Browsing by Autor "Prithvi Simha"

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China should focus beyond access to toilets to tap into the full potential of its Rural Toilet Revolution
(Elsevier BV, 2021) Xiaoqin Zhou; Prithvi Simha; Luis Fernando Perez-Mercado; Melissa A. Barton; Yaping Lyu; Shaoming Guo; Xiaoqin Nie; Fangni Wu; Zifu Li
Circular fertilisers combining dehydrated human urine and organic wastes can fulfil the macronutrient demand of 15 major crops
(Elsevier BV, 2024) Luis Fernando Perez-Mercado; Prithvi Simha; Aline Paiva Moreira; Paula Loureiro Paulo; Björn Vinnerås
This study evaluated the potential for combining dehydrated human urine with one other form of organic waste to create circular fertilisers tailored to meet the macronutrient demand of 15 major crops cultivated globally. Through a reverse blending modelling approach, data on 359 different organic wastes were used to identify 38 fertiliser blends. Materials found to be particularly suitable as blending materials were various biochars and ashes, due to their low nitrogen and high phosphorus and/or potassium content, and byproduct concentrates, due to their high phosphorus content, since the nitrogen content of human urine is disproportionately higher than its phosphorus content. Several organic wastes were suitable for fertilising more than one crop. The macronutrient content of the simulated fertiliser blends was comparable to that of blended inorganic fertilisers, but only a few blends precisely matched the macronutrient demand of crops. Fertilising crops with some simulated fertilisers would potentially result in excess application of one or more macronutrients, and thus overfertilisation. For organic wastes with data available on their content of six or more heavy metals, it was found that the simulated fertilisers generally met European Union regulations on use of fertilisers of organic origin in agriculture. Overall, these findings suggest that fertiliser blends combining dehydrated human urine and organic wastes, both of which are widely available globally, could replace inorganic blended fertilisers in agriculture. Such recycling would help the global food system and water sector transition to circularity and promote better management of plant-essential nutrients in society.
Erratum to “Willingness among food consumers to recycle human urine as crop fertiliser: Evidence from a multinational survey” [Sci. Total Environ. 765 (2021), 144438]
(Elsevier BV, 2021) Prithvi Simha; Melissa A. Barton; Luis Fernando Perez-Mercado; Jennifer McConville; Cecilia Lalander; Maria Elisa Magri; Shanta Dutta; Humayun Kabir; Albert Selvakumar; Xiaoqin Zhou
Nutrient stocks, flows and balances for the Bolivian agri-food system: Can recycling human excreta close the nutrient circularity gap?
(Frontiers Media, 2022) Luis Fernando Perez-Mercado; C.A. Pérez-Mercado; Björn Vinnerås; Prithvi Simha
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.
Poor awareness and attitudes to sanitation servicing can impede China's Rural Toilet Revolution: Evidence from Western China
(Elsevier BV, 2021) Shaomin Guo; Xiaoqin Zhou; Prithvi Simha; Luis Fernando Perez Mercado; Yaping Lv; Zifu Li
Willingness among food consumers to recycle human urine as crop fertiliser: Evidence from a multinational survey
(Elsevier BV, 2020) Prithvi Simha; Melissa A. Barton; Luis Fernando Perez-Mercado; Jennifer McConville; Cecilia Lalander; Maria Elisa Magri; Shanta Dutta; Humayun Kabir; Albert Selvakumar; Xiaoqin Zhou
Source-separating sanitation systems offer the possibility of recycling nutrients present in wastewater as crop fertilisers. Thereby, they can reduce agriculture's impacts on global sources, sinks, and cycles for nitrogen and phosphorous, as well as their associated environmental costs. However, it has been broadly assumed that people would be reluctant to perform the new sanitation behaviours that are necessary for implementing such systems in practice. Yet, few studies have tried to systematically gather evidence in support of this assumption. To address this gap, we surveyed 3763 people at 20 universities in 16 countries using a standardised questionnaire. We identified and systematically assessed cross-cultural and country-level explanatory factors that were strongly associated with people's willingness to consume food grown using human urine as fertiliser. Overall, 68% of the respondents favoured recycling human urine, 59% stated a willingness to eat urine-fertilised food, and only 11% believed that urine posed health risks that could not be mitigated by treatment. Most people did not expect to pay less for urine-fertilised food, but only 15% were willing to pay a price premium. Consumer perceptions were found to differ greatly by country and the strongest predictive factors for acceptance overall were cognitive factors (perceptions of risks and benefits) and social norms. Increasing awareness and building trust among consumers about the effectiveness of new sanitation systems via cognitive and normative messaging can help increase acceptance. Based on our findings, we believe that in many countries, acceptance by food consumers will not be the major social barrier to closing the loop on human urine. That a potential market exists for urine-fertilised food, however, needs to be communicated to other stakeholders in the sanitation service chain.