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14 pages, 1548 KiB

Open AccessArticle

Analysis of Reject Water Formed in the Mechanical Dewatering Process of Digested Sludge Conditioned by Physical and Chemical Methods

by Beata Bień and Jurand D. Bień

Energies 2022, 15(5), 1678; https://doi.org/10.3390/en15051678 - 24 Feb 2022

Cited by 15 | Viewed by 2191

Abstract

Reject water separated from digested sludge may be a potential source of nutrients due to its high content. However, most often, reject water after sludge dewatering is directed to sewage lines at wastewater treatment plants, negatively affecting their operation, especially in the biological [...] Read more.

Reject water separated from digested sludge may be a potential source of nutrients due to its high content. However, most often, reject water after sludge dewatering is directed to sewage lines at wastewater treatment plants, negatively affecting their operation, especially in the biological part. The activities related to sludge conditioning before dewatering have a direct impact on the quality of the reject water. The reject water of raw digested sludge is characterized by very high concentrations of ammonium nitrogen, at 1718 mgN-NH₄⁺/dm³; phosphates, at 122.4 mgPO₄³⁻/dm³; and chemical oxygen demand (COD), at 2240 mgO₂/dm³. The objective of the research was to determine the impact of selected sludge conditioning methods on the quality of reject water obtained after sludge dewatering. The following parameters were analyzed in the reject water: the chemical oxygen demand (COD), phosphates, ammonium nitrogen, and total suspended solids (TSS). It has been observed that the sludge sonification process increases the content of impurities (COD, phosphates) in reject water with an increase in the amplitude of the ultrasonic field. On the other hand, the chemical reagents cause a decrease in the concentration of the pollutants with an increase of the chemical dose. It has been found that the inorganic coagulant PIX 113 gives much better results regarding the reduction of contamination than the polyelectrolyte Zetag 8180. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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15 pages, 2089 KiB

Open AccessArticle

Potential and Mechanisms for Stable C Storage in the Post-Mining Soils under Long-Term Study in Mitigation of Climate Change

by Aneta Kowalska, Marek Kucbel and Anna Grobelak

Energies 2021, 14(22), 7613; https://doi.org/10.3390/en14227613 - 15 Nov 2021

Cited by 4 | Viewed by 2042

Abstract

Carbon storage in soil increases along with remediation of post-mining soils. Despite many studies on the issue of carbon sequestration in soils, there is a knowledge gap in the potential and mechanisms of C sequestration in post-mining areas. This research, including nuclear magnetic [...] Read more.

Carbon storage in soil increases along with remediation of post-mining soils. Despite many studies on the issue of carbon sequestration in soils, there is a knowledge gap in the potential and mechanisms of C sequestration in post-mining areas. This research, including nuclear magnetic resonance analysis, determines the soil organic carbon formation progress in a long-term study of limestone (S1), and lignite (S2) post-mining soil under different remediation stages. The main remediation target is reforesting; however, S2 was previously amended with sewage sludge. The study showed that for S1, the O-alkyl groups were the dominant fraction in sequestered soil. However, for S2, increased fractions of acetyl-C and aromatic C groups within remediation progress were observed. The remediation of S1 resulted in improved hydrophobicity and humification; however, the decrease in aromatic groups’ formation and C/N ratio was noted. For S2, we noticed an increase for all indicators for sequestered C stability, which has been assigned to the used sewage sludge in remediation techniques. While both post-mining soils showed huge potential for C sequestration, S2 showed much higher properties of sequestered C indicating its higher stabilization which can suggest that soils non-amended with sewage sludge (S1) require more time for stable storage of C. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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13 pages, 2430 KiB

Open AccessArticle

Estimation of Prediction Error in Regression Air Quality Models

by Szymon Hoffman

Energies 2021, 14(21), 7387; https://doi.org/10.3390/en14217387 - 5 Nov 2021

Cited by 5 | Viewed by 1529

Abstract

Combustion of energy fuels or organic waste is associated with the emission of harmful gases and aerosols into the atmosphere, which strongly affects air quality. Air quality monitoring devices are unreliable and measurement gaps appear quite often. Missing data modeling techniques can be [...] Read more.

