Tannery Solid Wastes for Animal Feed: Comparison
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Please note this is a comparison between Version 1 by Nelly Esther Flores Tapia and Version 2 by Jason Zhu.

The animal food industry boasted a remarkable global trade value of USD 40.9 billion in 2021. Out of 1217 traded products, it secured the 110th spot, meaning that animal food represents a commanding presence, accounting for the top 9% of all traded commodities.

  • leather waste
  • animal feed
  • wet blue recycling
  • global trade

1. Introduction

The animal food industry boasted a remarkable global trade value of USD 40.9 billion in 2021. Out of 1217 traded products, it secured the 110th spot, meaning that animal food represents a commanding presence, accounting for the top 9% of all traded commodities. From 2020 to 2021, the export value of animal food surged by 17.8%, rising from USD 34.7 billion to USD 40.9 billion. Such a significant increase, almost 18% within a year, underscores a mounting demand for animal food [1]. This surge might be attributed to factors such as an expansion in animal farming and a global uptick in pet ownership. In 2021, the top five leading animal food exporters were Germany (USD 4.43 billion), the Netherlands (USD 3.92 billion), the United States (USD 3.81 billion), France (USD 3.29 billion), and China (USD 2.53 billion). On the import side were countries such as Germany (USD 3.19 billion), the United States (USD 2.55 billion), France (USD 1.9 billion), the Netherlands (USD 1.83 billion), and Poland (USD 1.6 billion). Interestingly, there is a noticeable overlap between top importers and exporters [2]. This overlap hints at the intricate dynamics of the supply chain in this industry. It is worth noting that the industry has an accumulated value of USD 35.7 billion. Recognizing the potential, the sector has innovatively incorporated nutrient-rich waste materials to devise enhanced fattening and growth formulas [3][4][5][6].
While the leading animal exporters dominate discussions due to their significant contributions, it is essential to recognize the broader spectrum of worldwide production. In 2019, global layer feed production experienced a 4% growth, with Asia–Pacific leading at 7%, possibly due to the African swine fever crisis prompting increased egg production. In contrast, the Middle East saw an 11% decline, likely influenced by geopolitical tensions. Broiler feed production is equivalent to 10 million metric tons from the previous year. Africa and Asia–Pacific both marked a 6% growth, while other regions registered a 2–3% increase. This upward trajectory is expected to continue, driven by escalating protein needs [7]. Meanwhile, North America’s ruminant feed production was at 62.3%, and Europe contributed 21.9%. Asia–Pacific dominates in aquaculture feed, holding 30% of the global share, with China, Vietnam, and Bangladesh as major contributors. Additionally, pet feed saw a 4% global growth, especially in regions such as Asia–Pacific, Europe, and Latin America. Countries such as China, Indonesia, Portugal, Hungary, Ecuador, and Argentina were at the forefront of this growth [7][8].
The vast scale of the animal feed industry highlights its dependence on large amounts of both vegetable and animal-derived ingredients [9]. Given the high cost of protein in feed formulas, there is a pressing need to identify more affordable protein sources. One promising solution is the controlled use of edible waste, ensuring the continued quality of animal-derived products [10]. A WWF report about animal feed sources underscores the potential of alternative animal diets, such as those incorporating grocery and bakery waste, as well as black soldier fly larva flour. Their study encourages the integration of waste into animal diets to provide an environmentally friendly alternative to conventional feeds, all while ensuring the safety and well-being of the animals [11].
An estimated 5 billion livestock are earmarked globally for the meat industry and its derivatives [12]. In 2014, global statistics suggested an average meat consumption of 43 kg per person [13]. The meat industry generates large amounts of waste; 46 to 50% of each bovine is waste [14]. Slaughterhouse by-products, such as hides—which comprise 4 to 11% of live cattle weight—find their way to the tanning industry [15]. As reported by the FAO, by 2015, out of the 5,924,823,536 kg of processed raw hides worldwide, 506,662,677 kg were transformed into leather [16]. The tanning industries utilize part of the hides from slaughterhouses and convert these animal hides into leather, enhancing their utility for various products [17]. Yet, per Buljan and Ludvik [18], for every 1000 kg of wet salted hides, only 255 kg emerges as finished leather, turning 75% into waste. The tannery waste includes fleshings, hair, tails, masks, shavings from splitting, dust from buffing wet blue, and highly contaminated liquid effluents [19][20]. Among all these wastes, fleshings and shavings, and the buffing of the wet blue are being recycled to produce animal feed [21] and other valuable products such as carbon sources for steel production [22], adsorbents [23][24], adhesives [25], synthetic leather [26], biodiesel, bioplastics [27], fertilizers [28][29][30], elastin [31], among others [32].

2. Solid Waste Tannery Residues

The leather production process generates a diverse array of wastes, each with its unique characteristics and potential environmental ramifications. Approximately 80% of these wastes are residues from unutilized hides, encompassing tanned solid byproducts such as hair, cow tails, raw hides, fleshings, and hide trimmings. Many of these residues find utility in gelatin factories or are repurposed into distinctive products such as pet toys, fertilizers, collagen, and keratin [33]. Shavings, although collagen-rich, are tainted with chrome. Yet, they hold promise in collagen manufacturing, adhesive production [34][35] and as fillers in composite materials [36]. Liquid wastes pose significant challenges, both in terms of volume—with 50,000 L required to produce just 1 kg of leather [37], and composition, laden with heavy metals [38], sulfides [39] and organic matter. The tanning stage introduces tanning liquors, the composition of which varies with the tanning technique and includes substances such as tannins and chromium salts [40]. Historically, the focus was on lowering the contaminants in wastewater before releasing them back into the environment. However, modern industries recirculate wastewater, aiming to curtail water usage and, finally, decontamination processes [41]. Gaseous emissions are another concern. Compounds such as VOCs are emitted throughout the production process, with hydrogen sulfide and ammonia being especially prominent during beam house operations, also in this industry the odor is a mandatory concern to address [42]. Furthermore, sludges, the byproducts of wastewater treatment, comprise a mix of organic and inorganic substances, demanding meticulous disposal to minimize environmental repercussions [37][43]. In summation, the intricate waste landscape of the leather industry emphasizes the imperative for eco-friendly practices and forward-thinking waste management approaches.

