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14 pages, 3111 KiB

Open AccessArticle

Organic Waste for Bioelectricity Generation in Microbial Fuel Cells: Effects of Feed Physicochemical Characteristics

by Shubham Arun Parwate, Wenchao Xue, Thammarat Koottatep and Abdul Salam

Processes 2024, 12(6), 1110; https://doi.org/10.3390/pr12061110 - 28 May 2024

Cited by 1 | Viewed by 1272

Abstract

Food waste (FW), piggery waste (PW), and activated sludge (AS) were investigated as potential organic feeds for bioelectricity generation in laboratory-scale microbial fuel cells (MFCs). The MFCs fed by FW gained the highest maximum power density at 7.25 W/m³, followed by [...] Read more.

Food waste (FW), piggery waste (PW), and activated sludge (AS) were investigated as potential organic feeds for bioelectricity generation in laboratory-scale microbial fuel cells (MFCs). The MFCs fed by FW gained the highest maximum power density at 7.25 W/m³, followed by those fed by PW at 3.86 W/m³ and AS at 1.54 W/m³. The tCOD removal in the FW-, PW-, and AS-MFCs reached 76.9%, 63.9%, and 55.22%, respectively, within a 30-day retention time. Food waste, which resulted in the highest power density and tCOD removal, was selected for a series of following tests to investigate the effects of some physicochemical properties of organic feed on the performance of MFCs. The effect of feed particle size was tested with three controlled size ranges (i.e., 3, 1, and <1 mm) in MFCs. A smaller feed particle size provided a higher power density of 7.25 W/m³ and a tCOD removal of 76.9% compared to the MFCs fed with organic waste with a larger particle size. An increment in feed moisture from 70% to 90% improved the maximum power density from 7.2 to 8.5 W/m³, with a 17.5% enhancement, and improved the tCOD removal from 75.8% to 83.3%, with a 10.0% enhancement. A moderate C/N ratio of approximately 30/1 maximized the power density and COD removal (7.25 W/m³ and 81.73%) in the MFCs compared to C/N ratios of 20/1 (4.0 W/m³ and 64.14%) and 45/1 (4.38 W/m³ and 71.34%). Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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17 pages, 8423 KiB

Open AccessArticle

Experimental Study on Microwave Pyrolysis of Decommissioned Wind Turbine Blades Based on Silicon Carbide Absorbents

by Dongwang Zhang, Qiang Song, Bo Hou, Man Zhang, Da Teng, Yaning Zhang, Rushan Bie and Hairui Yang

Processes 2024, 12(6), 1065; https://doi.org/10.3390/pr12061065 - 23 May 2024

Cited by 1 | Viewed by 997

Abstract

The rapid expansion of the scale of wind power has led to a wave of efforts to decommission wind turbine blades. The pyrolysis of decommissioned wind turbine blades (DWTBs) is a promising technological solution. Microwave pyrolysis offers the benefits of fast heating rates [...] Read more.

The rapid expansion of the scale of wind power has led to a wave of efforts to decommission wind turbine blades. The pyrolysis of decommissioned wind turbine blades (DWTBs) is a promising technological solution. Microwave pyrolysis offers the benefits of fast heating rates and uniform heat transfer, making it a widely used method in various heating applications. However, there are few studies on the microwave pyrolysis of DWTBs, and pyrolysis characteristics under different boundary conditions remain unclear. In this paper, we investigate the pyrolysis characteristics of DWTBs by utilizing silicon carbide (SiC) particles as a microwave absorbent. The results demonstrated that, when the microwave heating power increased from 400 W to 600 W, the heating rate and pyrolysis final temperature of the material increased, resulting in a reduction in pyrolysis residual solid yield from 88.30% to 84.40%. At 600 W, pyrolysis gas components included C₂H₄, CH₄, and CO, while the tar components included phenol and toluene. The highest degree of pyrolysis was achieved under the condition of an SiC particle size of 0.85 mm, with better heating performance, and the calorific value of the pyrolysis gas generated was 36.95 MJ/Nm³. The DWTBs did not undergo pyrolysis when SiC was not added. However, when the mass ratio of SiC to DWTBs was 4, the tar yield was 4.7% and the pyrolysis gas yield was 17.0%, resulting in a faster heating rate and the highest degree of pyrolysis. Based on this, an optimal process for the microwave pyrolysis of DWTBs was proposed, providing a reference for its industrial application. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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13 pages, 1493 KiB

