Microbial etch: A novel construction method of functionalized biochar for enhanced uranium extraction in radioactive wastewater.

Nuclear energy is playing an increasingly important role on the earth, but the nuclear plants leaves a legacy of radioactive waste pollution, especially uranium-containing pollution. Straw biochar with wide sources, large output, low cost, and easy availability, has emerged as a promising material for uranium extraction from radioactive wastewater, but the natural biomass with suboptimal structure and low content of functional groups limits the efficiency. In this work, microbial etch was first came up to regulate the biochar's structure and function. The surface of the biochar becomes rougher and more microporous, and the mineral contents (Ca, P) indirectly increased by microbial etch. The biochar was modified by calcium phosphate and exhibited a remarkable uranium extraction capacity of 590.8 mg g-1 (fitted value). This work provides a cost-effective and sustainable method for preparing functionalized biochar via microbial etch, which has potential for application to uranium extraction from radioactive wastewater.

Thermal Air Oxidation-Mediated Synchronous Coordination and Carbonation of Lanthanum on Biochar toward Phosphorus Adsorption from Wastewater.

Biochar has attracted increasing attention as the sustainable and structure-tunable carrier for lanthanum (La) species for diverse applications. Carbonated La species possesses a higher biocompatibility and a lower leaching potential than other commonly used La species, while less attention is paid on the application of carbonated La in phosphorus (P) adsorption. Herein, thermal air oxidation (TAO) was applied as a novel strategy for synchronously tuning the coordination environment and chemical species of La on biochar surface. The results demonstrated that TAO induced the coordination of La with oxidation-generated oxygenated functional groups (OFGs) and carbonation of La species by the oxidation-generated CO2 on the biochar surface. The batch adsorption results showed that the Qm of resultant biochar remarkably increased from 68.92 to 132.49 mg/g at 1 g/L dosage. It also showed a robust adsorption stability in pH 2-6, a strong resistance to the co-existing Cl-, SO42-, NO3-, CO32-, or HCO3-, a stable adsorption recyclability, and an ultralow La leaching potential. The P adsorption was dominated by ligand exchange-induced inner-sphere complexation. In practical swine wastewater, the resultant biochar composite (1 g/L) removed 99.87% of P from 92.3 to 0.12 mg/L at a practical pH of 7.12. The density functional theory calculation further revealed the significant role of the binding of carbonated La by the biochar surface OFGs in reducing the P adsorption energies, indicating the synergism between the oxygenated biochar carrier and the carbonated La in P adsorption. Finally, this study provided a novel route to synchronously tune the coordination environment and chemical species of La on biochar via a facile TAO process for high-efficient P adsorption from wastewater.

A critical review on the development of lanthanum-engineered biochar for environmental applications.

Biochar and lanthanum (La) have been widely used in environment. However, there is a lack of knowledge and perspective on the development of La-engineered biochar (LEB) for environmental applications. This review shows that LEBs with a variety of La species via pre-/post-doping routes are developed for environmental applications. Specifically, precipitation, gelation, and calcination are the common sub-processes involved in the pre-/post-doping of La on the resultant LEB. The dominant La species for LEBs is La(OH)3, which is formed through precipitation of La ions with various bases. Various La carbonates, e.g., LaOHCO3, La2(CO3)3, La2CO5, and NaLa(CO3)2, are also involved in the preparation of LEBs. The LEBs are high-efficient in the adsorption of phosphate, arsenic, antimonate and fluoride ions, attributed to the strong affinity of La to oxyanions and Lewis hard base. Lanthanum is also favorable for co-doping with transition metal species to further enhance the performances in adsorption or catalysis. This review also analyzes the prospects and future challenges for the preparation and application of LEBs in environment. Finally, this review is beneficial to inspire new breakthroughs on the preparation and environmental application of LEBs.

Influence of thermal air oxidation on the chemical composition and uranium binding property of intrinsic dissolved organic matter from biochar.