3. Products for Animal Feed Obtained from Different Solid Tannery Wastes

3.1. Products Derived from the Residual Fleshings of Tanneries

The fleshings, a blend of skin, muscle, and tallow, are mechanically excised from hides to enhance the permeation of chemicals into the skin during the depilation and tanning processes [44]. The surplus skin and the portions not utilized in the tannery are sold to manufacturing units to produce gelatin/collagen [45] and adhesives [46]. Traditionally, meat remnants with tallow are disposed of in landfills. However, current trends are exploring recycling strategies for these wastes. These include their use in biodiesel production [47], hydrogen generation [48], and soap manufacturing [49]. Furthermore, they undergo processing to yield meals enriched with protein and fat, suitable for animal feed [50], as detailed below. The composition of rawhide trimmings varies from 70.4 to 82.6% of moisture, 5.1 to 7% protein, and 7.3 to 7.8% of fat [51][52]. Various methods, including acid, basic and enzymatic hydrolysis, can extract the proteins in the form of collagen [53]. In the raw trimmings through innovative acid hydrolysis, using mixes of acids, the collagen extraction yields 85% using acetic acid and 93% with propionic acid. This yield discrepancy was further supported by circular dichroism results, which showed that the collagen extracted with propionic acid solution had a higher ellipticity than collagen extracted with acetic acid at 222 nm, a feature indicative of a triple helical structure. The circular dichroism results confirmed that the collagen derived from trimming waste maintained its native triple helical conformation being a collagen of high quality [54]. Tannery fleshings also serve as a collagen source through mechanical defatting and enzymatic hydrolysis using a trio of enzymes such as (A) an alkaline proteolytic enzyme with exo-activity, (B) alkaline proteolytic enzyme with endo activity, both showing activity of 40,000 LV g−1 and (C) another an alkaline triacylglycerol lipase enzyme with 50,000 TBU g−1 activity. The process demonstrates efficiency, versatility with up to 85% protein recovery from greaves and significantly reduced water and chemical consumption. The resulting hydrolyzed collagen, suitable as a retaining agent and biostimulant, was successfully used in retaining wet blue leathers. Still, as it did not contain chromium, this collagen is helpful for animal feed formulations [55]. Another study explored using tannery fleshings as an alternative to fishmeal in aquaculture. Fermented fleshings replaced varying percentages of fishmeal in the rohu fish (Labeo rohita) diet. The most successful results were observed when fishmeal was replaced by 75% fermented tannery fleshing flour, showing superior growth and nutritional indices in the fish. Addressing this, D’Agaro embarked on an 88-day seabass (Dicentrarchus labrax) growth experiment, encompassing eight isoproteic and isolipidic distinct diets. The diets included a C1 control diet based on fishmeal; diets containing tannery wastes S1 and S2 with 100 and 200 g kg−1, respectively; AV1 and AV2 based on poultry meal; M1 and M2 with alfalfa concentrate; and A1 containing Haematococcus fluvialis meal. Results indicated that diets S2 and AV2, which partially replaced fishmeal with alternative protein sources by up to 40%, significantly reduced fish growth rates and exhibited poor fish conversion ratio values. Furthermore, introducing fleshing wastes to the seabass diet appeared promising but not economically viable [56]. There was no evidence of toxicity or contamination of fishes with diets S1 and S2 containing tannery wastes, which gives hope in using these residues, but more experiments are still necessary to discard future issues. Allam et al. directly transformed fleshings into flour destined as a dietary supplement for broiler chicks. First, the fleshings were boiled at 100 °C for 4–5 h, then dried and ground. When comparing the three diets, Diet 1 containing 10% protein concentrate, Diet 2 consisting of 5% protein concentrate and 5% tannery wastes, and Diet 3 incorporating 10% tannery waste, the findings show that the basic parameters such as feed intake, live weight, and feed conversion efficiency remain largely unaffected among the groups. Nevertheless, there is a notable variance in the cost of production and profitability, with diets incorporating tannery waste demonstrating enhanced profitability. Specifically, Diet 3 yielded a profitability of USD 0.13 per kilogram of live weight. While most meat yield traits were unaffected by the different diets, some specific characteristics such as gizzard and shank weight improved with increased tannery waste. The study concluded that producers can integrate residual fleshing from tanneries into broiler diets without causing adverse impacts [57]. A fermentation technique for delimed tannery fleshings was established to maximize protein hydrolysis and antioxidant activity using Enterococcus faecium HAB01 (GenBank #FJ418568). Under optimized conditions, which consisted of 12.5% (v/w) inoculum, 17.5% (w/w) glucose, and a fermentation period of 96 h at a temperature of 37 °C, maximal hydrolysis was achieved. The chemical evaluation of the hydrolysate unveiled an abundance of essential amino acids, particularly arginine and leucine when compared to a reference protein. Furthermore, the liquid portion of the hydrolysate exhibited robust antioxidant activities, suggesting its promising role as a high-quality feed ingredient [58]. These methods prove that it is possible to convert fleshing with no chromium content-rich protein sources for animal feed if considering quality and extraction processes.

3.2. Products Derived from the Residual Tallow in the Tanning Process

Due to its large volume, tallow has become a significant waste issue for slaughterhouses and tanneries. Most of it ends in landfills, with only a tiny fraction being recycled [59]. Freshly sourced beef tallow, coming directly from the animal’s stomach after slaughter, holds superior quality [60][61][62]. In 2019, global tallow production reached 6,606,876,775 kg [63], positioning it as an economical source of edible fats. Tallow is abundant in polyunsaturated fatty acids, including linoleic and α-linolenic acids, with a higher triacylglycerol concentration in adipose tissue and a significant presence of phospholipids in muscle tissue [64]. Historically, this beef fat was a staple in candle making, lubricants, and even in the industrial preparation of French fries [65]. However, health concerns related to its high saturated fat content have diminished its dietary role, leading to its substitution for unsaturated vegetable oils [65]. Today, tallow is an additive in balanced animal feed [66][67]. Tannery tallow undergoes recycling via solvent extraction [68] and thermal processes, where it is cooked until it separates into fat, flesh, and water [69] despite the thermal methods’ inefficiencies and high energy consumption. One study introduced a more efficient way of using solid-state fermentation. The researchers produced an enzyme (lipase) that effectively breaks down and solubilizes the fats, with 92% recovery when applied to tannery fleshing. This method offers a potential source for biodiesel production and repurposes the remaining residue as a protein-rich feed for animals [70]. A key challenge in fat recovery is achieving a high yield. Devaraj et al. designed an industrially viable process, employing 4% H2SO4 at 120 °C for 1.5 h, successfully extracting 98% of fat from leather fleshing waste. Subsequent analyses indicated that this fat has more potential utility as a biodiesel feedstock [71]. The extraction processes produce low-quality fats; thus, further investigation is required to refine these fats for consumption. In addition to the previously described defatting methods, another innovative process has been explored. Instead of using traditional solvents, this method exclusively uses supercritical CO2 in specialized high-pressure view cell equipment to extract fat from double-face lambskins. By optimizing conditions to 2 × 107 Pa, 80 °C temperature, and a duration of 2 h, the researchers achieved a fat yield of 78.57%. The results suggest that supercritical fluid CO2 extraction is a highly efficient and environmentally friendly alternative to fat separation processes [72]. While there is a lack of research on using recycled tallow in animal feed formulas, tallow has been successfully incorporated into feeds for cattle, equines [73], lambs, poultry [74], and other animal species due to its palatability and nutrient content. Okur, N. investigated the effects of soy oil, poultry fat, and tallow in broiler feed at fixed energy: protein ratio on field and slaughter parameters. The research evaluated several parameters. The study was conducted over 41 days with 12,600 Ross 308 broiler chicks. Ten different diets were used, including soy oil in the starter poultry fat, tallow in the grower, and various combinations in the finisher. The results indicated that using tallow instead of Soy oil, especially in grower feed, improved field performance. The study concluded that animal fat instead of soy oil could be an economical alternative if specific ratios are maintained [74]. Research performed by Wickramasuriya et al. involved 384 one-day-old Ross 308 broiler chicks, which were subjected to eight different dietary treatments. These diets were primarily corn–soybean meal-based, with beef tallow as the fat source. The study found that broiler chickens fed a diet supplemented with Polysorbate-20 and Candida rugosa lipases (NC + POL + CRL) exhibited improved growth performance, especially during the grower phase from day 21 to 35. These chickens also showed enhanced gut health, with increased villi height and a higher villi-to-crypt ratio. Furthermore, the NC + POL + CRL diet improved fat and energy digestibility compared to the negative control diet. The study concluded that combining Polysorbate-20 with Candida rugosa lipases can enhance the growth performance of broiler chickens on a low-energy diet without affecting other health parameters [75]. In a study by Ahmed et al., a 63-day experiment with 15 lambs evaluated three dietary treatments: T0 (control without beef tallow), T1 (2% beef tallow), and T2 (4% beef tallow) with five lambs per group. Notably, the T1 group exhibited a marked rise in body weight and improved feed conversion ratio. Meat quality and chemical composition remained consistent across all groups. However, lambs in the T1 group saw an 11.5% surge in cholesterol levels. The findings suggest that introducing 2% beef tallow into lamb diets can boost their performance without any detrimental impacts [76].

