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Severely degraded coastal salt marshes with impaired ecological functions urgently need to be restored to improve blue carbon sequestration. Although plant residues and biochar have been used to restore degraded wetlands, the dose-effects of these plant additives on soil organic carbon fractions in degraded coastal wetlands are still unclear. Here, we investigated the dynamic changes in DOC components and mineral-associated organic carbon, such as calcium-bound organic carbon (Ca-OC) and iron/aluminum-bound organic carbon (Fe/Al-OC), in a degraded coastal salt marsh in a 60-day incubation experiment with low (0.1%), medium (1%), and high (3%) doses of Phragmites australis straw (PS) and Phragmites australis -derived biochar (PB) addition treatments. The results showed that the medium and high doses of PB additives increased humus-like substances, with the maximum proportion occurring on day 60 of the incubation. The fluorescence index (FI) and biological index (BIX) were >1.9 and 0.8, respectively, and the humification index (HIX) was < 4 in most treatment groups. The mineral-associated organic carbon (Ca-OC and Fe/Al-OC) contents were higher in the 1% PS and 3% PS treatments (p < 0.05). The PS additives increased the soil Ca-OC/SOC and Fe/Al-OC/SOC ratios, whereas the PB additives decreased them. This study demonstrated that PS and PB are potential carbon-rich additives for enhancing soil organic carbon stability and carbon sequestration in coastal wetland restoration projects, contributing to regional carbon neutrality. • Carbon-rich additives regulated soil organic carbon fractions in salt marshes. • Phragmites australis straw increased soil mineral-associated organic carbon. • Carbon-rich additives improved soil humification degree and mineral protection. [ABSTRACT FROM AUTHOR]

Large amounts of dredged sediment have been produced from dredging projects worldwide, and utilizing it as a resource has become particularly important. This work improved the dredged sediment using biochar (BC), humic acid (HA), and desulfurized gypsum (DG) to restore wetland substrate. The effects of different amendments, applied alone or in combination, on the physicochemical properties and nutrient contents of the dredged sediment were analyzed. The improvement effects were evaluated through reed planting experiments for three months. The results indicated that BC significantly improved the plant nutrient indicator of the dredged sediment. HA reduced the BD and pH of the dredged sediment and increased its contents of various nutrients. DG enhanced the physical indicators of the dredged sediment and could be considered for dredged sediment with high nutrient contents. The two-way ANOVA results indicated that the H3 (BC-6% + HA-6% + DG-10%) combined amendment treatment group showed the optimal improvement effect on the dredged sediment. In the reed planting experiments, the average plant height and average growth rate in the H9 (BC-6% + HA-4% + DG-20%) combined amendment treatment group were the maximum, reaching 45.18 cm and 0.486 cm/d, respectively. This work is expected to raise awareness of the need to utilize marine dredged sediments as resources. [Display omitted] • BC decreases 27.00% BD and increases 23.99-fold OM, 3.08-fold AP and 7.24-fold AK. • DG decreases 1.72 units pH and performs 2.76-fold increase in electrical conductivity. • HA increases 4.98-fold cation exchange capacity and 1.68-fold hydrolyzable nitrogen. • A-5 group germination number and C-4 group total biomass both reach maximum. • H9 group, A-5 group and H3 group show maximum average plant height at high, medium and low water levels, respectively. [ABSTRACT FROM AUTHOR]

