Lime Sludge Research Articles

Utilization of waste from paper industry as a heterogeneous base catalyst for the synthesis of biodiesel

AbstractTo meet the pressing demand for alternative biofuel in the contemporary world, the production cost of biodiesel has to be decreased. Hence, this work addresses the usage of CaCO3‐rich industrial waste produced in a local paper industry in Assam, India for the synthesis of a heterogeneous catalyst for biodiesel synthesis. The collected lime sludge waste was subjected to calcination at 800°C for 3 h producing a CaO‐rich catalyst which was then employed in the transesterification of cottonseed oil. The optimized reaction conditions obtained were 5 wt% catalyst concentration, oil to methanol molar ratio of 1:12 at 65°C temperature, and 3 h of reaction time. The catalyst's reusability was evaluated up to four cycles. Besides, the prepared catalyst has been characterized using Fourier transfer infrared spectroscopy (FTIR), powder X‐ray Diffraction (p‐XRD), Scanning Electron Microscope (SEM), Energy Dispersive X‐ray analysis (EDX), and Brunauer–Emmett–Teller (BET) techniques and its basicity was measured using Hammett indicators. Moreover, the biodiesel obtained was characterized with 1H‐nuclear magnetic resonance (NMR), 13C‐NMR, Gas Chromatography‐ Mass Spectrometry (GC–MS), and FTIR techniques. A biodiesel yield of 98.03% was achieved and the quality of biodiesel formed during the transesterification of CSO also conforms to EN 14214 and ASTM D 6751 standards. Thus, our study highlights the sustainability and the potential for future industrial application of paper industrial waste in the production of biodiesel.

Biostabilization of fecal sludge and tannery liming sludge: A novel approach

Fecal sludge and tannery liming sludge management is essential for humans and the environment. The emitted amount of waste from two industries is reduced in composting leading to value-added products. This research focused on the effectiveness and feasibility of co-composting fecal sludge and hair-burning liming sludge from tannery. Fecal sludge was intermittently mixed with hair-burning liming sludge which also consisted of chicken manure and sawdust. Five piles (Pile 1, Pile 2, Pil3, Pile 4, and Pile 5) indicated respectively as P#1, P#2, P#3, P#4, and P#5, contained various ratios of composting materials were mixed, piled onto a horizontal bamboo frame, and observed for 120 days. To ensure a suitable oxygen supply, the composting piles were turned on in the thermophilic stage so that pathogens could not survive. The highest temperatures in the thermophilic stage were 39.0°C, 49.2°C, 55.7°C, 41.7°C, and 51.3°C. These referred to the respective piles P#1, P#2, P#3, P#4, and P#5. The Dewar stability index confirmed the stability of each composting pile, and the maximum degradation was found for P#3. The metals chromium (Cr), zinc (Zn), lead (Pb), iron (Fe), and nickel (Ni) in the final compost were found to be 38.1, 144.7, 15.1, 450.5, and 22.7 mg/kg, respectively. TCLP results reveal only an insignificant amount of metal leaching. Fecal coliform of the compost was below the standard level; Helminth eggs and Salmonella spp. were absent. SEM micrographs reflect the decomposition of composting materials. The maximum germination index and germination capacity of compost pile P#3 for compost-soil ratio 1:0 and 1:1 were 90%-92.8% and 100%, respectively. The present approach produced nutrient-enriched compost from fecal sludge and hair-burning liming sludge from a tannery emerges as a suitable solution for reducing solid wastes.

Revealing the interplay of dissolved organic matters variation with microbial symbiotic network in lime-treated sludge landscaping

