Nitrogen Fertilizer Production Research Articles

Sustainable production and in-place utilization of a liquid nitrogenous fertilizer

Sustainable production and in-place utilization of a liquid nitrogenous fertilizer

(Invited) Next Generation Electrified Membrane Technology for Simultaneous Wastewater Treatment and Production of Nitrogen Fertilizer

Recovery and repurposing of wastewater nitrogen such as nitrate (NO3 −) and nitrite (NO2 −) receive increasing attention as the current approaches of biological nitrogen removal or conversion into nitrogen gas (N2) renders high energy footprints. This study reported the first electrified membrane upcycling of NO3 − into NH3 that further converted into ammonia sulfate (NH4SO4), a liquid fertilizer readily for use. Paired electrolysis was used to couple simultaneous cathodic and anodic electrochemical half-reactions to enable nitrate reduction and eliminate the external acid/base consumption. Under a partial current density of 63.8±4.4 mA·cm−2 on a cathodic membrane made of a mixed-valence copper oxide and a polytetrafluoroethylene (PTFE) hydrophobic substrate, a recovery rate and energy consumption of 3100±91 g-(NH4)2SO4·m−2·d−1 and 21.8±3.8 kWh·kg−1-(NH4)2SO4 were achieved with the synthetic feed solution (150 mM NO3 −) flowing into the cathode chamber and the produced NH3 migrating across the cathodic membrane into a trap and anode chambers filled with the flowing 0.5 M Na2SO4 solution. 99.9% NO3 − was removed in the feed after 5 h operation with a NH3 recovery rate of 99.5%. This electrified membrane process was demonstrated to achieve comparable performances of synergistic nitrate decontamination and nutrient recovery using real nitrate wastewater with durable catalytic activity and stability. Specifically, the required electricity cost for converting 10 to 100 mM NO3 − to (NH4)2SO4 was $675 to $408 ton−1, respectively. The obtained (NH4)2SO4 may be sold as fertilizer at a price of 533 $·ton−1 (according to USDA) and further offset the cost of the NO3 − removal.According to the International Fertilizer Association, in 2018 the U.S. ranked second in nitrogen production, representing 11.6% of global production. However, it still requires the importation of nitrogen fertilizer, to fully meet the national demand. The US Environmental Protection Agency reports that in 2013, ~38 kg of nitrogen per acre per year was used for fertilization, and in 2016, 94 million acres of corn were planted in the US, representing ~40% of US fertilizer demand. Roughly, this equates to ~8.9 billion kg of nitrogen per year needed to meet total US fertilization demand. The nitrogen available in drinking water sources is roughly 65 million kg per year, and the nitrogen available in wastewater sources is roughly 2.4 billion kg per year. Thus, by fully recovering the nitrogen from wastewater 34.3% of the US nitrogen fertilizer requirement could be met. This could also further mitigate the increase in nitrogen fertilizer prices due to blocked nitrogen fertilizer imports and even free the US from nitrogen fertilizer imports. According to U.S. Department of Agriculture, the average U.S. farm price of sulfate of ammonium fertilizers is $533 per ton. Even leaving aside the revenue generated by the treatment of nitrogen-containing sewage, the market size of nitrogen fertilizer produced through sewage is as high as $12.8 billion.

High-Rate and Sustainable Production of Urea and Ammonia via Electrochemical Reduction of CO2 and Nitrates

