Special Issue on Sustainable Phosphorus in Science of the Total Environment Jan 15, 2016

[arnorosem...@gmail.com]

Science of The Total Environment, Volume 542, Part B, 15 January 2016, Page IFC, ISSN 0048-9697, http://dx.doi.org/10.1016/S0048-9697(15)00699-3.

(http://www.sciencedirect.com/science/article/pii/S0048969715006993)

 

Andrea E.Ulrich, Taking Stock: Phosphorus Supply from Natural and Anthropogenic Pools in the 21st Century, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1005-1007, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.10.036.

(http://www.sciencedirect.com/science/article/pii/S0048969715308524)

Keywords: Phosphorus; Supply risk; Scarcity; Recycling; Food security; Environmental health; Residual soil phosphorus century

 

M.C. Mew, Phosphate rock costs, prices and resources interaction, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1008-1012, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.08.045.

(http://www.sciencedirect.com/science/article/pii/S0048969715305489)

Abstract:

This article gives the author's views and opinions as someone who has spent his working life analyzing the international phosphate sector as an independent consultant. His career spanned two price hike events in the mid-1970's and in 2008, both of which sparked considerable popular and academic interest concerning adequacy of phosphate rock resources, the impact of rising mining costs and the ability of mankind to feed future populations. An analysis of phosphate rock production costs derived from two major industry studies performed in 1983 and 2013 shows that in nominal terms, global average cash production costs increased by 27% to $38 per tonne fob mine in the 30 year period. In real terms, the global average cost of production has fallen. Despite the lack of upward pressure from increasing costs, phosphate rock market prices have shown two major spikes in the 30 years to 2013, with periods of less volatility in between. These price spike events can be seen to be related to the escalating investment cost required by new mine capacity, and as such can be expected to be repeated in future. As such, phosphate rock price volatility is likely to have more impact on food prices than rising phosphate rock production costs. However, as mining costs rise, recycling of P will also become increasingly driven by economics rather than legislation.

Keywords: Phosphate; Phosphorus; Fertilizer; Resources; Costs; Prices; Recycling

 

Sylvia Kratz, Judith Schick, Ewald Schnug, Trace elements in rock phosphates and P containing mineral and organo-mineral fertilizers sold in Germany, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1013-1019, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.08.046.

(http://www.sciencedirect.com/science/article/pii/S0048969715305490)

Abstract

68 rock phosphates and 162 P containing (organo-)mineral fertilizers sold in Germany were evaluated with regard to trace element contents. While Al, As, B, Be, Cd, Cr, Mo, Ni, Pb, Sb, Se, Tl, U, and Zn were higher in sedimentary than in igneous rock phosphates, the opposite was true for Co, Cu, Sn, Mn, Ti, Fe, and Sr. Comparing element concentrations to the currently valid legal limit values defined by the German Fertilizer Ordinance, it was found that some PK and many straight P fertilizers (superphosphate, triple superphosphate, partly acidulated rock phosphates) exceeded the limit of 50 mg Cd/kg P2O5. Mean values for As, Ni, Pb, and Tl remained below legal limits in almost all cases. While no legal limit has been defined for U in Germany yet, the limit of 50 mg U/kg P2O5 for P containing fertilizers proposed by the German Commission for the Protection of Soils was clearly exceeded by mean values for all fertilizer types analyzed. A large share of the samples evaluated in this work contained essential trace elements at high concentrations, with many of them not being declared as such. Furthermore, trace elements supplied with these fertilizers at a fertilization rate leveling P uptake would exceed trace element uptake by crops. This may become most relevant for B and Fe, since many crops are sensitive to an oversupply of B, and Fe loads exceeding plant uptake may immobilize P supplies for the crops by forming Fe phosphate salts. The sample set included two products made from thermochemically treated sewage sludge ash. The products displayed very high concentrations of Fe and Mn and exceeded the legal limit for Ni, emphasizing the necessity to continue research on heavy metal removal from recycled raw materials and the development of environmentally friendly and agriculturally efficient fertilizer products.

Keywords: Rock phosphates; Mineral P fertilizers; Trace elements; Heavy metals

 

Wenbo Xie, Dongye Zhao, Controlling phosphate releasing from poultry litter using stabilized Fe–Mn binary oxide nanoparticles, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1020-1029, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.063.