Combustion of energy fuels or organic waste is associated with the emission of harmful gases and aerosols into the atmosphere, which strongly affects air quality. Air quality monitoring devices are unreliable and measurement gaps appear quite often. Missing data modeling techniques can be used to complete the monitoring data. Concentrations of monitored pollutants can be approximated with regression modeling tools, such as artificial neural networks. In this study, a long-term set of data from the air monitoring station in Zabrze (Silesia, South Poland) was analyzed. Concentration prediction was tested for the main air pollutants, i.e., O₃, NO, NO₂, SO₂, PM₁₀, CO. Multilayer perceptrons were used to model the concentrations. The predicted concentrations were compared to the observed ones to evaluate the approximation accuracy. Prediction errors were calculated separately for the whole concentration range as well as for the specified concentration subranges. Some different measures of error were estimated. It was stated that the use of a single measure of the approximation accuracy may lead to incorrect interpretation. The application of one neural network to the entire concentration range results in different prediction accuracy in various concentration subranges. Replacing one neural network with several networks adjusted to specific concentration subranges should improve the modeling accuracy. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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11 pages, 3377 KiB

Open AccessArticle

Ultrasounds Energy as an Agent of Polyelectrolyte Modification Prior to Sewage Sludge Conditioning

by Lidia Wolny and Paweł Wolski

Energies 2021, 14(19), 6165; https://doi.org/10.3390/en14196165 - 27 Sep 2021

Cited by 5 | Viewed by 1421

Abstract

The presented research concerned the phenomenon of polyelectrolyte changes resulting from modification by applying the ultrasonic field. The main aim of this research was to determine the activation degree of this macromolecular chemical compound and its effect on sewage sludge subjected to conditioning [...] Read more.

The presented research concerned the phenomenon of polyelectrolyte changes resulting from modification by applying the ultrasonic field. The main aim of this research was to determine the activation degree of this macromolecular chemical compound and its effect on sewage sludge subjected to conditioning and followed by dewatering. The overall goal was to investigate the potential way of reducing the dosage of chemical compounds prior to sewage sludge conditioning. The polyelectrolyte samples were sonicated with the ultrasonic disintegrator UD-20 coupled with a sandwich concentrator. The power output of the generator was 180 W and the ultrasonic field frequency was 22 kHz. To describe the geometrical characteristics of the separated phases, the following parameters were determined: surface area (A_A), perimeter (L_A) and non-dimensional coefficient. With reference to the obtained results, the most significant quantitative changes in shape and size of the separated phases were observed for the ultrasonic field exposure time in the range of 0 to 10 s. This was in agreement with the results observed during dewatering of the investigated sewage sludge. In view of the quantitative analysis of the structure of the polyelectrolyte subjected to the ultrasonic modification, dewatering of sewage sludge was considerably improved by the application of the presented method. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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16 pages, 1229 KiB

Open AccessArticle

Towards a Circular Economy: Analysis of the Use of Biowaste as Biosorbent for the Removal of Heavy Metals

by Magdalena Madeła and Monika Skuza

Energies 2021, 14(17), 5427; https://doi.org/10.3390/en14175427 - 31 Aug 2021

Cited by 33 | Viewed by 4096

Abstract

Industrial human activity has led to the release of substantial amounts of heavy metals into the environment. Contamination of water with heavy metals such as lead, cadmium, copper, zinc, chromium, or nickel represents a serious problem. As part of the circular economy, it [...] Read more.

Industrial human activity has led to the release of substantial amounts of heavy metals into the environment. Contamination of water with heavy metals such as lead, cadmium, copper, zinc, chromium, or nickel represents a serious problem. As part of the circular economy, it is appropriate to use biowaste from agriculture, fisheries, and the timber industry as biosorbents. In this literature review, the potential of using these biowaste groups as biosorbents for metal removal is presented. This biowaste is characterized by the presence of carboxyl, hydroxyl, carbonyl, amide, amine, sulfydryl, and other groups on their surface, which form complexes and chelates with metals present in water. Biosorption seems to be a potential alternative to conventional technologies for removing or recovering heavy metals from water or wastewater, which are uneconomical and generate additional waste. The paper demonstrates that harnessing the potential of biowaste to remove metals is beneficial to the environment as they can solve the problem of incineration and realise recycling that meets the circular economy. Although the choice of a suitable biosorbent for the removal of a particular metal involves a lot of research, the high biosorption efficiency, low cost, and renewability justify their use. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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14 pages, 1816 KiB