Over the past century, nitrogen fertilization has fed approximately 27% of the world’s population.1 Urea and ammonia are two of the most important nitrogen fertilizers used world-widely. The current industrial production of urea is mainly realized by an energy-intensive reaction of carbon dioxide and ammonia under harsh conditions (150-200 °C, 150-250 bar) with large energy consumption, for which nearly 80% of synthesized ammonia is used.2 Furthermore, ammonia is also produced under extreme condition (350-550 °C, 150-350 bar) by an energy-consuming Haber-Bosch method.3 Therefore, it is of great significance to synthesize urea and ammonia under mild conditions to meet the demands of ever-increasing population in the world. The electrocatalytic co-reduction of CO2 and NO3 - emerges as a promising approach to realize the direct synthesis of urea via C-N coupling, with ammonia produced as a side product. However, the state-of-the-art yield rates of urea and ammonia through this electrosynthesis are typically below 1 mg h-1 mgcat -1 and 3 mg h-1 mgcat -1.4, 5 In this study, we realize high-rate production of urea on an economic Cu-based organic molecule catalyst through electrochemically coupling CO2 with NO3 -, with ammonia as another useful byproduct. The rationally design of the catalysts guarantees the accurate adsorption and activation of NO3 - and CO2, which further promotes the desired electrochemical C-N coupling in urea synthesis. Efficient urea synthesis was achieved with yield rates ranging from 2.7 to 3.6 mg h-1 mgcat -1 in a potential window of -0.49~-0.67V vs. RHE, together with ammonia with high yield rates ranging from 0.15 to 9.7 mg h-1 mgcat -1. This work proposes an appealing route of sustainable production of artificial nitrogen fertilizers with high efficiencies. Widespread adoption of this approach is promising to re-use the greenhouse gas CO2 and NO3 - from waste toward a full circulate of economy and sustainable energy consumption. The demonstrated production of nitrogen fertilizer in conjunction with renewable electricity is of great potential to meet the rising demand for global food security. Acknowledgements Research Grants Council (26206115, 16304821 and 16309418) and Innovation and Technology Commission (grant no. ITC-CNERC14EG03) of the Hong Kong Special Administrative Region. The work described in this paper was substantially supported by a fellowship award from the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. HKUST PDFS2021-4S12). References J. W. Erisman, M. A. Sutton, J. Galloway, Z. Klimont and W. Winiwarter, Nat. Geosci., 2008, 1, 636-639.M. Yuan, J. Chen, Y. Xu, R. Liu, T. Zhao, J. Zhang, Z. Ren, Z. Liu, C. Streb, H. He, C. Yang, S. Zhang and G. Zhang, Energy Environ. Sci., 2021, 14, 6605-6615.A. J. Martín, T. Shinagawa and J. Pérez-Ramírez, Chem, 2019, 5, 263-283.C. Lv, L. Zhong, H. Liu, Z. Fang, C. Yan, M. Chen, Y. Kong, C. Lee, D. Liu, S. Li, J. Liu, L. Song, G. Chen, Q. Yan and G. Yu, Nat. Sustain., 2021, 4, 868-876.X. Wei, X. Wen, Y. Liu, C. Chen, C. Xie, D. Wang, M. Qiu, N. He, P. Zhou, W. Chen, J. Cheng, H. Lin, J. Jia, X.-Z. Fu and S. Wang, J. Am. Chem. Soc., 2022, 144, 11530-11535.

Environmental impact of organic and conventional wine grape production, a case study from Wuwei wine region, Gansu Province, China

The City of Wuwei was the first place in Gansu province to cultivate grapes for wine production and is representative of wine grape growing in arid areas across China. In the interest of advancing green agricultural development and in order to cope with a changing climate, viticulture in China is experiencing a shift towards greener production methods. In order to do this, a better understanding of the environmental impacts associated with production at the farm level is needed. This study assessed three different wine grape production chains (one organic and two conventional) using life cycle assessment (LCA) in the Wuwei wine region of Gansu Province. Results show that non-renewable energy (NR) consumption is higher at the pre-farm stage compared to on-farm consumption. In addition, nitrogen fertilizer (N) and electricity production, account for 32.5% and 30% respectively in conventional production, whilst in organic farming, electricity generation and pesticide production account for 62% and 22% respectively. Pre-farm activities were found to have a higher impact on global warming potential (GWP) than on-farm operations. The average contribution of N and electricity production was 36% and 32% respectively in conventional production during the pre-farm stage, while in organic farming, the contribution of electricity generation dominated at 68%. Organic fertilizer, N and electricity production are the major contributors to acidification potential (AP) and pesticide production contributes the most to eutrophication potential (EP) in the pre-farm phase·NH3 and NO3--N emissions are dominant contributors to on-farm AP and EP respectively. N2O, NH3, and NO3--N emissions are the top 3 contributors to GWP, AP and EP in the on-farm stage are mainly caused by overuse of N. In general, organic production has a lower environmental impact index than conventional farming. Options for minimizing environmental burdens include: the use of biotic materials in vineyard infrastructure; soil testing-based fertilization; deficit irrigation, policy innovation and strengthening the enabling environment for laws and regulations.