In this work, uranium (U(VI)) binding characteristics of the intrinsic dissolved organic matters (DOM) from the biochars prepared under thermal air oxidation (TAO) and non-TAO conditions were studied using synchronous fluorescence spectra (SFS) and Fourier transform infrared (FTIR) in conjunction with the general two-dimensional correlation spectroscopy (2D-COS), heterospectral 2D-COS and moving-window (MW) 2D-COS. The chemical compositions of the intrinsic DOMs from biochars with/without TAO were investigated by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). Results showed that the preferential binding of U(VI) to functional groups followed the order: 937 (carboxyl γC-OH), 981 (carboxyl γC-OH), 1511 (aromatic vC = C), 1108 (esters or ethers vC-O), 1282 (esters or carboxyl vC-O), 1698 (saturated carboxylic acid or ketone vC = O) cm-1 for biochar DOM after TAO (OB600), and 937 (carboxyl γC-OH), 1484 (lipids δC-H or phenolic vC-O), 1201 (esters or carboxyl vC-O), 1112 (esters or ethers vC-O), 1706 (saturated aldehyde, carboxylic acid or ketone vC = O), 1060 (phenolic, esters or ethers vC-O), 1014 (phenolic, esters or ethers vC-O) cm-1 for the pristine biochar (B600). Fulvic-like substances at 375 nm in the biochar DOM showed a preferential binding with U(VI) after TAO, while humic-like substances played a more critical role in the U(VI) complexation with biochar DOM obtained from non-TAO condition. The results also indicated that TAO increased the content of fluorescent DOM and the chemical stability of DOM-U(VI) complexes. The FT-ICR MS results showed an increase in the relative abundance of protein-like, carbohydrates-like, tannins-like, unsaturated hydrocarbons, and condensed aromatic structure and a decrease in the relative abundance of lipid-like and lignin-like after TAO. Consequently, although biochar after TAO had a much poorer content of intrinsic DOM, its intrinsic DOM showed a much higher capacity in U(VI) precipitation. Therefore, the TAO substantially changed the chemical composition, binding property and environmental behavior of intrinsic DOM from biochar.

Effect of biochar-derived DOM on the interaction between Cu(II) and biochar prepared at different pyrolysis temperatures.

The structure and composition of biochar-derived dissolved organic matter (DOM) at different pyrolysis temperatures differed significantly, affecting the environmental geochemical behavior of heavy metals (HMs). Herein, the binding properties of Cu(II) onto walnut-shell DOM were investigated using spectroscopic methods. The results showed that the DOM at low pyrolysis temperatures (300 °C and 500 °C) showed higher Cu(II) affinity than that at high pyrolysis temperature (700 °C). There was a preferential Cu(II) binding with fulvic-like substances (360 nm) at 300 °C, and with protein-like materials (275 nm) at 500 °C and 700 °C. The C-O group of alcohols, ethers, and esters showed preferential binding with Cu(II) at 300 °C and 700 °C pyrolysis temperatures. However, preferential bonding of Cu(II) to the C-O stretching vibration and O-H bending vibration of carboxyl was exhibited at 500 °C pyrolysis temperature. Pyrolysis temperature played a crucial role in the release of biochar-derived DOM and in the migration and bioavailability of HMs. Meanwhile, the adsorption effect of Cu(II) increased by 11.2% for biochar at 300 °C, and decreased by 15.0% and 61.1% for biochar at 500 °C and 700 °C, respectively, after the removal of DOM, suggesting that the presence of DOM influenced the adsorption behavior of biochar towards Cu(II).

Tuning oxygenated functional groups on biochar for water pollution control: A critical review.

Biochar has attracted increasing attention in water pollution control, attributed to its various merits, e.g., tunable physico-chemical properties. The oxygenated functional groups (OFGs) on biochar are key active sites for removing pollutants from water through interfacial adsorption/redox reaction. However, there is still a lack of comprehensive knowledge and perspective on tuning OFGs on biochar for enhanced performance in water pollution control. Here, this review highlighted the mechanisms of biochar OFGs in water pollution control, analyzed the strategies and mechanisms for tuning OFGs on biochar, and investigated the performances of biochars with tuned OFGs in removing inorganic/organic pollutants via adsorption/redox reactions. Specifically, strategies for tuning OFGs on biochar are far more than the well-recognized ex-situ oxidation of pristine biochar. These strategies include in-situ low temperature preservation of hydroxyl and carboxyl, in-/ex-situ oxidation of biochar, and in-/ex-situ grafting of carboxyl on biochar via cycloaddition/acylation reaction. The resultant biochars showed enhanced performances in adsorption (mainly mediated by hydroxyl, carboxyl and ketone through surface complexation, H-bonding, and electrostatic attraction) and redox reaction (mainly mediated by redox-active hydroxyl and ketone). Finally, this review presented future directions on developing biochar with specially tuned surface OFGs as a sustainable high-performance adsorbent/carbocatalyst for water pollution control.