Open AccessArticle

Conditioning of Sewage Sludge with Physical, Chemical and Dual Methods to Improve Sewage Sludge Dewatering

by Beata Bień and Jurand D. Bień

Energies 2021, 14(16), 5079; https://doi.org/10.3390/en14165079 - 18 Aug 2021

Cited by 18 | Viewed by 3553

Abstract

The paper presents the impact of different methods of sewage sludge conditioning on the improvement of sludge dewatering during pressure filtration processes. The following conditioning methods were tested for sludge preparation: sonication, addition of organic and inorganic chemicals (Zetag 8180, PIX 113 and [...] Read more.

The paper presents the impact of different methods of sewage sludge conditioning on the improvement of sludge dewatering during pressure filtration processes. The following conditioning methods were tested for sludge preparation: sonication, addition of organic and inorganic chemicals (Zetag 8180, PIX 113 and the combined action of both substances). The research covered: physical and chemical analysis of sewage sludge, measurement of capillary suction time as an indicator of sludge dewaterability, some technical parameters of sludge pressure filtration process and the analysis of filtrate to assess the degree of contamination. The results of the research showed that the final water content of the prepared sludge decreased, while the specific filtration resistance increased. Among the tested methods the best results of sludge dewatering effects were obtained for sonicated sludge and its preparation with inorganic coagulant PIX 113. The combined effect of sonication with the addition of chemicals Zetag 8180 and PIX113 to sludge allowed for the reduction of organic substances, ammonium nitrogen and phosphates in filtrate after sludge dewatering. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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19 pages, 18176 KiB

Open AccessArticle

Organizations towards the Evaluation of Environmental Management Tools ISO 14001 and EMAS

by Agnieszka Ociepa-Kubicka, Iwona Deska and Ewa Ociepa

Energies 2021, 14(16), 4870; https://doi.org/10.3390/en14164870 - 10 Aug 2021

Cited by 14 | Viewed by 5766

Abstract

The purpose of this article is to analyze and compare the benefits of and barriers to the implementation of Environmental Management Systems (EMS)—International Standard ISO 14001 and Eco-Management and Audit Scheme (EMAS)—by organizations. This paper attempts to answer the following research questions: 1. [...] Read more.

The purpose of this article is to analyze and compare the benefits of and barriers to the implementation of Environmental Management Systems (EMS)—International Standard ISO 14001 and Eco-Management and Audit Scheme (EMAS)—by organizations. This paper attempts to answer the following research questions: 1. Does the implementation of either ISO 14001 or EMAS bring the same benefits and barriers to organizations? 2. Does the system functioning duration in the company influence internal and external benefits resulting from EMS implementation? 3. Are economic aspects of EMS adoption as important for entrepreneurs as the ecological aspects? This topic is important due to the large disproportions appearing in recent years between the number of companies registered in ISO 14001 and in EMAS, and due to relatively frequent cases of non-renewal of EMAS certifications in recent years. It is crucial because each EMS certified institution has implemented procedures which contribute to better protection of the natural environment. The study was conducted in the form of a survey; questions and answers were specified based on the literature review and the authors’ research. Results indicate that the knowledge-based and organizational problems, as well as the time invested in preparing the documentation, are much more significant than financial problems associated with EMS implementation. Even organizations that previously introduced ISO 14001 still have difficulties with EMAS implementation. The perception of benefits resulting from EMS introduction is related to the system functioning duration in the company. The analysis shows that it is necessary to strengthen economic incentives in order to enable the widest possible dissemination of EMS among companies. Research results can contribute to further simplification and increases in EMS implementation, which may lead to more sustainable development and climate change mitigation, inter alia, due to the improvement in energy efficiency, increased use of renewable energy, and reduction of greenhouse gas emissions. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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19 pages, 1648 KiB