Life cycle assessment of potential environmental burden and human capital loss caused by apple production system in China

As one of the representative fruits of China, apple plays an important role in the overall agricultural production system. However, the large amount of chemical inputs in apple production has potential detrimental impacts on the environment and human health, and thus threatens the achievement of sustainable development goals. Therefore, a comprehensive evaluation of the environmental burden (EB) and human capital (refer to human lives) loss (HCL) caused by apple production system (APS) is urgently needed to suggest directions for improvement. A method widely used to measure impacts from both the use of resources and the emissions generated in the agriculture sector is the life cycle assessment (LCA). In this study, the EB and HCL caused by the APS have been determined from two phases using the LCA methodology in China. The results show that the leading cause of EB in the agricultural materials' production phase is nitrogen fertilizer (N) production, and in the farming phase is chemical fertilizer use. The top 5 major pollutants that cause potential damage to human health in APS are carbon dioxide (CO2), ammonia (NH3), nitrogen dioxide (N2O), nitrate (NO3), and sulfur oxides (SOx). The human health risk (HHR) is 5.84 × 10-2 disability-adjusted life year to cultivate 1ha of the apple orchard 1year, and the corresponding HCL is about 4230 Chinese yuan (CNY). Under the scenario analysis of a 15% reduction in chemical fertilizer use and a 20% increase in organic fertilizer (mainly dried sheep dung) use, most of the environmental impact categories have a decreasing trend, and the HCL decreased by 438 CNY of 10.36%. Therefore, chemical fertilizer (especially N) is the most critical environmental hotspot in APS, and our results suggest that the replacement of chemical fertilizers by organic fertilizers is an effective solution to reduce the potential EB and HCL and improve the sustainability of the APS.

Toward Reducing the Energy Cost of NOx Formation in a Spark Discharge Reactor through Pinpointing Its Mechanism

Interest in sustainable nitrogen fertilizer production using plasma technology is rapidly growing, and this method is a promising way to decentralize fertilizer synthesis and achieve carbon-free production. However, improving efficiency remains a major challenge for the industrial application of this technology. Herein, we present comprehensive experiments using spark discharge to pinpoint the key factors affecting the efficiency of this process and provide technical approaches to improve the energy usage. We found that applying a bipolar voltage at high frequencies greatly benefited the NOx yield and its efficiency via the utilization of residual species. Measurements using active cooling for the reactor and electrodes revealed that the chemical loss process was not significant, but the energy loss during the heating of the electrode was the dominant loss process, particularly at high frequencies (>20 kHz) where an anchor state of the spark was reached. However, the beneficial effects of higher frequencies compensated for and mitigated the higher power loss resulting in slowing the increase of the energy cost with the energy density. Moreover, enlarging the plasma zone (reaction channel) by increasing the electrode gap was an effective approach for enhancing the energy usage for the desired reaction. Further, the limitations of enlarging the gap were resolved by inserting a floating electrode in the large gap, yielding higher NOx production (1.8%–3.0%) at a lower energy cost (1.9–4.4 MJ/mol), and further enhancements could be achieved by optimizing the reactor configuration. Therefore, the results provide an important basis for the further development and optimization of plasma reactors for efficient chemical reactions.

Sustainable ammonia recovery from anaerobic digestion effluent through pretreating the feed by biomass ash

Ammonia recovery from anaerobic digestion (AD) effluent by vacuum membrane distillation (VMD) is a sustainable and low-carbon footprint strategy for nitrogen fertilizer production and waste treatment. However, due to the good buffering performance of AD effluent, lots of alkali chemicals are consumed to adjust the pH value, thereby increasing the treatment cost. To reduce the consumption of alkali chemicals, biomass ash (BA) is proposed as the alternative to replace the alkali chemical for pretreating the AD effluent before ammonia recovery in this study. Compared with the case using NaOH for pH adjustment, the ammonia separation factor increases by 40 % for BA addition case. Meanwhile, the 30-h VMD experiment for AD effluent treatment is conducted to testify to the stability. Additionally, the high germination index (GI) value (0.84) illustrates the potential of ammonia-removed AD effluent in agricultural applications. Furthermore, the greenhouse emission of ammonia recovery from AD effluent pretreated with BA is only 2.06 kg-CO2 eq/kg, which decreases by 51 % compared with that of the Haber-Bosch process. Finally, BA addition adopted for AD effluent pretreatment has economic superiority to NaOH addition. Inferably, using BA to pretreat the AD effluent can be acted as a high-efficacy and sustainable candidate strategy for ammonia recovery.