Bioenergy from dairy manure: technologies, challenges and opportunities.

Dairy manure (DM) is a kind of cheap cellulosic biomass resource which includes lignocellulose and mineral nutrients. Random stacks not only leads damage to the environment, but also results in waste of natural resources. The traditional ways to use DM include returning it to the soil or acting as a fertilizer, which could reduce environmental pollution to some extent. However, the resource utilization rate is not high and socio-economic performance is not utilized. To expand the application of DM, more and more attention has been paid to explore its potential as bioenergy or bio-chemicals production. This article presented a comprehensive review of different types of bioenergy production from DM and provided a general overview for bioenergy production. Importantly, this paper discussed potentials of DM as candidate feedstocks not only for biogas, bioethanol, biohydrogen, microbial fuel cell, lactic acid, and fumaric acid production by microbial technology, but also for bio-oil and biochar production through apyrolysis process. Additionally, the use of manure for replacing freshwater or nutrients for algae cultivation and cellulase production were also discussed. Overall, DM could be a novel suitable material for future biorefinery. Importantly, considerable efforts and further extensive research on overcoming technical bottlenecks like pretreatment, the effective release of fermentable sugars, the absence of robust organisms for fermentation, energy balance, and life cycle assessment should be needed to develop a comprehensive biorefinery model.

Enrichment of waste sewage sludge for enhancing methane production from cellulose.

Low ability of waste sewage sludge to degrade cellulose is observed due to its less cellulolytic bacteria content. The enrichment of sewage sludge in the absence or presence of carboxymethylcellulose (CMC) was conducted to improve anaerobic digestion (AD) of cellulose in this study. Compared to initial sewage sludge (IS), enriched sludge without CMC addition (ES) displayed 69.81% higher CH4 yield and about 1.7-fold greater anaerobic biodegradation of cellulose. In particular, bacterial and archaeal diversities in samples inoculated with ES were significantly altered, with Ruminiclostridium and Methanobacterium as the predominant genera. Enriched sludge with CMC addition (ESC) displayed enhanced methane production at initial cellulose fermentation but showed no distinct difference compared with the control after incubation 24 days. These findings suggest that enrichment of waste sewage sludge without CMC addition is more beneficial for promoting AD of cellulose, providing a novel insight for efficient energy utilization of lignocellulosic wastes.

Biochar-mediated enhanced ethanol fermentation (BMEEF) in Zymomonas mobilis under furfural and acetic acid stress.

BACKGROUND: Pretreatment of lignocellulosic biomass generates different types of inhibitors (e.g., furfural and acetic acid), which could remarkably inhibit subsequent ethanol fermentation. Here, biochar as an additive in the fermentation broth was first applied to enhance ethanol production by Z. mobilis wild-type strain ZM4 in the presence of typical inhibitors. RESULTS: This study showed that the biochar-mediated tolerance to furfural and acetic acid for the strain Z. mobilis ZM4 was the highest reported level, resulting in much higher ethanol productivity under stress conditions than that in non-treated conditions. Further analysis showed that adsorptive detoxification was not the controlling factor for enhanced ethanol production under stress conditions, attributed to its low removal of furfural (< 20%) and incapability of acetic acid removal. When biochar was filtered from the biochar-treated inhibitor-containing broth, it still showed enhanced ethanol production. Furthermore, Z. mobilis immobilized on biochar was also observed. Thus, biochar extracts in the fermentation broth and cell immobilization on biochar might be the controlling factors for enhanced ethanol production under stress conditions. CONCLUSIONS: These results indicate that biochar-mediated enhanced ethanol fermentation (BMEEF) might be a promising strategy for ethanol production from lignocellulosic biomass.

Regulation of nitrogen dynamics at the sediment-water interface during HAB degradation and subsequent reoccurrence.

