Calcium Phosphate Research Articles

A particle-filled hydrogel based on alginate and calcium phosphate nanoparticles as bone adhesive

The clinical need for bone adhesives as an alternative to osteosynthesis is evident. However, this is a challenging problem due to the moist environment in surgical sites with bone surfaces covered with blood and biomolecules like lipids or proteins. A nanoparticle-loaded hydrogel that is based on a freeze-dried powder of silica-coated calcium phosphate/carboxymethyl cellulose nanoparticles (CaP/CMC/SiO2) and an aqueous solution of sodium alginate (2 wt%) was developed and optimized with respect to the gluing ability in air and in water. The final paste was crosslinked within about one minute by calcium ions released from the calcium phosphate nanoparticles and contained about 20 wt% nanoparticles and 80 wt% water. The mechanical properties of the hydrogel were determined by extensive rheological tests. The thixotropic pasty hydrogel can be applied with a syringe. The adhesion strength was about 84 kPa between moist bone fragments in air. The hydrogel kept fragments of cortical bone well connected for >3 months during complete submersion in water. Besides water, the material consists only of biocompatible and biodegradable components (calcium phosphate, CMC, alginate). It carries only a very low dose of these materials into the bone site (mainly calcium phosphate nanoparticles). In-vitro cell culture with hMSCs that differentiated to osteoblasts confirmed a good biocompatibility of the bone adhesive formulation.Graphical

Investigating the impact of coagulation bath temperature on the properties of biphasic calcium phosphate/poly(vinylidene fluoride)‐based membrane scaffold via immersion precipitation

AbstractIn this study, composite membrane scaffolds comprising poly(vinylidene fluoride) (PVDF) and boron‐containing biphasic calcium phosphate (BCP) are developed using a non‐solvent‐induced phase separation technique at coagulation bath temperatures of −5, 0, 10, and 20 °C. The morphology, pore size and tensile strength of the scaffolds are primarily influenced by the bath temperature. Moreover, raising the bath temperature enhances the thermal properties and β‐crystalline phase fraction. Results demonstrate that changes in the temperature increase the surface hydrophilicity and reduce the degree of swelling. According to the in vitro bioactivity analysis, apatite growth is affected by the interactive relation between the surface of the samples and the simulated body fluid (SBF) medium, in addition to the superior bioactivity of the scaffolds. In vitro cytotoxicity assay results confirm the extensive spreading of L‐929 cells on the sample surfaces, indicating the high biocompatibility of the scaffolds. Based on these favorable properties, the novel composite membranes produced, particularly at 20 °C coagulation bath temperature, may contribute to applications in bone tissue engineering.

Insights into the Various Cellular Antimicrobial Responses, Biocompatibility, Osteogenesis, Wound Healing, and Angiogenesis of Copper-Doped Nano-Hydroxyapatite Composite Calcium Phosphate Bone Cement In Vitro

Calcium phosphate bone cement (CPC) is a popular material for bone remodeling, and nanohydroxyapatite (nHA) represents a breakthrough that has a wide range of clinical applications. During the early stages of bone repair, antibacterial and angiogenesis effects are essential to remodel new bone tissues. In this study, an antibacterial effect was achieved by incorporating Cu2+-doped nano-hydroxyapatite (Cu–nHA) synthesized through hydrothermal methods into CPC, and the impact of various amounts of Cu–nHA addition on the antibacterial and mechanical properties of CPC hybridization was evaluated. Moreover, the effects of Cu–nHA/CPC composites on the proliferation and mineralization of mouse progenitor osteoblastic cells (D1 cells) were characterized; the cell migration and angiogenesis ability of vascular endothelial cells (HUVECs) were also studied. Results indicated that incorporating 5 wt.% and 10 wt.% Cu–nHA into CPC led to a practical short-term antibacterial effect on S. aureus but not on E. coli. These Cu–nHA/CPC slurries remained injectable, anti-disintegrative, and non-toxic. Furthermore, compared with pure CPC, these Cu–nHA/CPC slurries demonstrated positive effects on D1 cells, resulting in better proliferation and mineralization. In addition, these Cu–nHA/CPC slurries were more effective in promoting the migration and angiogenesis of HUVECs. These findings indicate that 10 wt.% Cu–nHA/CPC has great application potential in bone regeneration.

