Enhancing simultaneous nitrogen and phosphorus availability through biochar addition during Chinese medicinal herbal residues composting: Synergism of microbes and humus.

The disposal of Chinese medicinal herbal residues (CMHRs) derived from Chinese medicine extraction poses a significant environmental challenge. Aerobic composting presents a sustainable treatment method, yet optimizing nutrient conversion remains a critical concern. This study investigated the effect and mechanism of biochar addition on nitrogen and phosphorus transformation to enhance the efficacy and quality of compost products. The findings reveal that incorporating biochar considerably enhanced the process of nutrient conversion. Specifically, biochar addition promoted the retention of bioavailable organic nitrogen and reduced nitrogen loss by 28.1 %. Meanwhile, adding biochar inhibited the conversion of available phosphorus to non-available phosphorus while enhancing its conversion to moderately available phosphorus, thereby preserving phosphorus availability post-composting. Furthermore, the inclusion of biochar altered microbial community structure and fostered organic matter retention and humus formation, ultimately affecting the modification of nitrogen and phosphorus forms. Structural equation modeling revealed that microbial community had a more pronounced impact on bioavailable organic nitrogen, while humic acid exerted a more significant effect on phosphorus availability. This research provides a viable approach and foundation for regulating the levels of nitrogen and phosphorus nutrients during composting, serving as a valuable reference for the development of sustainable utilization technologies pertaining to CMHRs.

[Effects of Biochar on Growth and Pollutant Accumulation of Lettuce in Soil Co-contaminated with Tetracycline and Copper].

Through lettuce potting experiments, the effects of different types of biochar (apple branch, corn straw, and modified sorghum straw biochar with phosphoric acid modification) on lettuce growth under tetracycline (TC) and copper (Cu) co-pollution were investigated. The results showed that compared with those under CK, the addition of biochar treatment significantly increased the plant height, root length, shoot fresh weight, and root fresh weight of lettuce (P < 0.05). The addition of different biochars significantly increased the nitrate nitrogen, chlorophyll, and soluble protein content in lettuce physiological indicators to varying degrees, while also significantly decreasing the levels of malondialdehyde, proline content, and catalase activity. The effects of biochar on lettuce physiological indicators were consistent during both the seedling and mature stages. Compared with those in CK, the addition of biochar resulted in varying degrees of reduction in the TC and Cu contents of both the aboveground and underground parts of lettuce. The aboveground TC and Cu levels decreased by 2.49%-92.32% and 12.79%-36.47%, respectively. The underground TC and Cu levels decreased by 12.53%-55.64% and 22.41%-42.29%, respectively. Correlation analysis showed that nitrate nitrogen, chlorophyll, and soluble protein content of lettuce were negatively correlated with TC content, whereas malondialdehyde, proline content, and catalase activity were positively correlated with TC content. The resistance genes of lettuce were positively correlated with TC content (P < 0.05). In general, modified biochar was found to be more effective in improving lettuce growth quality and reducing pollutant accumulation compared to unmodified biochar, with modified sorghum straw biochar showing the best remediation effect.

Synthesis of struvite-enriched slow-release fertilizer using magnesium-modified biochar: Desorption and leaching mechanisms.

To improve the retention and slow-release abilities of nitrogen (N) and phosphorus (P), an 82 %-purity struvite fertilizer (MAP-BC) was synthesized using magnesium-modified biochar and a solution with a 2:1 concentration ratio of NH4+ to PO43- at a pH of 8. Batch microscopic characterizations and soil column leaching experiments were conducted to study the retention and slow-release mechanisms and desorption kinetics of MAP-BC. The slow-release mechanism revealed that the dissolution rate of high-purity struvite was the dominant factor of NP slow release. The re-adsorption of NH4+ and PO43- by biochar and unconsumed MgO prolonged slow release. Mg2+ ionized by MgO could react with PO43- released from struvite to form Mg3(PO4)2. The internal biochar exhibited electrostatic attraction and pore restriction towards NH4+, while magnesium modification and nutrient loading formed a physical antioxidant barrier that ensured long-term release. The water diffusion experiment showed a higher cumulative release rate for PO43- compared to NH4+, whereas in soil column leaching, the trend was reversed, suggesting that soil's competitive adsorption facilitated the desorption of NH4+ from MAP-BC. During soil leaching, cumulative release rates of NH4+ and PO43- from chemical fertilizers were 3.55-3.62 times faster than those from MAP-BC. The dynamic test data for NH4+ and PO43- in MAP-BC fitted the Ritger-Peppas model best, predicting release periods of 163 days and 166 days, respectively. The leaching performances showed that MAP-BC reduced leaching solution volume by 5.58 % and significantly increased soil large aggregates content larger than 0.25 mm by 24.25 %. The soil nutrients retention and pH regulation by MAP-BC reduced leaching concentrations of NP. Furthermore, MAP-BC significantly enhanced plant growth, and it is more suitable as a NP source for long-term crops. Therefore, MAP-BC is expected to function as a long-term and slow-release fertilizer with the potential to minimize NP nutrient loss and replace part of quick-acting fertilizer.