3.3. Recycling of Wet Blue Waste and Its Potential Alternatives for Animal Nutrition

After undergoing the chromium tanning process, the leather is termed wet blue. The skin’s thickness is harmonized during the subsequent finishing stages, producing wastes such as shavings and wet blue sanding dust [77]. These wet blue residues, which contain various levels of chromium-stabilized collagen, have seen research advancements that enable the reduction in chromium content. After chrome removal, theoretically, collagen-based protein is appropriate for feeding poultry, ruminants [78], and pets. It is vital to exclude chromium from the final product due to its notorious toxicity and associated health risks, from allergic reactions to cancer [79]. One noteworthy advancement is the increase in studies for efficient chrome extraction from protein hydrolysates [80][81]. This process leverages collagen of different qualities, which can be converted into valuable products such as gelatin, elastin, and animal feed. The efficiency and Cr (III) recovery depends on extraction methods. Furthermore, the profitability of this process depends on the market demand for these protein-based products. Recycling wet blue waste plays a dual role; it not only aids in reducing waste within the leather industry but also generates substantial economic value, as in the case of Bangladesh, which, in 2022, started exporting wet blue waste, capitalizing on its growing demand and utility worldwide [82]. The environmental challenge posed by chromium-tanned leather waste disposal stems from the potential conversion of trivalent chromium salts to the more soluble and carcinogenic chromium (VI) salts. This conversion can be instigated by factors such as UV light exposure, temperature fluctuations above 353 K, changes in humidity, natural pH shifts in landfills, and the leather hydrolysis process.
-
In an alkaline medium:
2Cr2O3+8OH−+3O2→4CrO4−+4H2O ΔG0<0
-
In an acid medium:
2Cr2O3+2H2O+3O2→4Cr2O72−+4H+ ΔG0<0
These reactions (1) and (2) are pH sensitive and can be accelerated in metal soils such as those containing cerium and manganese [83][84]. To avert Cr (VI) contamination and ensure premium collagen quality, collagen extraction from chromed wastes involves acid, basic, enzymatic hydrolysis [85], and combined methods [86][87]. These extraction processes require controlling pH and keeping temperatures between 70 °C and boiling. These unique measurements during hydrolysis, as supposed, increase the production costs. In these processes, protein yields vary from 25 to 30%; likewise, high-quality gelatins have been obtained that can compete in price with commercial gelatins [88].

4. Evaluation of Security of Recycled Solid Chromed Tannery Wastes for Animal Feed

Trace amounts of Cr (III) are integral to human metabolic functions. While the upper intake level for chromium has not been defined due to the absence of observed toxicities from food and prolonged high-dose supplement intake, recommended doses do vary. The recommendation for women aged 19–50 is 25 micrograms daily, increasing to 45 micrograms during lactation [89]. Meanwhile, the FDA advises an intake of 120 micrograms daily [90], whereas the no observed adverse effect level is 1468 mg kg−1-day−1 recommended by EPA [91]. Nonetheless, an excessive presence of heavy metals can lead to severe adverse impacts on human health [92]. Assuming that Cr (III) is the only contaminant, a 65 kg individual could safely consume up to 285 g of poultry daily. However, the potential conversion of Cr (III) to the more dangerous Cr (VI) during cooking raises genuine concerns about meat chemistry [93]. Hexavalent chromium, or Cr (VI), is particularly hazardous; prolonged exposition to this ion can lead to significant health issues such as skin disorders, respiratory problems, gastrointestinal tract damage, provoking cancer, and severe DNA damage depending on the exposure route [94]. The Office of Environmental Health Hazard has set the maximum allowable dose level for Cr (VI) at 8.2 µg day−1 [95]. However, findings by Mazumder et al. [96] sounded alarm bells. Chickens fed on tannery waste-derived protein showed Cr (VI) levels between 86 and 177 µg kg−1 in over 25% of samples, potentially exceeding the safety threshold [96]. Such findings cast serious doubt on using chromed waste residues in animal feeds. Interestingly, if present in feed at concentrations below 0.6 mg mL−1 (maximum 0.46 μg Cr mL−1), chrome hydrolysates have no adverse effects on zebrafish embryo development. This safety with zebrafish embryos is consistent across various extraction methods such as alkaline, enzymatic, or combined, even when extracted collagen contains 783 mg kg−1 of chromium [97]. In Bangladesh, chrome-containing constituents such as raw skin trimmings and wet blue scraps are used in poultry feed due to their high protein content. However, there is a rising concern over chromium contamination in poultry, posing potential risks to human consumers. A study by Ahmed et al. revealed that while specific poultry feed components maintained chromium within safe limits, others showcased alarmingly high concentrations. The experiments with broiler chickens (Gallus gallus domesticus) fed on chrome-infused feed revealed that raw skin trimmings and several poultry feed samples contained chromium levels below 0.03 mg kg−1. In contrast, wet blue shaving dust, starter feed (FS10), and grower feed (FS11) exhibited significantly elevated chromium concentrations, ranging from 3.02 to a staggering 29,854.4 mg kg−1 [98]. Moreover, processes applied to these tannery wastes did not reduce chromium concentration to safe levels. In the case of chickens consuming these feeds, chromium accumulation ranged between 0.42 and 0.84 mg kg−1 across various body parts. Such levels surpass the daily adequate intake for humans. Crucially, for broiler chicken feed, regulations stipulate that total chromium from supplemental sources should not exceed 0.2 mg kg−1 [99]. This underlined the need for stricter control measures in feed formulations to safeguard human health. This concern was echoed in the research by Bari et al. [100], where broiler chicken, desi chicken, and free-ranging chicken were fed chromium shavings, with chromium concentrations varying from 0.27 to 0.98 mg/kg and lead concentrations ranging from 10.27 to 10.36 mg kg−1. Given that these chromium concentrations exceeded the recommended dose of 0.2 mg kg−1, the findings highlighted potential risks for humans consuming poultry fed with chromed tannery waste-based concentrates. Silva et al. investigation further highlighted the risks of using wet blue in animal feeds. Upon feeding 48 Wistar diets containing 0 to 50% of tannery chromed wastes, adverse effects on the animals’ weight gain and kidney impacts were observed. The damage was directly proportional to the concentration of wet blue. The injuries were even worse with diets that replaced 25% to 50% of the weight with previously purified wastes (80% less chrome). The authors recommend removing at least 99% of chrome to consider wet blue for animal feed [101]. However, not all tannery waste derivatives pose risks. A study on delimed tannery fleshing hydrolysates, processed through acid hydrolysis and fermentation, showed promise. The investigation used male Wistar rats fed diets up to 15% of these hydrolysates. The study comprised acute toxicity assessments over 15 days and subacute evaluations spanning 30 days. The biochemical examinations of all serum, liver, and urine samples showed no notable alterations. This consistency was also evident in the liver histology outcomes, comparable to those from the control group. Thus, the study conclusively determined that incorporating up to 15% of delimed tannery fleshing hydrolysates into diets is safe, making them a valuable protein-rich ingredient for livestock feed formulations [102]. Lastly, a study assessing tannery waste protein concentrate as a potential replacement for a commercial protein named Jasoprot in cattle feed revealed optimistic results. Twelve cattle were subjected to various diets. The results indicated that diets with tannery waste protein concentrate significantly improved weight gain and profitability. Notably, the concentrate was free of aflatoxin and met typical beef chemical standards, including safe chromium levels under 24 ng g−1 (2 μg/serving). Organoleptic scores remained consistent across diets, suggesting no compromise in meat quality. Thus, combined with Jasoprot, tannery waste protein concentrate emerged as a cost-effective substitute in the cattle industry without affecting meat or carcass quality [103][104].

