficits is to increase domestic production of synthetic fertilisers. Our analysis also shows that there is a sufficient stock of nutrients already available in human excreta (39 kt N and 5 kt P) to cover 100% of the nitrogen deficit and 64% of the phosphorus deficit. The low-altitude zone of Chiquitania-Pantanal alone accounts for 65% of cultivation and 80% of the nutrient demand in the country. Here, export-oriented crops like soybean and sorghum are grown, but less than 25% of the nitrogen is recirculated. In contrast, there are nutrient surpluses of 41 kt N and 34 kt P in agro-ecological zones like the Valleys and Altiplano where traditional agriculture is practiced, and the majority of food is grown for local consumption. Overall, we find that recycling of human excreta, combined with transfer of regional nutrient surpluses, could be an effective strategy to reduce the overall nutrient deficit in the system.

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Phosphorus flow analysis for Malawi: Identifying potential sources of renewable phosphorus recovery

Cited by 19 publications

References 32 publications

Role of Urban Metabolism Assessments in Addressing Food Security through Urban Agriculture in Informal Settlements: A Critical Review

Role of Urban Metabolism Assessments in Addressing Food Security through Urban Agriculture in Informal Settlements: A Critical Review

Synthesis and characterization of silica xerogel and aerogel from rice husk ash and pulverized beach sand via sol-gel route

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

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