• Combined application of biochar and plants stimulate the removal of PCBs. • Green garden biochar improved plant growth and microbial count. • Higher levels of PCBs-degrading bacteria were observed in the rhizosphere. • Suitable combination for effective plant-tandem removal of PCBs are presented. Polychlorinated Biphenyls (PCBs) are xenobiotic chlorinated aromatic compounds with high toxicity to both fauna and flora. PCBs can enter the environment through close interactions of multiple environmental matrices such as sediments, soils, water and food web. Biogeochemical cycle of PCBs can transport them far from their initial source of production. The present study aims to investigate the effects of organic and chemical amendments during rhizoremediation of PCBs in aged contaminated soil. Italian ryegrass (Lolium multiflorum) was grown in PCB-contaminated soil, whereas different combinations of two biochar (i.e., beech woodchip and green garden waste) and a surfactant (i.e., sodium dodecyl sulfate) were applied to assess the removal efficiency. The overall system's performance was evaluated based on plant growth, PCBs degradation, and proliferation of PCBs degrading bacteria after 5-months of sowing of ryegrass. We found that PCBs removal was significantly high in the vegetated soils as compared to the un-vegetated soils. Maximum removal (85% of total PCBs load) was observed in the presence of green garden waste biochar whereas less removal was observed with the surfactant application. The observations on PCBs degrading bacteria and plant growth parameters were consistent with the degradation scheme, which suggest the potential role of bacteria in the overall degradation process. We conclude that appropriate combinations of vegetation, soil amendments, and PCB degrading bacteria can help to improve the degradation of PCBs impacted soils. [ABSTRACT FROM AUTHOR]

Highlights • Novel approach was developed to prepare eggshell-biochar composites. • Engineered biochar surface was covered with eggshell ultrafine particles. • Engineered biochar showed strong sorption ability to Pb2+. • Dosage, initial solution pH, and ionic strength affected Pb2+ removal. Abstract Engineered biochars were prepared by slow pyrolysis of three types of biomass pretreated with eggshell waste. The resulting biochars were composite materials with eggshell particles on carbon surface within the pore networks, which were confirmed by various characterization tools. The engineered biochars showed relatively fast adsorption kinetics to Pb2+ aqueous solutions. In addition, adsorption isotherms showed that the Langmuir maximum Pb2+ adsorption capacities of the engineered biochars (103–261 mg/g) were higher than those of the pristine biochars (32.9–56.0 mg/g). The adsorption of Pb2+ onto the biochars were affected by adsorbent dosage, initial solution pH, and ionic strength. Findings from this work indicated that the engineered biochar from eggshell-treated biochar can be used as an effective agent for soil and water remediation and conservation. [ABSTRACT FROM AUTHOR]

Abstract Increased adoption of denitrifying bioreactors to mitigate nutrient export in agricultural drainage can improve water quality but also raises concerns about potential unintended consequences of widespread implementation. Greenhouse gas (GHG) emissions, especially as nitrous oxide (N 2 O) produced during denitrification, are of particular concern. To gain understanding of the variables controlling bioreactor GHG production, the effects of nutrient loading, hydraulic residence time, and biochar addition on emissions of N 2 O, methane (CH 4), and carbon dioxide (CO 2) were tested in 6550 cm3 laboratory columns. Biochar, an organic carbon pyrolysis product, was hypothesized to reduce GHG emissions, as has been reported with its use as an agricultural soil amendment. GHG fluxes were measured during 5-day trials using the closed dynamic chamber technique. The 36 combinations of three media types (woodchips, 10% biochar, and 30% biochar), three residence times (3, 6, and 12 h), and four influent formulations, all combinations of high and low nitrogen as nitrate (16.1 and 4.5 mg NO 3 -N L−1) and phosphorus as orthophosphate (1.9 and 0.6 mg PO 4 -P L−1) concentrations, were tested in triplicate. Treatment effects were assessed with linear mixed effects models. Biochar addition, particularly at the 30% rate, was found to increase N 2 O and CO 2 emissions and the proportion of removed NO 3 -N released as N 2 O-N. However, quantified GHG flux rates were not environmentally concerning. Methane fluxes were negligible, and CO 2 fluxes were not considered to increase net GHG emissions. Nitrous oxide fluxes normalized to surface area averaged 2.92 mg N 2 O-N m−2 d−1, and 98% of measured fluxes were within the range previously reported for woodchip bioreactors and considered acceptable. [ABSTRACT FROM AUTHOR]