Open AccessArticle

Transition to Circular Economy in the Fertilizer Sector—Analysis of Recommended Directions and End-Users’ Perception of Waste-Based Products in Poland

by Marzena Smol

Energies 2021, 14(14), 4312; https://doi.org/10.3390/en14144312 - 17 Jul 2021

Cited by 28 | Viewed by 4152

Abstract

Circular economy (CE) is an economic model, in which raw materials remain in circulation as long as possible and the generation of waste is minimized. In the fertilizer sector, waste rich in nutrients should be directed to agriculture purposes. This paper presents an [...] Read more.

Circular economy (CE) is an economic model, in which raw materials remain in circulation as long as possible and the generation of waste is minimized. In the fertilizer sector, waste rich in nutrients should be directed to agriculture purposes. This paper presents an analysis of recommended directions for the use of nutrient-rich waste in fertilizer sector and an evaluation of possible interest in this kind of fertilizer by a selected group of end-users (nurseries). The scope of research includes the state-of-the-art analysis on circular aspects and recommended directions in the CE implementation in the fertilizer sector (with focus on sewage-based waste), and survey analysis on the potential interest of nurseries in the use of waste-based fertilizers in Poland. There are more and more recommendations for the use of waste for agriculture purposes at European and national levels. The waste-based products have to meet certain requirements in order to put such products on the marker. Nurserymen are interested in contributing to the process of transformation towards the CE model in Poland; however, they are not fully convinced due to a lack of experience in the use of waste-based products and a lack of social acceptance and health risk in this regard. Further actions to build the social acceptance of waste-based fertilizers, and the education of end-users themselves in their application is required. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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18 pages, 2442 KiB

Open AccessArticle

Biomethane Potential of Selected Organic Waste and Sewage Sludge at Different Temperature Regimes

by German Smetana, Ewa Neczaj and Anna Grosser

Energies 2021, 14(14), 4217; https://doi.org/10.3390/en14144217 - 13 Jul 2021

Cited by 2 | Viewed by 1922

Abstract

Sewage sludge (SS) generation and its management still pose a problem in many countries. Anaerobic co-digestion (AcD) of SS with grease trap sludge (GTS) and organic fraction of municipal sewage waste (OFMSW), which are two easily biodegradable substrates, may improve biogas production and [...] Read more.

Sewage sludge (SS) generation and its management still pose a problem in many countries. Anaerobic co-digestion (AcD) of SS with grease trap sludge (GTS) and organic fraction of municipal sewage waste (OFMSW), which are two easily biodegradable substrates, may improve biogas production and AcD kinetics. Algae biomass (AB) of the species Undaria pinnatifida can be the third co-digestion component that may also affect the AcD performance. The aim of the study was therefore to evaluate the performance of mesophilic and thermophilic SS batch AcD with OFMSW, GTS as well as AB through biochemical methane potential (BMP) assay in relation to cumulative specific biogas (Y_B) and methane yields (Y_m). Three kinetic models were applied within the scope of the kinetic study. Results of the study showed that the mixture containing SS, GTS and AB brought the most noticeable improvements in Y_m compared to other studied mixtures and in respect to standalone SS digestion, the improvement amounted to 88.37% at mesophilic temperature (260.83 ± 15.02 N mL CH₄/g-VS_add and for standalone SS 138.47 ± 4.70 N mL CH₄/g-VS_add) and 71.09%, respectively, at the thermophilic one (275.66 ± 4.11 N mL-CH₄/g-VS_add and for SS standalone 161.13 ± 13.11 N mL-CH₄/g-VS_add). Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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22 pages, 9270 KiB

Open AccessFeature PaperArticle

Use of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans in the Recovery of Heavy Metals from Landfill Leachates

by Tomasz Kamizela, Anna Grobelak and Malgorzata Worwag

Energies 2021, 14(11), 3336; https://doi.org/10.3390/en14113336 - 6 Jun 2021

Cited by 15 | Viewed by 3300

Abstract

Among the methods used to remove metals and their compounds from landfill leachates with low application costs and high efficiency are bioleaching and biosorption. The most effective bacteria used in the metal removal process are Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The aim [...] Read more.

