Biochar Adsorption Research Articles

Machine learning-driven prediction of biochar adsorption capacity for effective removal of Congo red dye

Congo red, a widely utilized dye in the textile industry, presents a significant threat to living organisms due to its carcinogenic properties and non-biodegradable nature. This study proposes a data-driven machine-learning approach to optimize biochar characteristics and environmental conditions to maximize the adsorption capacity of biochar for the removal of Congo red dye. Therefore, six machine learning models were trained and tested on a dataset containing eleven input parameters (related to biochar properties and environmental conditions) and adsorption capacity. The models were evaluated using performance metrics such as R-squared (R2), Mean Squared Error (MSE), and Root Mean Squared Error (RMSE). With the highest R2 (0.9785) and lowest RMSE (0.1357), Random Forest Regression (RF) outperformed other machine learning models. DT and XGB also performed well, achieving slightly lower R2 values of 0.9741 and 0.9577, respectively. The LR model performed the worst, with the lowest R2 (0.4575) and the highest RMSE (0.6821). Moreover, the reliability of these models was validated using a 10-fold cross-validation method. RF once again performed the best with an R2 value of 0.9762. Feature analysis revealed that the initial dye concentration relative to biochar dosage (C0), specific surface area (BET), and pore volume (PV) are the most significant factors affecting the dye adsorption capacity of biochar, while parameters such as carbon content (C), the oxygen and nitrogen to carbon molar ratio [(O + N)/C], and pore diameter (D) had minimal impact. This research demonstrates that machine learning models can accurately predict biochar’s contaminant adsorption capacity, enhancing wastewater treatment and promoting efficient, cost-effective environmental management.Graphical

Dynamics of Contaminant Flow Through Porous Media Containing Random Adsorbers

Many porous media are mixtures of inert and reactive materials, manifesting spatio-chemical heterogeneity. We study the evolution of scalar transport in a chemically heterogeneous material that mimics a green roof soil substrate, fractionally composed of inert and reactive adsorbing particles. These adsorbing particles are equivalent to biochar within a real soil substrate. The scalar transport evolution is determined using experiments and simulations calibrated from experimental data. Experiment 1 is used to determine the equilibrium capacity and adsorption rate of two biochar types when immersed in a methylene blue solution. Breakthrough curves of a packed bed of glass beads with randomly interspersed biochar are determined in experiment 2. Simulations are then run to investigate the solute transport and adsorption dynamics at the pore-scale. An analytical model is proposed to capture the behavior of the biochar adsorption capacity, and the simulation results are compared with experiment 2. A pore-scale analysis showed that uniformly sized beds are superior in contaminant breakthrough reduction, which is related to the adsorptive surface area and the rate at which adsorption capacity is reached. Cases using the adsorption capacity model display a tight distribution of particle surface concentration at later simulation times, indicating maximum possible adsorption. The beds with dissimilar particle sizes create more channeling effects which reduce adsorptive particle efficiency and consequently higher breakthrough concentration profiles. Comparison between experiments and simulations show good agreement. Improved biochar performance can be achieved by maintaining particle size uniformity alongside high adsorption capacity and adsorption rates appropriate to the rainfall intensity.

A novel biochar adsorbent for treatment of perfluorooctanoic acid (PFOA) contaminated water: Exploring batch and dynamic adsorption behavior

Perfluoroalkyl substances (PFAS), like perfluorooctanoic acid (PFOA), are of concern worldwide given they are ubiquitous in the environment. In this study, the treatment of PFOA-contaminated water was assessed using biochar adsorbents produced from raw canola straw (RCS) through chemical activation with H3PO4 and ZnCl2 and microwave-assisted pyrolysis (MWP). MWP conditions were evaluated to create optimal H3PO4-treated (PBC) and ZnCl2-treated (ZnBC) biochar adsorbents with treatments determined using a central composite design (CCD) based on the response surface methodology (RSM) considering activator concentration, and microwave heating time and power. The highest PFOA removal efficiency for PBC (3.0 mol/L) was achieved at 92 % (368 μg/g), while for ZnBC (0.55 mol/L) it was 84 % (336 μg/g). In contrast, untreated biochar and RCS had markedly lower PFOA removals of 5 % and 1 %, respectively. Activation of biochar under optimal pyrolysis conditions (6 min at 600 W) led to increased chemical functional groups, porosity, and surface area, as confirmed by FT-IR, XPS, and BET. The kinetic study indicated that chemisorption was the primary PFOA adsorption mechanism, while the Freundlich isotherm model suggested heterogeneous multilayer adsorption for PFOA removal. Further, background salts enhanced PFOA adsorption through divalent bridges and salting-out mechanisms. PBC and ZnBC adsorbents performed well over a broad pH range of 3 to 9. Lastly, Yan and Yoon-Nelson models were used to assess adsorption breakthrough for a model fixed-bed adsorption system. This study exhibits that PBC and ZnBC adsorbents, derived from accessible biomass, offer an environmentally friendly solution to remove PFOA from contaminated water.