(http://www.sciencedirect.com/science/article/pii/S0048969715307233)

Abstract

Animal wastes contain high concentrations of phosphorus (P), most of which is lost into the environment due to uncontrolled release rates. Polysaccharide stabilized Fe–Mn binary oxide nanoparticles were prepared and tested for phosphate adsorption from water and for controlling leachability of P from poultry litter. A water soluble starch and carboxymethyl cellulose (CMC) were used as a stabilizer. Both the Freundlich and Langmuir models were able to adequately interpret the isotherm data. The Langmuir maximum capacity was determined at 252, 298 and 313 mg-P/g for bare, CMC- and starch-stabilized nanoparticles, respectively. The presence of the stabilizers not only enhanced the sorption capacity, but facilitated delivery and dispersion of the nanoparticles in poultry litter (PL) and in soil. High phosphate sorption capacity was observed over a broad pH range of 4–9. FTIR analyses indicated that inner sphere surface complexation (Fe–O–P) was the key mechanism for the enhanced uptake of P. When applied to poultry litter, the stabilized nanoparticles reduced water leachable phosphate by > 86% at a dose of 0.2 g/L as Fe, and simultaneously, water leachable arsenic by > 87–95%. Under conditions of simulated land application of PL, the nanoparticle amendment of PL reduced the water soluble P from 66% (for untreated PL) to 4.4%, and lowered the peak soluble P concentration from 300 to < 20 mg/L. By transferring the peak soluble P to the nanoparticle-bound P, the nanoparticles not only greatly reduce the potential runoff loss of P from PL, but also provide a long-term slow-releasing nutrient source. Fortuitously, the nanoparticle treatment was able to immobilize arsenic from PL. With excellent adsorption capacity, easy deliverability, low cost and environmental innocuousness, the stabilized Fe–Mn nanoparticles appear promising for controlling P releases from poultry litter or other animal wastes and for phosphate recovery from water.

Keywords: Nutrient; Phosphorus; Phosphate; Arsenic; Nanoparticle; Poultry litter

 

Andrea E. Ulrich, Diane F. Malley, Paul D. Watts, Lake Winnipeg Basin: Advocacy, challenges and progress for sustainable phosphorus and eutrophication control, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1030-1039, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.106.

(http://www.sciencedirect.com/science/article/pii/S004896971530766X)

Abstract

Intensification of agricultural production worldwide has altered cycles of phosphorus (P) and water. In particular, loading of P on land in fertilizer applications is a global water quality concern. The Lake Winnipeg Basin (LWB) is a major agricultural area displaying extreme eutrophication. We examined the eutrophication problem in the context of the reemerging global concern about future accessibility of phosphate rock for fertilizer production and sustainable phosphorus management. An exploratory action research participatory design was applied to study options for proactivity within the LWB. The multiple methods, including stakeholder interviews and surveys, demonstrate emerging synergies between the goals of reversing eutrophication and promoting food security. Furthermore, shifting the prevalent pollutant-driven eutrophication management paradigm in the basin toward a systemic, holistic and ecocentric approach, integrating global resource challenges, requires a mutual learning process among stakeholders in the basin to act on and adapt to ecosystem vulnerabilities. It is suggested to continue aspects of this research in a transdisciplinary format, i.e., science with society, in response to globally-expanding needs and concerns, with a possible focus on enhanced engagement of indigenous peoples and elders.

Keywords: Phosphorus; Eutrophication; Nutrient management; Water management; Action research; Lake Winnipeg; Indigenous

 

Raphael A. Viscarra Rossel, Elisabeth N. Bui, A new detailed map of total phosphorus stocks in Australian soil, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1040-1049, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.119.

(http://www.sciencedirect.com/science/article/pii/S0048969715307804)