Endemic Bladder Stone Disease in Children, Pattern And Current Management: Experience From A Centre In Peri-Urban Setting In Pakistan.

To share our recent experience of the pattern and demography of endemic bladder calculi in children and the outcomes of current management strategies for the removal of bladder calculi in a peri-urban setting. This retrospective longitudinal study was carried out at a dedicated urology centre. All patients with endemic bladder stones from January 2020 to December 2021 managed at our centre were included in this study. After discharge, each patient was followed up for 1 year. Data analysis was carried out with IBM SPSS v23. Mean and standard deviation were calculated for normally distributed continuous variables; for non-normally distributed continuous variables, median and IQR were calculated; frequency and percentage were calculated for categorical variables. This study included 254 patients, with a male-to-female ratio of 10.5:1. The mean age of the patients was 4.80 ± 2.86 years. Ninety-one percent of the patients belonged to rural areas. Open cystolithotomy (OC) was performed in 11 (4.3%) patients, transurethral cystolithotripsy (TUCL) in 165 (65.0%), and percutaneous cystolithotomy (PCCL) in 78 (30.7%). The mean operative time was 48.8 ± 4.34 minutes for TUCL, 36.18 ± 7.4 minutes for open cystolithotomy, and 38.6 ± 5.2 minutes for PCCL. The most common stone composition was ammonium urate + calcium phosphate (33.1%). The complication rate was 4.8% in TUCL, 12.8% in PCCL, and 27.3% in open cystolithotomy. Stone clearance was 98.1% for TUCL and 100% for both PCCL and OC. Paediatric bladder calculus is still endemic in rural areas of Sindh with poor socioeconomic backgrounds. Timely diagnosis and early intervention with preventive measures can lead to better outcomes and fewer complications. Minimally invasive methods of cystolithotomy have a shorter hospital stay, are more cost-effective, and have fewer complications as compared to open cystolithotomy.

Transforming waste into wealth in sustainable shrimp aquaculture: Effective phosphate removal and recovery using shrimp shell-derived adsorbents

The growing global demand for shrimp has driven the intensification of shrimp aquaculture, leading to significant environmental challenges due to nutrient-rich wastewater and solid waste. This study developed shrimp shell-derived adsorbents (SSs) by pyrolysis and calcium hydroxide (Ca(OH)2) activation to remove phosphate (PO43−) from aqueous solutions. Ca(OH)2 activated adsorbent achieved higher PO43− removal than adsorbent obtained at higher pyrolysis temperature, with adsorption capacities up to 381.24 mg/g of PO43− at 20 °C. The primary mechanism driving PO43− removal was chemical precipitation between Ca and PO43−. SSs were found to release Ca2+ from hydroxylellestadite (HDL), Ca(OH)2, and calcium carbonate (Ca(CO)3). Additionally, ligand exchange of PO43− by Ca(CO)3 and π-π interactions from aromatic rings further enhanced the PO43− adsorption. SEM-EDS showed PO43− dispersed on the SSs surface. XPS revealed that Ca-O bond was shifted to Ca-P bond with a higher binding energy and a new π-π interaction peak appeared at 293.60 eV. FTIR confirmed ligand exchange between PO43− and CO32−, with the 1400 cm−1 band disappearing and a new 870 cm−1 band appearing. The XRD, FTIR, and XPS analyses confirmed the formation of various calcium-phosphate (Ca-P) groups, including calcium apatite (Ca-apatite), monocalcium phosphate (Ca(H2PO4)2), and dicalcium phosphate (CaHPO4), on the saturated SSs. Specifically, all XPS spectra of Ca-O moved to higher binding energy, reflecting Ca-P linkages. This study provides a sustainable alternative for handling shrimp shell waste and suggests a promising approach for PO43− recovery, thereby contributing to a circular system in shrimp aquaculture.