Magnetic nanoparticle modified moss Biochar: A novel solution for effective removal of enrofloxacin from aquaculture water.

The presence of residual antibiotics in water constitutes a potential threat to aquatic environments. Therefore, designing environmentally friendly and efficient biochar adsorbents is crucial. Aquaculture by-product moss (bryophyte) was transformed into biochar, which can eliminate antibiotics from wastewater through adsorption. This study successfully fabricated moss biochar (BC) and magnetically modified moss biochar (MBC), and explored their adsorption performance for enrofloxacin (ENR). Characterization analyses revealed that the specific surface area, total pore volume, and the quantity of functional groups of the MBC were significantly larger than those of the BC. The Langmuir isotherm model suggests that the maximum adsorption capacities of BC and MBC for ENR are 7.24mgg⁻1 and 11.62mgg⁻1. The adsorption process conforms to a pseudo-second-order kinetic model. Studies carried out at different temperatures disclose the spontaneous and endothermic thermodynamic characteristics of the system. Under neutral conditions, the adsorption efficiency attains its peak. The existence of various coexisting ions in water exerts a negligible influence on the adsorption process; furthermore, when the concentration of humic acid (HA) ranges from 0 to 20mg/L, the removal rate remains above 90%. In actual water samples, the antibiotic removal rate can be as high as 96.84%. After three cycles of reuse, the structure of MBC remains unchanged while maintaining a high removal efficiency. The primary mechanisms for antibiotic adsorption by MBC involve electrostatic interactions, hydrophobic interactions, pore-filling effects, hydrogen bonding, and π-π interactions. This reusable magnetic moss biochar provides a promising research direction for effectively eliminating antibiotics from water sources.

Super-effective biochar adsorbents from Co-pyrolysis of rice husk and sewage sludge: Adsorption performance, advanced regeneration, and economic analysis

Super-effective biochar adsorbents from Co-pyrolysis of rice husk and sewage sludge: Adsorption performance, advanced regeneration, and economic analysis

Predicting biochar adsorption capacity for methylene blue removal using machine learning

Predicting biochar adsorption capacity for methylene blue removal using machine learning

Biochar Adsorption: A Green Approach to PFAS Contaminant Removal

ABSTRACTThe widespread use of PFAS in nonstick cookware, hydrophobic textiles, stain‐resistant fabrics, cosmetics, and floor coverings has led to their persistent presence in wastewater streams, posing significant human health and ecological risks. Exposure to PFAS is linked to adverse reproductive outcomes and elevated blood pressure in pregnant individuals, and it negatively impacts aquatic ecosystems, particularly algal populations and microbial communities. This evaluation focuses on biochar's efficacy and cost‐efficiency in removing PFAS from water, highlighting its potential as a sustainable remediation method. Biochar's high microporous volumes (0.1–1.0 cm³/g), aromaticity, and surface oxygen‐containing functional groups make it effective for PFAS adsorption. Various biochar production methods, such as pyrolysis of biomass waste, and innovative modification techniques like acid treatment, ball milling, and metal nanoparticle incorporation are explored to enhance PFAS adsorption capacity. The mechanisms, kinetics, and thermodynamics of PFAS adsorption onto biochar are examined, providing insights into molecular‐level interactions and adsorption isotherms. Furthermore, machine learning models are utilized to understand the impact of processing parameters on PFAS removal efficiency. The review also presents toxicological studies on the harmful effects of PFAS exposure on organisms and humans, emphasizing the urgent need for effective remediation strategies. Ultimately, the potential of biochar‐based approaches in treating PFAS‐contaminated water is underscored by optimizing its physicochemical properties through innovative production and modification methods, along with predictive modeling of adsorption behavior.