Abstract

Accurate data are needed to effectively monitor environmental condition, and develop sound policies to plan for the future. Globally, current estimates of soil total phosphorus (P) stocks are very uncertain because they are derived from sparse data, with large gaps over many areas of the Earth. Here, we derive spatially explicit estimates, and their uncertainty, of the distribution and stock of total P in Australian soil. Data from several sources were harmonized to produce the most comprehensive inventory of total P in soil of the continent. They were used to produce fine spatial resolution continental maps of total P in six depth layers by combining the bootstrap, a decision tree with piecewise regression on environmental variables and geostatistical modelling of residuals. Values of percent total P were predicted at the nodes of a 3-arcsecond (approximately 90 m) grid and mapped together with their uncertainties. We combined these predictions with those for bulk density and mapped the total soil P stock in the 0–30 cm layer over the whole of Australia. The average amount of P in Australian topsoil is estimated to be 0.98 t ha− 1 with 90% confidence limits of 0.2 and 4.2 t ha− 1. The total stock of P in the 0–30 cm layer of soil for the continent is 0.91 Gt with 90% confidence limits of 0.19 and 3.9 Gt. The estimates are the most reliable approximation of the stock of total P in Australian soil to date. They could help improve ecological models, guide the formulation of policy around food and water security, biodiversity and conservation, inform future sampling for inventory, guide the design of monitoring networks, and provide a benchmark against which to assess the impact of changes in land cover, land use and management and climate on soil P stocks and water quality in Australia.

Keywords: Total phosphorus; Phosphorus stocks; Predictive modelling; Digital soil mapping; Phosphorus cycling

 

Marcos Rodrigues, Paulo Sergio Pavinato, Paul John Anthony Withers, Ana Paula Bettoni Teles, Wilfrand Ferney Bejarano Herrera, Legacy phosphorus and no tillage agriculture in tropical oxisols of the Brazilian savanna, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1050-1061, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.08.118.

(http://www.sciencedirect.com/science/article/pii/S0048969715306197)

Abstract

Crop production in the Brazilian Cerrado is limited by soil phosphorus (P) supply without large inputs of inorganic P fertilizer, which may become more costly and scarce in the future. Reducing dependency on fertilizer P requires a greater understanding of soil P supply in the highly weathered soils in this important agricultural region. We investigated the impact of no tillage (NT) and conventional tillage (CT) agriculture on accumulated (legacy) soil P and P forms in four long-term sites. Compared to the native savanna soils, tilled soils receiving regular annual P fertilizer inputs (30–50 kg P ha− 1) increased all forms of inorganic and organic P, except highly recalcitrant P associated with the background lithology. However, 70–85% of the net added P was bound in moderately labile and non-labile forms associated with Fe/Al oxyhydroxides rather than in plant available forms. Under NT agriculture, organic P forms and labile and non-labile inorganic P forms were all significantly (P < 0.05) increased in the surface soil, except for one site with maize residues where labile inorganic P was increased more under CT agriculture. The contribution of organic P cycling in these tropical soils increased after conversion to agriculture and was proportionally greater under NT. The results highlight the large amounts of unutilized legacy P present in Brazil's Cerrado soils that could be better exploited to reduce dependency on imports of finite phosphate rock. No tillage agriculture confers a positive albeit relatively small benefit for soil P availability and overall soil function.

Keywords: Phosphorus fractionation; Inorganic P; Organic P; No tillage; Cerrado; Brazilian savanna

 

Remigiusz Łukowiak, Witold Grzebisz, Gretchen F. Sassenrath, New insights into phosphorus management in agriculture — A crop rotation approach, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1062-1077, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.009.

(http://www.sciencedirect.com/science/article/pii/S0048969715306690)

Keywords: Oil seed rape; Maize; Calcium chloride extractable phosphorus; Soil profile; Soil system phosphorus budget

 

Kimo C. van Dijk, Jan Peter Lesschen, Oene Oenema, Phosphorus flows and balances of the European Union Member States, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1078-1093, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.08.048.

(http://www.sciencedirect.com/science/article/pii/S0048969715305519)

Abstract

Global society faces serious “phosphorus challenges” given the scarcity, essentiality, unequal global distribution and, at the same time, regional excess of phosphorus (P). Phosphorus flow studies can be used to analyze these challenges, providing insight into how society (re)uses and loses phosphorus, identifying potential solutions.

 

Phosphorus flows were analyzed in detail for EU-27 and its Member States. To quantify food system and non-food flows, country specific data and historical context were considered. The sectors covered were crop production (CP), animal production (AP), food processing (FP), non-food production (NF) and consumption (HC).