Impact of feeding biochar sources in rohu (Labeo rohita): Evaluating the growth, nutrient absorption, carcass composition, haematology and mineral status.

Biochar, an organic carbonaceous matter, is a unique feed additive that is now being used in aquaculture industry to formulate a cost-effective and eco-friendly diet. This experiment (in door) was conducted over course of 90 days to determine the most effective form of biochar, produced from various sources, for supplementation in Moringa oleifera seed meal-based diet. These sources were: farmyard manure biochar, parthenium biochar (PB), vegetable waste biochar, poultry waste biochar (PWB) and corncob waste biochar, added at 2 g/kg concentration to determine the effect of supplementation on the growth indices, nutrient absorption, carcass composition, haematology and mineral status of Labeo rohita (rohu) fingerlings. The research design consisted of six test diets with three replications (6 × 3) of each. Total of 270 fingerlings (6.30 ± 0.020 g) were fed at 5% body weight and 15 of them were kept in separate steel tanks. The results indicated that PWB was most effective in improving weight gain (285.58 ± 4.54%) and feed conversion ratio (1.060 ± 0.040) compared to control diet and other test diets. The same type of biochar (PWB) produced the best results for nutrient digestibility, that is, crude protein, crude fat and gross energy and carcass composition. In terms of haematology and mineral status, PWB showed the best results. In conclusion, it was found that PWB significantly enhanced (p < 0.05) L. rohita fingerling's growth, carcass composition, nutrient digestibility, haematological parameters (red blood cells, white blood cells, platelets and haemoglobin) and mineral composition (Ca, Na, P, Mg, Fe, Mn, Zn, K and Cu) whereas PB negatively affected all parameters. It is anticipated that the potential use of biochar will increase in aquaculture industry, as research on its incorporation in fish feeds is still limited.

[Effects of Biochar Application Two Years Later on N2O and CH4 Emissions from RiceVegetable Rotation in a Tropical Region of China].

The effects of biochar application on soil nitrous oxide （N2O） and methane （CH4） emissions in a typical rice-vegetable rotation system in Hainan after two years were investigated. The aim was to clarify the long-term effects of biochar on greenhouse gas emissions under this model， and it provided a theoretical basis for N2O and CH4 emission reduction in rice-vegetable rotation systems in tropical regions of China. Four treatments were set up in the field experiment， including no nitrogen fertilizer control （CK）； nitrogen， phosphorus， and potassium fertilizer （CON）； nitrogen， phosphorus， and potassium fertilizer combined with 20 t·hm-2 biochar （B1）； and nitrogen， phosphorus， and potassium fertilizer combined with 40 t·hm-2 biochar （B2）. The results showed that： ① compared with that in the CON treatment， the B1 and B2 treatments significantly reduced N2O emissions by 32% and 54% in the early rice season （P < 0.05， the same below）， but the B1 and B2 treatments significantly increased N2O emissions by 31% and 81% in the late rice season. The cumulative emissions of N2O in the pepper season were significantly higher than those in the early and late rice seasons， and the B1 treatment significantly reduced N2O emissions by 35%. There was no significant difference between the B2 and CON treatments. ② Compared with that in the CON treatment， B1 and B2 significantly reduced CH4 emissions by 63% and 65% in the early rice season， and the B2 treatment significantly increased CH4 emissions by 41% in the late rice season. There was no significant difference between the B1 and CON treatments. There was no significant difference in cumulative CH4 emissions between treatments in the pepper season. ③ The late rice season contributed to the main global warming potential （GWP） of the rice-vegetable rotation system， and CH4 emissions determined the magnitude of GWP and greenhouse gas emission intensity （GHGI）. After two years of biochar application， B1 reduced the GHGI of the whole rice-vegetable rotation system， and B2 increased the GHGI and reached a significant level. However， the B1 and B2 treatments significantly reduced GHGI in the early rice season and pepper season， and only the B2 treatment increased GHGI in the late rice season. ④ Compared with that in the CON treatment， the B1 and B2 treatments significantly increased the yield of early rice by 33% and 51%， and the B1 and B2 treatments significantly increased the yield of pepper season by 53% and 81%. In the late rice season， there was no significant difference in yield except for in the CK treatment without nitrogen fertilizer. The results showed that the magnitude of greenhouse gas emissions in the tropical rice-vegetable rotation system was mainly determined by CH4 emissions in the late rice season. After two years of biochar application， only low biochar combined with nitrogen fertilizer had a significant emission reduction effect， but high and low biochar combined with nitrogen fertilizer increased the yield of early rice and pepper crops continuously.