5. Analysis of Global Leather Waste Trade Data

According to the United Nations Comtrade database and Observatory of Economic Complexity (OEC) [105][106], the trade of leather waste, leather dust, and raw animal hides saw steady growth in their business between 2020 and 2021. In global trade, leather waste occupied the 1200th position as the most traded product, with a cumulative trade value of USD 37,500,000 in 2021. China is the top exporter, primarily due to its manufacturing prowess, with Indonesia as the leading importer. This highlights the significance of leather waste trade, potential growth, or partnerships based on trade dynamics. While the exact volumes of tannery wastes used for animal feed are unclear, their global economic impact is evident. Bangladesh uses tanning residues for poultry feed for economic reasons, but its safety needs further study. A wealth of waste exists for animal feed, with ample suppliers available [106].

6. Economic Implications of Dechroming Tannery Waste Residues

Collagen extraction and chrome recovery from tannery residues are understudied, with most data from older research or being proprietary. Environmental regulations prioritize chromium recovery from wastewater. Untanned collagen-rich residues, typically sent to gelatin manufacturers, are easier to recycle than tanned residues. The latter requires intensive processing compared to simple hydrolysis. Pretreatments help to reduce chromed residue purification costs [107], and after solubilizing the solid wastes, the recovery of chromium can be performed in dechroming plants. Low et al. developed a technology where an imprinted polymer bead can recover chromium from tanning liquor, improving the sustainability and efficiency of the tanning industry by reducing contamination in waterways. The economic analysis, based on an industrial-scale chromium recovery plant designed to process 5000 L of tanning liquor per hour, shows incomes, and the author recommends this plant for medium- or high-throughput enterprises. An alternative solution [108], especially in regions with multiple small tanneries, is establishing a centralized chromium recovery plant. Buljan [109] stated that a central chrome recovery unit in Santa Croce sull’Arno, Italy, was established, recovering 490 tons of Cr (III) 2000 for USD 1.45 million. While India had about 100 chrome recovery units using magnesium oxide, many ceased operations due to leather quality and cost concerns, similar to China. Khan et al. deemed the chromium recycling plant at Riaz Tanneries economically and environmentally beneficial. Despite its environmental importance, another study by Khan et al. found the plant’s financial model unviable without adjustments, such as alternative machinery suppliers and better integration with tannery operations [110].