Open AccessArticle

Impact of TEMPO-Oxidation Pretreatment of Red Ginseng Residual on Nanofibrillation

by Audrey Zahra, Virginia Ghita Firsty and Soo-Jeong Shin

Processes 2024, 12(5), 1035; https://doi.org/10.3390/pr12051035 - 20 May 2024

Viewed by 1058

Abstract

Red ginseng extract is one of the most widely used herbal medicines to prevent and cure various diseases. Among the processed products derived from red ginseng, the water-insoluble part as red ginseng residual (RGR) becomes waste, even though it contains important ingredients. TEMPO-oxidation [...] Read more.

Red ginseng extract is one of the most widely used herbal medicines to prevent and cure various diseases. Among the processed products derived from red ginseng, the water-insoluble part as red ginseng residual (RGR) becomes waste, even though it contains important ingredients. TEMPO-oxidation (TO) can be used as a pre-treatment with different degrees of oxidation (DO) (0 to 0.4) in red ginseng residual (RGR-TO) by introducing chemical oxidation and high-pressure homogenizer (HPH) as a nanofibrillation process. ¹H NMR was used to determine the carbohydrate composition and calculate DO, size was examined using a nanoparticle analyzer, and the zeta potential was used to determine surface charge density. RGR-TO with different concentrations had different compositions; glucose and uronic acid were the main ingredients. All treated RGR-TO showed higher oxidant levels than the untreated counterpart (RGR-TO 0). As the oxidant levels increased, the zeta potential and uronic acid increased, but the size of the nanofibril from RGR-TO decreased. The results of this study showed that TEMPO-oxidation pretreatment was effective in producing RGR cellulose nanofibril (CNF) with a variety of properties by adjusting the level of oxidation pretreatment and the number of HPH passes. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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13 pages, 2861 KiB

Open AccessEditor’s ChoiceArticle

Fixed Bed Batch Slow Pyrolysis Process for Polystyrene Waste Recycling

by Galo Albor, Amin Mirkouei, Armando G. McDonald, Ethan Struhs and Farid Sotoudehnia

Processes 2023, 11(4), 1126; https://doi.org/10.3390/pr11041126 - 6 Apr 2023

Cited by 7 | Viewed by 3463

Abstract

This study evaluates the potential of recycling polystyrene (PS) plastic wastes via a fixed bed (batch) slow pyrolysis reactor. The novelty lies in examining the reactor design, conversion parameters, and reaction kinetics to improve the process yield, activation energy, and chemical composition. PS [...] Read more.

This study evaluates the potential of recycling polystyrene (PS) plastic wastes via a fixed bed (batch) slow pyrolysis reactor. The novelty lies in examining the reactor design, conversion parameters, and reaction kinetics to improve the process yield, activation energy, and chemical composition. PS samples were pyrolyzed at 475–575 °C for 30 min under 10–15 psi. Process yield and product attributes were evaluated using different methods to understand PS thermal degradation characteristics better. The results show that PS decomposition started within 2 min from all temperatures, and the total decomposition point of 97% at 475 °C at approximately 5 min. Additionally, analytical results indicate that the average necessary activation energy is 191 kJ/mol. Pyrolysis oil from PS was characterized by gas chromatography–mass spectrometry. The results show that styrene was produced 57–60% from all leading oil compounds (i.e., 2,4-diphenyl-1-butene, 2,4,6-triphenyl-1-hexene, and toluene), and 475 °C has the major average of conversion effectiveness of 91.3%. The results show that the reactor temperature remains the main conversion parameter to achieve the high process yield for oil production from PS. It is concluded that pyrolysis provides a sustainable pathway for PS waste recycling and conversion to value-added products, such as resins and polymers. The proposed method and analytical results are compared with earlier studies to identify directions for future studies. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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20 pages, 6613 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Engineered Biomaterials for Reducing Phosphorus and Nitrogen Levels from Downstream Water of Aquaculture Facilities

by W. F. Rance Bare, Ethan Struhs, Amin Mirkouei, Kenneth Overturf and Brian Small