[Adsorption Properties of Magnetic Phosphorous Camellia Oleifera Shells Biochar to Sulfamethoxazole in Water].

Magnetic phosphorous biochar （MPBC） was prepared from Camellia oleifera shells using phosphoric acid activation and iron co-deposition. The materials were characterized and analyzed through scanning electron microscopy （SEM）， X-ray diffractometry （XRD）， specific surface area and pore size analysis （BET）， Fourier infrared spectroscopy （FT-IR）， and X-ray photoelectron spectroscopy （XPS）. MPBC had a high surface area （1 139.28 m2·g-1） and abundant surface functional groups， and it could achieve fast solid-liquid separation under the action of an external magnetic field. The adsorption behavior and influencing factors of sulfamethoxazole （SMX） in water were investigated. The adsorbent showed excellent adsorption properties for SMX under acidic and neutral conditions， and alkaline conditions and the presence of CO32- had obvious inhibition on adsorption. The adsorption process conformed to the quasi-second-order kinetics and Langmuir model. The adsorption rate was fast， and the maximum adsorption capacity reached 356.49 mg·g-1. The adsorption process was a spontaneous exothermic reaction， and low temperature was beneficial to the adsorption. The adsorption mechanism was mainly the chemisorption of pyrophosphate surface functional groups （C-O-P bond） between the SMX molecule and MPBC and also included hydrogen bonding， π-π electron donor-acceptor （π-πEDA） interaction， and a pore filling effect. The development of MPBC adsorbent provides an effective way for resource utilization of waste Camellia oleifera shells and treatment of sulfamethoxazole wastewater.

Efficient Adsorption of Nitrogen and Phosphorus in Wastewater by Biochar.

Nitrogen and phosphorus play essential roles in ecosystems and organisms. However, with the development of industry and agriculture in recent years, excessive N and P have flowed into water bodies, leading to eutrophication, algal proliferation, and red tides, which are harmful to aquatic organisms. Biochar has a high specific surface area, abundant functional groups, and porous structure, which can effectively adsorb nitrogen and phosphorus in water, thus reducing environmental pollution, achieving the reusability of elements. This article provides an overview of the preparation of biochar, modification methods of biochar, advancements in the adsorption of nitrogen and phosphorus by biochar, factors influencing the adsorption of nitrogen and phosphorus in water by biochar, as well as reusability and adsorption mechanisms. Furthermore, the difficulties encountered and future research directions regarding the adsorption of nitrogen and phosphorus by biochar were proposed, providing references for the future application of biochar in nitrogen and phosphorus adsorption.

Effects of biochar immobilization of Serratia sp. F4 OR414381 on bioremediation of petroleum contamination and bacterial community composition in loess soil.