Improving the Bioactivity and Antibiofilm Properties of Metallic Implant Materials via Controlled Surface Microdeformation.

Although metallic implants provide most of the required properties for bone-related applications, especially orthopedic implants, insufficient osseointegration, which may lead to loosening of the implant or prolonged healing time, is still an issue to be resolved. Osseointegration can be improved via application of various surface treatments on the metal surface. The current study focuses on a novel surface microdeformation method, which enables the formation of controlled surface patterns of various parameters. With this purpose, a surface microdeformation procedure was applied on 316L stainless steel surfaces, forming four different patterns which affected various surface parameters such as roughness, surface energy, dislocation activities close to the surface, and wettability. Static immersion tests in a simulated body fluid (SBF) environment showed that modifying the surface parameters via controlled surface patterning promoted the formation of a stable oxide layer and calcium-phosphate (CaP) deposition on the metal surfaces, improving bioactivity. Moreover, the higher amount of CaP deposition and oxide layer formation on the modified surfaces led to reduced ion release, which contributed to improved corrosion resistance. Finally, the effect of the formed surface patterns on antibiofilm formation was investigated via incubation with C. albicans for 24 h, which exhibited that microdeformation patterns remarkably inhibited the biofilm formation. Throughout the experiments, certain patterns yielded outstanding results among the four patterns formed. Overall, it was concluded that forming controlled patterns on stainless steel surfaces via surface microdeformation significantly contributed to the metal's biocompatibility via improving bioactivity, corrosion resistance, and antibiofilm formation properties. Especially, the specific surface properties such as increased surface energy, high surface roughness, and dislocation density close to the metal surface as well as increased hydrophilicity obtained via forming the pattern with relatively deeper and narrowly spaced indents yielded the most promising outcomes. These methodologies constitute novel approaches to be used while designing new methodologies for the surface modification of metallic implant materials for improved osseointegration.

SGLT2 Inhibitors and Their Effect on Urolithiasis: Current Evidence and Future Directions.

Urolithiasis (UL) is increasingly prevalent due to rising cardiorenometabolic diseases, posing significant management challenges despite advances in urological techniques. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, primarily used for type 2 diabetes mellitus, chronic kidney disease, and heart failure, have emerged as a potential novel approach for UL treatment. These inhibitors may help reduce the risk of urolithiasis, particularly in patients with diabetes, by improving glycemic control and altering urinary chemistry, which are crucial factors in stone formation. However, the changes in urinary composition induced by SGLT2 inhibitors might also increase the risk of uric acid stone formation. This review evaluates the potential of SGLT2 inhibitors in managing UL, highlighting both the benefits and the risks. While these inhibitors show promise in reducing new and recurrent urinary stones in patients with diabetes, data on their effects in patients without diabetes who form stones are limited. Current human evidence largely comes from post hoc analyses of randomized controlled trials (RCTs) and large-scale database studies, with only one study providing detailed stone composition data. Experimental studies in animal models and cell lines have focused on calcium oxalate (CaOx) stones, showing that SGLT2 inhibitors specifically target CaOx stone formation and related renal inflammation. Although primarily studied for CaOx stones, their potential impact on other calcium-containing stones, such as calcium phosphate, remains promising. Further research is needed to explore their therapeutic potential and optimize treatment strategies.

Micro-arc oxidation for balancing antibacterial activity and bone formation on titanium surface

Ti surfaces must balance bone formation and antibacterial activity to achieve bone reconstruction and prevent infections. In this study, a Ti surface was electrochemically modified via micro-arc oxidation in an electrolyte containing calcium ions, phosphate ions, and either Ag, or Cu ions to form an antibacterial porous oxide layer on Ti surface. The resultant porous oxide layers consisted of both electrolyte and substrate elements. The Ag- and Cu-incorporated porous oxide layers exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus. Furthermore, animal experiments were performed to reveal the bone-formation on the Ag- and Cu-incorporated porous oxide layers. Both porous oxide layers promoted bone formation more effectively than untreated Ti. Thus, the Ag- and Cu-incorporated porous oxide layers formed on the Ti surface by micro-arc oxidation balanced bone formation and antibacterial activity owing to their structural and compositional features. Our findings will be useful for the surface design of Ti-based medical devices and can provide a simple electrochemical treatment to form porous surfaces to balance antibacterial activity and bone formation on Ti surfaces.