Electrocatalytic Nitrate Reduction to Ammonia By Oxide-Derived Copper with Stacking Faults

The significant change of nitrogen cycle as a result of growing production and industrial use of nitrogen fertilizers has led to great environmental concern. The nitrate (NO3 -) in groundwater and industrial wastewater pose a serious threat to the nitrogen cycle and human health, which creates a need for efficient methods that can convert nitrate species. Although many techniques such as biological denitrification, ion exchange, reverse osmosis, and electrodialysis have been developed for NO3 --rich water remediation, electrocatalytic nitrate reduction reaction (NO3RR) is a promising technology that utilize electricity from renewable solar/wind energies to selectively reduce NO3 - to nitrogen (N2) or ammonia (NH3). Of note that NH3 is a fertilizer source and is also considered as a green hydrogen-rich fuels. Therefore, converting NO3 - in wastewater to recyclable NH3 is attractive with regard to environmental protection and energy saving.Metal oxide catalysts with well-controlled shape and size are currently developed to explore catalytic performance trends and intrinsic mechanism for the NO3RR. For example, Co3O4-based nanoparticles and nanosheet array exhibit improved performance because of the optimized exposed surface and size distribution. TiO2 nanotube arrays with anatase structure displayed better electrocatalytic activity than those with rutile structure. These findings have demonstrated that metal oxide catalysts with subtle composition and crystal structure play an important role in enhanced performance for the NO3RR. However, the redox potential for metal oxide reduction is more positive than the potential required for the NO3RR, so metal oxides can be further reduced to metal state under NO3RR.During the reduction process, the loss of structural oxygen ions in metal oxide catalyst would lead to its nonstoichiometry. Accordingly, the electrochemical reduction conditions may drive the generation of defects to accommodate the nonstoichiometry. Therefore, we hypothesized that the substantial structural perturbations such as dislocations could induce lattice strains in the defect region. Such lattice strains will modulate the local surface electronic structure of the catalysts, tuning the interaction between the reaction species and catalyst surface. As a result, the catalytic activity of metal oxides could be optimized.In this study, we selected Cu-based oxide electrodes to fully investigate the structural change and its effects on catalytic performance towards NO3RR. We found that Cu oxide catalysts have a distinct structural change during the NO3RR. The Cu oxide catalysts were reduced to metallic Cu under the negative potential of NO3RR, which serves as the actual active species. More importantly, we found that abundant stacking faults were formed on the oxide-derived Cu surfaces due to the applied negative potential during the NO3RR or the electroreduction pretreatment. The in situ electrochemical reduction-generated stacking faults can be utilized to increase NO3 --N removal, NH4 +-N selectivity, and NH3 Faradaic efficiency up to 93, 94, and 80%, respectively. On the basis of theoretical and experimental investigations, it is concluded that the tensile strain resulting from the stacking faults facilitates NO3 - adsorption and suppresses hydrogen evolution reaction. This work not only helps explain the improved reactivity of related metal oxide for the NO3RR, but also provides a general strategy to develop active and stable electrocatalysts with rational designed surface structure. Figure 1

Influence of modified fertilizers on crop growth, productivity and soil biological values under rice (Oryza sativa) - wheat (Triticum aestivum) cropping system of Punjab, India

In the last 60 years, chemical fertilizer has played a significant role in world food production. It provides around half of the total amount of N that crops need. Nitrates (NO3) leaching, ammonia (NH3) volatilization and nitrous oxide (N2O) emissions contribute to low crop production efficiency (10 to 50 percent) principally due to the loss of N through these processes. Furthermore, nitrogen fertilizer production costs are extremely high. Technology like nitrogen inhibitors and slow-releasing nitrogen fertilizers are used to boost nutrient uptake, fertilizer use efficiency, and crop yields as a result of these situations. Typical haplustept soils were studied to see how changing fertilizers affected growth, yield, and soil genetic indicators. Fertilizer doses and sources affect soil biological characteristics, which in turn affects enzymatic activity. In the right circumstances, enzymes alter the nitrogen supply in the soil and the plant's expansion and limestone structure. The Lovely Professional University School of Agriculture, Phagwara, Punjab, conducted two years of fertilizer studies in a rice-wheat cropping system on typical Haplustept soils from 2018 to 2020. Neem coated urea + PK + S + Zn–EDTA performed significantly better than the other treatments for almost all crop growth and agronomic yield attributing characteristics (plant height, number of tillers, effective tillers, panicle/spikelet length and grain per spik, test weight, grain and straw yields). At various stages of rice-wheat growth, enzyme activity in the soil (dehydrogenase and aryl sulfatase) was also measured in the current study. Enzyme activity peaked at the heading stage in surface soil in all treatments, and then steadily declined thereafter. For both stages of crop growth in surface soil, the highest dehydrogenase and aryl sulfatase activity was found in urea + PK + S + Zn –EDTA covered with Neem. Anhydrous ammonia was shown to have the lowest enzymatic activity.