Petroleum hydrocarbons pose a significant threat to human health and the environment. Biochar has increasingly been utilized for soil remediation. This study investigated the potential of biochar immobilization using Serratia sp. F4 OR414381 for the remediation of petroleum-contaminated soil through a pot experiment conducted over 90 days. The treatments in this study, denoted as IMs (maize straw biochar-immobilized Serratia sp. F4), degraded 82.5% of the total petroleum hydrocarbons (TPH), 59.23% of the aromatic, and 90.1% of the saturated hydrocarbon fractions in the loess soils. During remediation, the soil pH values decreased from 8.76 to 7.33, and the oxidation-reduction potential (ORP) increased from 156 to 229 mV. The treatment-maintained soil nutrients of the IMs were 138.94 mg/kg of NO3- -N and 92.47 mg/kg of available phosphorus (AP), as well as 11.29% of moisture content. The activities of soil dehydrogenase (SDHA) and catalase (CAT) respectively increased by 14% and 15 times compared to the CK treatment. Three key petroleum hydrocarbon degradation genes, including CYP450, AJ025, and xylX were upregulated following IMs treatment. Microbial community analysis revealed that a substantial microbial population of 1.01E+ 09 cells/g soil and oil-degrading bacteria such as Salinimicrobium, Saccharibacteria_genera_incertae_sedis, and Brevundimonas were the dominant genera in IMs treatment. This suggests that the biochar immobilized on Serratia sp. F4 OR414381 improves soil physicochemical properties and enhances interactions among microbial populations, presenting a promising and environmentally friendly approach for the stable and efficient remediation of petroleum-contaminated loess soil.

Nano La(OH)3 modified lotus seedpod biochar: A novel solution for effective phosphorus removal from wastewater.

Effective removal of phosphorus from water is crucial for controlling eutrophication. Meanwhile, the post-disposal of wetland plants is also an urgent problem that needs to be solved. In this study, seedpods of the common wetland plant lotus were used as a new raw material to prepare biochar, which were further modified by loading nano La(OH)3 particles (LBC-La). The adsorption performance of the modified biochar for phosphate was evaluated through batch adsorption and column adsorption experiments. Adsorption performance of lotus seedpod biochar was significantly improved by La(OH)3 modification, with adsorption equilibrium time shortened from 24 to 4 h and a theoretical maximum adsorption capacity increased from 19.43 to 52.23 mg/g. Moreover, LBC-La maintained a removal rate above 99% for phosphate solutions with concentrations below 20 mg/L. The LBC-La exhibited strong anti-interference ability in pH (3-9) and coexisting ion experiments, with the removal ratio remaining above 99%. The characterization analysis indicated that the main mechanism is the formation of monodentate or bidentate lanthanum phosphate complexes through inner sphere complexation. Electrostatic adsorption and ligand exchange are also the mechanisms of LBC-La adsorption of phosphate. In the dynamic adsorption experiment of simulated wastewater treatment plant effluent, the breakthrough point of the adsorption column was 1620 min, reaching exhaustion point at 6480 min, with a theoretical phosphorus saturation adsorption capacity of 6050 mg/kg. The process was well described by the Thomas and Yoon-Nelson models, which indicated that this is a surface adsorption process, without the internal participation of the adsorbent.

Promoting nitrogen conversion in aerobic biotransformation of swine slurry with the co-application of manganese sulfate and biochar.

This study aimed to explore the co-application of MnSO4 (Mn) and biochar (BC) in nitrogen conversion during the composting process. A 70-day aerobic composting was conducted using swine slurry, supplemented with different levels of Mn (0, 0.25%, and 0.5%) and 5% BC. The results demonstrated that the treatment with 0.5MnBC had the highest levels of NH4+-N (3.07 g kg-1), TKN (29.90 g kg-1), and NO3--N (1.94 g kg-1) among all treatments. Additionally, the 0.5MnBC treatment demonstrated higher urease, protease, nitrate reductase, and nitrite reductase activities than the other treatments, with the peak values of 18.12, 6.96, 3.57, and 15.14 mg g-1 d-1, respectively. The addition of Mn2+ increased the total organic nitrogen content by 29.59%-47.82%, the acid hydrolyzed ammonia nitrogen (AN) content by 13.84%-57.86% and the amino acid nitrogen (AAN) content by 55.38%-77.83%. The richness of Chloroflexi and Ascomycota was also enhanced by the simultaneous application of BC and Mn. Structural equation modeling analysis showed that Mn2+ can promote the conversion of Hydrolyzed Unknown Nitrogen (HUN) into AAN, and there is a positive association between urease and NH4+-N according to redundancy analysis. Firmicutes, Basidiomycota, and Mortierellomycota showed significant positive correlations with ASN, AN, and NH4+-N, indicating their crucial roles in nitrogen conversion. This study sheds light on promoting nitrogen conversion in swine slurry composting through the co-application of biochar and manganese sulfate.