References

  1. OEC—The Observatory of Economic Complexity Animal Food. Available online: https://oec.world/en/profile/hs/animal-food (accessed on 6 August 2023).
  2. OEC—The Observatory of Economic Complexity Dog or Cat Food (Retail). Available online: https://oec.world/en/profile/hs/dog-or-cat-food-retail?redirect=true (accessed on 6 August 2023).
  3. OEC—The Observatory of Economic Complexity Food Waste and Animal Feed. Available online: https://oec.world/en/profile/sitc/food-waste-and-animal-feed (accessed on 6 August 2023).
  4. Shurson, G.C. “What a Waste”—Can We Improve Sustainability of Food Animal Production Systems by Recycling Food Waste Streams into Animal Feed in an Era of Health, Climate, and Economic Crises? Sustainability 2020, 12, 7071.
  5. Rahmani, M.; Azadbakht, M.; Dastar, B.; Esmaeilzadeh, E. Production of Animal Feed from Food Waste or Corn? Analyses of Energy and Exergy. Bioresour. Technol. Rep. 2022, 20, 101213.
  6. Dou, Z.; Toth, J.D.; Westendorf, M.L. Food Waste for Livestock Feeding: Feasibility, Safety, and Sustainability Implications. Glob. Food Sec. 2018, 17, 154–161.
  7. Our World in Data. Feed Required to Produce One Kilogram of Meat or Dairy Product. Available online: https://ourworldindata.org/grapher/feed-required-to-produce-one-kilogram-of-meat-or-dairy-product (accessed on 29 September 2023).
  8. ALTECH. 2020 Global Feed Survey. 2020. Available online: https://www.alltech.com/sites/default/files/GFS_Brochure_2020.pdf (accessed on 25 September 2023).
  9. Our World in Data. Share of Cereals Allocated to Animal Feed. 2020. Available online: https://ourworldindata.org/grapher/share-cereals-animal-feed?time=2020 (accessed on 29 September 2023).
  10. IFIF-FAO. International Feed Industry Federation—IFIF/FAO Manual ‘Good Practices for the Feed Sector’. Available online: https://ifif.org/our-work/project/ifif-fao-feed-manual/ (accessed on 29 September 2023).
  11. Loyola, C.; Papadimitriou, C.; Dettling, J. LCA of Waste-to-Feed Diets for Laying Hens. 2021. Available online: https://files.worldwildlife.org/wwfcmsprod/files/Publication/file/8ddrh2pmtk_WWF_Food_Waste_As_Feed_LCA_Report.pdf?_ga=2.107023367.422577038.1697078295-1311783399.1696051296 (accessed on 2 August 2023).
  12. Clark, M.; Tilman, D. Comparative Analysis of Environmental Impacts of Agricultural Production Systems, Agricultural Input Efficiency, and Food. Environ. Res. Lett. 2017, 12, 064016.
  13. Our World in Data. Number of Cattle, 2016 to 2020. Available online: https://ourworldindata.org/grapher/cattle-livestock-count-heads?tab=table&time=2016.2020 (accessed on 28 September 2022).
  14. Mozhiarasi, V.; Natarajan, T.S. Slaughterhouse and Poultry Wastes: Management Practices, Feedstocks for Renewable energy production, and recovery of value added products. In Biomass Conversion and Biorefinery; Springer: Berlin/Heidelberg, Germany, 2022.
  15. Patel, K.; Munir, D.; Santos, R.M. Beneficial Use of Animal Hides for Abattoir and Tannery Waste Management: A Review of Unconventional, Innovative, and Sustainable Approaches. Environ. Sci. Pollut. Res. 2022, 29, 1807–1823.
  16. UN-FAO. World Statistical Compendium for Raw Hides and Skins, Leather and Leather Footwear. 1993–2012; FAO: Rome, Italy, 2013; ISBN 9789251092132. Available online: https://www.fao.org/markets-and-trade/publications/detail/en/c/1438160/ (accessed on 6 August 2023).
  17. Thanikaivelan, P.; Rao, J.R.; Nair, U.; Ramasami, T.; Nair, B.U. Recent Trends in Leather Making: Processes, Problems, and Pathways Recent Trends in Leather Making: Processes, Problems, and Pathways. Crit. Rev. Environ. Sci. Technol. 2005, 35, 37–79.
  18. Buljan, J.; Reich, G.; Ludvik, J. Mass Balance in Leather Processing; UNIDO: Vienna, Austria, 2000; Available online: https://leatherpanel.org/sites/default/files/publications-attachments/mass_balance.pdf (accessed on 27 September 2023).
  19. Vinicius, C.; Rigueto, T.; Rosseto, M.; Dal, D.; Krein, C.; Elisangela, B.; Ostwald, P.; Avila Massuda, L.; Zanella, B.B.; Dettmer, A. Alternative Uses for Tannery Wastes: A Review of Environmental, Sustainability, and Science. J. Leather Sci. Eng. 2020, 2, 21.
  20. Korpe, S.; Rao, P.V. Application of Advanced Oxidation Processes and Cavitation Techniques for Treatment of Tannery Wastewater—A Review. J. Environ. Chem. Eng. 2021, 9, 105234.
  21. Li, Y.; Guo, R.; Lu, W.; Zhu, D. Research Progress on Resource Utilization of Leather Solid Waste. J. Leather Sci. Eng. 2019, 1, 6.
  22. Nur-A-Tomal, M.S.; Biswal, S.; Pahlevani, F.; Sahajwalla, V. Recycling Tannery Solid Wastes as an Alternative Carbon Resource for Ironmaking. J. Mater. Cycles Waste. Manag. 2022, 24, 2030–2040.
  23. Oliveira, L.C.A.; Gonçalves, M.; Oliveira, D.Q.L.; Guerreiro, M.C.; Guilherme, L.R.G.; Dallago, R.M. Solid Waste from Leather Industry as Adsorbent of Organic Dyes in Aqueous-Medium. J. Hazard. Mater. 2007, 141, 344–347.
  24. Oliveira, D.Q.L.; Gonçalves, M.; Oliveira, L.C.A.; Guilherme, L.R.G. Removal of As(V) and Cr (VI) from Aqueous Solutions Using Solid Waste from Leather Industry. J. Hazard. Mater. 2008, 151, 280–284.
  25. Imam, S.; Bilbao-Sainz, C.; Chiou, B.-S.; Glenn, G.; Orts, W. Biobased Adhesives, Gums, Emulsions, and Binders: Current Trends and Future Prospects. J. Adhes. Sci. Technol. 2013, 27, 18–19.
  26. Bufalo, G.; Molino, B.; Ambrosone, L. Selection of Tanned-Leather Waste in Recovering Novel Raw Material for Manufacturing Rubber Artifacts: Towards a Zero-Waste Condition. Appl. Sci. 2020, 10, 5374.
  27. Parisi, M.; Nanni, A.; Colonna, M. Recycling of Chrome-Tanned Leather and Its Utilization as Polymeric Materials and in Polymer-Based Composites: A Review. Polymers 2021, 13, 429.
  28. Mikula, K.; Konieczka, M.; Taf, R.; Skrzypczak, D.; Izydorczyk, G.; Moustakas, K.; Kułażyński, M.; Chojnacka, K.; Witek-Krowiak, A. Tannery Waste as a Renewable Source of Nitrogen for Production of Multicomponent Fertilizers with Biostimulating Properties. Environ. Sci. Pollut. Res. 2023, 30, 8759–8777.