Axonal Energy Crisis and Calcium Phosphate Dysregulation as Pathogenesis of Optic Disc Drusen.

Soft tissue ectopic calcification is due to abnormal accumulation of calcium and phosphate outside the bone. It is the result of the failure of a complex, active, and highly regulated process - much of which is still not well understood. Some of our understanding of ectopic calcification come from studies on diseases such as atherosclerosis, aortic valve disease and kidney stone disease. In the eye, the most common causes of visual defects due to ectopic calcification include optic disc drusen (ODD) and age-related macular degeneration (AMD). In ODD, ectopic calcification occurs only in the most anterior, unmyelinated portion of optic nerve - the sole output of the eye and particularly susceptible to hypoxic and metabolic stress. In this article, we review the effects of hypoxia on mitochondrial function and calcium regulation and delineate the key processes likely involved in ectopic calcification. We propose a working hypothesis for ODD centering on the role of hypoxia-induced calcium and phosphate overload, mitochondrial dysfunction and osteogenic differentiation, leading to hydroxyapatite deposition and biomineralization.

3D distribution of biomineral and chitin matrix in the stomatopod dactyl club by high energy XRD-CT

Stomatopods are ferocious hunters that use weaponized appendages to strike down their pray. The clubs of species such as Odontodactylus scyllarus undergo tremendous forces, and in consequence they have intricate structures, consisting of hydroxyapatite, chitin, amorphous calcium phosphate and carbonate, and occasionally calcite. These materials are distributed differently across the four major zones of the dactyl club: the impact, periodic lateral and medial, and striated regions. While stomatopod clubs and their structure have been studied for a long time, studies have thus far been constrained to 2D mapping experiments with moderate resolution due to difficulties in preparing whole club thin sections, and absorption tomography that gives information on densities but not molecular length scales. To address this problem, and shed light on the structure of entire clubs, we herein used X-ray powder diffraction computed tomography (XRD-CT) using high energy X-rays at the P07 beamline of PETRA-III to allow penetrating the large samples whilst still obtaining high resolution information. This allowed mapping the 3D distribution of diffraction phases including the biomineral apatite and the semi-crystal chitin matrix. This showed that hydroxyapatite forms an envelope around the club, and that chitin forms 2D sheets in the periodic region of the club.

Fluoride-incorporated apatite coating on resin-based composite via laser-assisted rapid pseudo-biomineralization

A thin-layer of fluoride-incorporated hydroxyapatite (FAp) is useful as an acid-resistant antibacterial mineralized coating to protect a tooth surface. Recently, we achieved rapid and area-specific FAp coating on the surfaces of human tooth substrates via precoating with a light-absorbing agent, indocyanine green, followed by laser irradiation in a fluoride-containing supersaturated calcium phosphate solution. In the present study, this FAp coating technique was applied to a substrate of resin-based composite (RBC), an artificial material with no biomineral component. Similar to the case of tooth substrates, a mineralized layer consisting of needle-like FAp crystals was formed on the RBC surface after laser irradiation for 3 min. The needle-like crystals increased in size with increasing laser power. In the absence of fluoride ions in the supersaturated solution, a layer consisting of plate-like octacalcium phosphate crystals was formed on the RBC surface. The present FAp coating technique was finally applied to an RBC-restored tooth substrate. Cross-sectional analyses revealed that the boundary region between the tooth and RBC was coated and sealed with a mineralized layer. The present FAp coating technique is potentially a new tool to seal the tooth–RBC boundary and reduce the risk of secondary caries associated with RBC restorations.

