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28 pages, 15654 KiB

Open AccessArticle

Geological Formation Mechanism and Thermal Resources Assessment of Geothermal Spring in Lushan County, China

by Qing Zhang, Zhaohui Bin, Yongji Xu, Shaohe Luo, Li Zhao and Jiazhong Qian

Appl. Sci. 2020, 10(2), 592; https://doi.org/10.3390/app10020592 - 14 Jan 2020

Cited by 1 | Viewed by 2619

Geothermal resource is green and clean energy, and geothermal field is widely distributed in the world. Its development and utilization has little harm to the environment, can change the current situation of energy consumption mainly based on fossil energy, reduce carbon emissions, and [...] Read more.

Geothermal resource is green and clean energy, and geothermal field is widely distributed in the world. Its development and utilization has little harm to the environment, can change the current situation of energy consumption mainly based on fossil energy, reduce carbon emissions, and promote the development of techniques for sustainable processing of natural resources. However, each geothermal field has its own characteristic structure, origin, and storage, so it is necessary to carry out targeted research. In this paper, the geothermal characteristics and geological characteristics of the geothermal belt in Lushan County, China are analyzed by means of remote sensing interpretation, field investigation and observation, geophysical exploration, long-term observation, pumping test, and hydrochemical analysis. Result of this study shows that the geothermal belt of Lushan geothermal fields is as a result of primary thermal control and heat conduction structures of the near east-west Checun-Xiatang deep fault as well as secondary thermal control and heat conduction structures of near north-east and north-west secondary faults; and annual recoverable geothermal energy of whole geothermal field is 4.41 × 10¹¹ MJ. The research results will be beneficial for the development and utilization of Lushan hot springs. At the same time, it also provides reference for more geothermal research. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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18 pages, 274 KiB

Open AccessArticle

Can Phosphorus from Recycled Fertilisers Replace Conventional Sources? An Agronomic Evaluation in Field-Scale Experiments on Temperate Luvisols

by Magdalena Jastrzębska, Marta K. Kostrzewska and Agnieszka Saeid

Appl. Sci. 2019, 9(10), 2086; https://doi.org/10.3390/app9102086 - 21 May 2019

Cited by 7 | Viewed by 2513

Abstract

Facing phosphate rock scarcity, growing food requirements and pollution problems with phosphorus (P)-containing waste, re-using P as fertiliser is becoming a real need. Innovative fertilisers from sewage sludge ash, animal bones and blood, activated by phosphorus solubilising microorganisms (PSM), were tested in field [...] Read more.

Facing phosphate rock scarcity, growing food requirements and pollution problems with phosphorus (P)-containing waste, re-using P as fertiliser is becoming a real need. Innovative fertilisers from sewage sludge ash, animal bones and blood, activated by phosphorus solubilising microorganisms (PSM), were tested in field experiments with winter or spring wheat and compared with commercial fertilisers (superphosphate, phosphorite). Three levels of P doses were established (17.6, 26.4 and 35.2 kg/ha). This paper discusses the fertilisers’ impact on total soil P content and on the P content and P accumulation in wheat grain and straw, weeds and post-harvest residues. Recycled fertilisers maintained soil P stocks and supplied plants with P in the same way as traditional fertilisers, and ensured a comparable P pool in the post-harvest residues to traditional fertilisers. They also did not favour weeds during competitive crop-weed interactions. The PSM included in waste-fertilisers did not exert an evident effect on the soil P content or on the P content and P accumulation in plant biomass. The findings show the potential of recycled fertilisers to act as a substitute to fertilisers from primary sources. Further field research is needed to settle the question of the reasonability of PSM inclusion into fertilisers. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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13 pages, 1579 KiB

Open AccessArticle

Rapid Green Extractions of C-Phycocyanin from Arthrospira maxima for Functional Applications

by Mari Carmen Ruiz-Domínguez, Marjorie Jáuregui, Elena Medina, Carolina Jaime and Pedro Cerezal

Appl. Sci. 2019, 9(10), 1987; https://doi.org/10.3390/app9101987 - 15 May 2019

Cited by 32 | Viewed by 3643

Abstract

Cyanobacteria are a rich source of bioactive compounds, mainly in the Arthospira sp., and one of the most interesting components in recent years has been C-phycocyanin (C-PC). There have been several conventional methods for their extraction, among which stand out: chemical products, freezing-thawing [...] Read more.