Modified Biochar Adsorption Combined with Alkaline Solution Absorption for Sulfur-Containing Odor Gases Removal from Domestic Waste Transfer Stations

Odor emission has become a major issue in waste transfer stations. Hydrogen sulfide, methyl mercaptan (MM), and dimethyl disulfide (DMDS) are the main odorous gases. They have a low odor threshold and are difficult to remove. In this study, pine bark biochar was produced and modified with metal ions, including Ni2+, Ti2+, Mn2+, Zn2+, Mg2+, and Cu2+. It was then used for the removal of hydrogen sulfide, methyl mercaptan, and dimethyl disulfide. Among all modifications, the Cu2+ modified biochar showed the best sorption capacity, and the maximum sorption amounts were 20.50 mg/g for H2S, 36.50 mg/g for MM, and 57.98 mg/g for DMDS. To understand the adsorption, BET, SEM, and XPS of the original and modified biochar were performed. This illustrated that modification with Cu2+ increased the surface area and porosity, thus enhancing the adsorption capacity. In the alkaline absorption study, it was found that the removal of the three odor gases increased with the pH increase. Based on the results, a combined process called absorption–adsorption was established to treat the odor gas generated in a local waste transfer station. Thirty-one gas components were detected in the odor gas of the waste transfer station. The process proceeded for 30 days, and these gas components were not found in the effluent during treatment. Regarding H2S, MM, and DMDS, they were not detected even after 90 days. This indicates the high adsorption capacity of the modified biochar toward the three odor gases. In addition, the process is simple and easy to operate. This suggests that it is suitable for treating odor in places where there is no technician, and the odor needs efficient treatment. The study provides a feasible alternative for domestic waste transfer stations to control the odor problem.

Synthesis and Evaluation of an Innovative Biochar Nanocomposite Adsorbent Derived from Cycas Revoluta Seeds, with Potential Applications in the Removal of Cationic Dyes

In this study, novel and functional adsorbents were synthesized by using Cycas revoluta seed (CS) biomass. The biomass was subjected to a slow pyrolysis process at a final temperature of 500°C with a heating rate of 10°C/min to synthesize Cycas revoluta seed biochar (CSB). After the thermochemical conversion of biomass into biochar, the nanocomposite structure (ZrO2NP@CSB) was synthesized by adding 5% zirconium oxide (ZrO2) nanoparticles into biochar to increase the adsorption capacity. The synthesized adsorbents (CS, CSB, and ZrO2NP@CSB) were characterized by XRD, FTIR, SEM, and EDX. The adsorption efficiency of these three adsorbents was investigated to remove Malachite Green (MG) and Methylene Blue (MB) dye from an aqueous solution. According to the results obtained from the adsorption experiments of the nanocomposite structure, solution pH had a significant effect on the process and the highest adsorption efficiencies were achieved at pH 9. The optimum adsorbent dose was 0.5 g/L. The process reached an equilibrium after 45 minutes and 90 minutes for MG and MB, respectively. The relevant data were in good agreement with the pseudo-second-order kinetic model. The maximum adsorbent capacities were 129.87 and 117.93 mg/g for MG and MB, respectively. The adsorption mechanism follows a monolayer Langmuir isotherm model. Experiments were carried out at different temperatures (25, 35, 45°C) to determine the effect of temperature on adsorption, and dye removal efficiency slightly increased with temperature. When repeated batch adsorption experiments were compared for raw biomass, biochar, and biochar nanocomposite adsorbents, it was observed that the raw adsorbent had a lower adsorption capacity than the biochar adsorbent. It was found that the biochar nanocomposite had the highest adsorption capacity among these three adsorbents. The findings suggest that ZrO2NP@CSB composite is a promising, cost-effective, and functional material for water treatment and can be employed as an alternative adsorbent for removing dyes.

Predicting the adsorption of ammonia nitrogen by biochar in water bodies using machine learning strategies: Model optimization and analysis of key characteristic variables.