Exploiting the Potential of Bioreactors for Creating Spatial Organization in the Soil Microbiome: A Strategy for Increasing Sustainable Agricultural Practices

Industrial production of synthetic nitrogen fertilizers and their crop application have caused considerable environmental impacts. Some eco-friendly alternatives try to solve them but raise some restrictions. We tested a novel method to produce a nitrogen bioinoculant by enriching a soil microbial community in bioreactors supplying N2 by air pumping. The biomass enriched with diazotrophic bacteria was diluted and applied to N-depleted and sterilized soil of tomato plants. We estimated microbial composition and diversity by 16S rRNA metabarcoding from soil and bioreactors at different run times and during plant uprooting. Bioreactors promoted the N-fixing microbial community and revealed a hided diversity. One hundred twenty-four (124) operational taxonomic units (OTUs) were assigned to bacteria with a greater Shannon diversity during the reactor’s steady state. A total of 753 OTUs were found in the rhizospheres with higher biodiversity when the lowest concentration of bacteria was applied. The apparent bacterial abundance in the batch and continuous bioreactors suggested a more specific functional ecological organization. We demonstrate the usefulness of bioreactors to evidence hidden diversity in the soil when it passes through bioreactors. By obtaining the same growth of inoculated plants and the control with chemical synthesis fertilizers, we evidence the potential of the methodology that we have called directed bioprospecting to grow a complex nitrogen-fixing microbial community. The simplicity of the reactor’s operation makes its application promising for developing countries with low technological progress.

Determination of Optimum Conditions with Regression Analysis within the Scope of 6 Sigma for Eliminating Caking Problem in Nitrogen Fertilizers

In the nitrogen fertilizer industry, the nitrogen content of chemical fertilizers is an important parameter that determines its physical strength, storage capacity and storage life. The production variables that determine this physical parameter, which is characterized as degradation and caking, can be expressed as the characteristics that determine the course of the chemical process. Although there are improvements in reaction conditions to solve the caking problem, the cost problem of the manufacturer limits the processing conditions. For this reason, in order to minimize the cost problem in any nitrogen fertilizer production process, the analysis of working conditions and the development of quality management systems accordingly constitute the focus of the manufacturer. In this study, within the scope of lean production, regression analysis of the 6-sigma quality method system was performed, the process parameters during the production were analyzed, the optimum conditions were determined and the effect on the production cost was investigated by comparing with the current production conditions.

Dynamic Control of Liquid Biomass Digestate Distillation Combined with an Integrated Solar Concentrator Cycle for Sustainable Nitrogen Fertilizer Production

Dynamic Control of Liquid Biomass Digestate Distillation Combined with an Integrated Solar Concentrator Cycle for Sustainable Nitrogen Fertilizer Production

Production and Properties of Native Potato Starch-Coated Urea

This work is dedicated to researching the possibilities of using starch coating for slow-release fertilizers. Urea was used as nitrogen containing component, because it is the most suitable for the production of slow-release nitrogen fertilizers and has the highest concentration of nitrogen – 46.6 %. During the studies, native potato starch film was prepared and its stability was evaluated, subsequently, urea was coated with starch film/coating and the influence on properties of fertilizer granules (hygroscopicity and strength) was evaluated. Single and/or multiple layered films were formed during the coating process and the influence of coating thickness on urea solubility was researched. It was found that the mechanical properties of urea with double coating change quite insignificantly while coating reduces the solubility of urea by more than 20 %.