The effects of harmful algal blooms (HABs) on nutrient dynamics have been extensively studied; however, the response of nitrogen to continuous HAB degradation and subsequent reoccurrence is not well understood. Here, a small-scale experiment was conducted to assess how nitrogen in the sediment-water interface (SWI) responds to HAB degradation and subsequent reoccurrence at different initial algal densities. The results showed that during the algae decomposition stage, the NH4 +-N flux of the SWI remained positive but decreased with the increase in algal density from 3.5 × 107 to 2.3 × 108 cells per L, indicating that the sediment was the source of NH4 +-N. In contrast, the deposit was a sink of NO3 --N. However, during the reoccurrence of HAB, the distribution of NH4 +-N and NO3 --N fluxes was completely converted. Nitrogen flux analysis throughout algae decomposition and reoccurrence indicated that although the sediment acted as a sink of nitrogen, the flux was dependent on the initial algal density. Our results confirmed that algae decomposition and reoccurrence would greatly affect the nitrogen cycle of the SWI, during which dissolved oxygen (DO) and initial algal density dominated. This study is the first to show that the regulation of nitrogen flux and migration changes during continuous HAB decomposition and subsequent reoccurrence.

Correction: Regulation of nitrogen dynamics at the sediment-water interface during HAB degradation and subsequent reoccurrence.

[This corrects the article DOI: 10.1039/C9RA10673A.].

Post-engineering of biochar via thermal air treatment for highly efficient promotion of uranium(VI) adsorption.

Biochar from pyrolysis/gasification is relatively poor in oxygen-containing groups and low in micro/mesoporosity, which constrains its adsorption performance. Here, thermal air treatment (TAT) at a mild condition (300 °C in air) was applied to oxygenate the surfaces of various biochars and modify their pore structures for the promotion of their uranium (U(VI)) adsorptions. Results showed that TAT had a high product yield (>76%), increased the O contents, O/C ratios and O-containing groups in biochars, and substantially developed the micro/mesoporosities of biochars. Batch adsorption results showed that TAT remarkably improved U(VI) adsorption capacities of various biochars. Specifically, the maximum U(VI) adsorption capacities of ash-poor corn cob biochar and ash-rich sewage sludge biochar were increased by 137% to 163 mg/g and 23% to 97 mg/g, respectively. Thus, TAT might be a promising strategy to engineer various biochars for adsorptive applications.

Oxygen-rich biochar from torrefaction: A versatile adsorbent for water pollution control.

Compared to pyrochar (PC), little is known about the capability of torrefaction char (TC) in water pollution control. In this study, the physicochemical properties of TC and PC, and their adsorption performances for uranium (U(VI)) and methylene blue (MB) were investigated. Results showed that TC was higher in oxygen content, and richer in oxygen-containing functional groups. The maximum U(VI) and MB adsorption capacities were increased from 56.21 and 192.67 mg/g for PC, respectively, to >100 and >350 mg/g for TC, respectively, indicating that TC was much more efficient than PC. Furthermore, torrefaction atmosphere affected the adsorption performance of resulting TC. For example, TC from N2 was more efficient in MB adsorption, while TC from air was more efficient in U(VI) adsorption. Thus, attributed to the lower processing temperature, simpler preparation route, and higher adsorption capacity, TC could be a competent candidate for water pollution control.

Interactions between suspended particulate matter and algal cells contributed to the reconstruction of phytoplankton communities in turbulent waters.

The effect of turbulence on phytoplankton growth has been widely studied; however, its effects with respects to suspended particulate matter (SPM) on the development of phytoplankton communities and the behavioral responses of phytoplankton to turbulence and SPM are poorly understood. Here, an approximately homogeneous turbulence simulation system (AHTS, mainly consisting of an oscillating-grid apparatus) was established to gain insight into the mechanisms underlying phytoplankton community responses in turbid, well-mixed waters. The results revealed that maintaining the turbulence dissipation rates (Ɛ) of 2.25 × 10-3 and 1.80 × 10-2 m2/s3 caused significant reductions in algal density, and the effects could be substantially enhanced when 500 mg/L of SPM were added before day 12. In contrast to the constant decrease of algal density for the Ɛ of 2.25 × 10-3 m2/s3, a dramatic increase in the phytoplankton density occurred after 16 days of incubation for a Ɛ of 1.80 × 10-2 m2/s3, irrespective of SPM. Addition of SPM in the Ɛ of 1.80 × 10-2 m2/s3 treatments did not considerably affect the algal density profile compared to that without SPM, of which unicellular algae decreased and colonial algae dominated the phytoplankton community. On the other hand, the phytoplankton can regulate the SPM properties. During the 18 days' coincubation, extracellular polymeric substances (EPS) released from algal cells induced larger particle sizes and round surfaces of SPM, which can reduce the damage received to algal cells. Here we demonstrated that the phytoplankton communities could actively counteract the effects of turbulence + SPM and adapt the couple stress, jointly through the release of EPS, the modification of SPM surface properties and the conversion of their assemblage pattern, thereby contributing to rebalance the ecosystem. These findings highlight the strategies employed during the reconstruction of phytoplankton under the dual effects of turbulence and SPM for the first time, consequently enabling the forecasting of the dominant species of phytoplankton in turbulent waters.