 

The results show that the EU-27 imported 2392 Gg P in 2005, half of which accumulated in agricultural soils (924 Gg) and half was lost as waste (1217 Gg). Net accumulation was 4.9 kg P/ha/year ranging between + 23.2 (Belgium) and − 2.8 (Slovakia). From the system losses, 54% was lost from HC in diverse waste flows and 28% from FP, mainly through incinerated slaughter residues. The largest HC losses (655 Gg) were wastewater (55%), food waste (27%), and pet excreta (11%). Phosphorus recycling rates were 73% in AP, 29% in FP, 21% in HC and ~ 0% in NF. The phosphorus use efficiencies showed that, relative to sector input, about 70% was taken up by crops (CP), 24% was retained in animals (AP), 52% was contained in food products (FP), 76% was stored in non-food materials (NF), and 21% was recycled (HC).

 

Although wide-ranging variation between countries, generally phosphorus use in EU-27 was characterized by relatively (1) large dependency on (primary) imports, (2) long-term accumulation in agricultural soils, especially in west European countries, (3) leaky losses throughout entire society, especially emissions to the environment and sequestered waste, (4) little recycling with the exception of manure, and (5) low use efficiencies, because of aforementioned issues, providing ample opportunities for improvement.

Keywords: Phosphorus cycle; Agricultural balance; Food system; EU-27; Europe; Resource management; Nutrient use efficiency; Substance flow analyses

 

Jiechen Wu, Daniel Franzén, Maria E. Malmström, Anthropogenic phosphorus flows under different scenarios for the city of Stockholm, Sweden, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1094-1105, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.024.

(http://www.sciencedirect.com/science/article/pii/S0048969715306847)

Abstract

Today, concerns prevail about the unsustainable use of phosphorus and worldwide eutrophication, thus requiring efficient management of phosphorus flows. With increasing population and associated urban growth, urban management of phosphorus flows in the perspectives of recycling, eutrophication and total budget becomes increasingly important. This study mapped phosphorus flows for a reference year (2013) and a future year (2030) using different scenarios for the city of Stockholm, Sweden. The results indicated that the Swedish goal of recycling phosphorus from wastewater would cover the majority of the total phosphorus budget for Stockholm. However, in 2013, only 10% of phosphorus was recycled for agricultural use, around half of which was from sewage sludge and the other half from food waste. Almost 50% of total phosphorus was sent to landfill/mining waste capping with sewage sludge, for economic reasons and lack of market. Among the scenarios of upstream and downstream urban management options studied in combination with population growth, recovery of phosphorus from sewage sludge had the greatest potential to increase the fraction recycled to agriculture. However, only upstream measures, e.g. changed diet, were able to reduce the total phosphorus budget. Urban management of phosphorus flows based on the different perspectives of recycling, eutrophication or total budget was shown to potentially result in different preferred management actions and both upstream and downstream measures need to be considered. Moreover, management needs to pay attention to small but environmentally sensitive flows, particularly when setting city goals on phosphorus recycling by percentage in a large budget.

Keywords: Phosphorus flow analysis; Scenarios; Phosphorus recycling; Total budget; Eutrophication

 

Bussarakam Thitanuwat, Chongchin Polprasert, Andrew J. Englande Jr., Quantification of phosphorus flows throughout the consumption system of Bangkok Metropolis, Thailand, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1106-1116, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.065.

(http://www.sciencedirect.com/science/article/pii/S0048969715307257)

Abstract

Due to unequal distribution of the world's Phosphorus (P) sources for fertilizer production, an evaluation of P flows throughout the consumption system of a city is needed. The prime objective of this paper is to assess and prioritize P recovery options as to bring about, as much as possible, a close-looped P-for-food system. Using the Bangkok Metropolitan Administration (BMA) as a case study, the aim of this work is to quantify the potential mass flow of P for four major types of urban wastes: domestic wastewater (DWW), septage sludge (SS), food waste (FW) and green garbage (GB) and to determine the recoverable stock of P available. The consumption of food and supplements such as cleansing products and fertilizer is estimated at a rate of 1146.4 g P·cap− 1·year− 1. P contained in wastes being discarded from its average 7.9 million population plus 33.8 million Bangkok-visiting tourists per annum is determined to be 8.01 kt P annually. Only 4% of the above quantity is recycled and used internally for cultivating plants grown in public parks. An annual amount of 7.68 kt P was found to be disposed of in landfills (6.23 kt P) and in the river systems (1.45 kt P). From the findings of this study, therefore, it is recommended that P recovery efforts from BMA's urban wastes should be focused on wastes enrouted to landfills since these constitute 81% of P discarded. As a consequence, solid waste combustion coupled with energy recovery from P-binding organics may be an appropriate means of P recovery. This technology has the potential to reduce waste volume, generate electricity, and produce P-containing ash that can be used for further application on farm lands.