Highlights • Different fungal strains solubilised phosphorus from sewage sludge thermal residues. • The highest rate of P solubilisation was found in sewage sludge incineration ash. • P. bilaiae P solubilisation increased with the addition of specific C and N sources. • P. bilaiae amended ash did not promote ash fertilising effect in a pot trial. Abstract Biochars and ashes from sewage sludge have a high phosphorus (P) content, but plant P availability is typically rather low. Phosphate-solubilising microorganisms (PSM) have been shown to have the ability to solubilise P from different compounds. The aim of this study was to explore the P-solubilisation potential of different PSM on various biochars and ashes, and the effect of the addition of different carbon (C) and nitrogen (N) sources on their P-solubilisation activity. The most promising combination of PSM, thermal residue and nutrients was then tested for its effect on plant growth and P uptake in a pot trial. Six PSM strains (four Penicillium bilaiae (Pb), one Penicillium aculeatum (Pa) and one Aspergillus niger (An)) were tested on two sewage sludge ashes and one biochar. Pb.4 and An showed the highest P-solubilisation rates on fluid-bed incineration (FB-I) ash. Pb.4 solubilised higher amounts of P when it was supplied with fructose in combination with NH 4 -N, while An performed equally well with fructose, maltose, mannose and xylose in combination with NH 4 -N. Increasing the concentration of the C source generally also increased the P solubilisation. However, when FB-I ash was inoculated with Pb.4 plus xylose/NH 4 -N and applied to spring wheat in a pot trial with γ-irradiated soil, the inoculation did not significantly affect plant shoot biomass or P uptake. The results indicate that the amount and temporal availability of P solubilised by the fungal strain from the ash did not match plant requirements, suggesting that further work is required that focuses on further increasing solubilisation efficiency. [ABSTRACT FROM AUTHOR]

Biochar has been identified as a media amendment to improve nutrient removal from wastewater, and N retention and plant growth in agroforestry. It therefore has the potential for treating domestic wastewater. The aim of this research was to compare nitrogen removal and plant growth in pure sand and sand amended with biochar, in wetland mesocosms (240 L) receiving sewage. There were seven media treatments based on the proportions of biochar in the sand media (100% sand, sand and coir peat, 5, 10, 15, 20, 25% biochar). The plant species were Paperback tree ( Melaleuca quinquenervia ) and Lemongrass ( Cymbopogon citratus ). The mesocosms were continuously loaded for 8 months with secondary clarified wastewater (SCW) (16 L/day). Septage was then intermittently loaded (20 L/2 days) for a further 8 months. Inflow and outflow samples were monitored for TN, NH 4 -N, and NO x -N. All treatments showed good nitrogen removal efficiency. Average removal efficiencies of TN, NO x -N and NH 4 -N in the mesocosms loaded with SCW ranged from 71 to 87%, 81 to 93% and 65 to 79%, for 100% Sand to 25% Biochar respectively. For septage, the removal efficiencies ranged from 63 to 81%, 69 to 87% and 66 to 81%, for 100% Sand to 25% Biochar respectively. Significant differences of nitrogen outflow concentrations were observed between pure sand and sand amended with biochar. Physical chemical properties of the biochar would have facilitated microbial processes and adsorption. Strong positive correlations were observed between biochar content in the media and nitrogen removal rates. The increased nitrogen removal may be attributed to higher mineralisation of organic nitrogen and NH 4 -N, especially in the case of septage where strong correlation was observed between BOD 5 and TN removal. Total N biomass in the plants harvested after 21 months ranged from 13.4–14.0 g N. The addition of biochar did not increase plant N biomass in either species. [ABSTRACT FROM AUTHOR]