  29. Skrzypczak, D.; Szopa, D.; Mikula, K.; Izydorczyk, G.; Baśladyńska, S.; Hoppe, V.; Pstrowska, K.; Wzorek, Z.; Kominko, H.; Kułażyński, M.; et al. Tannery Waste-Derived Biochar as a Carrier of Micronutrients Essential to Plants. Chemosphere 2022, 294, 133720.
  30. Guilherme Esteves Nogueira, F.; Alves de Castro, I.; Amaral de Souza, G.; Nogueira, F.G.; Castro, I.A.; Bastos, A.R.; Souza, G.A.; de Carvalho, J.G.; Oliveira, L.C. Recycling of Solid Waste Rich in Organic Nitrogen from Leather Industry: Mineral Nutrition of Rice Plants. J. Hazard. Mater. 2010, 186, 1064–1069.
  31. Yoseph, Z.; Gladstone Christopher, J.; Assefa Demessie, B.; Tamil Selvi, A.; Sreeram, K.J.; Raghava Rao, J. Extraction of Elastin from Tannery Wastes: A Cleaner Technology for Tannery Waste Management. J. Clean. Prod. 2020, 243, 118471.
  32. Kumari, P.; Sen, S.; Suneetha, V. Production of Glue from Tannery Effluent by Physical, Chemical and Biological Methods. Res. J. Pharm. Technol. 2016, 9, 1–13.
  33. Pan, F.; Xiao, Y.; Zhang, L.; Zhou, J.; Wang, C.; Lin, W. Leather Wastes into High-Value Chemicals: Keratin-Based Retanning Agents via UV-Initiated Polymerization. J. Clean. Prod. 2023, 383, 135492.
  34. Wang, X.; Zhu, J.; Liu, X.; Zhang, H.J.; Zhu, X. Novel Gelatin-Based Eco-Friendly Adhesive with a Hyperbranched Cross-Linked Structure. Ind. Eng. Chem. Res. 2020, 59, 5500–5511.
  35. Wang, X.; Zhao, W.; Dang, X.; Wang, Y.; Zhang, H. Bio-Inspired Gelatin-Based Adhesive Modified with Waterborne Polyurethane on Click Chemistry. J. Renew. Mater. 2022, 10, 2747–2763.
  36. Yorgancioglu, A.; Onem, E.; Basaran, B. Preparation, Characterization and Application of Lubricating Protein Filler for Sustainable Leather Production. J. Nat. Fibers 2021, 18, 1946–1956.
  37. Hu, B.; Zhang, C.; Wang, H.; Zhang, G.; Li, Q.; Wang, M.; Wang, M. Extraction of Chromium from Tannery Sewage Sludge Extraction of Chromium from Tannery Sewage Sludge. Can. Metall. Q. 2022, 61, 183–189.
  38. Shukla, A.; Mahmood, Z.; Singh, L.K. Studies on Recovery of Heavy Metals from Tannery Wastewater. Int. J. Eng. Sci. Technol. 2021, 13, 76–80.
  39. Bykovsky, N.A.; Kantor, E.A.; Rahman, P.A.; Puchkova, L.N.; Fanakova, N.N. Removal of Sulfides from Tannery-Sourced Wastewaters. IOP Conf. Ser. Earth. Environ. Sci. 2019, 350, 012030.
  40. Mella, B.; Glanert, A.C.; Gutterres, M. Removal of Chromium from Tanning Wastewater and Its Reuse. Process. Saf. Environ. Prot. 2015, 95, 195–201.
  41. Religa, P.; Kowalik, A.; Gierycz, P. Effect of Membrane Properties on Chromium(III) Recirculation from Concentrate Salt Mixture Solution by Nanofiltration. Desalination 2011, 274, 164–170.
  42. Shivasankaran, N.; Balan, A.V.; Sankar, S.P.; Magibalan, S.; Dinesh, C.M. Removal of Hydrogen Sulphide and Odour from Tannery & Textile Effluents. Mater. Today Proc. 2020, 21, 777–781.
  43. Sodhi, V.; Bansal, A.; Jha, M.K. Excess Sludge Disruption and Pollutant Removal from Tannery Effluent by Upgraded Activated Sludge System. Biores Technol. 2018, 263, 613–624.
  44. Taylor, M.M.; Cabeza, L.F.; Brown, E.M.; Marmer, W.N. Chemical Modification of Protein Products Isolated from Chromium-Containing Solid Tannery Waste and Resultant Influence on Physical and Functional Properties. J. Am. Leather Chem. Assoc. 1999, 94, 171–181.
  45. Amertaning, D.; Bachrudin, Z.J.; Chin, K.B.; Erwanto, Y. Characteristics of Gelatin Extracted from Indonesian Local Cattle Hides Using Acid and Base Curing. Pak. J. Nutr. 2019, 18, 443–454.
  46. Adhikari, B.; Chae, M.; Bressler, D. Utilization of Slaughterhouse Waste in Value-Added Applications: Recent Advances in the Development of Wood Adhesives. Polymers 2018, 10, 176.
  47. Šánek, L.; Pecha, J.; Kolomazník, K.; Bařinová, M. Biodiesel Production from Tannery Fleshings: Feedstock Pretreatment and Process Modeling. Fuel 2015, 148, 16–24.
  48. Chowdhury, M.W.; Nabi, M.N.; Arefin, M.A.; Rashid, F.; Islam, M.T.; Gudimetla, P.; Muyeen, S.M. Recycling Slaughterhouse Wastes into Potential Energy and Hydrogen Sources: An Approach for the Future Sustainable Energy. Bioresour. Technol. Rep. 2022, 19, 101133.
  49. Chakawa, D.P.; Nkala, M.; Hlabangana, N.; Muzenda, E. The Novel Use of Calcium Sulphate Dihydrate as a Bleaching Agent for Pre-Processing Beef Tallow in the Soap Manufacturing Process. Procedia Manuf. 2019, 35, 911–916.
  50. Thazeem, B.; Umesh, M.; Mani, V.M.; Beryl, G.P.; Preethi, K. Biotransformation of Bovine Tannery Fleshing into Utilizable Product with Multifunctionalities. Biocatal. Biotransformation 2020, 39, 81–99.
  51. Puhazhselvan, P.; Pandi, A.; Sujiritha, P.B.; Antony, G.S.; Jaisankar, S.N.; Ayyadurai, N.; Saravanan, P.; Kamini, N.R. Recycling of Tannery Fleshing Waste by a Two Step Process for Preparation of Retanning Agent. Process. Saf. Environ. Prot. 2022, 157, 59–67.
  52. Bhaskar, N.; Sakhare, P.Z.; Suresh, P.V.; Gowda, L.; Mahendrakar, N. Biostabilization and Preparation of Protein Hydrolysates from Delimed Leather Fleshings. J. Sci. Ind. Res. 2007, 66, 1054–1063.
  53. Muralidharan, V.; Palanivel, S.; Balaraman, M. Turning Problem into Possibility: A Comprehensive Review on Leather Solid Waste Intra-Valorization Attempts for Leather Processing. J. Clean. Prod. 2022, 367, 133021.
  54. Masilamani, D.; Madhan, B.; Shanmugam, G.; Palanivel, S.; Narayan, B. Extraction of Collagen from Raw Trimming Wastes of Tannery: A Waste to Wealth Approach. J. Clean. Prod. 2016, 113, 338–344.
  55. Pérez-Aguilar, H.; Lacruz-Asaro, M.; Arán-Ais, F. Towards a Circular Bioeconomy: High Added Value Protein Recovery and Recycling from Animal Processing by-Products. Sustain. Chem. Pharm. 2022, 28, 100667.
  56. D’agaro, E. Alternative Protein Sources in Sea Bass Nutrition Alternative Protein Sources in Sea Bass Nutrition. J. Anim. Sci. 2003, 2 (Suppl. S1), 637–639.
  57. Alam, M.J.; Amin, M.R.; Samad, M.A.; Islam, M.A.; Wadud, M.A. Use of Tannery Wastes in the Diet of Broiler. Asian-Australas J. Anim. Sci. 2002, 15, 1773–1775.