Cyanobacteria are a rich source of bioactive compounds, mainly in the Arthospira sp., and one of the most interesting components in recent years has been C-phycocyanin (C-PC). There have been several conventional methods for their extraction, among which stand out: chemical products, freezing-thawing (FT); enzymatic, and maceration (M); which have come to be replaced by more environmentally friendly methods, such as those assisted by microwaves (MW) and high-pressure homogenization (HPH). The aim of the research was to use these two “green extraction processes” to obtain C-PC from cyanobacteria Arthrospira maxima because they improve functionality and are fast. Extractions of C-PC were studied by means of two experimental designs for MW and HPH, based on a response surface methodology (RSM) employing, firstly, a factorial design 3³: power (100, 200, and 300 W), time (15, 30, and 60 s), and types of solvents (distiller water, Na-phosphate buffer and, distiller water: Na-phosphate buffer (Ph 7.0; 1:1, v/v); and secondly, two factors with different levels: Pressure (800, 1000, 1200, 1400, and 1600 bar) and, types of solvents (distilled water, Na-phosphate buffer (pH 7.0) 100 mM and, Na-phosphate buffer:water 1:1, (v/v)). Optimum C-PC content was achieved with the HPH process under Na-phosphate solvent at 1400 bar (291.9 ± 6.7 mg/g) and the MW method showed improved results using distilled water as a solvent at 100 W for 30 s (215.0 ± 5.5 mg/g). In the case of conventional methods, the freeze–thawing procedure reached better results than maceration using the buffer (225.6 ± 2.6 mg/g). This last one also did not show a significant difference between solvents (a range of 147.7–162.0 mg/g). Finally, the main advantage of using green extractions are the high C-PC yield achieved, effectively reducing both processing times, costs, and increasing the economic and functional applications of the bioactive compound. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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12 pages, 976 KiB

Open AccessArticle

Partition of Cu and Pb in a Two-Stage Fluidized-Bed Waste Gasification System

by Chiou-Liang Lin, Jing-Dong Chou and Wang-Chang Weng

Appl. Sci. 2019, 9(8), 1576; https://doi.org/10.3390/app9081576 - 16 Apr 2019

Cited by 1 | Viewed by 1882

Abstract

In this study, a two-stage fluidized-bed gasification system was used to determine the distribution of heavy metal contaminants in simulative waste and evaluate the effect of the bed operating temperature, Equivalence ratio (ER), and Steam/Biomass ratio (S/B) in stage 1. The heavy metal [...] Read more.

In this study, a two-stage fluidized-bed gasification system was used to determine the distribution of heavy metal contaminants in simulative waste and evaluate the effect of the bed operating temperature, Equivalence ratio (ER), and Steam/Biomass ratio (S/B) in stage 1. The heavy metal concentrations in bed materials and fly ash were measured in two stages. The results show that as the operating temperature of stage 1 increased, the quantity of heavy metals entrapped by stage 1 bed material decreased, while that captured by stage 2 bed material increased. The less volatile Cu was mostly entrapped in stage 1 bed material. The ER and S/B results show that increasing the ER and S/B caused a slight increase in the concentrations of heavy metals entrapped in stage 1 and stage 2 bed materials. However, the influences of ER and S/B were less than that of temperature. The major factors affecting the heavy metal distribution were the operating temperature and the heavy metal volatility. Stage 2 bed material was able to entrap gaseous heavy metals or particles containing heavy metals by particle filtration and chemical adsorption. Thus, the heavy metals (Cu and Pb) had a downward trend after passing through stage 2. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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10 pages, 1537 KiB

Open AccessArticle

Methods for Sampling Biogas and Biomethane on Adsorbent Tubes after Collection in Gas Bags

by Karine Arrhenius, Andreas Fischer and Oliver Büker

Appl. Sci. 2019, 9(6), 1171; https://doi.org/10.3390/app9061171 - 20 Mar 2019

Cited by 16 | Viewed by 8288

Abstract

Biogas is a renewable energy source with many different production pathways and numerous excellent opportunities for use; for example, as vehicle fuel after upgrading (biomethane). Reliable analytical methodologies for assessing the quality of the gas are critical for ensuring that the gas can [...] Read more.

Biogas is a renewable energy source with many different production pathways and numerous excellent opportunities for use; for example, as vehicle fuel after upgrading (biomethane). Reliable analytical methodologies for assessing the quality of the gas are critical for ensuring that the gas can be used technically and safely. An essential part of any procedure aimed at determining the quality is the sampling and transfer to the laboratory. Sampling bags and sorbent tubes are widely used for collecting biogas. In this study, we have combined these two methods, i.e., sampling in a gas bag before subsequent sampling onto tubes in order to demonstrate that this alternative can help eliminate the disadvantages associated with the two methods whilst combining their advantages; with expected longer storage stability as well as easier sampling and transport. The results of the study show that two parameters need to be taken into account when transferring gas from a bag on to an adsorbent; the water content of the gas and the flow rate used during transfer of the gas on to the adsorbent. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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8 pages, 1841 KiB

Open AccessArticle

Effects of Mixing Conditions on Floc Properties in Magnesium Hydroxide Continuous Coagulation Process

by Yanmei Ding, Jianhai Zhao, Lei Wei, Wenpu Li and Yongzhi Chi

Appl. Sci. 2019, 9(5), 973; https://doi.org/10.3390/app9050973 - 07 Mar 2019

Cited by 12 | Viewed by 2951

Abstract

Magnesium hydroxide continuous coagulation process was used for treating simulated reactive orange wastewater in this study. Effects of mixing conditions and retention time on the coagulation performance and floc properties of magnesium hydroxide were based on the floc size distribution (FSD), zeta potential, [...] Read more.