Electrocatalytic Reduction of Nitrogen to Ammonia in Ionic Liquids

Ammonia (NH3) is an important raw material for nitrogen fertilizer production and is widely used in industry. It is also a carbon-free renewable fuel and an excellent hydrogen storage material. Reaction conditions of the traditional Haber–Bosch process are very harsh even though it supports most of today’s NH3 production. Recently, the electrocatalytic nitrogen reduction reaction (NRR) has become one of the effective alternative methods to the traditional Haber–Bosch process due to the advantages of mild operation conditions and almost no environmental pollution. Ionic liquids (ILs) act as one of the green solvents that possess a lot of unique features and have shown excellent performance in the electrocatalytic NRR process. In this perspective, we summarize the fundamentals of the electrocatalytic NRR, the role of ILs in several typical electrocatalytic processes, and the possible role of ILs in the electrocatalytic NRR process. Moreover, the selection principles and issues of the application of ILs as well as the future development directions for the electrocatalytic NRR process are presented.

Digitally manufactured air plasma-on-water reactor for nitrate production

The sustainable production of food to support the increasing world population is one of humanity’s most pressing challenges. Plasma activated water, produced using renewable energy, can help fulfill plants’ needs in sustainable agriculture approaches. The design, implementation, and characterization of a digitally manufactured air plasma-on-water reactor (POWR) for the synthesis of nitrate as green nitrogen fertilizer is presented. The interaction of air plasma-generated reactive oxygen and nitrogen species with water produces nitrate (NO3 −) and related species, which are the main nitrogen-containing nutrients for plants. The mild conditions of the operation of the POWR opens the possibility to use plastics, particularly through digital manufacturing strategies such as 3D-printing, for its fabrication. A pin-to-plate reactor configuration powered by high-voltage alternating power is chosen due to its simplicity and efficacy. A computational thermal-fluid model is used to evaluate the design and attain expected operational characteristics. The experimental characterization of the POWR encompassed design and operation parameters, namely electrode-water spacing, air flow rate, and voltage level. A machine learning approach is implemented to extract and quantify characteristic features of the plasma–water interaction, such plasma volume and plasma–water interface area. Experimental results revealed that the nitrate production rate varies linearly with dimensionless plasma volume. The design, fabrication, and characterization methods presented can be adapted to other POWRs and help enable on-demand nitrogen fertilizer production at low environmental and economic cost.

Люцерна — высокобелковая кормовая культура

The results of selection studies conducted at the Central Experimental Base of the V.R. Williams in the Non-Chernozem Zone of the Russian Federation are presented. Brief data on promising varieties of alfalfa created in the department of alfalfa breeding for the yield of green and dry mass, crude protein and other indicators are presented. Alfalfa varieties of a new generation adapted to local soil and climatic conditions have been created. Alfalfa is one of the best legume grasses for the preparation of high-protein feed. Alfalfa is a culture that is characterized by ecological plasticity, longevity, capable in many regions of Russia to solve the problem of eliminating the deficiency of vegetable protein in the diets of farm animals. It can be used as a legume component of grass mixtures on pastures and hayfields of the Non-Chernozem zone of Russia. The level of productivity and sustainability of fodder agrophytocenoses is determined by the competitiveness of species and varieties. Alfalfa varieties have a low competitive ability, do not withstand three or four times mowing, quickly fall out of the grass stand. It is known that the use of mineral nitrogen in meadow and field feed production is limited due to high energy costs in the production of nitrogen fertilizers. Therefore, the need for nitrogen in meadows and pastures should be met by legume-cereal grass mixtures, for which it is necessary to create new varieties of legumes, in particular alfalfa variable or hybrid.

China’s greenhouse gas emissions for cropping systems from 1978–2016

China has committed to reaching carbon neutrality by 2060, which will require a drastic cut in greenhouse gas (GHG) emissions from all sectors, including those from agricultural activities. A comprehensive, long-term, and spatially-precise profile of agricultural GHG emissions can help to accurately understand drivers of historical emissions and their implications for future mitigation. This study constructs province-level agricultural GHG emissions in China from 1978 to 2016. It considers primary and secondary emissions from a full range of agricultural activities related to crop farming, including crop residue open burning, rice cultivation, cropland change, cropland emissions, machinery use, nitrogen fertilizer production, and pesticide production. Annual or interpolated activity data from official sources and the latest emission factors available for China were adopted in this study. The data can be used in spatial and temporal analysis of emissions from cropping systems as well as the design of mitigation strategy in China.

Greenhouse gas emissions intensity of food production systems and its determinants.