Biochar influences nitrogen and phosphorus dynamics in two texturally different soils.

Nitrogen (N) and phosphorus (P) are vital for crop growth. However, most agricultural systems have limited inherent ability to supply N and P to crops. Biochars (BCs) are strongly advocated in agrosystems and are known to improve the availability of N and P in crops through different chemical transformations. Herein, a soil-biochar incubation experiment was carried out to investigate the transformations of N and P in two different textured soils, namely clay loam and loamy sand, on mixing with rice straw biochar (RSB) and acacia wood biochar (ACB) at each level (0, 0.5, and 1.0% w/w). Ammonium N (NH4-N) decreased continuously with the increasing incubation period. The ammonium N content disappeared rapidly in both the soils incubated with biochars compared to the unamended soil. RSB increased the nitrate N (NO3-N) content significantly compared to ACB for the entire study period in both texturally divergent soils. The nitrate N content increased with the enhanced biochar addition rate in clay loam soil until 15 days after incubation; however, it was reduced for the biochar addition rate of 1% compared to 0.5% at 30 and 60 days after incubation in loamy sand soil. With ACB, the net increase in nitrate N content with the biochar addition rate of 1% remained higher than the 0.5% rate for 60 days in clay loam and 30 days in loamy sand soil. The phosphorus content remained consistently higher in both the soils amended with two types of biochars till the completion of the experiment.

Response of antioxidant activity, active constituent and rhizosphere microorganisms of Salvia miltiorrhiza to combined application of microbial inoculant, microalgae and biochar under Cu stress.

Salvia miltiorrhiza, a widely used medicinal herb renowned for its properties in promoting blood circulation, removing blood stasis and alleviating pain, is currently facing quality degradation due to excessive heavy metal levels, posing a threat to medication safety. In order to investigate the effects of microbial inoculant, microalgae and biochar on the growth of Salvia miltiorrhiza under copper (Cu) stress, as well as its Cu absorption, antioxidant activity, active component contents and rhizosphere microbial community, a pot experiment was conducted. Salvia miltiorrhiza plants were cultivated in the soil containing 400 mg/kg of Cu for six months and treated with microbial inoculant, microalgae and biochar, either individually or in combination. Almost all soil amendment treatments led to an increase in root biomass. Notably, co-application of microbial inoculant and microalgae had the optimal effect with a 63.07 % increase compared to the group treated solely with Cu. Moreover, when microbial inoculant was applied alone or in combination with microalgae, the Cu content in plant roots was reduced by 19.29 % and 25.37 %, respectively, whereas other treatments failed to show a decreasing trend. Intriguingly, Cu stress increased the active component contents in plant roots, and they could also be enhanced beyond non-stress levels when microbial inoculant and microalgae were applied together or in combination with biochar. Analyses of plant antioxidant activity, soil properties and rhizosphere microorganisms indicated that these amendments may alleviate Cu stress by enhancing peroxidase activity, facilitating plant nutrient absorption, and enriching beneficial microorganisms capable of promoting plant growth and mitigating heavy metal-induced damage. This study suggests that the combined application of microbial inoculant and microalgae can reduce Cu levels in Salvia miltiorrhiza while enhancing its quality under Cu stress.

Petroleum-contaminated soil bioremediation and microbial community succession induced by application of co-pyrolysis biochar amendment: An investigation of performances and mechanisms.