Landfill leachate contains high concentrations of ammonia and recalcitrant organic compounds, which can interfere with wastewater treatment processes. Hybrid constructed wetlands (CWs), consisting of Vertical Flow (VF) CWs followed by Horizontal Flow (HF) CWs, are low cost technologies for onsite leachate treatment. This study investigated the potential of low-cost adsorbent materials, a natural zeolite mineral (clinoptilolite) and biochar, to enhance leachate treatment in hybrid CWs. Two mesocosm hybrid CWs were set up at a Florida (US) landfill. In the Adsorbent-CW 10% (v /v) of zeolite was added to the VF-CW to enhance nitrification and 13% (v /v) biochar was added to the HF-CW to increase microbial activity and plant growth. A Control-CW contained only gravel. Both systems were planted with cattails (Typha latifolia) and cordgrass (Spartina alterniflora) and operated at varying hydraulic loading rates for ~2 years. A HF-CW containing wood chips (Woodchip-CW) was added downstream of the Adsorbent-CW during the final 6-months of operation to enhance denitrification. Results showed that zeolite addition to the VF-CW significantly increased nitrification rates by 16–93% due to cycles of ammonium adsorption and bioregeneration under intermittent loading conditions. Biochar addition increased removal of organic matter (21–26% to 29–44%) and color (1–18% to 7–49%), and improved wetland plant growth and nitrogen removal due to enhanced plant growth and rhizosphere microbial activity. Addition of the Woodchip-CW reduced nitrate accumulation, resulting in total nitrogen removals of up to 79%. [Display omitted] • Zeolite addition reduced free ammonia inhibition and improved nitrification rate. • Biochar addition enhanced removals of COD, color, organic matter, and heavy metals. • Adsorbent addition improved plant growth for enhanced nitrogen uptake. • Woodchip-CW reduced nitrate accumulation for enhanced nitrogen removal. • Nitrification/denitrification was the main pathway for nitrogen removal. [ABSTRACT FROM AUTHOR]

Biochar addition to soil has been found to be a useful practice to control erosion. However, few studies have explored the effects of biochar produced from husk of rice on rill erosion, due to overland flow in deforested areas. This study has evaluated the rill detachment capacity (D c) and erodibility (K r) in soil samples treated with rice husk biochar in comparison to untreated sites (control), collected in deforested hillslopes of Northern Iran. D c was measured in a lab-scale hydraulic flume at four-bed slopes (9.7, 14.3, 19.5, and 24.2%) and five water discharges (0.24, 0.36, 0.47, 0.59, and 0.69 L m−1 s−1). Moreover, organic carbon, aggregate stability and bulk density of soils were measured. D c was lower (on average − 32%) in the treated soil compared to the control. D c was not correlated to the other physico-chemical properties of soil. K r , estimated by linear regressions between D c and shear stress, was noticeably lower (−79%) in the treated soil compared to the control. These results evidence that rice husk biochar is effective at controlling and mitigating soil detachment, and at improving organic matter content and aggregate stability in deforested hillslopes. The proposed values of rill erodibility and shear stress of deforested hillslopes (treated or untreated) are helpful to model soil resistance to rill erosion in process-based erosion models. • Scarce knowledge exists about biochar effects on rill detachment capacity (D c). • D c was lower by 32% in the soil treated with biochar compared to the untreated soil. • This reduction was due to organic matter addition to soil treated with biochar. • D c was not correlated to the other physico-chemical properties of soil. • Rill erodibility was lower (−79%) in the soil treated with biochar. [ABSTRACT FROM AUTHOR]

The addition of biochar in acidic mine spoils contaminated areas has been suggested for buffering and improving the fertility as well as the reduction in the metal bioavailability. This study evaluated the effect of biochar on reducing the heavy metal content in the Bacopa monnieri L. grown in the biochar amended acidic mine spoil and associated toxicological risks. The mine spoil (overburden) was treated with a biochar made from the fast pyrolysis of waste of Cymbopogon flexuosus at 450 °C at application rates of 15% and 20%. Plant analysis (biomass, chlorophyll, protein and lipid peroxidises), metabolite content and metal levels (Al, Cd, Cr, Cu, Fe and Pb) in the Bacopa monnieri L. herb. Hazardous quotient and acute oral toxicity of plant and its extract cultivated was carried out. The results showed that biochar amendment significantly improved biomass of the plant as well as reduced the metal content in plant tissues. The concentrations of Al, Cd, Cr, Cu, Fe and Pb in the plant tissues were within the international permissible limits. The risk assessment for bacopa consumption showed that the hazard quotients values were lower than the threshold level for herb (<1). Application of biochar further reduced hazard quotients values the indicating safe to the consumers. In vivo toxicity also suggests that no toxic effect of bacopa extract on the albino mice. It is concluded that the application of biochar in acidic mine spoils can be not only useful for the plant growth, but also for reduction in the metal toxicity of Bacopa monnieri L., if consumed. [ABSTRACT FROM AUTHOR]