Among the methods used to remove metals and their compounds from landfill leachates with low application costs and high efficiency are bioleaching and biosorption. The most effective bacteria used in the metal removal process are Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The aim of the study was to determine the usefulness of the A. ferrooxidans and A. thiooxidans population in removing heavy metals from landfill leachate. In addition, development opportunities for bacterial population using landfill leachate as growth medium were identified. The substrate for the research was the raw leachate before the reverse osmosis process. In order to increase the efficiency of trace elements removal and recovery from leachate, variable combinations have been used which differ by the addition of sulfuric acid, A. ferrooxidans culture, A. thiooxidans culture, mixed culture containing populations of both bacteria, and elemental sulfur. Based on the research, it was found that the removal of heavy metals from leachate was a selective process. High bioleaching efficiency, from 80% to 90%, was obtained for all metals for which the sample acidification or sulfur addition was used. The simultaneous combination of both these additives turned out to be the most advantageous. The A. thiooxidans culture was the most effective in bioleaching reverse osmosis effluents. For the A. ferrooxidans culture used, much lower efficiencies were obtained, while by contrast, the use of mixed culture of two bacterium species had no significant effect. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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18 pages, 32372 KiB

Open AccessArticle

Production of Volatile Fatty Acids in a Semi-Continuous Dark Fermentation of Kitchen Waste: Impact of Organic Loading Rate and Hydraulic Retention Time

by Justyna Swiatkiewicz, Radoslaw Slezak, Liliana Krzystek and Stanislaw Ledakowicz

Energies 2021, 14(11), 2993; https://doi.org/10.3390/en14112993 - 21 May 2021

Cited by 16 | Viewed by 2869

Abstract

The aim of the study was to evaluate the possibility of using the process of dark fermentation to convert kitchen waste into valuable volatile fatty acids in a semi-continuous process at different values of the organic loading rate (2.5 and 5.0 gVS/(L × [...] Read more.

The aim of the study was to evaluate the possibility of using the process of dark fermentation to convert kitchen waste into valuable volatile fatty acids in a semi-continuous process at different values of the organic loading rate (2.5 and 5.0 gVS/(L × d)) and hydraulic retention time (5 and 10 d) using anaerobic mixed microbial consortia. The experiments were performed in a bioreactor of working volume 8L with pH control. The maximum volatile fatty acids yield in a steady state (22.3 g/L) was achieved at the organic loading rate of 5.0 gVS/(L × d) and HRT of 10 days. The main products of dark fermentation were acetic and butyric acids, constituting, respectively, 35.2–47.7% and 24.1–30.0% of all identified volatile fatty acids. Additionally, at the beginning of the fermentation and in a steady-state condition, the microbial population analysis (16S rDNA) of the fermentation mixture with the most effective volatile fatty acids generation has been performed to monitor the DF microflora development. The dominant microorganisms at a phylum level in a steady state were Firmicutes (44.9%) and Bacteroidetes (30.1%), which indicate the main role of those phyla in the volatile fatty acids synthesis. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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20 pages, 3341 KiB

Open AccessArticle

Heavy Metals Behavior in Soil/Plant System after Sewage Sludge Application

by Urszula Wydro, Agata Jabłońska-Trypuć, Eliza Hawrylik, Andrzej Butarewicz, Joanna Rodziewicz, Wojciech Janczukowicz and Elżbieta Wołejko

Energies 2021, 14(6), 1584; https://doi.org/10.3390/en14061584 - 12 Mar 2021

Cited by 18 | Viewed by 2508

Abstract

One of the possibilities of removing heavy metals (HMs) from soil is the use of phytoremediation techniques supported with biosolids, which also allow for their disposal. Therefore, the objective of the research was the determination of the sewage sludge suitability after its application [...] Read more.