This study aimed to remediate petroleum-contaminated soil using co-pyrolysis biochar derived from rice husk and cellulose. Rice husk and cellulose were mixed in various weight ratios (0:1, 1:0, 1:1, 1:3 and 3:1) and pyrolyzed under 500 °C. These biochar variants were labeled as R0C1, R1C0, R1C1, R1C3 and R3C1, respectively. Notably, the specific surface area and carbon content of the co- pyrolysis biochar increased, potentially promoting the growth and colonization of soil microorganisms. On the 60th day, the microbial control group achieved a 46.69% removal of pollutants, while the addition of R0C1, R1C0, R1C3, R1C1 and R3C1 resulted in removals of 70.56%, 67.01%, 67.62%, 68.74% and 67.30%, respectively. In contrast, the highest efficiency observed in the abiotic treatment group was only 24.12%. This suggested that the removal of petroleum pollutants was an outcome of the collaborative influence of co-pyrolysis biochar and soil microorganisms. Furthermore, the abundance of Proteobacteria, renowned for its petroleum degradation capability, obviously increased in the treatment group with the addition of co-pyrolysis biochar. This demonstrated that co-pyrolysis biochar could notably stimulate the growth of functionally associated microorganisms. This research confirmed the promising application of co-pyrolysis biochar in the remediation of petroleum-contaminated soil.

Adsorption effect and mechanism of Cd(II) by different phosphorus-enriched biochars.

The resource utilization of agricultural and forestry waste, especially the high-value transformation of low-grade phosphate rock and derivatives, is an important way to achieve sustainable development. This study focuses on the impregnation and co-pyrolysis of rice straw (RS) with fused calcium magnesium phosphate (FMP), FMP modified with citric acid (CA-FMP), and calcium dihydrogen phosphate (MCP) to produce three phosphorous-enriched biochars (PBC). The Cd(II) removal efficiency of biochars before and after phosphorus modification was investigated, along with the adsorption mechanism and contribution of biochars modified with different phosphorus sources to Cd(II) adsorption. The result indicated that CA-FMP and MCP could be more uniformly loaded onto biochar, effectively increasing the specific surface area (SSA) and total pore volume. The adsorption of Cd(II) onto PBC followed a mono-layer chemisorption process accompanied by intraparticle diffusion. The adsorption of Cd(II) by PBC involved ion exchange, mineral precipitation, complexation with oxygen-containing functional groups (OFGs), cation-π interaction, electrostatic interaction, and physical adsorption. Ion exchange was identified as the primary adsorption mechanism for Cd(II) by BC and FBC (51.53% and 53.15% respectively), while mineral precipitation played a major role in the adsorption of Cd(II) by CBC and MBC (51.10% and 47.98% respectively). Moreover, CBC and MBC significantly enhanced the adsorption capacity of Cd(II), with maximum adsorption amounts of 128.1 and 111.5 mg g-1 respectively.

Asynchronous application of modified biochar and exogenous fungus Scedosporium sp. ZYY for enhanced degradation of oil-contaminated intertidal mudflat sediment.

Intertidal mudflats are susceptible to oil pollution due to their proximity to discharges from industries, accidental spills from marine shipping activities, oil drilling, pipeline seepages, and river outflows. The experimental study was divided into two periods. In the first period, microcosm trials were carried out to examine the effect of chemically modified biochar on biological hydrocarbon removal from sediments. The modified biochar's surface area increased from 2.544 to 25.378 m2/g, followed by a corresponding increase in the hydrogen-carbon and oxygen-carbon ratio, indicating improved stability and polarity. In the second period, the effect of exogenous fungus - Scedoporium sp. ZYY on the bacterial community structure was examined in relation to total petroleum hydrocarbon (TPH) removal. The maximum TPH removal efficiency of 82.4% was achieved in treatments with the modified biochar, followed by a corresponding increase in Fluorescein diacetate hydrolysis activity. Furthermore, high-throughput 16S RNA gene sequencing employed to identify changes in the bacterial community of the original sediment and treatments before and after fungal inoculation revealed Proteobacteria as the dominant phylum. In addition, it was observed that Scedoporium sp. ZYY promoted the proliferation of specific TPH-degraders, particularly, Hyphomonas adhaerens which accounted for 77% of the total degrading populations in treatments where TPH removal was highest. Findings in this study provide valuable insights into the effect of modified biochar and the fundamental role of exogenous fungus towards the effective degradation of oil-contaminated intertidal mudflat sediments.

Study on the solidification performance and mechanism of heavy metals by sludge/biomass ash ceramsites, biochar and biomass ash.