Biochar adsorption technology has been widely used to remove ammonia nitrogen from water bodies. However, existing methods for predicting adsorption efficiency often lack sufficient accuracy and practical usability. This study evaluated eight machine learning models, including XGB, LR, KNN, DT, RF, GBR, SVR, and ANN, to predict the adsorption efficiency of ammonia nitrogen. The evaluation utilized a dataset comprising 770 instances of ammonia nitrogen adsorption by biochar. The models' prediction performances were systematically compared, and cross-validation was applied to enhance their generalization ability, leading to the selection of the best-performing model. The selected model's parameters were further optimized using Bayesian optimization to improve the prediction accuracy. The Bayesian-optimized XGB model achieved the highest predictive performance, with a coefficient of determination (R2) of 0.978. The R2 values of the other models ranged from 0.556 (LR) to 0.927 (RF). Key factors influencing ammonia nitrogen adsorption efficiency were identified using SHAP analysis. These factors included biochar dosage, adsorption time, initial ammonia nitrogen concentration, solution pH, pyrolysis time, and O%. Their optimal ranges were further determined through partial dependency plots. This study developed a reliable machine learning tool for accurately predicting ammonia nitrogen adsorption efficiency. Additionally, it provided insights into optimizing the preparation processes and adsorption conditions of biochar, contributing to its practical application in treating ammonia nitrogen pollution in water bodies.

Prediction of CO2 adsorption of biochar under KOH activation via machine learning

To effectively increase the CO2 adsorption capacity of biochar, the activation process is often an indispensable link. However, the introduction of an activation process poses challenges in clarifying the relationship between the characterization parameters of biochar, adsorption parameters, and CO2 adsorption capacity. Herein, a comprehensive dataset encompassing the CO2 adsorption data of KOH-activated biochar using a “two-sep method” was compiled. Subsequently, ridge regression, multi-layer perceptron, and random forest models were employed to predict its CO2 adsorption performance. To comprehensively explore the effects of activation conditions, physicochemical properties and adsorption parameters on CO2 adsorption capacities, partial dependence via Shapley additive explanation (SHAP) values analysis was conducted. The results demonstrate that the multilayer perceptron model exhibits the highest prediction accuracy with a test R2 value of 0.961. Additionally, it was found that the CO2 adsorption capacity of activated biochar is primarily determined by micropores and nitrogen-containing groups rather than total pore volume at low adsorption pressure (< 0.3 bar). Moreover, it increases significantly with decreasing average pore size, increasing pore volume, and increasing nitrogen content at low adsorption temperatures (< 20 °C). When the ratio of KOH to biochar is in the range of 1–2 and the activation temperature is ∼ 700 °C, activated biochar with high CO2 adsorption performance can be obtained. This study may provide valuable insights for the application of activated biochar in CO2 adsorption.

Enrichment of Nanoplastics in Waters Using Magnetic Solid Phase Extraction With Magnetic Biochar Adsorbents and Their Determination by Pyrolysis Gas Chromatography-Mass Spectrometry.

Nanoplastics (NPs) are emerging water contaminants that threaten human health and ecological security. Developing a method for detecting NPs is significant because of their biological toxicity and mobility. In this study, magnetic solid-phase extraction (MSPE) combined with pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) was used for the pretreatment and qualitative detection of NPs in complex matrices to avoid sample dissolution and eluent usages. The developed methodology can quickly achieve low detection limits in tap and river water, with 0.7283 and 0.6474µg/L, respectively. To enrich NPs in water, magnetic biochars derived from cornstalks (Fe3O4/BCs, i.e., Fe3O4/YMG and Fe3O4/YMG-ZnCl2) were conveniently fabricated using activation and coprecipitation methods and employed as adsorbents for MSPE. The results indicated that the incorporation of Fe3O4 into BC not only rendered it magnetic but also enhanced the diversity of its surface functional groups and adsorption sites, making it suitable for MSPE. Fe3O4/YMG-ZnCl2 demonstrated excellent extraction and enrichment capacity for polystyrene NPs (PSNPs) over various competitive species. Additionally, it exhibited good resistance to pH and anions, and its reaction mechanism was verified using adsorption kinetics and isothermal models. In addition, after extracting PSNPs from tap and river water using Fe3O4/YMG-ZnCl2, they were successfully qualitatively analyzed by Py-GC/MS.