Processes 2023, 11(4), 1029; https://doi.org/10.3390/pr11041029 - 29 Mar 2023

Cited by 2 | Viewed by 2095

Abstract

The United States (U.S.) has a nearly USD 17 billion seafood trade deficit annually. However, the U.S. aquaculture industry faces strict micronutrient (e.g., phosphorus and nitrogen) level mandates that negatively impact fish production, especially for the state of Idaho, which produces 70–75% of [...] Read more.

The United States (U.S.) has a nearly USD 17 billion seafood trade deficit annually. However, the U.S. aquaculture industry faces strict micronutrient (e.g., phosphorus and nitrogen) level mandates that negatively impact fish production, especially for the state of Idaho, which produces 70–75% of the nation’s rainbow trout. This study investigates the sustainability benefits of producing engineered biomaterials from lignocellulosic-based feedstocks near collection sites via portable biorefineries for use by fish farms to reduce eutrophication (oversupply of micronutrients) impacts. In this study, sustainability assessments are performed on a case study in southern Idaho, the largest U.S. commercial producer of rainbow trout. The results show that 20 and 60 min of water treatment, using small particle size biomaterial from lodgepole pine, has the highest total phosphorus removal rate, at 150–180 g of phosphorus per 1 metric ton of engineered biomaterials. The results of techno-economic and environmental impacts studies indicate that pinewood-based biomaterials production cost ranges from USD 213 USD 242 per ton and reduces the eutrophication potential by 5–17 kg PO₄eq/ton. Additionally, the environmental impact results show that the total greenhouse gas emission for biomaterial production is 47–54 kg CO₂eq/ton; however, the used biomaterials after water treatment can be sold for around USD 850 per ton as nutrient-rich soil conditioners. This study concluded that engineered biomaterials from lignocellulosic-based feedstocks could be a sustainable solution to the challenge that aquaculture faces, particularly capturing micronutrients from eutrophic water and reusing them as fertilizers. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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13 pages, 1443 KiB

Open AccessArticle

Development of Agar Substitute Formulated with Mucilage and Pectin from Opuntia Local Waste Matter for Cattleya sp. Orchids In Vitro Culture Media

by Arantza Elena Sánchez-Gutiérrez, Genaro Martín Soto-Zarazúa, Beatriz Liliana España-Sánchez, Sarahí Rodríguez-González and Sergio Zamora-Castro

Processes 2023, 11(3), 717; https://doi.org/10.3390/pr11030717 - 28 Feb 2023

Viewed by 3149

Abstract

The technology for reproducing orchids in vitro has had to evolve due to the demand for these plants and the high cost of the biotechnology used due to the agar, the gelling agent. Consequently, research has tended to search for natural substitutes for [...] Read more.

The technology for reproducing orchids in vitro has had to evolve due to the demand for these plants and the high cost of the biotechnology used due to the agar, the gelling agent. Consequently, research has tended to search for natural substitutes for agar. Our work describes the use of pectin and mucilage hydrocolloids extracted from the local waste matter of two species of Opuntia (O. ficus-indica and O. robusta) to study as a gelling agent in vitro culture media for Cattleya sp. These hydrocolloids were obtained by alkaline hydrolysis. Subsequently, these were used in proportions of 0.8%, 0.6%, 0.4%, and 0.2% in combination with agar to study the gelation time, texture profile analysis (TPA), seed germination under light and dark conditions, and a phenological study, including orchid analyses of leaves and roots, root and leaf length, seedling height, and width of the best-designed treatment were studied. Our results demonstrate that the treatment composed of 0.4% O. ficus-indica pectin and 0.4% agar improves the germination time, plant growth, and the number of leaves and roots, resulting in a biostimulant formula for optimal in vitro growth of Cattleya sp. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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18 pages, 6081 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Single-Step Fabrication of a Dual-Sensitive Chitosan Hydrogel by C-Mannich Reaction: Synthesis, Physicochemical Properties, and Screening of its Cu²⁺ Uptake