Keywords: Food consumption; Human excreta; Landfill; Phosphorus recovery; Urban wastes; Wastewater treatment

 

Geneviève S. Metson, Graham K. MacDonald, Daniel Haberman, Thomas Nesme, Elena M. Bennett, Feeding the Corn Belt: Opportunities for phosphorus recycling in U.S. agriculture, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1117-1126, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.08.047.

(http://www.sciencedirect.com/science/article/pii/S0048969715305507)

Abstract

The supply of phosphorus (P) is a critical concern for food security. Concentrated mineral P deposits have been the source of almost all new P entering the biosphere. However, this resource is often used inefficiently, raising concerns about both nutrient pollution and future access to fertilizers. One solution to both of these problems is to enhance our ability to capture and recycle P from waste streams. However, the efficacy of doing this has not been rigorously explored. Here, we examine the potential for recycling major P sources in the United States to supply the necessary P for domestic corn (maize) production. Using 2002 population and agricultural census data, we examine the distribution of three key recyclable P sources (human food waste, human excreta, and animal manure) and P demand from grain and silage corn across the country to determine the distance P would need to be transported from sources to replenish P removed from soils in harvested corn plants. We find that domestic recyclable P sources, predominantly from animal manures, could meet national corn production P demands with no additional fertilizer inputs. In fact, only 37% of U.S. sources of recyclable P would be required to meet all P demand from U.S. corn harvested annually. Seventy-four percent of corn P demand could be met by recyclable P sources in the same county. Surplus recyclable P sources within-counties would then need to travel on average 302 km to meet the largest demand in and around the center of the ‘Corn Belt’ region where ~ 50% of national corn P demand is located. We find that distances between recyclable sources and crop demands are surprisingly short for most of the country, and that this recycling potential is mostly related to manure. This information can help direct where recycling efforts should be most-effectively directed.

Keywords: Phosphorus; Corn; Agriculture; Sustainability; Recycling

 

Sirja Hukari, Ludwig Hermann, Anders Nättorp, From wastewater to fertilisers — Technical overview and critical review of European legislation governing phosphorus recycling, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1127-1135, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.064.

(http://www.sciencedirect.com/science/article/pii/S0048969715307245)

Keywords: Phosphorus recycling; Legislation; Wastewater; Sewage sludge; Fertiliser; European Union

 

Hannes Herzel, Oliver Krüger, Ludwig Hermann, Christian Adam, Sewage sludge ash — A promising secondary phosphorus source for fertilizer production, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1136-1143, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.08.059.

(http://www.sciencedirect.com/science/article/pii/S0048969715305623)

Abstract

Sewage sludge incineration is extensively practiced in some European countries such as the Netherlands, Switzerland, Austria and Germany. A survey of German sewage sludge ash showed that the recovery potential is high, approx. 19,000 t of phosphorus per year. However, the survey also discovered that the bioavailability of phosphorus in the sewage sludge ash is poor and that more than half of the ashes cannot be used as fertilizers due to high heavy metal content. A new thermochemical process for sewage sludge ash treatment was developed that transforms the ash into marketable fertilizer products. Sewage sludge ash was thermochemically treated with sodium and potassium additives under reducing conditions, whereby the phosphate-bearing mineral phases were transformed into plant available phosphates. High P-bioavailability was achieved with a molar Na/P ratio > 1.75 in the starting materials. Sodium sulfate, carbonate and hydroxide performed comparably as additives for this calcination process. Potassium carbonate and -hydroxide have to be added in a molar K/P ratio > 2.5 to achieve comparable P-solubility. The findings of the laboratory scale investigations were confirmed by an industrial demonstration trial for an ash treatment with sodium sulfate. Simultaneously, the volatile transition metal arsenic (61% removal) as well as volatile heavy metals such as cadmium (80%), mercury (68%), lead (39%) and zinc (9%) were removed via the off-gas treatment system. The product of the demonstration trial is characterized by high bioavailability and a toxic trace element mass fraction below the limit values of the German fertilizer ordinance, thus fulfilling the quality parameters for a P-fertilizer.