Lime pretreatment is commonly used for sludge hygienization. Appropriate lime dosage is crucial for achieving both sludge stabilization (lime dosage >0.2 g/g-TS) and promoting plant and soil health during subsequent landscaping (lime dosage <0.8 g/g-TS). While much research has been conducted on sludge lime treatment, few studies have examined the effects of lime dosing on integrating sludge stabilization and plant growth promotion during landscaping. In this study, we investigated microbial dynamics and dissolved organic matter (DOM) transformation during sludge landscaping with five lime dosage gradients (0, 0.2, 0.4, 0.6, 0.8 g lime/g-TS) over 90 days. Our results showed that a lime dosage of 0.4 g/g-TS is the lower threshold for achieving waste activated sludge (WAS) stabilization during landscaping, leading to maximum humic substance formation and minimal phytotoxicity. Specifically, at 0.4 g/g-TS lime dosage, protein degradation and decarboxylation-induced humification were significantly enhanced. The predominant microbial genera shifted from Aromatoleum to Exiguobacterium and Romboutsia (both affiliated with the phylum Firmicutes). Reactomics analysis further indicated that a 0.4 g/g-TS lime dosage promoted the hydrolysis of proteins (lyase reactions on C-C, C-O, and C-N bonds), amino acid metabolism, and decarboxylation-induced humification (e.g., C1H2O2, C2H4O2, C5H4O2, C6H4O2). The co-occurrence network analysis suggested that the phyla Firmicutes, Proteobacteria, and Bacteroidetes were key players in DOM transformation. This study provides an in-depth understanding of microbe-mediated DOM transformation during sludge landscaping and identifies the optimal lime dosage for improving sludge landscaping efficiency.

A systematic analysis of binary blend cement concrete infused with lime sludge and fly ash

Lime sludge is a residual substance came from the paper sector. The current research investigates that the effects of adding lime sludge to concrete as a cementitious substance on its mechanical properties. Lime sludge replaces cement in various amounts to provide the appropriate mechanical properties. The resulting material is then compared to standard concrete. The research on supplemental cementation resources that equivalent Portland cements's potency without compromising stability. According to the Indian standard (IS 10262–2009), the study used M20, M30, and M40 concrete. Lime sludge replaced cement 0 ​%, 10 ​%, 20 ​%, and 30 ​%. Also investigated were lime sludge and fly ash mixtures of 10 ​%, 20 ​%, and 30 ​% by weight. Mechanical parameters of concrete classes M20, M30, and M40 were measured at 7 and 28 days. The grades show that the 10 ​% lime sludge out performed normal concrete. This work represents can be applied as unique additional cementitious substance up to the definite proportions.

Assessment of fracture toughness in fibrous concrete via Brazilian test: Experimental study with low-clinker cementitious binder

As the predominant and cost-effective material in the construction industry, concrete is susceptible to tension weaknesses, leading to significant flaws such as cracking and brittle fracturing. Recent advancements in fibrous concrete have emerged as a solution to mitigate these issues. Incorporating steel fibers in concrete has emerged as a promising solution to improve crack resistance and structural integrity. This study focuses on developing eco-friendly concrete using a low-clinker cementitious binder and short steel fibers to enhance fracture toughness and mitigate the environmental impact by effectively utilizing lime sludge. Concrete specimens were prepared with three binder types: treated lime sludge (TLS) at 15 % and 30 % and calcined clay (CC) at 15 % and 30 %, replacing conventional clinker. Short steel fibers were added at 1.5 % by volume to enhance mechanical properties. Fracture toughness was evaluated using notched Brazilian disc specimens, assessing mode I, II, and mixed-mode (I/II) fracture at multiple notch orientations (β = 0°, 15°, 28.83°, 45°, 60°, 75°, and 90°). Microstructural analysis during strength development was performed using scanning electron microscopy and X-ray diffraction. The findings revealed that specimens containing 15 % TLS, 30 % CC, and 1.5 % steel fibers exhibited the highest fracture toughness. Mode II fracture toughness exceeded mode I, indicating improved resistance to crack propagation. The addition of fibers to the specimens under mode II demonstrated improved fracture toughness, ranging from 0.44 to 0.53 MPa·m^1/2 compared to the corresponding non-fibrous specimens. The fibrous specimens showed significantly higher ultimate loads at β = 90° compared to β = 0°, indicating superior crack resistance and structural integrity under perpendicular loading conditions. The Brazilian disc specimens demonstrated variability in fracture toughness across different loading orientations, highlighting their suitability for mixed-mode fracture assessment.