Smoke water is well known for its role in seed germination. Many pyrolysis by-products from industry may provide the same ecological function as smoke water, including stimulation of seed germination. Germination responses were assessed for 17 grass species (native to western Canada and commonly used in land reclamation) and 6 pyrolysis by-product solutions (karrikinolide, smoke water, coke, bottom ash, fly ash, biochar) in a laboratory experiment. For 10 of the 17 species studied, germination percentage was significantly increased by at least one pyrolysis by-product, and 3 species were stimulated by all pyrolysis by-products; 3 species had germination reduced by pyrolysis by-products; and almost a quarter of the species were unaffected by pyrolysis by-products. [ABSTRACT FROM AUTHOR]

A type of biochar-supported iron phosphate nanoparticle stabilised by a sodium carboxymethyl cellulose (CMC@BC@ Fe 3 (PO 4 ) 2 ) composite was synthesised to remediate cadmium (Cd)-polluted soil. The surface morphology and functional groups of the composite were characterised by scanning electron microscopy and Fourier transform infrared spectrometry, respectively. Batch experiments showed that the composite (soil-to-solution ratio 1 g:10 mL) could effectively immobilise Cd in soil. The immobilisation efficiency of Cd was 81.3% after 28 days of remediation, and physiological-based extraction test bioaccessibility was reduced by 80.0%. The results of sequential extraction procedures indicated that the transformation from more easily extractable Cd to the least available form was responsible for the decrease in Cd bioavailability in soils. Plant growth experiments proved that the composite could inhibit Cd uptake to the belowground and aboveground parts of cabbage mustard by 44.8% and 70.2%, respectively, thus promoting cabbage mustard growth and development after remediation. [ABSTRACT FROM AUTHOR]

Soil microbes are of great importance in assessing key ecosystem functions due to their high sensitivity and capacity of providing ecologically relevant information. Benefits of biochar have been demonstrated, including enhancing carbon (C) sequestration and improving soil fertility. Considerable attention has been taken to effects of biochar on soil properties; however, information regarding effects of biochar on seasonal changes of soil microbial activities in field experiments in dryland soil was not well known. Based on a 2-year spring maize ( Zea mays L.) field experiment, we examined changes in soil microbial biomass carbon (MBC), nitrogen (MBN), phosphorus (MBP), urease and alkaline phosphatase activities with three biochar application rates (0, 10, and 30 t ha −1 ) at 0–10 cm and 10–20 cm soil layers in year 2013 and 2014 in silty loam soils on the Loess Plateau in North-Western China. Our results indicated that biochar increased MBC except at silking stage (R1) in 2013, whereas it tended to decrease MBC except at 6-leaf stage (V6) in 2014. MBN in the shallower (0–10 cm) soil layer in 2013 and MBP in 2014 generally increased with biochar rates. Significant positive correlations between microbial biomass and soil water content (SWC) were observed. Results also showed that there were considerable fluctuations in enzymes activities across the growth periods and depths. Biochar significantly increased alkaline phosphatase activities in 2014, and resulted in small but detectable shifts in soil urease activities in both years. These results provided evidence that biochar addition could be an effective management practice for soil microbial activities throughout crop growing season in a dry agricultural system, although soil factors from different climates might lead to some shifts of effects of biochar. [ABSTRACT FROM AUTHOR]