One of the possibilities of removing heavy metals (HMs) from soil is the use of phytoremediation techniques supported with biosolids, which also allow for their disposal. Therefore, the objective of the research was the determination of the sewage sludge suitability after its application to urban soil in order to increase the phytoremediation efficiency of contaminated soil. A field experiment was established on lawns in Białystok (Poland) in two locations with different traffic. The research plots were fertilized with sludge in doses of 14.5 t DM/ha and 29 t DM/ha. A mixture of lawn grasses was sown on the prepared plots. During two years of experiment soil/plant samples were collected, and pH, organic matter, dehydrogenase and catalase activity (soil), the total content of Cd, Cr, Cu, Mo, Ni, Pb, Zn, and Hg (soil/plant), and their fractions (soil) were determined. The HMs in soil were present mainly in residual and reducible fractions. Zn had the highest share in acid-soluble fractions (17–45%). The efficiency of urban soil phytoremediation was determined by the calculation of bioconcentration (BCF) and translocation (TF) factors. The highest values for BCF and TF were obtained for Mo (1.97 and 1.99, respectively). In the presented study, sludge amendment caused an immobilization of heavy metals. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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18 pages, 5146 KiB

Open AccessArticle

The Impact of an Ultrasonic Field on the Efficiency of Coke Wastewater Treatment in a Sequencing Batch Reactor

by Anna Kwarciak-Kozłowska and Małgorzata Worwąg

Energies 2021, 14(4), 963; https://doi.org/10.3390/en14040963 - 11 Feb 2021

Cited by 9 | Viewed by 2386

Abstract

The growing production of coke and, consequently, coke wastewater is a significant problem for the environment. Coke wastewater, because it contains high amounts of toxic substances, is classified as an extremely hazardous industrial wastewater. The treatment of such wastewater requires a combination of [...] Read more.

The growing production of coke and, consequently, coke wastewater is a significant problem for the environment. Coke wastewater, because it contains high amounts of toxic substances, is classified as an extremely hazardous industrial wastewater. The treatment of such wastewater requires a combination of advanced physicochemical and biological methods. The aim of the research was to investigate the effectiveness of the application of the ultrasonic disintegration of coke wastewater in a sequencing batch reactor (SBR). The tests were conducted in two stages, wherein the first stage involved determining the most favorable sonication conditions, that is, time and amplitude. The authors used the following amplitudes: 31 µm; 61.5 µm; 92 µm; 123 µm and times: 120 s; 240 s; 480 s; 960 s. The second stage focused on treating coke wastewater in SBRs (Reactor A—a proportion of coke wastewater in the mixture: 5%, 10%, and 20%; reactor B—sonicated coke wastewater, proportion in mixture: 5%, 10%, 20%). The efficiency of the treatment process was determined based on the rate of removal of selected parameters: chemical oxygen demand (COD), total organic carbon (TOC), inorganic carbon (IC), ammoniacal nitrogen (N-NH₄), total nitrogen (TN), the course of pH changes. The study revealed that sonication of coke wastewater increased biodegradability and reduced its toxicity. The use of the preliminary sonication of coke wastewater before biological treatment improved the degree of removal of the tested parameters by approximately 10%. The volumetric ratio of coke wastewater in the mixture had the greatest impact on the obtained results. The use of an ultrasound field allows the treatment process to be executed with a coke wastewater addition exceeding 10%. In addition, it was found that in order to increase the coke wastewater treatment efficiency, one should optimize individual phases in the SBR and the pollution load. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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17 pages, 3613 KiB

Open AccessArticle

Solid Fuel Characteristics of Pellets Comprising Spent Coffee Grounds and Wood Powder

by Duk-Gam Woo, Sang Hyeon Kim and Tae Han Kim

Energies 2021, 14(2), 371; https://doi.org/10.3390/en14020371 - 11 Jan 2021

Cited by 18 | Viewed by 3187

Abstract

To help mitigate the effects of global warming and fossil fuel depletion caused by human use of fossil fuels, solid fuel pellets were developed from a mixture of spent coffee grounds (SCG) and pine sawdust (PS). The feasibility of SCG-PS pellets as biofuel [...] Read more.