Beneficial Use of Water Treatment Sludge with Stabilizers for Application in Road Pavements

Water treatment sludge (WTS) is the residue produced during water treatment processes for public use. Exploring the reintroduction of these wastes into the production chain to generate new, value-added materials presents a current challenge. This could promote their reuse and reduce the negative environmental impacts associated with their disposal. This study assessed the technical feasibility of using aluminum-based WTS to partially replace silty sand soil in mixtures that include two stabilizers (hydrated lime and Portland cement), potentially for use in road pavements. After conducting a thorough physical, chemical, and geotechnical characterization of both the soil and the sludge, bench-scale experiments were carried out to test the mixtures’ resistance, with WTS proportions of 5%, 8%, 10%, 15%, and 20%, stabilized with either lime or cement. The findings confirm that WTS does not contain potentially toxic elements, according to Brazilian standards, and all tested composites appear suitable for paving. However, the mechanical resistance of the soil–sludge–cement mixtures decreases as the WTS content increases, with an optimum California bearing ratio (CBR) of 41.50% achieved at a 5% WTS addition. Meanwhile, incorporating 15% WTS into soil–sludge–lime mixtures resulted in the highest CBR value of 21.25% for this type of mixture. It is concluded that incorporating stabilizers into soil–WTPS mixtures for road construction allows for an increased percentage of WTPS in silty-sandy soils. Further studies are recommended with different soil types and the addition of fibers to the mixes, to assess the long-term performance of the structure, along with economic and environmental analyses.

Innovative MOS-based fiber cement boards: Effect of kraft pulp mills waste and curing by accelerated carbonation

The increasing global waste generated by industrial activities poses significant environmental challenges. Eco-waste management emerges as an economically viable solution for converting, valorizing, and repurposing these byproducts, aligning with circular economy principles, and aiming to reduce greenhouse gas emissions. Construction, known for its unsustainability due to high energy consumption, non-renewable resource utilization, waste generation, and greenhouse gas emissions, particularly from cement production, has led to the exploration of alternative materials. Magnesium oxide (MgO)-based cement, an alternative to Ordinary Portland Cement (OPC), has gained attention, leveraging Brazil's prominence as a major magnesite producer. This study explores the valorization of waste from kraft pulp mills of the paper industry, specifically lime sludge (LS) and lime slaker grits (grits), to produce magnesium oxysulfate (MOS)-based fiber cement boards. The effect of accelerated carbonation on cementitious composites produced with formulations containing grits and LS was investigated. Replacing 25% of the limestone with grits showed no noticeable differences in the properties of the boards, and MOR values close to 11.17 MPa were obtained. However, the physical-mechanical performance showed a decrease with the use of LS and higher concentrations of grits, associated with Na2SO4.XH2O formation in the system and ITZ structure formed around the aggregated particle, respectively. Carbonation in a saturated atmosphere led to the carbonation of the 5–1–7 phase, which was related to the decrease in mechanical strength of the boards after the curing process. The thermal decomposition of the Hydrated Magnesium Carbonates (HMCs) formed during accelerated carbonation corroborated with the changes in the physical properties of the composites, demonstrating that the carbonation products are formed within the voids and pores of the material and contribute to the reduction in water absorption of the boards.

Applying SVR-PPSO, SVR-SSO, and SVR-BBO to estimate california bearing capacity of stabilized pond ash using admixtures

In the present study, three hybrid models include support vector regression-salp swarm optimization (SVR-SSO), support vector regression-biogeography-based (SVR-BBO), and support vector regression-phasor particle swarm optimization (SVR- PPSO) was applied to forecast pond ash’s CBR value modified with lime sludge (LS) and lime (LI). In the developed models, five variables were selected as inputs. It can result that the developed integrated models have R2 bigger than 0.9952. It means the agreement between observed and forecasted values by hybrid models is mainly similar to represent the highest accuracy. In both the training and testing stages, PSO-SVR results from better performance than the BBO-SVR model, with R2, RMSE, MAE, and PI equal to 0.9983, 0.6439, 0.3181, and 0.0081 for training data, and 0.9975, 0.7319, 0.4135, and 0.0141 for testing data, respectively. So, by considering the OBJ index, the OBJ value for PSO-SVR is 12.966, lower than BBO-SVR at 16.9957. Therefore, the PSO-SVR model outperforms another model to estimate the CBR of pond ash modified with LI and LS, consequently being recognized as the proposed model that makes it to be used for practical applications.