Biochars, the carbonaceous residue from biomass pyrolysis, have been proposed as an agriculture soil amendment to improve soil fertility and retain a broad range of environmental contaminants. The objective of this research was therefore to investigate whether the additions of cassava wastes-based biochars obtained at 750 °C (noted as MS750) with the specific area of 430 m 2 /g to an agriculture soil could effectively attenuate the transport of atrazine by using laboratory batch sorption studies and soil thin-layer chromatography. To illustrate the worst-case sorption, MS750 with different application percentages (w/w: 0%, 0.1%, 0.5%, 1%, 3%, 5%) were added into krasnozem soil only with 0.75% organic matter to determine sorption-desorption behavior and migration of atrazine. The results obtained indicated that the occurrence of cassava wastes-derived biochar significantly enhanced the sorption capacity of the soil for atrazine. The sorption affinity augmented as expected with application rates of MS750, and the distribution coefficients in biochar-added soils were greater than that in soil alone, likely due to enhancement of soil organic carbon content and favorable sorption domains for organic compounds caused by amendment of biochars. Sorption isotherms were characterized by nonlinear curves, which indicated the heterogeneous sites on MS750-soil mixture. Desorption work exhibited a remarkable impact of biochars amendment into soils on desorption of atrazine, in which an apparent hysteresis was undergone. This study clearly revealed that biochars from cassava wastes application enhanced retention of soil for atrazine to some extent, nevertheless, the magnitude of enhancement of the sorption affinity was still of dependence on the solution pH value, environmental temperature, as well as contact time between soil and biochars. The △G o values with less than −20 kJ/mol and the effect of solution pH variation on sorption capacity of 6 sorbents indicated that the equilibrium process may be involved physisorption, as well as accompanied with chemisorption. The results from thermodynamic analysis showed that sorption of atrazine in soils amended with MS750 was thermodynamically endothermic. Positive correlation between the mobility level of pesticide and the addition percentage of biochars suggested that the application of biochars derived from cassava waste was available to retain pesticides and attenuate the leach into groundwater. These observations provide important information on the application of biochars produced at 750 °C as engineered sorbents for soil remediation and compounds elimination. [ABSTRACT FROM AUTHOR]

Pollution of greenhouse soils and crops by heavy metals as a result of annual application of large amounts of pesticides and fertilizers is of great concerns. We investigated the effect of biochar (BC) as a potential immobilizing medium for cadmium (Cd) by assessing Cd bioavailability, fractions, and uptake of metals by lettuce plants in metal-contaminated greenhouse soils. Experiments were conducted in two typical vegetable greenhouses displaying different levels of heavy metal pollution (GH1, lightly heavy-metal-polluted greenhouse; GH2, heavily heavy-metal-polluted greenhouse), in Wuhan City suburbs, Hubei Province, China. For each greenhouse site three replicates of each of three levels of BC (B 0 , 0 t ha −1 ; B 10 , 10 t ha −1 ; B 20 , 20 t ha −1 ) were arranged in a randomized complete block design. The application of BC increased soil pH and soil organic matter and changed Cd fractions in the soil. The exchangeable Cd fraction decreased and there was an increase in the oxide- and organic-bound and residual fractions with the application of BC, implying that BC application could immobilize the Cd in greenhouse soil. The rates of Cd immobilization in soil increased with the amount of BC applied. The exchangeable Cd fractions in soils amended with B 10 decreased by 45–62% and in soils amended with B 20 by 66–89% compared to the control. The addition of BC reduced the concentration of Cd in lettuce shoots in the lightly heavy-metal-polluted soils, but in the heavily heavy-metal-contaminated soils it had either no effect, or promoted Cd absorption by lettuce shoots. Total Cd measured in lettuce tissues did not decrease with the addition of BC when compared to the control, as there was increased accumulations of lettuce biomass with biochar application. [ABSTRACT FROM AUTHOR]