Histodynamics of calcium phosphate coating on the osseointegration of medical-grade polycaprolactone β-tricalcium phosphate scaffolds

Bone formation on implant surfaces occurs via distance and contact osteogenesis, with osseointegration influenced by the implant’s surface topography and coating. However, the traditional mechanisms of osseointegration around metal implant surfaces may not fully encompass the ultimate outcomes of using medical-grade polycaprolactone β-tricalcium phosphate calcium phosphate coated (mPCL-TCP-CaP) scaffolds for the reconstruction of large bone defects. Using histology, immunohistochemical (IHC) and scanning electron microscopy (SEM) analyses our studies on large bone defects using mPCL-TCP-CaP scaffolds show osteogenic cells forming a fibrous connective matrix around these scaffolds. Despite extensive research, the in vivo mechanisms of osseointegration of CaP-coated mPCL-TCP-CaP scaffolds remain unclear. This study investigates the structural details and spatial organization of the mPCL-TCP-CaP scaffold’s interface, providing insights into the histodynamic processes involved in their osseointegration with CaP coatings.

Phage-Loaded Biomimetic Apatite Powder With Antibiofilm Activity to Treat Bone-Associated Infections.

For decades, calcium phosphate (CaP)-based ceramics have been used for coating of bone and joint substitutes after arthroplasty due to their biocompatible properties. Infections following orthopedic replacement occur in 1%-5% of cases, causing serious complications. Biofilm formation either on the biomaterial's surface or on patient's tissues greatly enhances the resistance against antibiotic treatments and can induce a chronic infection, emphasizing the need for novel antimicrobial delivery systems. In this study, we established a protocol enabling bacteriophage loading during the synthesis of a CaP-based powder. The resulting biomaterial proved to be noncytotoxic against human osteoblastic cells and able to significantly inhibit 24-h matured S. aureus biofilm cultures or even completely eradicate it after 5 days of contact. Additional S. aureus biofilm assays with a freeze-dried material using two different excipients showed that sucrose had a protective role against Remus bacteriophage treatment of S. aureus biofilms, whereas lactose-freeze-dried powder maintained the antibiofilm activity.

The Effect of Lacticaseibacillus paracasei LPC100 and Lactiplantibacillus plantarum LP140 on Bone Mineral Density in Postmenopausal Women: A Multicenter, Randomized, Placebo-Controlled Study

Objectives: modulation of gut microbiota by probiotics has been proposed as a target for intervention to reduce bone mineral density (BMD) loss in the postmenopausal period. This study aims to evaluate the effect of Lacticaseibacillus (L.) paracasei LPC100 and Lactiplantibacillus (L.) plantarum LP140 on BMD in postmenopausal women in a multicenter, randomized, double-blind, placebo-controlled trial. Methods: the primary outcome was the change in T-score of the lumbar spine measured by dual-energy X-ray absorptiometry assessed after twelve-month probiotic supplementation. Secondary outcomes included changes in serological markers of inflammation and calcium–phosphate metabolism, body mass index, gastrointestinal symptoms, and satisfaction with the intervention. Results: a decrease in T-score indicating the progressive bone demineralization reached a statistically significant difference in the placebo group (from mean values of 0.06 ± 1.04 to −0.28 ± 1.12, p = 0.041) but not in the probiotic group (0.19 ± 0.99 and −0.08 ± 1.05, respectively, p = 0.125) with a p-value = 0.089 between the groups. No significant differences were found in secondary outcomes with the exception of vitamin D concentration and a significant reduction in some gastrointestinal symptoms in the probiotic group. A significant decrease in vitamin D level was observed only in the placebo group (p = 0.014). Probiotics were safe and well tolerated. Conclusions: this study suggests that the oral administration of L. paracasei LPC100 and L. plantarum LP140 may be a viable strategy to prevent BMD loss and vitamin D deficiency in postmenopausal women, but further research is necessary to confirm clinical benefits and to know the mechanism of action [ClinicalTrial.gov NCT06375668].