Adsorption-oxidation process for dyestuff removal from tannery wastewater

In leather processing, dyeing is one of the most important operations. A significant amount of wastewater is emitted from the tannery after the dyeing operation. The dyeing wastewater harms aquatic life. Removal of dyestuffs from the real dyeing wastewater has become a great challenge to lessen the tannery's pollution load. In this work, the adsorption-oxidation process has been studied for acid dyestuff removal from real tannery effluent. The preparation of cost-effective adsorbent was performed through thermal alteration of liming sludge leftover from a tannery. Adsorbent had been distinguished, implementing Fourier Transform Infrared (FTIR) Spectroscopy, Energy Dispersive Spectrometer (EDS), Scanning Electron Microscope (SEM), and X-ray diffraction (XRD) both immediately before and following. The parameters of adsorbent dosage, oxidant dosage, contact time, settling time, oxidant reaction time, and initial pH were performed to maximize the efficiency of dyestuff removal from tannery wastewater. Adsorption was performed without prior regulating the initial pH to remove dyestuff and other pollutants present in the effluent. Then, oxidation was performed to degrade the remaining color of the dyestuff. After adsorption-oxidation, the treated effluent’s pH level was 6.9. The combined effect of adsorbent and oxidant results showed dyestuff removal at 75.82%. The co-efficient obtained from Pseudo-Second-Order (PSO) kinetics, Freundlichisotherm, and thermodynamic analysis, elucidated the adsorption responseof an exothermic chemisorption reaction, with significant interconnectivity between adsorbent and dyestuff molecules. The mechanism of adsorption of Green V dyestuff on liming sludge adsorbent was also studied. The reusability study revealed that the regeneration efficiency was 91.85% after the 4th cycle of the adsorption–regeneration process. Moreover, the process reduced biochemical oxygen demand (BOD) and chemical demand (COD) was 72.41%, and 58.63%, respectively from the dyeing wastewater. The present approach would be implemented as an affordable and sustainable methodology to remove acid dyestuff from real tannery wastewater.

Physical and thermal insulation properties of foam concrete with the use of lime sludge (chemical waste)

The article investigates the physical and thermal insulation, the physical display of sand and lime sludge (waste), the electron microscopic analysis of foam concrete of the application of lime sludge (waste) to foam concrete. The results of a study of the physical and thermal insulation of foam concrete with lime waste and the compressive strength of structural foam concrete are presented.. For more efficient use in the development of new energy-saving foam concrete building products, laboratory experiments have established that lime slurry can be used as a filler for foam concrete.

Impact of the Addition of Sugar Beet Lime Sludge on the Composting of Argan Oil By-Products

Impact of the Addition of Sugar Beet Lime Sludge on the Composting of Argan Oil By-Products

Effect of recycled lime sludge, calcined clay and silica fume blended binder-based fibrous concrete with superior impact strength and fracture toughness

This study investigated the impact strength of fibrous concrete and its mode I, mode III, and mixed-mode I/III fracture toughness. Three binders were produced with varying compositions. The first binder was created by combining 95% clinker and 5% gypsum. The second binder consisted of 50% clinker, 30% calcined clay, 15% recycled lime sludge (RLS), and 5% gypsum. The third binder was composed of 50% clinker, 15% RLS, 30% silica fume, and 5% gypsum. There were three groups of binders used to classify the twelve different mixes. Each group comprises four different concrete mixtures: non-fibrous concrete, conventional fibrous concrete and two functionally graded fibrous concrete (FGFC) with three layers. Short-crimped steel fibres were utilized at an average dosage of 1.5% by volume. The fibre dosage of 2 and 2.25% was used in the top and bottom layers of FGFC and 0 and 0.5% were used in the middle. Besides, a microstructure study was performed to evaluate the strength development phases, utilizing X-ray diffraction, scanning electron microscopy, and thermogravimetric analysis techniques. Findings reveal that the mixture comprising an RLS and calcined clay binder combination exhibited the best compressive and impact strength performance. Introducing a three-layered concrete specimen with higher fibre content at the outer layer exhibits exceptional impact resistance compared to traditional fibrous concrete. Besides, fracture toughness under mode III is more critical than mode I and I/III and an increase in the load angle results in a reduced rate of improvement in fracture toughness.