  58. Rai, A.K.; General, T.; Bhaskar, N.; Suresh, P.V.; Sakhare, P.Z.; Halami, P.M.; Gowda, L.R.; Mahendrakar, N.S. Utilization of Tannery Fleshings: Optimization of Conditions for Fermenting Delimed Tannery Fleshings Using Enterococcus Faecium HAB01 by Response Surface Methodology. Bioresour. Technol. 2010, 101, 1885–1891.
  59. Zhou, C.; Wang, Y. Recent Progress in the Conversion of Biomass Wastes into Functional Materials for Value-Added Applications. Sci. Technol. Adv. Mater. 2020, 21, 787–804.
  60. Wood, J.D.; Enser, M.; Fisher, A.V.; Nute, G.R.; Sheard, P.R.; Richardson, R.I.; Hughes, S.I.; Whittington, F.M. Fat Deposition, Fatty Acid Composition and Meat Quality: A Review. Meat. Sci. 2008, 78, 343–358.
  61. Guerrero, A.; Muela, E.; Valero, M.V.; Prado, I.N.; Campo, M.M.; Olleta, J.L.; Catalán, O.; Sañudo, C. Effect of the Type of Dietary Fat When Added as an Energy Source on Animal Performance, Carcass Characteristics and Meat Quality of Intensively Reared Friesian Steers. Anim. Prod. Sci. 2016, 56, 1144–1151.
  62. Li, Y.; Zhao, J.; Xie, X.; Zhang, Z.; Zhang, N.; Wang, Y. A Low Trans Margarine Fat Analog to Beef Tallow for Healthier Formulations: Optimization of Enzymatic Interesterification Using Soybean Oil and Fully Hydrogenated Palm Oil. Food Chem. 2018, 255, 405–413.
  63. Knoema. Tallow Production in the World. Available online: https://knoema.com/data/agriculture-indicators-production+tallow (accessed on 29 September 2022).
  64. Ockerman, H.W.; Basu, L. By-Products | Hides and Skins. In Encyclopedia of Meat Sciences; Academic Press: Cambridge, MA, USA, 2014; pp. 125–136. ISBN 9780123847317.
  65. DeFow, C.; Zabik, M.; Gray, J.I. Fractionated Edible Beef Tallow as a Deep-Fat Frying Medium for French Fries. J. Food Sci. 1981, 46, 452–456.
  66. Ariaeenejad, S.; Kavousi, K.; Mamaghani, A.S.A.; Ghasemitabesh, R.; Hosseini Salekdeh, G. Simultaneous Hydrolysis of Various Protein-Rich Industrial Wastes by a Naturally Evolved Protease from Tannery Wastewater Microbiota. Sci. Total Environ. 2022, 815, 152796.
  67. Rombenso, A.N.; Trushenski, J.T.; Schwarz, M.H. Beef Tallow Is Suitable as a Primary Lipid Source in Juvenile Florida Pompano Feeds. Aquac. Nutr. 2017, 23, 1274–1286.
  68. Pathan, E.; Ahmed, S.; Shakil, S.R. Utilization of Limed Flesh Through Fat Extraction and Soap Preparation. Eur. J. Eng. Res. Sci. 2019, 4, 198–202.
  69. Kumar Verma, S.; Prakash, S.C. Current Trends in Solid Tannery Waste Management. Crit. Rev. Biotechnol. 2022, 43, 805–822.
  70. Dayanandan, A.; Rani, S.H.V.; Shanmugavel, M.; Gnanamani, A.; Rajakumar, G.S. Enhanced Production of Aspergillus Tamarii Lipase for Recovery of Fat from Tannery Fleshings. Braz. J. Microbiol. 2014, 44, 1089–1095.
  71. Devaraj, K.; Aathika, S.; Mani, Y.; Thanarasu, A.; Periyasamy, K.; Periyaraman, P.; Velayutham, K.; Subramanian, S. Experimental Investigation on Cleaner Process of Enhanced Fat-Oil Extraction from Alkaline Leather Fleshing Waste. J. Clean. Prod. 2018, 175, 1–7.
  72. Onem, E.; Renner, M.; Prokein, M. Green Separation and Characterization of Fatty Acids from Solid Wastes of Leather Industry in Supercritical Fluid CO2. Environ. Sci. Pollut. Res. Int. 2018, 25, 22213–22223.
  73. Mad Barn Tallow Beef—Equine Nutrition Analysis. Available online: https://madbarn.com/feeds/tallow-beef/ (accessed on 8 August 2023).
  74. Okur, N. The Effects of Soy Oil, Poultry Fat and Tallow with Fixed Energy : Protein Ratio on Broiler Performance. Arch. Anim. Breed. 2020, 63, 91.
  75. Wickramasuriya, S.S.; Macelline, S.P.; Cho, H.M.; Hong, J.S.; Park, S.H.; Heo, J.M. Physiological Effects of a Tallow-Incorporated Diet Supplemented with an Emulsifier and Microbial Lipases on Broiler Chickens. Front. Vet. Sci. 2020, 7, 583998.
  76. Ahmed, S.; Khatun, J.; Manirul Islam, M.; Kabirul Islam Khan, M.; Niaz Mahmud, S.M.; Abdullah Al Noman, M.; Zohorul Islam, M. Effect of Beef Tallow on Growth Performance, Carcass Characteristics, Meat Composition, and Lipid Profile of Growing Lambs. J. Adv. Vet. Anim. Res. 2015, 2, 346–352.
  77. Catalina, M.; Attenburrow, G.; Cot, J.; Covington, A.D.; Antunes, A.P.M. Isolation and Characterization of Gelatin Obtained from Chrome-Tanned Shavings. Available online: https://www.aaqtic.org.ar/congresos/istanbul2006/Visual%20Displays/V%2020%20-%20Isolation%20and%20characterization%20of%20gelatin%20obtained%20from%20chrome-tanned%20shavings.pdf (accessed on 29 September 2022).
  78. Silva, R.C.; de Resende Júnior, J.C.; de Lima, R.F.; de Sousa, R.V.; de Oliveira, L.C.A.; Daniel, J.L.P.; de Oliveira Moreira, A. Potential of Wet Blue Leather Waste for Ruminant Feeding. Rev. Bras. Zootec. 2012, 41, 1070–1073.
  79. Famielec, S. Chromium Concentrate Recovery from Solid Tannery Waste in a Thermal Process. Materials 2020, 13, 1533.
  80. Gotschall, M.G. Making Big Money from Garbage: How Companies Are Forming International Alliances to Recycle Trash for Profit. Columbia J. World Bus. 1996, 31, 100–107.
  81. Fortune. Tanneries to Start Recycling Waste for Profit. Available online: https://addisfortune.news/tanneries-to-start-recycling-waste-for-profit/2020 (accessed on 28 September 2023).
  82. The Daily Star. Not Waste Anymore: Maiden Shipment of Solid Tannery Soon|Daily Star. Available online: https://www.thedailystar.net/business/economy/news/not-waste-anymore-3128301 (accessed on 1 October 2022).
  83. Guo, S.; Yu, C.; Zhao, X.; Chen, Y.; Wang, J.; Su, M.; Yang, X.; Yang, J. The Chromium Migration Risk from Tannery Sludge into Shallow Soil and Groundwater: Influence Factors, Modeling, and Microbial Response. J. Clean. Prod. 2022, 374, 133776.
  84. Siddique, H.R.; Gupta, S.C.; Dhawan, A.; Murthy, R.C.; Saxena, D.K.; Chowdhuri, D.K. Genotoxicity of Industrial Solid Waste Leachates in Drosophila Melanogaster. Environ. Mol. Mutagen. 2005, 46, 189–197.
  85. Hinojosa, J.B.; Saldaña, L.M. Optimization of Alkaline Hydrolysis of Chrome Shavings to Recover Collagen Hydrolysate And Chromium Hydroxide. Leather Footwear J. 2020, 20, 15–28.