To help mitigate the effects of global warming and fossil fuel depletion caused by human use of fossil fuels, solid fuel pellets were developed from a mixture of spent coffee grounds (SCG) and pine sawdust (PS). The feasibility of SCG-PS pellets as biofuel was also verified by evaluating its fuel quality. An increase in the proportion of SCG in the pellet led to an increase in its calorific value, owing to the high C, H, and oil contents, and increases in the ash and S contents, owing to the high S content in SCG. Analysis of the feedstock particle size distribution revealed that SCG particles are smaller than PS particles; thus, the durability of the pellet decreases as the proportion of SCG increases. Accordingly, the samples with higher SCG proportions (70 and 90 wt.%) did not meet the moisture content standards for biomass solid refuse fuel (bio-SRF) set by the Korea Ministry of Environment, whereas the samples with lower SCG proportions did. In particular, CP10 (10 wt.% SCG + 90 wt.% PS) satisfied the quality standards of Grade 1 wood pellets, demonstrating the feasibility of using SCG as a raw material for biofuel pellet production. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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10 pages, 1829 KiB

Open AccessArticle

Impact of Conditioning Substances and Filtration Pressure on Dewatering Efficiency of Sewage Sludge

by Tomasz Kamizela and Mariusz Kowalczyk

Energies 2021, 14(2), 361; https://doi.org/10.3390/en14020361 - 11 Jan 2021

Cited by 13 | Viewed by 2267

Abstract

Sludge dewatering is a key element in sludge’s processing and management. Solid-phase separation, sludge volume reduction and the separation of a high-quality supernatant are the main tasks of the dewatering devices. The effectiveness of this task, in turn, results from the selection of [...] Read more.

Sludge dewatering is a key element in sludge’s processing and management. Solid-phase separation, sludge volume reduction and the separation of a high-quality supernatant are the main tasks of the dewatering devices. The effectiveness of this task, in turn, results from the selection of the dewatering method and conditioning of the sludge before dewatering. The aim of the research was to determine the influence of conditioning substances (polyelectrolyte, fly ash and zeolite) on the efficiency of dewatering at variable filtration pressure. The use of polyelectrolyte in sludge conditioning was a solution that increased the efficiency of the filtration process. On the contrary, the use of structure-forming substances (fly ash and zeolite) slows the process but reduces the hydration of the filter cake. The same trends were obtained in dual conditioning combining dosing of polyelectrolyte and ash or zeolite. It was also shown that the dewatering efficiency of conditioned sludge with these two different substances (ash and zeolite) was the same. The use of zeolite in independent or dual conditioning was important for the quality of the supernatant. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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16 pages, 645 KiB

Open AccessArticle

Sludge Stabilization Process, Drying Depth and Polymeric Material Addition: Implication on Nitrogen Content, Selected Chemical Properties and Land Requirement in Sand Drying Beds

by Taruvinga Badza, Eyob H. Tesfamariam and Craig Cogger

Energies 2020, 13(24), 6753; https://doi.org/10.3390/en13246753 - 21 Dec 2020

Cited by 6 | Viewed by 3743

Abstract

Drying beds are a simple and economical means to dewater municipal sludge and are widely used in places with a suitable climate for air-drying. However, research-based information on drying thickness/drying depth effects on nutrient content and land size requirements for sludge drying is [...] Read more.

Drying beds are a simple and economical means to dewater municipal sludge and are widely used in places with a suitable climate for air-drying. However, research-based information on drying thickness/drying depth effects on nutrient content and land size requirements for sludge drying is scarce. In this study, aerobically digested (AeD), and anaerobically digested without polymer (AnDP0) and with polymer (AnDP1) sludge types were dried in sand drying beds at 5, 10, 15, 20 and 25 cm depths in South Africa. Measured nitrogen (N) fractions and other parameters were more strongly influenced by sludge types than by drying depth. Total N content followed the order of AeD > AnDP1 > AnDP0. Polymeric material addition tended to increase total and inorganic N content and reduce the length of sludge drying period and land size requirement. The study showed that larger land size is required to dry sludge at shallower depths, even though the sludge dried more quickly. Drying sludge at 15 cm was the best option across sludge types in winter, taking an average land area between 261 and 383 m² over the fewest days of sludge drying, whereas in spring, drying at 20 to 25 cm depth was most favorable. The findings suggest that drying bed management can be based on land area requirements with little concern for biosolid quality changes. For wastewater treatment plants relying on drying in beds, adding polymeric materials may be beneficial where land area for drying beds is limited, but not otherwise. Therefore, land availability is critical in decision making for sustainable sludge drying thickness. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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20 pages, 6154 KiB