Industrial by-products are stored in large quantities in the open, leading to wasted resources and environmental pollution, and the natural environment is similarly faced with phosphate depletion and serious water and soil pollution. This study uses these by-products to produce a new sludge/biomass ash ceramsite that will be used to adsorb nitrogen and phosphorus from wastewater, and solidify heavy metals in the soil while releasing Olsen P. The sludge/biomass ash ceramsites are made using sewage sludge and biomass ash in a certain ratio calcined at high temperatures and modified for the adsorption of nitrogen and phosphorus from wastewater. Sludge/biomass ash ceramsites before and after phosphorus adsorption, biochar and biomass ash were compared to analyze their heavy metal adsorption capacity and potential as phosphate fertilizer. After phosphorus adsorption, the sludge/biomass ash ceramsites released effective phosphorus steadily and rapidly in the soil, with a greater initial release than biochar and biomass ash, and the ceramsites were in a granular form that could be easily recycled. Biochar and biomass residue, due to their surface functional groups, are better at solidifying heavy metals than sludge/biomass ash ceramsites. Biochar, biomass ash and sludge/biomass ash ceramsites significantly reduced the concentrations of Cd, Cu, Pb and Zn in the soil. Correlation analysis demonstrated that there was a synergistic relationship between the increase in soil Olsen P content and the change in pH, with the increase in soil Olsen P content and the increase in pH contributing to heavy metal solidification.

Divergent responses of phosphorus solubilizing bacteria with P-laden biochar for enhancing nutrient recovery, growth, and yield of canola (Brassica napus L.).

The growing global population has led to a heightened need for food production, and this rise in agricultural activity is closely tied to the application of phosphorus-based fertilizers, which contributes to the depletion of rock phosphate (RP) reserves. Considering the limited P reserves, different approaches were conducted previously for P removal from waste streams, while the adsorption of ions is a novel strategy with more applicability. In this study, a comprehensive method was employed to recover phosphorus from wastewater by utilizing biochar engineered with minerals such as calcium, magnesium, and iron. Elemental analysis of the wastewater following a batch experiment indicated the efficiency of the engineered biochar as an adsorbent. Subsequently, the phosphorus-enriched biochar, hereinafter (PL-BCsb), obtained from the wastewater, underwent further analysis through FTIR, XRD, and nutritional assessments. The results revealed that the PL-BCsb contained four times higher (1.82%) P contents which further reused as a fertilizer supplementation for Brassica napus L growth. PL-BCsb showed citric acid (34.03%), Olsen solution (10.99%), and water soluble (1.74%) P desorption. Additionally, phosphorous solubilizing bacteria (PSB) were incorporated with PL-BCsb along two P fertilizer levels P45 (45 kg ha-1) and P90 (90 kg ha-1) for evaluation of phosphorus reuse efficiency. Integrated application of PL-BCsb with half of the suggested amount of P45 (45 kg ha-1) and PSB increased growth, production, physiological, biochemical, and nutritional qualities of canola by almost two folds when compared to control. Similarly, it also improved soil microbial biomass carbon up to four times, alkaline and acid phosphatases activities both by one and half times respectively as compared to control P (0). Furthermore, this investigation demonstrated that waste-to-fertilizer technology enhanced the phosphorus fertilizer use efficiency by 55-60% while reducing phosphorus losses into water streams by 90%. These results have significant implications for reducing eutrophication, making it a promising approach for mitigating environmental pollution and addressing climate change.

Study on the removal efficacy and mechanism of phosphorus from wastewater by eggshell-modified biochar.

The excessive discharge of phosphorus from rural domestic sewage is a problem that worthy of attention. If the phosphorus in the sewage were recovered, addressing this issue could significantly contribute to mitigating the global phosphorus crisis. In this study, corn straw, a common agricultural waste, was co-pyrolytically modified with eggshells, a type of food waste from university cafeterias. The resulting product, referred to as corn straw eggshell biochar (EGBC) was characterized using SEM, XRD, XPS, XRF, and other methods. Batch adsorption experiments were conducted to determine the optimal preparation conditions of EGBC and to explore its adsorption characteristics. EGBC showed strong adsorption effectiveness within a pH range of 5-12. The adsorption isotherm closely followed the Sips model (R2 > 0.9011), and the adsorption kinetics were more consistent with the pseudo-second-order model (R2 > 0.9899). The process was found to be both spontaneous and endothermic. Under optimal conditions, the phosphorus adsorption capacity of EGBC was measured to be 288.83 mg/g. This demonstrates the high efficiency of EGBC for phosphorus removal and illustrates an effective method of utilizing food waste for environmental remediation. PRACTITIONER POINTS: Biochar prepared from waste eggshell was used to removal and recovery phosphorus in wastewater treatment. EGBC has an impressive adsorption capacity that can reach up to 288.83 mg/g. EGBC has excellent adsorption and filtration capabilities, and there is a sudden increase in concentration at 900 min in the breakthrough curve of EGBC. EGBC has good regeneration performance, with an adsorption effect of 65% and an adsorption capacity of 121 mg/g after four desorption and regeneration cycles.