Natural polymer konjac glucomannan mediated assembly of graphene oxide as versatile sponges for water pollution control.

Three-dimensional network structure of konjac glucomannan/graphene oxide (KGM/GO) sponges was successfully prepared by ice template method. The KGM/GO sponges was rich in functional groups, negatively charged under pH 2 to 10. Batch adsorption experiment was conducted to investigate the adsorption performance of the as-prepared KGM/GO sponges for organic dye (malachite green (MG)) and radionuclide (uranium U(Ⅵ)). The results showed that the maximum adsorption capacities of KGM/GO sponges were 266.97, 189.96 mg/g for U(Ⅵ) and MG, respectively. Moreover, the KGM/GO sponges exhibited an excellent selectivity for capturing U(Ⅵ) in multi-ion system. The adsorption process was fitted better to pseudo-second order model, while adsorption isotherms for these pollutants were well matched up to Langmuir models. In addition, KGM/GO sponges can be easily separated from the aqueous solution and could be effectively reused for 5 times without obvious loss in adsorption performance. The advantages of eco-friendliness, low cost, simple preparation process, controllable shape and size, as well as high adsorption capacities for MG and U(Ⅵ), suggested that KGM/GO sponges promising in water pollution control.

Calcium-rich biochar from crab shell: An unexpected super adsorbent for dye removal.

Adsorption is the common-used method to remove dyes from wastewater, and many efforts have been made to develop low-cost but excellent adsorbents. Here, calcium-rich biochar (CRB) as a low-cost adsorbent was directly prepared from crab shell via a simple pyrolysis process without any modification. Batch adsorption results suggested that CRB was among the dye adsorbents with highest adsorption capacities and fastest adsorption rate. Specifically, it showed high adsorption capacities of 12,502 and 20,317 mg/g for cationic malachite green and anionic Congo red, respectively. The adsorption equilibrium for Congo red onto CRB could be achieved as short as 2 min. Furthermore, the dye adsorption mechanism for CRB, as investigated by zeta potential and FTIR spectra, could be attributed to electrostatic attraction, hydrogen bonding and π-π interaction. Finally, this study suggested that, attributed to its cheap source, simple synthesis process and excellent adsorption performance, CRB was promising in dye removal.

Application of sequential extraction analysis to Pb(II) recovery by zerovalent iron-based particles.

Zerovalent iron (ZVI) is an environmental-friendly reactive reagent for recovering heavy metals. However, the detailed recovery mechanism remains unclear due to a lack of quantitative analysis of recovery products. Herein, microscale ZVI, nanoscale ZVI and Ni/Fe nanoparticles were used to recover Pb(II) in aqueous solution and a sequential extraction procedure (SEP) was applied to determine the formed lead species quantitatively. At high initial Pb(II) concentration (500 mg L-1), more than 99.5% of Pb(II) was immobilized by Ni/Fe and n-ZVI, whereas m-ZVI caused inferior recovery efficiency (<25%). XRD and XPS results revealed that Pb(II) was reduced to Pb0 prior to the formation of metal hydroxides as the external shell of ZVI. SEP results showed that the fraction bound to carbonates (PbO), fraction bound to iron oxides and exchangeable fraction were the main lead species conducted by Ni/Fe, n-ZVI and m-ZVI, respectively. Consequently, (co-)precipitation and specific adsorption dominated Pb(II) recovery by Ni/Fe and n-ZVI, whereas m-ZVI conducted Pb(II) recovery mainly via weak adsorption. The reactivity of ZVI toward Pb(II) followed the increasing order of m-ZVI << n-ZVI ≤ Ni/Fe. The detailed mechanisms of Pb(II) recovery conducted by different ZVI were proposed.

Replacing process water and nitrogen sources with biogas slurry during cellulosic ethanol production.