Removal of Cr(VI) from water using microalgae-based modified biochar: Adsorption performance, mechanisms, and life cycle assessment

Two types of biochar adsorbents, ZnCl₂-modified biochar (ZABC-5 and ZLBC) and H₃PO₄-modified biochar (HABC-5), were synthesized using algae powder and lake bloom algae. ZnCl2 as activator can change the surface structure of algal biochar and increase the adsorption site. ZABC-5 exhibited superior adsorption efficiency, achieving a maximum removal rate of 98.68 % for Cr(VI), featuring a defined surface area of 34.58 m2·g−1. Furthermore, it demonstrated excellent regeneration performance, maintaining over 98 % removal rate for Cr(VI) after three cycles using HCl as the desorbing agent. The multifaceted adsorption mechanism of Cr(VI) removal by ZABC-5 encompassed pore filling, electrostatic interaction, redox reactions, surface complexation, and ion exchange. Response surface optimization determined the optimal adsorption conditions for ZLBC, yielding an actual removal rate of 76 ± 4 %. Life cycle assessment revealed that the production of 1kg ZLBC and its utilization significantly reduce environmental impact, and the global warming potential is 12.70 kg CO2-Eq, while remaining cost-effective. Overall, this work provides a precedent by using lake bloom algae to create biochar adsorbents, showcasing the effectiveness and sustainability of algal biochar for removing Cr(VI) from water bodies and aiding environmental remediation.

Modeling of an adsorption study of a synthesized hematite composite for the removal of lead and cadmium from contaminated water

The use of enormous nanomaterials with enhanced functionality, and improved structural morphology is thought of this era for water pollution treatment. Loaded nanomaterials using different low-cost and wasted biomass could be synthesized for efficient functional properties. .Nanostructures with different structures and morphology have been prepared with efficiency to handle single and multi-component aqueous solutions. Iron oxide-loaded rice husk biochar, named hematite nanomaterial (HLRHBC) was used for lead and cadmium removal and its surface removal capacity was compared with raw rice husk (RH) and rice husk biochar (RHBC) adsorbents. Biochar was obtained by pre-pyrolysis at 400-500 °C and nanocomposite was then prepared by loading on biochar surface. The 89.45% removal efficiency was obtained for lead remediation by nanomaterial and 89.3%, and 88.3% by rice husk biochar and raw form of rice husk respectively. For cadmium adsorption 73.4%, 70.6% and 54.76% were removal efficiency for nanomaterials, rice husk biochar, and rice husk respectively. Isothermal calculations were applied to experimental data and it revealed favorable adsorption results by Freundlich, Dubinin–Radushkevich, and Temkin isotherms as indicated by their R 2 values approaching near 1, efficient adsorption capacity values and constant calculations within favorable approach revealed nanomaterial suitable for adsorption purposes. Error analysis favored nanomaterial adsorption results by limiting value to small error results. Kinetic calculations revealed maximum Qe (mg/g) value 22.57 ± 0.013 mg/g in case of lead adsorption and 22.93 ± 0.013 mg/g for cadmium adsorption HLRHBC. Kinetic and thermodynamic calculations proved spontaneous physicochemical sorption experiments. Desorption experiments separated metal and adsorbent for recovery and reuse of nanomaterial. Hematite biomass composite was found efficient and novel sorbent for lead and cadmium uptake and recovery.

Synthesis of a Novel Magnetic Biochar from Lemon Peels via Impregnation-Pyrolysis for the Removal of Methyl Orange from Wastewater