Lime sludge assisted anaerobic bioreactor landfilling of municipal solid waste for enhanced leachate stabilization and bioenergy yield

Bioreactor landfilling even being advanced technology for enhanced stabilization of municipal solid waste (MSW), often suffers with adverse acidogenic conditions. Such conditions reinforce poor leachate stabilization, and reduced biomethane yield. This work attempts to counter the challenges of adverse MSW landfilling conditions through incorporation of waste alkaline sludge from paper industry. The amendment in anaerobic bioreactor landfilling of MSW was practiced by adding lime sludge (LS) with MSW in three distinct proportions: 20 g LS/kg MSW (LS100), 50 g LS/kg MSW (LS250) and 100 g LS/kg MSW (LS500), keeping LS0 as control. Periodic leachate and biomethane analysis showed benefits of proportionate LS addition. The control reactor often experienced leachate ponding and inhibitory conditions for anaerobic digestion. However, reactor LS250 achieved highest decrease in leachate organic strength removal (76.47 %) and biomethane production (8.315 L) over the period of landfilling. The pH and volatile fatty acids (VFAs) were in coordination with LS proportions. The LS addition beyond 100 g LS/kg MSW (LS500) could decrease the leachate pollution removal and biomethane yield. Finally, the Gompertz growth model showed excellent fit (R2 >0.997) to recorded biomethane. The study expands the scope of utilizing similar sludges for amendment of existing landfilling practices for efficient bioconversion of organic fractions of MSW.

Mechanical and Thermal Characterization of Jute Fibre Reinforced Epoxy Composites and Lime Sludge as a Filler

Mechanical and Thermal Characterization of Jute Fibre Reinforced Epoxy Composites and Lime Sludge as a Filler

Investigating the performance of ternary cementitious systems incorporating wollastonite powder and lime sludge in concrete

The production of cement results in a significant amount of energy consumption and CO2 emissions, which are major contributors to environmental pollution. Researchers have developed a ternary blended mix concrete to address these concerns by partially substituting cement with a combination of lime sludge (LS) and wollastonite powder (WP). This study investigated the mechanical properties (compressive strength, spilt tensile strength, and flexural strength) of a ternary blended concrete mix with a grade of M30. 180 specimens, including 60 cubes, 60 cylinders, and 60 prisms, were prepared for testing. The blended concrete mix was produced using different percentages of cement replacement by LS (5%, 10%, 15%) and WP (10%, 15%, 20%). The compressive strength for the ternary mix at 10% LS and 15% WP was 44.78% higher than the conventional mix, the flexural strength ternary mix at 10% LS and 15% WP was 25.46% higher than the conventional mix, and spilt tensile strength ternary mix at 10% LS, and 15% WP was 27.30% higher than the conventional mix at 28 days and trend is almost same for 7,56 and 90 days . The results showed that a ternary mix containing 75% cement, 10% LS, and 15% WP exhibited the best mechanical properties.

Production of low carbon dioxide cement containing sewage sludge ash as mineral admixture

Cement is an essential construction ingredient, and the demand for it has increased multifold during the last couple of years due to various construction activities. For the manufacturing of cement, limestone is a key component, which is a major source of carbon dioxide (CO2) emission. Moreover, municipalities all over the world have long been concerned about the disposal of sewage sludge. Due to increased generation of sewage sludge, urgent alternative solutions are required for sludge disposal, one of which is recycling of waste into construction materials. In accordance with the concept of sustainability, low carbon dioxide cement is produced in the current study by blending sewage sludge ash (SSA) and carbide lime sludge (CLS) (industrial waste) with ordinary Portland cement (OPC). In terms of physical properties, the influence of low carbon dioxide cement containing different percentages of SSA with 10% CLS is compared with that of composite cement containing fly ash at different percentages with 10% CLS. The outcome from the study shows that the utilization of OPC blended with up to 45% SSA with CLS would be possible, as it results in an acceptable level of compressive strength, conservation of depleting limestone reserves, savings in thermal and electrical energy and reduction of carbon dioxide emissions.

Green Ironmaking Industry: Production of Iron Pellets Using Lime Sludge

The use of alternative raw materials is essential for establishing a circular economy in the mineral and ironmaking sectors. Therefore, this study investigates the potential of lime sludge as fluxing material during pelletization and proposes an alternative route for the usage of waste. The pellets were manufactured with different binary basicity values (CaO/SiO2) (0.15-0.45) and bentonite (0.5-0.7 wt%) and fixed carbon (0.5-1.1 wt%) contents. The results demonstrated that lime sludge has significant potential for application in pelletization. Pellet quality was evaluated using drop number, mechanical strength, tumble index, porosity, and kinetic analyses. Pellets with the optimal composition using lime sludge withstood 3.6 drops/pellet, a tumble test of 1.57 wt.%, and a mechanical strength test of 214.83 kgf/pellet and exhibited a porosity of 31.28%. Lime sludge did not influence the reducibility of the iron-ore pellets. In the temperature range of 800-900 °C, the reaction was controlled by diffusion, with Ea between 179.89 and 233.10 kJ/mol.