BACKGROUND: Environmental issues, such as the fossil energy crisis, have resulted in increased public attention to use bioethanol as an alternative renewable energy. For ethanol production, water and nutrient consumption has become increasingly important factors being considered by the bioethanol industry as reducing the consumption of these resources would decrease the overall cost of ethanol production. Biogas slurry contains not only large amounts of wastewater, but also the nutrients required for microbial growth, e.g., nitrogen, ammonia, phosphate, and potassium. Therefore, biogas slurry is an attractive potential resource for bioethanol production that could serve as an alternative to process water and nitrogen sources. RESULTS: In this study, we propose a method that replaces the process water and nitrogen sources needed for cellulosic ethanol production by Zymomonas mobilis with biogas slurry. To test the efficacy of these methods, corn straw degradation following pretreatment with diluted NaOH and enzymatic hydrolysis in the absence of fresh water was evaluated. Then, ethanol fermentation using the ethanologenic bacterial strain Z. mobilis ZMT2 was conducted without supplementing with additional nitrogen sources. After pretreatment with 1.34% NaOH (w/v) diluted in 100% biogas slurry and continuous enzymatic hydrolysis for 144 h, 29.19 g/L glucose and 12.76 g/L xylose were generated from 30 g dry corn straw. The maximum ethanol concentration acquired was 13.75 g/L, which was a yield of 72.63% ethanol from the hydrolysate medium. Nearly 94.87% of the ammonia nitrogen was depleted and no nitrate nitrogen remained after ethanol fermentation. The use of biogas slurry as an alternative to process water and nitrogen sources may decrease the cost of cellulosic ethanol production by 10.0-20.0%. By combining pretreatment with NaOH diluted in biogas slurry, enzymatic hydrolysis, and ethanol fermentation, 56.3 kg of ethanol was produced by Z. mobilis ZMT-2 through fermentation of 1000 kg of dried corn straw. CONCLUSIONS: In this study, biogas slurry replaced process water and nitrogen sources during cellulosic ethanol production. The results suggest that biogas slurry is a potential alternative to water when pretreating corn straw and, thus, has important potential applications in cellulosic ethanol production from corn straw. This study not only provides a novel method for utilizing biogas slurry, but also demonstrates a means of reducing the overall cost of cellulosic ethanol.

A synergistic combination of nutrient reclamation from manure and resultant hydrochar upgradation by acid-supported hydrothermal carbonization.

Cattle manure was hydrothermally carbonized in acid solutions (0-2% HCl), then nutrient concentration in liquid product and physicochemical properties of hydrochar were characterized to investigate the effects of acid addition on hydrochar properties and nutrient recovery from manure. Results showed that hydrothermal carbonization (HTC) in 2% HCl extracted almost 100% and 63.38% of phosphorus and nitrogen, respectively; specifically, >90% of the extracted phosphorus was PO4-P in liquid from HTC with acid addition, and increasing amount of extracted nitrogen was NH4-N with increasing acid addition. Generally, higher heating value, surface area, total pore volume, fixed carbon, atomic ratios of H/C and O/C were increased in hydrochars from HTC with acid addition, while yield, volatile matter, contents of nitrogen, sulfur and oxygen of these hydrochars were decreased. These results indicated that HTC with acid addition could simultaneously facilitate nutrient recovery from manure and resulting hydrochar upgradation.

Calcium-rich biochar from the pyrolysis of crab shell for phosphorus removal.

Calcium-rich biochars (CRB) prepared through pyrolysis of crab shell at various temperatures were characterized for physicochemical properties and P removal potential. Elemental analysis showed that CRB was rich in calcium (22.91%-36.14%), while poor in carbon (25.21%-9.08%). FTIR, XRD and TG analyses showed that calcite-based CRB was prepared at temperature ≤600 °C, while lime-based CRB was prepared at temperature ≥700 °C. Phosphorus removal experiment showed that P removal efficiencies in 80 mg P/L phosphate solution and biogas effluent ranged from 26% to 11%, respectively, to about 100% and 63%, respectively, depending on the pyrolysis temperature of the resulting biochar. Specifically, compared to common used CaCO3 and Ca(OH)2, P removal potential of calcite-based CRB was much higher than that of CaCO3; while that of lime-based CRB was close to that of Ca(OH)2. These results suggested that CRB was competent for P removal/recovery from wastewater.