It is estimated that about 1/4th of all greenhouse gas (GHG) emissions may be caused by the global food system. Reducing the GHG emissions from food production is a major challenge in the context of the projected growth of the world’s population, which is increasing demand for food. In this context, the goal should be to achieve the lowest possible emission intensity of the food production system, understood as the amount of GHG emissions per unit of output. The study aimed to calculate the emission intensity of food production systems and to specify its determinants based on a panel regression model for 14 countries, which accounted for more than 65% of food production in the world between 2000 and 2014. In this article, emission intensity is defined as the amount of GHG emissions per value of global output. Research on the determinants of GHG emissions related to food production is well documented in the literature; however, there is a lack of research on the determinants of the emission intensity ratio for food production. Hence, the original contribution of this paper is the analysis of the determinants of GHG emissions intensity of food production systems. The study found the decreased of emission intensity from an average of more than 0.68 kg of CO2 equivalent per USD 1 worth of food production global output in 2000 to less than 0.46 in 2014. The determinants of emission intensity decrease included the yield of cereals, the use of nitrogen fertilizers, the agriculture material intensity, the Human Development Index, and the share of fossil fuel energy consumption in total energy use. The determinants of growth of emission intensity of food production systems included GDP per capita, population density, nitrogen fertilizer production, utilized agriculture area, share of animal production, and energy use per capita.

Efficient production of lignin-based slow-release nitrogen fertilizer via microwave heating

Microwave heating was first introduced into the Mannich reaction to prepare lignin-based organic slow-release nitrogen fertilizers. The response surface method was applied to acquire optimal conditions (amount of ethylenediamine, microwave heating temperature and time) for lignin with high organic nitrogen content. FT-IR spectra result revealed that the organic nitrogen was successfully grafted into the macromolecular structure of lignin. Elemental analysis showed that the organic nitrogen content increased (4.11–7.26 %) in lignin with the ethylenediamine content (4.0–8.0 g) or temperature (60–80 °C) or time (10–40 min) of microwave heating increased. By response surface analysis, the highest organic nitrogen content (7.84 %) was obtained under the condition (8.0 g ethylenediamine, 80 °C, 40 min). Contact angle, scanning electron microscopy, particle size, zeta potential, and thermal analysis results showed that lignin-based nitrogen fertilizers exhibited good slow-release properties of nitrogen. In short, lignin could be efficiently converted into organic slow-release nitrogen fertilizers by microwave heating. The approach with short processing time and simple operation was a potential method for preparing lignin-based fertilizer. The experiment will help to promote the value-added application of TL in the agricultural field.

Environmental assessment of urine, black and grey water separation for resource recovery in a new district compared to centralized wastewater resources recovery plant

Current trends show that wastewater treatment plants (WWTPs) will intend to shift towards water resources recovery facility (WRRF), however nutrients recovery in WRRF is limited by the need of highly concentrated stream for the process. Source separation can help to increase this potential, but assessment is necessary to evaluate the whole system at district scale. In this study three scenarios based respectively on urine diversion, blackwater and greywater separation were compared to the conventional end-of-pipe strategy with adjunction of treatment at the centralized WRRF for producing renewable fertilizers and energy. Life cycle assessment was used to compare environmental impacts. The study was performed to represent the implementation of a new district in an urban context. Treatments have been chosen among the best technologies available for resource recovery. Results show that for maximizing nutrients recovery and limiting the greenhouse gas emissions, urine and blackwater separation are better scenarios than conventional mixing option and centralized WRRF. Indeed it allows to mitigate by at least 60% the nitrous oxide (N2O) emissions and to avoid nitrogen fertilizer production which emits large amount of greenhouse gases (8.6 kg CO2-Eq/kgN). Urine source separation is particularly beneficial by recovering nitrogen at a low environmental footprint: impact on climate change decreases by 45% compared to the Reference. The separation of blackwater treated at decentralized scale shows a decrease of 34% of impact on climate change compared to Reference, thus a little worse than Urine due to a higher external energy demand at decentralized scale for nitrogen recovery. Phosphorus can be recovered in all the source separation system without additional climate change impact. If the priority is given at water reclamation the treatment of blackwater and greywater separately is a valuable option. However energy balance and greenhouse gases emissions analysis do not support this scenario if highly energy consuming technology is used for greywater treatment (more than 0.56 kWh/m3 treated). It would become acceptable in case of decarbonized energy or if tap water production is a high greenhouse gases emitter.