by John Rey Apostol Romal and Say Kee Ong

Processes 2023, 11(2), 354; https://doi.org/10.3390/pr11020354 - 22 Jan 2023

Cited by 5 | Viewed by 2543

Abstract

Uncovering the value of waste materials is one of the keys to sustainability. In this current work, valorization of chitosan was pursued to fabricate a novel modified chitosan functional hydrogel using a process-efficient protocol. The fabrication proceeds by a one-pot and single-step C-Mannich [...] Read more.

Uncovering the value of waste materials is one of the keys to sustainability. In this current work, valorization of chitosan was pursued to fabricate a novel modified chitosan functional hydrogel using a process-efficient protocol. The fabrication proceeds by a one-pot and single-step C-Mannich condensation of chitosan (3% w/v), glutaraldehyde (20 eq.), and 4-hydroxycoumarin (40 eq.) at 22 °C in 3% v/v acetic acid. The Mannich base modified chitosan hydrogel (CS-MB) exhibits a dual-responsive swelling behavior in response to pH and temperature that has not been observed in any other hydrogel systems. Combining the pre-defined optimal swelling pH (pH = 4) and temperature (T = 22 °C), the CS-MB was screened for its Cu²⁺ adsorption capacity at this condition. The CS-MB achieved an optimal adsorption capacity of 12.0 mg/g with 1.2 g/L adsorbent dosage after 36 h with agitation. The adsorption of Cu²⁺ on the surface of CS-MB was verified by EDS, and an overview of the adsorption sites was exhibited by FT-IR. The simply fabricated novel CS-MB hydrogel under investigation presents a unique response to external stimuli that exhibits a promise in heavy metal removal from aqueous media. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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Review

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26 pages, 3154 KiB

Open AccessReview

Exploring Tannery Solid Wastes as a Source of Animal Feed

by Nelly Esther Flores Tapia and Hannibal Brito Moina

Processes 2023, 11(10), 2965; https://doi.org/10.3390/pr11102965 - 12 Oct 2023

Cited by 1 | Viewed by 2506

Abstract

This review delves into the processing of tannery solid waste, emphasizing fleshings and chromium-tanned leather waste. This paper centers on fat recovery, chromium elimination, and protein preservation, aiming to make them apt for animal consumption. This paper also assesses the potential of introducing [...] Read more.

This review delves into the processing of tannery solid waste, emphasizing fleshings and chromium-tanned leather waste. This paper centers on fat recovery, chromium elimination, and protein preservation, aiming to make them apt for animal consumption. This paper also assesses the potential of introducing such recycled products to the global market. Drawing on the literature from the past two decades, sourced comprehensively from Scopus and Web of Science, 36 articles were selected because of their significant contributions from leather production powerhouses such as India and Brazil. Fleshings have shown immense potential as animal feed, and the extraction of tallow and collagen from rawhide trimmings yields up to 98% and 93%, respectively. Fermented tannery fleshings, notably with Enterococcus faecium HAB01, also demonstrate strong antioxidant capabilities. The overarching consensus emphasizes the need for rigorous purification when dealing with chromium-containing wastes, addressing concerns tied to Cr (III) and Cr (VI). Furthermore, raw tannery fleshings stand out as a sustainable, cost-effective, and globally marketable solution for animal feed production. Full article

(This article belongs to the Special Issue Advances in Value-Added Products from Waste)

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