Alginate-encapsulated biochar as an effective soil ameliorant for reducing Pb phytoavailability to lettuce (Lactuca sativa L.).

The alginate-biochar formulation for metal removal from aquatic environments has been widely tried but its use for lowering phytoavailability of metals in the soil-crop continuum is limited. Biochar has been increasingly used as a soil amendment due to its potential for soil carbon sequestration and sorption capacity. Handling of powdery biochar as a soil top-dressing material is, however, cumbersome and vulnerable to loss by water and wind. In this experiment, biochar powder, which was pyrolyzed from oak trees, was encapsulated into beads with alginate, which is a naturally occurring polysaccharide found in brown algae. Both batch and pot experiments were conducted to examine the effects of the alginate-encapsulated biochar beads (BB), as compared to its original biochar powdery form (BP), on the Pb adsorption capacity and phytoavailability of soil Pb to lettuce (Lactuca sativa L.). The BB treatment improved reactivity about six times due to a higher surface area (287 m2 g-1) and five times due to a higher cation exchange capacity (50 cmolc kg-1) as compared to the BP treatment. The maximum sorption capacity of Pb was increased to 152 from 81 mg g-1 because of surface chemosorption. Adsorption of Pb onto BB followed multiple first-order kinetics and comprised fast and slow steps. More than 60% of the Pb was adsorbed in the fast step, i.e., within 3 h. Also, the BB treatment, up to the 5% level (w/w), increased soil pH from 5.4 to 6.5 and lowered the phytoavailable fraction of Pb in soil from 5.7 to 0.3 mg kg-1. The Pb concentrations in lettuce cultivated at 5% for the BP and BB treatments were similar but 63 and 66% lower, respectively, than those of the control soil. The results showed that the encapsulation of biochar with alginate enhanced adsorption by the biochar.

Enriched soil amendments influenced soil fertility, herbage yield and bioactive principle of medicinal plant (Cassia angustifolia Vahl.) grown in two different soils.

High cost of chemical fertilizers and poor nutrient content in conventional organic sources (manure, compost, charcoal etc.) can be addressed through development of enriched organic amendments. However, there is a need to evaluate enriched organic amendments as a potential alternative of chemical fertilizers. Therefore, an effort was made to prepare enriched organic amendments through blending distillation waste of aromatic plant biomass (DWB) with naturally available low-grade rock phosphate (RP) and waste mica (WM). Enrich compost (ENC) was produced from DWB in a natural composting process, blended with mineral powder, whereas biochar fortified mineral (BFM) was prepared by blending biochar, derived from DWB through hydrothermal reaction, with mineral powder. The main aims of the present study were to investigate the impacts of ENC and BFM applications on soil properties, and herbage yield and quality of a medicinal herb Senna (Cassia angustifolia Vahl.). The performances of ENC and BFM at two different rates (2.5 and 5 t ha-1) were compared with the application of conventional farmyard manure (FYM, 5 t ha-1) and chemical fertilizers (CF, NPK 60-40-20 kg ha-1) in two different soils in a pot experiment. Both, ENC and EBC improved soil quality and fertility by increasing soil organic carbon, available nutrients, microbial biomass and enzyme activity. The ENC and BFM increased total herbage yields by 21 and 16.3 % compared to FYM. In both soils, the CF treatment produced the maximum dry herbage yields (32.7-37.4 g pot-1), which however were comparable to ENC (31.9-33.7 g pot-1) and BFM (30.7-35.1 g pot-1) treatments. Bioactive compound (sennoside) production in senna was significantly improved by ENC and BFM compared to CF. The present study indicates that ENC and BFM could not only help to overcome the limitation of conventional FYM, but also have the potentials to substitute costly chemical fertilizers, particularly in medicinal plant cultivation.