The impact of the physicochemical properties of calcium phosphate ceramics on biocompatibility and osteogenic differentiation of mesenchymal stem cells

ObjectiveIn this study we have focused on biocompatibility and osteoinductive capacity analysis of self-manufactured single-phase (HAP) and two-phase (HAP and β-ТСР) bioactive ceramics with various chemical modifications (Fig. 1).ResultsWe demonstrate a reduction in solubility for all analyzed composite after the treatment with H2O and H2O2, accompanied by an enhancement in adsorption activity. This modification also resulted in an increase in micro- and macroporosity, along with a rise in the open porosity. Adipose-derived mesenchymal stromal cells demonstrated excellent cell adhesion and survival when cultured with these ceramics. Calcium phosphate ceramics (H-500, HT-500, and HT-1 series) stimulated alkaline phosphatase expression, promoted calcium deposition, and enhanced osteopontin expression in ADSCs, independently inducing osteogenesis without additional osteogenic stimuli. These findings underscore the promising potential of HAP-based bioceramics for bone regeneration/reconstruction.Graphical

Navigating the combinations of platelet-rich fibrin with biomaterials used in maxillofacial surgery.

Platelet-rich fibrin (PRF) is a protein matrix with growth factors and immune cells extracted from venous blood via centrifugation. Previous studies proved it a beneficial biomaterial for bone and soft tissue regeneration in dental surgeries. Researchers have combined PRF with a wide range of biomaterials for composite preparation as it is biocompatible and easily acquirable. The results of the studies are difficult to compare due to varied research methods and the fact that researchers focus more on the PRF preparation protocol and less on the interaction of PRF with the chosen material. Here, the literature from 2013 to 2024 is reviewed to help surgeons and researchers navigate the field of commonly used biomaterials in maxillofacial surgeries (calcium phosphate bone grafts, polymers, metal nanoparticles, and novel composites) and their combinations with PRF. The aim is to help the readers select a composite that suits their planned research or medical case. Overall, PRF combined with bone graft materials shows potential for enhancing bone regeneration both in vivo and in vitro. Still, results vary across studies, necessitating standardized protocols and extensive clinical trials. Overviewed methods showed that the biological and mechanical properties of the PRF and material composites can be altered depending on the PRF preparation and incorporation process.

Multiplexed Random Access Approach to DNA Microspheres for High‐Capacity Data Storage

AbstractWith the rapid growth of modern information data, DNA has emerged as a novel medium for data storage due to its durability, replicability, sustainability, and high density. This study focuses on the compatibility, high capacity, and random access of DNA data storage systems. A calcium phosphate (CaP) mineralized fluorescent SiO2 DNA (FSD@CaP) microspheres is developed by encapsulating fluorescence‐labeled encoding DNA files onto the surface of the SiO2 microspheres that are intrinsically sized and fluorescent as addressed two‐dimensional (2D) barcodes. The various sizes of SiO2 and various fluorescence‐labeled encoding DNA files forming 2D barcodes of FSD@CaP. The 2D barcodes enhance the system's compatibility while allowing multiplexed random access to DNA files. The high‐capacity DNA storage permits effective single access to the DNA file using a minimal number of FSD@CaP microspheres, without impacting the matrix of the system. Ultimately, random access to arbitrary DNA files within a complex pool of distinct 2D barcode‐tagged FSD@CaP microspheres is demonstrated by utilizing a flow cytometer for multiplexed sorting. Consequently, the strategy of this storage system provides a scalable concept for compatibility and multiplexed random access to DNA data sets.

Development of a Microfluidic Vascularized Osteochondral Model as a Drug Testing Platform for Osteoarthritis.