Open AccessArticle

Processing of Water Treatment Sludge by Bioleaching

by Tomasz Kamizela and Malgorzata Worwag

Energies 2020, 13(24), 6539; https://doi.org/10.3390/en13246539 - 11 Dec 2020

Cited by 18 | Viewed by 2657

Abstract

Biological metal leaching is a technology used in the mining and biohydrometallurgy industries where microorganisms mediate the dissolution of metals and semi-metals from mineral ores and concentrates. The technology also has great potential for various types of metal-rich waste. In this study, bioleaching [...] Read more.

Biological metal leaching is a technology used in the mining and biohydrometallurgy industries where microorganisms mediate the dissolution of metals and semi-metals from mineral ores and concentrates. The technology also has great potential for various types of metal-rich waste. In this study, bioleaching was used for sludge from water treatment. In addition to checking the applicability of the process to such a substrate, the influence of experimental conditions on the effectiveness of bioleaching of metals with sludge from water treatment was also determined, including sample acidification, addition of elemental sulfur, incubation temperature, and Acidithiobacillus thiooxidans-isolated strain. The measurement of metal concentration and, on this basis, the determination of bioleaching efficiency, as well as pH and oxygen redox potential (ORP), was carried out during the experiment at the following time intervals: 3, 6, 9, 12 days. After the experiment was completed, a mass balance was also prepared. After the experiment, high efficiency of the process was obtained for the tested substrate. The effectiveness of the process for most metals was high (Ca 96.8%, Cr 92.6%, Cu 80.6%, Fe 95.6%, Mg 91%, Mn 99.5%, Ni 89.7%, Pb 99.5%, Zn 93%). Only lower values were obtained for Al (58.6%) and Cd (68.4%). Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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Review

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24 pages, 11643 KiB

Open AccessReview

Effect of Biowastes on Soil Remediation, Plant Productivity and Soil Organic Carbon Sequestration: A Review

by Aneta Kowalska, Anna Grobelak, Åsgeir R. Almås and Bal Ram Singh

Energies 2020, 13(21), 5813; https://doi.org/10.3390/en13215813 - 6 Nov 2020

Cited by 22 | Viewed by 4312

Abstract

High anthropogenic activities are constantly causing increased soil degradation and thus soil health and safety are becoming an important issue. The soil quality is deteriorating at an alarming rate in the neighborhood of smelters as a result of heavy metal deposition. Organic biowastes, [...] Read more.

High anthropogenic activities are constantly causing increased soil degradation and thus soil health and safety are becoming an important issue. The soil quality is deteriorating at an alarming rate in the neighborhood of smelters as a result of heavy metal deposition. Organic biowastes, also produced through anthropogenic activities, provide some solutions for remediation and management of degraded soils through their use as a substrate. Biowastes, due to their high content of organic compounds, have the potential to improve soil quality, plant productivity, and microbial activity contributing to higher humus production. Biowaste use also leads to the immobilization and stabilization of heavy metals, carbon sequestration, and release of macro and micronutrients. Increased carbon sequestration through biowaste use helps us in mitigating climate change and global warming. Soil amendment by biowaste increases soil activity and plant productivity caused by stimulation in shoot and root length, biomass production, grain yield, chlorophyll content, and decrease in oxidative stress. However, biowaste application to soils is a debatable issue due to their possible negative effect of high heavy metal concentration and risks of their accumulation in soils. Therefore, regulations for the use of biowastes as fertilizer or soil amendment must be improved and strictly employed to avoid environmental risks and the entry of potentially toxic elements into the food chain. In this review, we summarize the current knowledge on the effects of biowastes on soil remediation, plant productivity, and soil organic carbon sequestration. Full article

(This article belongs to the Special Issue Energy and Matter Recovery from Organic Waste Processing and Reuse)

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