This research examined the elimination of methyl orange (MO) utilizing a novel magnetic biochar adsorbent (MLPB) derived from lemon peels via an impregnation-pyrolysis method. Material characterization was conducted using SEM, XRD, TGA, FTIR, and nitrogen adsorption isotherms. SEM-EDX analysis indicates that MLPB is a homogeneous and porous composite comprising Fe, O, and C, with iron oxide uniformly dispersed throughout the material. Also, MLPB is porous with an average pore diameter of 4.65 nm and surface area value (111.45 m2/g). This study evaluated pH, MO concentration, and contact time to analyze the adsorption process, kinetics, and isothermal behavior. Under optimal conditions, MLPB was able to remove MO dye from aqueous solutions with an efficiency of 90.87%. Results showed optimal MO removal at pH 4, suggesting a favorable electrostatic interaction between the adsorbent and dye. To ascertain the adsorption kinetics, the experimental findings were compared using several adsorption models, first- and second-orders, and intra-particle diffusion. According to the findings, the pseudo-second-order model described the adsorption kinetic promoting the formation of the chemisorption phase well. Modeling of intra-particle diffusion revealed that intra-particle diffusion is not the only rate-limiting step. A study involving isothermal systems showed that Langmuir is a good representation of experimental results; the maximum adsorption capacity of MLPB was 17.21 mg/g. According to the results, after four cycles of regeneration, the produced magnetic material regained more than 88% of its adsorption ability.

Experimental and density functional theory calculation study on the NO2 adsorption and reduction by KOH activated biochar

Biochar prepared from waste biomass as an adsorption and reduction material can effectively decrease decrease nitrogen dioxide (NO2) emissions. This work aims to select suitable materials to prepare biochar and improve its ability to adsorb and reduce NO2. In this study, the process of adsorption and reduction of NO2 by biochar and the effect of KOH activation on these reactions are studied by using fixed-bed reactor and density functional theory calculation. Experimental results indicate a positive correlation between the adsorption and reduction capabilities of biochar for NO2 and its specific surface area and surface oxygen groups. The biochar sample prepared by pyrolysis at 800 ℃ with the addition of 3 wt% KOH solution exhibits the highest adsorption capacity, likely due to the catalytic role of potassium (K) in the adsorption-reduction reaction. It is worth noting that the theoretical calculation results confirm this point. The K atom primarily facilitates the breaking of the N-O bond in NO2 and the desorption of the NO molecule on biochar through van der Waals forces, thereby lowering the reaction energy barrier. Thermodynamic and kinetic analyses further confirm these findings. This study has a new understanding of the mechanism of NO2 adsorption and reduction of by KOH activated biochar, which provides experimental basis and theoretical guidance for the application of this technology.

Enhancing CO2 capture performance through activation of olive pomace biochar: A comparative study of physical and chemical methods

This work contributes understanding technical feasibility use of an agro-industrial waste as raw material for CO2 capture. Physical and chemical activation treatments to enhance adsorption properties of exhausts olive pomace biochar were investigated. Innovatively, the effects of different kinds of activating agents (steam, CO2, H3PO4 and KOH) on activated biocarbon's properties were deeply examined, also through an original high-pressure thermobalance, that is enabled higher initial sample weights, temperatures, and pressures compared to those employed in conventional methods.The activation conditions significantly affect the biochar morphology and CO2 adsorption capacity. Chemical activation, particularly with KOH, produced highly microporous structures, greatly enhancing CO2 adsorption. Specifically, KOH activation achieved adsorption capacities of up to 3.04 mmol/g at 30 °C and 10 bar. Textural analysis showed that KOH activation primarily increased microporosity, while other methods produced both micropores and mesopores. Interestingly, acid and physical activations were less effective, as they reduced CO2 adsorption due to changes in the internal structure. Thus, olive pomace proves to be a promising precursor for developing efficient biochar adsorbents. The use of KOH as an activating agent particularly stands out, achieving notable CO2 adsorption capacities.

Upcycling heavy impure crude terephthalic acid into porous carbons for adsorption of dye pollutants: The role of endogenous ferric groups

Crude terephthalic acid (CTA), a byproduct in the textile industry, is generated from the acid-precipitation process during the treatment of alkali-peeling (AP) wastewater. Due to its heavy impurity, CTA is typically disposed of as solid waste through incineration and landfilling, leading to severe pollution and resource wastage. In this work, an upcycling method was explored to convert CTA into carbonaceous adsorbent through pyrolysis at temperatures ranging from 400 to 800 °C. The carbonization mechanism of CTA to carbon was thoroughly investigated by using TGA-MS, FT-IR and XPS analyses. The resulting CTA carbons exhibited excellent adsorption performance for dye adsorption. For instance, the adsorption capacity for methylene blue (MB) reached 87.9 mg/g, surpassing the performance of several biochar adsorbents. Besides, it was found that the adsorption performance of CTA carbons was better than that of Fe-PTA carbons which have larger specific surface area and such result was attributed to the rich acidic functional groups on CTA carbon surface. Moreover, used CTA carbons could be recovered efficiently by self-activating low-concentration peroxydisulfate, achieving the regeneration rate of 82 %. Our work offers a promising eco-friendly approach for CTA upcycling in textile industry.