  86. Sundar, V.J.; Raghavarao, J.; Muralidharan, C.; Mandal, A.B. Recovery and Utilization of Chromium-Tanned Proteinous Wastes of Leather Making: A Review Recovery and Utilization of Chromium-Tanned Proteinous Wastes of Leather Making: A Review. Crit. Rev. Environ. Sci. Technol. 2011, 41, 2048–2075.
  87. Vallejo, J.S.; Almonacid, L.Y.; Agudelo, R.N.; Hernández, J.A.; Ortiz, Ó.L. Evaluación de La Hidrólisis Alcalina-Enzimática Para La Obtención de Colágeno Hidrolizado a Partir Virutas de Cuero Curtido. Rev. ION 2019, 32, 55–62.
  88. Alcance, B.S.; De Matos, E.F.; Berwig, K.H.; Detmer, A.; Baldasso, C. Optimización Del Proceso de Extracción de Proteínas de Residuos de Cuero Tanque Cromados Por Hidrólisis. In Proceedings of the XXI Congresso Brasileiro de Engenharia Quimica, Fortaleza, CE, Brasil, 25–29 December 2016.
  89. Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc; National Academic Press (US): Washington, DC, USA, 2001.
  90. Food and Drug Administration. Part 101: Food Labeling: Reference Daily Intakes. 1995. Available online: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=101.9 (accessed on 30 September 2023).
  91. Grevatt, P. Toxicological Review of Trivalent Chromium (CAS No. 16065-83-1). Available online: https://nepis.epa.gov/Exe/ZyNET.exe/P1006DAR.TXT?ZyActionD=ZyDocument&Client=EPA&Index=1995+Thru+1999&Docs=&Query=&Time=&EndTime=&SearchMethod=1&TocRestrict=n&Toc=&TocEntry=&QField=&QFieldYear=&QFieldMonth=&QFieldDay=&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery=&File=D%3A%5Czyfiles%5CIndex%20Data%5C95thru99%5CTxt%5C00000024%5CP1006DAR.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=Zy (accessed on 5 August 2023).
  92. Mitra, S.; Chakraborty, A.J.; Tareq, A.M.; Emran, T.B.; Nainu, F.; Khusro, A.; Idris, A.M.; Khandaker, M.U.; Osman, H.; Alhumaydhi, F.A.; et al. Impact of Heavy Metals on the Environment and Human Health: Novel Therapeutic Insights to Counter the Toxicity. J. King Saud. Univ. Sci. 2022, 34, 101865.
  93. Parvin, S.; Mazumder, L.T.; Hasan, S.; Rabbani, K.A.; Rahman, M.L. What Should We Do with Our Solid Tannery Waste. IOSR J. Environ. Sci. Toxicol. Food Technol. 2017, 11, 82–89.
  94. Shin, D.Y.; Lee, S.M.; Jang, Y.; Lee, J.; Lee, C.M.; Cho, E.M.; Seo, Y.R. Adverse Human Health Effects of Chromium by Exposure Route: A Comprehensive Review Based on Toxicogenomic Approach. Int. J. Mol. Sci. 2023, 24, 3410.
  95. OEHHA Proposition 65 Oral Maximum Allowable Dose Level (MADL) for Developmental and Reproductive Toxicity for Chromium (Hexavalent Compounds). Available online: https://oehha.ca.gov/media/081210DraftMADLChromVI.pdf (accessed on 5 August 2023).
  96. Mazumder, L.T.; Hasan, S.; Rahman, L. Hexavalent Chromium in Tannery Solid Waste Based Poultry Feed in Bangladesh and Its Transfer to Food Chain. IOSR J. Environ. Sci. Toxicol. Food Technol. 2013, 3, 44–51.
  97. Zhao, L.; Mu, S.; Wang, W.; Gu, H. Toxicity Evaluation of Collagen Hydrolysates from Chrome Shavings and Their Potential Use in the Preparation of Amino Acid Fertilizer for Crop Growth. J. Leather Sci. Eng. 2022, 4, 2.
  98. Ahmed, S.; Zohra, F.T.; Khan, S.H.; Hashem, A. Chromium from Tannery Waste in Poultry Feed: A Potential Cradle to Transport Human Food Chain. Cogent Environ. Sci. 2017, 3, 1312767.
  99. Food and Drug Administration. CFR—Code of Federal Regulations Title 21. Available online: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=573.304 (accessed on 4 August 2023).
  100. Bari, M.L.; Simol, H.A.; Khandoker, N.; Begum, R.; Sultana, U.N. Potential Human Health Risks of Tannery Waste-Contaminated Poultry Feed. J. Health Pollut. 2015, 5, 68–77.
  101. Silva, R.C.; de Resende Júnior, J.C.; Varaschin, M.S.; de Sousa, R.V.; Oliveira, L.C.A.; Daniel, J.L.P.; de Lima, R.F.; Moreiva, A.O. Chromium Poisoning in Rats Feeding on Tannery Residues. Anim. Prod. Sci. 2010, 50, 293–299.
  102. Jini, R.; Bijinu, B.; Baskaran, V.; Bhaskar, N. Utilization of Solid Wastes from Tanneries as Possible Protein Source for Feed Applications: Acute and Sub-Acute Toxicological Studies to Assess Safety of Products Prepared from Delimed Tannery Fleshings. Waste Biomass Valorization 2016, 7, 439–446.
  103. Anderson, R.A.; Bryden, N.A.; Polansky, M.M. Dietary Chromium Intake—Freely Chosen Diets, Institutional Diets, and Individual Foods. Biol. Trace Elem. Res. 1992, 32, 117–121.
  104. Jahangir-Alam, M.; Mufazzal-Hossain, M.; Anwarul-Haque Beg, M.; Nam, K.-C.; Lee, S.-S. Effects of Tannery Wastes on the Fattening of Growing Cattle, Carcass, and Meat Quality. Korean J. Food Sci. Animal. Resour. 2010, 30, 190–197.
  105. United Nations. UN Comtrade Database. Available online: https://comtradeplus.un.org/TradeFlow?Frequency=A&Flows=X&CommodityCodes=TOTAL&Partners=0&Reporters=all&period=2022&AggregateBy=none&BreakdownMode=plus (accessed on 4 August 2023).
  106. The Observatory of Economic Complexity Leather Waste. Available online: https://oec.world/en/profile/hs/leather-waste (accessed on 4 August 2023).
  107. Fernández-Rodríguez, J.; Lorea, B.; González-Gaitano, G. Biological Solubilisation of Leather Industry Waste in Anaerobic Conditions: Effect of Chromium (III) Presence, Pre-Treatments and Temperature Strategies. Int. J. Mol. Sci. 2022, 23, 13647.
  108. Low, A.; Holtz, N.; Madden, T.; Petcu, M.; Ericksen, R.; Slaughter, N.; Low, J.; Yu, M.; Lay, M.; Glasgow, G. Chromium Recovery from Tannery Wastewater Using Moleculary Imprinted Polymers: Water New Zealand. Available online: https://www.waternz.org.nz/Article?Action=View&Article_id=1387 (accessed on 30 September 2023).
  109. Buljan, J.; Fifteenth Session of the Leather and Leather Products Industry Panel. Costs of Waste Treatment. 2005. Available online: https://leatherpanel.org/sites/default/files/publications-attachments/costs_of_tannery_waste_treatment.pdf (accessed on 30 September 2023).
  110. Khan, M.R.; Naqvi, K.X. Down-Costing of Tannery Waste Water Chromium Recovery Plants in Pakistan: A Case Study of Techno-Economic Evaluation of a Chromium Recycling Plant. IJISET-Int. J. Innov. Sci. Eng. Technol. 2014, 1, 1–22.
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