Magnesium hydroxide continuous coagulation process was used for treating simulated reactive orange wastewater in this study. Effects of mixing conditions and retention time on the coagulation performance and floc properties of magnesium hydroxide were based on the floc size distribution (FSD), zeta potential, and floc morphology analysis. Floc formation and growth in different reactors were also discussed. The results showed that increasing rapid mixing speed led to a decrease in the final floc size. The floc formation process was mainly carried out in a rapid mixer; a rapid mixing speed of 300 rpm was chosen according to zeta potential and removal efficiency. Reducing retention time caused a relatively small floc size in all reactors. When influent flow was 30 L/h (retention time of 2 min in rapid mixer), the average floc size reached 8.06 μm in a rapid mixer; through breakage and re-growth, the floc size remained stable in the flocculation basin. After growth, the final floc size reached 11.21 μm in a sedimentation tank. The removal efficiency of reactive orange is 89% in the magnesium hydroxide coagulation process. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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17 pages, 3052 KiB

Open AccessFeature PaperArticle

Optimal Depressants and Collector Dosage in Fluorite Flotation Process Based on DoE Methodology

by J.R. Corpas-Martínez, A. Pérez, C. Amor-Castillo, R. Navarro-Domínguez, M.A. Martín-Lara and M. Calero

Appl. Sci. 2019, 9(3), 366; https://doi.org/10.3390/app9030366 - 22 Jan 2019

Cited by 5 | Viewed by 2994

Abstract

Alternative processes have been proposed for selective separation of fluorite and gangue minerals (carbonates and silicates) present in fluorspar ores. Calcination and gravity separation processes are methods that have low efficiency and high cost. Flotation is a chemical process that becomes important when [...] Read more.

Alternative processes have been proposed for selective separation of fluorite and gangue minerals (carbonates and silicates) present in fluorspar ores. Calcination and gravity separation processes are methods that have low efficiency and high cost. Flotation is a chemical process that becomes important when high ore grades are required; however, the selectivity is inhibited by the superficial similarity of the chemical composition of minerals. Accordingly, interactions between dissolved ionic species of fluorite, carbonates, and silicates with some reagents under determinate conditions obstruct the flotation process. In order to optimize the flotation process of a Spanish fluorite ore, this research uses a mathematical model. In this study, the variables were the dose of potato starch, quebracho tree, white dextrine, oleic acid, and sodium silicate. On the other hand, the factors studied were the law of carbonates, silica, and fluorite, in addition to the metallurgical recovery of fluorite. The statistical technique of factor analysis that relates the variables and factors allowed to the optimization of the reagent dosage. Maximum metallurgical recovery was achieved without sacrificing the fluorite grade. The mathematical model adjusts satisfactorily to the results with a correlation coefficient of 91.58% for metallurgical recovery and 98.51% for fluorite grade. Optimizing the process 60.45% of metallurgical recovery and 68.99% of fluorite grade are achieve in the roughing step, using a dosage of 1.68 g·kg⁻¹ of potato starch, 0.86 g·kg⁻¹ of quebracho tree, 1.25 g·kg⁻¹ of dextrin, 3 g·kg⁻¹ of oleic acid, and 0.85 g·kg⁻¹ of water glass. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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Review

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29 pages, 665 KiB

Open AccessReview

Recent Updates on the Use of Agro-Food Waste for Biogas Production

by Marisa Carmela Caruso, Ada Braghieri, Angela Capece, Fabio Napolitano, Patrizia Romano, Fernanda Galgano, Giuseppe Altieri and Francesco Genovese

Appl. Sci. 2019, 9(6), 1217; https://doi.org/10.3390/app9061217 - 22 Mar 2019

Cited by 65 | Viewed by 8831

Abstract

The production of biogas from anaerobic digestion (AD) of residual agro-food biomasses represents an opportunity for alternative production of energy from renewable sources, according to the European Union legislation on renewable energy. This review provides an overview of the various aspects involved in [...] Read more.

The production of biogas from anaerobic digestion (AD) of residual agro-food biomasses represents an opportunity for alternative production of energy from renewable sources, according to the European Union legislation on renewable energy. This review provides an overview of the various aspects involved in this process with a focus on the best process conditions to be used for AD-based biogas production from residual agro-food biomasses. After a schematic description of the AD phases, the biogas plants with advanced technologies were described, pointing out the strengths and the weaknesses of the different digester technologies and indicating the main parameters and operating conditions to be monitored. Subsequently, a brief analysis of the factors affecting methane yield from manure AD was conducted and the AD of fruit and vegetables waste was examined. Particular attention was given to studies on co-digestion and pre-treatments as strategies to improve biogas yield. Finally, the selection of specific microorganisms and the genetic manipulation of anaerobic bacteria to speed up the AD process was illustrated. The open challenges concern the achievement of the highest renewable energy yields reusing agro-food waste with the lowest environmental impact and an increment of competitiveness of the agricultural sector in the perspective of a circular economy. Full article

(This article belongs to the Special Issue Techniques for Sustainable Processing of Natural Resources)

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