Keywords: Sewage sludge ash; Phosphorus recovery; Thermochemical treatment; Reducing conditions; Heavy metal evaporation; Bioavailability; Sodium sulfate

 

Sebastian Hupfauf, Silvia Bachmann, Marina Fernández-Delgado Juárez, Heribert Insam, Bettina Eichler-Löbermann, Biogas digestates affect crop P uptake and soil microbial community composition, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1144-1154, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.025.

(http://www.sciencedirect.com/science/article/pii/S0048969715306859)

Abstract

Fermentation residues from biogas production are known as valuable organic fertilisers. This study deals with the effect of cattle slurry, co-digested cattle slurry, co-digested energy crops and mineral fertilisers on the activity and composition of soil microbiota. Furthermore, the effect of solid–liquid separation as a common pre-treatment of digestate was tested. The fertilising effects were analysed in an 8-week pot experiment on loamy sand using two crops, Amaranthus cruentus and Sorghum bicolor. Amaranth, as a crop with significantly higher P uptake, triggered stress for occurring soil microbes and thereby caused a reduction of microbial biomass C in the soil. Irrespective of the crop, microbial basal respiration and metabolic quotient were higher with the digestates than with the untreated slurry or the mineral treatments. Community level physiological profiles with MicroResp showed considerable differences among the treatments, with particularly strong effects of solid–liquid separation. Similar results were also found on a structural level (PCR-DGGE). Alkaline phosphatase gene analyses revealed high sensitivity to different fertilisation regimes.

Keywords: Biogas residues; Solid–liquid separation; CLPP; Phosphate solubilising bacteria; ALPS; Phosphorus; Soil

 

Manuel Krähenbühl, Bastian Etter, Kai M. Udert, Pretreated magnesite as a source of low-cost magnesium for producing struvite from urine in Nepal, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1155-1161, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.08.060.

(http://www.sciencedirect.com/science/article/pii/S0048969715305635)

Abstract

Struvite is a solid phosphorus fertilizer that can be recovered easily from source-separated urine by dosing it with a soluble form of magnesium. The process is simple and low-cost, however, previous studies have shown that the cost of magnesium in low-income countries is crucial to the viability and implementation of struvite precipitation. Literature has proposed producing inexpensive magnesium locally by making magnesium oxide from magnesite. This paper aimed to investigate whether process requirements, costs, and environmental impacts would make this process viable for magnesium production in decentralized settings. Magnesite samples were calcined at temperatures between 400 °C and 800 °C and for durations between 0.5 h and 6 h. The release of magnesium was tested by dissolution in phosphate-depleted urine. The optimal processing conditions were at 700 °C for 1 h: magnesite conversion was incomplete at lower temperatures, and the formation of large crystallites caused a decrease in solubility at higher temperatures. The narrow optimal range for magnesium production from magnesite requires reliable process control. Cost estimations for Nepal showed that using local magnesite would provide the cheapest source of magnesium and that CO2 emissions from transport and production would be negligible compared to Nepal's overall CO2 emissions.

Keywords: Calcination; Magnesium ammonium phosphate (MAP); Magnesite; Nutrient recovery; Struvite precipitation; Urine separation

 

Kazuyo Matsubae, Eiji Yamasue, Tadahiro Inazumi, Elizabeth Webeck, Takahiro Miki, Tetsuya Nagasaka, Innovations in steelmaking technology and hidden phosphorus flows, Science of The Total Environment, Volume 542, Part B, 15 January 2016, Pages 1162-1168, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2015.09.107.

(http://www.sciencedirect.com/science/article/pii/S0048969715307671)

Abstract

This article will outline the historical transition in the flow of phosphorus in steelmaking technology, and examine the current and future phosphorus flow in steel production and the peripheral steelmaking processes.

 

History provides many instances of innovative changes in steelmaking processes driven by various issues associated with raw materials which emerged over time, such as supply, quality and cost issues. The major steel countries with a long history, including Sweden and Japan, have shown flexibility in their ability to adapt to the changes in the value of resources and geopolitical conditions over times, and have enacted survival resource utilization measures over many centuries, leading to improvements in their respective steelmaking processes. Considering these success stories, it stands to reason that the ideal state of steelmaking is one with a clear stance with regard to resource policy.

Keywords: Dephosphorization; Steelmaking slag; Phosphorus removal; Technology innovation