Improvement of swelling soil by using lime sludge and sodium chloride

Construction on swelling soil is a major challenge to geotechnical engineers all around the world. This type of soil has a quite complex behavior as they undergo the category of problematic soils. The seasonal variations in the climate cause swelling and shrinkage, affecting soil’s water retention. The prediction of future climate change will worsen this problem, increasing the importance of the matter. The attention has been directed to experimental modeling and field investigations. In previous references, this problem was targeted by adding additives which are relatively expensive and non-environment friendly. In this study, waste and recycled materials are used in the lab to enhance the undesirable expansive soil characteristics to keep the environment clean and sustainable and reduce pollution. The additives are selected not only for its availability and cheapness but also to reduce the damage of environment due to disposal of waste. Therefore, the aim of study is to observe the behavior of expansive soils when mixing with various percentages of sodium chloride (NaCl) and lime sludge (LS). The percentages used in this work to determine the swelling properties of expansive soil were 1%, 2%, and 3% NaCl by weight with 3%, 6%, 9%, 10%, 12%, 15%, and 20% of LS by weight. The experimental tests held in the laboratory were liquid limit (LL), plastic limit (PL), free swell (FS), plasticity index (PI), swelling pressure, swelling and infiltration test, and physical models. The results show that by increasing the percentage of NaCl and LS, a significant improvement is obvious to the swelling properties of soils. Added to that, a decrease in PI of the swelling soil is clearly observed which reflects a decrease in swelling pressure and free swell of the swelling soil.

A study on validation of moment-curvature relationship of lime sludge-based blended cement concrete on numerical modeling (ATENA)

It is evident that the deformation capacity of any RCC structure is always very significant in the flexural design, other than the compressive strength aspect. When a structure is fully-loaded, adequate deformation capacity available in the structure can ensure safety. The present study focused on the flexural behavior of RCC beams consisting of industrial by-products from the paper industry known as lime sludge. The parameters considered in the present study include the strength of control mix concrete (30 MPa, 50 MPa, and 70 MPa), the combination of mineral admixtures (fly ash, silica fume, and lime sludge) as a partial replacement of cement in the preparation of blended concrete mix and type of reinforced section (under-reinforced and over-reinforced beams). Beams of size 1800 mm × 100 mm × 200 mm were cast and tested for flexural strength and the moment-curvature relationships. The improvement in the moment carrying capacity of under and over-reinforced RCC beams was noticed to be 40.12 %, 30.64 %, 22.98 %, 34.80 %, 30.13 %, and 19.44 % in 30 MPa, 50 MPa, and 70 MPa concrete respectively. The curvature of under and over-reinforced concrete RCC beams has improved by 7.64 %, 7.58 %, 7.44 %, 10.30 %, 7.30 %, and 5.15 % in 30 MPa, 50 MPa, and 70 MPa concrete respectively. Validation of the experimental M-ϕ relationship was obtained through the numerical model using FEM-based software ATENA. The experimental results of the moment-curvature relationship are in good agreement with the numerical model.

Chromium adsorption on surface activated biochar made from tannery liming sludge: A waste-to-wealth approach

In a beamhouse, liming plays a key role in the removal of hair/wool and epidermis, but problems are created when waste liming sludge is discharged to the environment. The treatment of tannery wastewater is another major challenge to the industry. In this study, thermally-activated biochars derived from liming sludge were studied for their effective adsorption of chromium (Cr) from the tannery wastewater. The thermally activated biochars (B500, B550, B600, and B650) were prepared at different temperatures from the liming sludge. Their characteristics before and after the treatment were investigated using Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, and scanning electron microscopy analyses. The related functional groups (C–H, O–H, C–N, and =C–O) and chromium adsorption capacity were determined according to the surface morphology, element contents (C, O, Ca, Na, Al, Mg, and Si), surface area (5.8–9.2 m2/g), pore size (5.22–5.53 nm), and particle size (652–1 034 nm) of the experimental biochars. The biochar originated at 600°C from the tannery liming sludge (B600) had a greater surface area with a chromium adsorption capacity of 99.8% in comparison to B500, B550, and B650 biochars. This study developed an innovative way of utilizing liming sludge waste to minimize the pollution load and wastewater treatment cost in the tannery industry.