Osteoarthritis (OA) is a degenerative joint disease characterized by changes in cartilage and subchondral bone. To date, there are no available drugs that can counteract the progression of OA, partly due to the inadequacy of current models to recapitulate the relevant cellular complexity. In this study, an osteochondral microfluidic model is developed using human primary cells to mimic an OA-like microenvironment and this study validates it as a drug testing platform. In the model, the cartilage compartment is created by embedding articular chondrocytes in fibrin hydrogel while the bone compartment is obtained by embedding osteoblasts, osteoclasts, endothelial cells, and mesenchymal stem cells in a fibrin hydrogel enriched with calcium phosphate nanoparticles. After developing and characterizing the model, Interleukin-1β is applied to induce OA-like conditions. Subsequently, the model potential is evaluated as a drug testing platform by assessing the effect of two anti-inflammatory drugs (Interleukin-1 Receptor antagonist and Celecoxib) on the regulation of inflammation- and matrix degradation-related markers. The model responded to inflammation and demonstrated differences in drug efficacy. Finally, it compares the behavior of the "Cartilage" and "Cartilage+Bone" models, emphasizing the necessity of incorporating both cartilage and bone compartments to capture the complex pathophysiology of OA.

Effects of phosphate-solubilizing bacteria Aspergillus flavus AF-LRH1 on promoting phosphorus solubilization, wheat growth and soil heavy metal remediation

Increasing nutrient supply level and eliminating pollution risk are essential to promote farmland soil use. In the soil-plant nutrition cycle, phosphorus is a limiting nutrient, toxic metals such as Cd and Pb are stress threats. Utilizing microorganisms as a bio-amendment could be a viable approach to enhance the cycling of soil phosphorus nutrients and immobilize Cd and Pb in the soil. This study involved the isolation of Aspergillus flavus AF-LRH1, a phosphate solubilizing fungal strain from soil. The strain exhibited the capacity to solubilize calcium phosphate, attaining a phosphorus concentration of 220.73 mg L−1 in the medium. High performance liquid chromatography analysis showed that AF-LRH1 produced a combination of organic acids (tartaric acid 260.7 mg L−1, fumaric acid 0.8 mg L−1, citric acid 911.9 mg L−1) to dissolve Ca3(PO4)2 by providing H+ ions. AF-LRH1 also utilizes NH4+ for the biosynthesis of amino acids and releases protons, which facilitate the dissolution of insoluble Ca3(PO4)2 and calcium phytate. Through these processes, calcium phosphate is partly converted into hydroxyapatite because of biological solubilization. AF-LRH1 strain showed the capability to recover phosphorus from various types of sludge-based solid residue by increasing the solubility of insoluble phosphate compounds for plant nutrient supply. In addition, the combining addition of AF-LRH1 strain and phosphate-containing amendments (calcium phosphate, sludge ash and biochar) benefited the decontamination of Pb and Cd contaminated soil. This finding confirmed the AF-LRH1 could be a promising environmental-friendly biofertilizer suitable for agricultural applications and bioremediation of heavy metal contaminated soil.

A two-step approach to recycling hydroponics waste nutrient solutions using fertiliser drawn forward osmosis and chemical precipitation

Hydroponic waste nutrient solutions (HWNS) present significant environmental and economic challenges due to their high phosphorus content and potential for eutrophication. Addressing these issues requires innovative approaches that mitigate environmental impacts and recover valuable resources. This study introduces a novel two-step approach that combines Fertiliser Drawn Forward Osmosis (FDFO) and chemical precipitation to recycle HWNS effectively.In the first phase, FDFO was employed to concentrate HWNS using a commercial hydroponic fertiliser as the draw solution. This process resulted in a diluted fertiliser solution (potentially suitable for reuse in hydroponics irrigation) and a concentrated HWNS rich in phosphorus. The concentrated HWNS was then subjected to chemical precipitation in the second phase, where phosphorus was recovered as calcium phosphate by adding sodium hydroxide at an optimised pH of 9.5.Bench-scale experiments demonstrated a 93% water recovery rate using FDFO and an impressive 99.5% phosphorus removal efficiency through chemical precipitation. These results indicate that the combined FDFO and chemical precipitation processes effectively recover water and phosphorus from HWNS and reduce reliance on synthetic fertilisers and freshwater in hydroponic systems.The findings of this study demonstrate that the two-step approach not only enhances water and phosphorus recovery but also improves the efficiency of the chemical precipitation process by achieving higher recovery rates resulting in more sustainable hydroponic systems.