Techno-economic analysis of nutrient recovery from urine: Centralized treatment of hydrolyzed urine vs. decentralized treatment of fresh urine

The centralized process integrating “Thermal NH3 stripping → Na-chabazite adsorption → Struvite precipitation” has been proposed for nutrient recovery from hydrolyzed urine. Meanwhile, a decentralized approach involving Na-chabazite and biochar adsorption has been suggested for fresh urine, followed by urea hydrolysis and the subsequent centralized integration of struvite precipitation and thermal stripping. However, a systematic comparison of nutrient recovery processes for fresh and hydrolyzed urine, evaluating both technical viability and financial feasibility, is lacking. This study addresses the gap by thoroughly examining both scenarios over a 30-year project, using Université Laval as a case study. It provides a comprehensive roadmap for techno-economic assessment, offering guidance for evaluating nutrient recovery processes prior to scaling up. The decentralized process achieved higher recovery efficiencies for nitrogen and phosphorus, at 89.4 % and 98.7 %, respectively. Financially, the decentralized scenario demonstrated its advantage in the lower initial investment requirement, thereby generating higher gross profits compared to the centralized scenario. As a result, it is projected to reach the break-even point in the 21st year, demonstrating its potential economic feasibility. Sensitivity analysis indicated that a 20 % increase in urine inflow rate and the price of urea-enriched biochar could further enhance the economic viability of both processes. Beyond financial considerations, both scenarios have the potential to reducing the contaminant loading rate in the downstream wastewater treatment plants and promote nutrient recovery and recycling.

Low-cost Biochar from Parthenium Hysterophorus for Efficient Cr⁶⁺ Removal: A Sustainable Wastewater Treatment Solution

Aims: This study explores the development of innovative, cost-effective methods for removing Cr6+ from wastewater, focusing on biochar derived from Parthenium hysterophorus shoots. The biochar was prepared using a conventional slow-pyrolysis process and evaluated for its potential to treat Cr⁶⁺ in aqueous solutions. Study Design: Batch adsorption experiments are carried out in the study. Place and Duration of Study: The study was conducted in the Department of Environmental Science, G B Pant University of Agriculture &amp; Technology, between Feb 2024 and July 2024. Methodology: Parthenium hysterophorus shoots were collected, reagents were purchased from HiMedia, and Cr⁶⁺ solutions were prepared and adjusted using NaOH and HCl. Shoots were washed, sun-dried, ground into powder and pyrolysed at 350°C for 180 minutes. Biochar yield was calculated, pH, proximal parameters (moisture, volatile matter, ash, fixed carbon) and ultimate analysis were measured, chemical functional groups by FTIR and morphology by XRD using Bruker D8 Advance was done. Cr⁶⁺ removal was studied using biochar adsorbent under varying pH, initial Cr6+ concentration, adsorbent dose and contact time, adsorption capacity (q) and removal percentage were then calculated. Results: Characterization techniques such as Fourier Transform Infrared (FTIR) spectroscopy and X-Ray Diffraction (XRD) confirmed the presence of multiple functional groups and crystalline structures, which contribute to its adsorption efficiency. Batch adsorption experiments were conducted to investigate the influence of prepared biochar dosage, initial Cr⁶⁺ concentration, pH and contact time. The optimal removal efficiency of 72.77% was achieved under conditions of pH 10, a biochar dose of 1 g/L, an initial Cr⁶⁺ concentration of 30 mg/L and a contact time of 72 hours. Conclusion: Although challenges remain in optimizing production and functionalization, this research highlights the potential of biochar for sustainable water treatment. Addressing production costs and practical challenges will further enhance its applicability, contributing to environmental sustainability efforts.