Bauxite residue sand (BRS) is the primary growth medium for rehabilitating Alcoa’s residue storage areas in south-west Western Australia. Successful revegetation of highly alkaline BRS can be hindered by its low nitrogen (N) use efficiency. Biochar, a carbon (C)-rich material, has been suggested to have the potential to improve water and nutrient retention in soil. However, little is still known about the effect of biochar amendment on N use efficiency in the alkaline BRS environment. This incubation study aimed to evaluate the impact of biochars with different characteristics on N retention and dynamics in BRS. The BRS (pH 9.5 after being pre-treated with 1% gypsum and leached with water) was amended with the acidic biochar (pH 3.86; AC, from wild fire) and alkaline biochars (pH 9.58–10.8; greenwaste, GW; Jarrah, JL; mallee, ML) at a rate of 10% (w/w). The N loss via NH 3 volatilization was much lower from the AC treatment (24% of di-ammonia phosphate (DAP)-N added) than the alkaline biochars treatments (76–80% of the DAP-N added). The AC treatment can retain about 73% of N added to BRS, compared with <25% in alkaline biochar treatments. This can be attributed to the acidic nature and the greater NH 4 + -N sorption capacity arising from the presence of a high density of the oxygen-containing functional groups on the surface of acidic biochar as revealed by the FTIR spectroscopy. These results imply acidic biochar can be used as an effective amendment for increasing N use efficiency by plants growing in alkaline BRS. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) are constructed systems that simulate natural wetlands and can be used to treat wastewater from several sources of pollution through physical, chemical and biological depuration processes. This work aims to critically review the updated literature on constructed wetlands (CWs) integrating biochar in the substrate. In detail, the study focuses on the characteristics of biochar that are generally integrated into this treatment ecotechnology and the processes used to prepare the materials, including conditions of thermal conversion and the kind of feedstock used (e.g., agricultural, food, and wood wastes, sewage sludge and algal marine feedstock). Based on the literature review, it is found that the feedstock must be rich in carbon and low in the mineral matter to produce good quality biochar, i.e. large pore volume and high specific surface area, thus allowing to effectively remove pollutants from wastewater. The biochar quality is affected by the conditions involved in preparing biochars (e.g., pyrolysis temperature, heating rate and carbonization time). The properties of biochar used for wastewater treatment, the effect of its implementation as CW substrate and its treatment efficiency have also been described. Several factors alter the removal efficiency of pollutants in CWs, such as substrate chemical and physical properties, hydraulic retention time, oxygenation, and redox conditions in the reed bed. In addition, the mode by which biochar is implemented in the filter and the choice of macrophyte are crucial for regulating the efficiency of the treatment system. Phragmites australis was the most used plant in the previous studies because of its large advantages. Different configurations of CWs integrating biochar into the wetland as a filling medium, were reported and compared. In vertical flow CWs (VF-CWs), which are the system mostly investigated, several studies have shown that the optimal position for the biochar substrate is the intermediate one between two layers of inert materials, to avoid clogging of the filtration system or biochar flotation. • Investigations on constructed wetland integrating biochar (CWB) were reviewed • Pyrolysis time, heat and feedstock origin determine prepared biochar properties • Biochar substrate (BS) improves CW efficiency and pollutants adsorption capacity • Biochar in the substrate interlayer is the optimal ecotechnology configuration • In situ experiments are needed to test effectiveness and current effect of CWB [ABSTRACT FROM AUTHOR]

The sorption affinity and desorption resistance of two types of biochars as soil amendments was evaluated in laboratory. The softwood and hardwood-biochars demonstrated a high sorption affinity for progesterone. The effective distribution coefficient (K d eff ) of soil-soft wood-derived biochar (SBS 450 ) was significantly higher (H0: P < 0.05) than soil-hardwood-derived biochar (SBH 750 ), indicating its stronger sorption affinity for progesterone. Accordingly, a field-lysimeter study was conducted to elucidate the fate and transport of manure-borne progesterone in soil matrix and aquatic media in the presence of 1% softwood-biochar (BS 450 ) in upper 0.1 m layer of soil. The spatial–temporal stratification of progesterone was monitored at four depths over a 46-day period where two different types of manures (swine and poultry) were applied to the topsoil of lysimeters under two treatments, soil (S) and SBS 450 . The progesterone concentrations in SBS 450 were significantly higher (H0: P < 0.05) and persisted for a longer period in the surface soil than in the control (S); however, the concentration was significantly lower in the deeper profile and in leachates. The results clearly showed that the application of biochar as a soil amendment can be used in alleviating the threat of pollution from manure borne progesterone. [ABSTRACT FROM AUTHOR]

Water contamination by Cadmium (Cd) from industrial wastewater discharge is a critical global predicament. Its remediation creates an imperative need for the development of low-cost adsorbents with high efficiency. We demonstrate use of a novel adsorbent- Ipomoea fistulosa biochar as a low cost, efficient method to remove Cd from aqueous solution with minimum contact time period and adsorbent dose. Biochars produced from the abundantly available Ipomoea plant by slow pyrolysis at 350, 400, 500 and 550 °C were found to be effective in removal of Cd from aqueous solution. The efficiency of Cd removal has been considerably improved by activation of biochar using KOH which subsequently enhanced the porous structure resulting in more adsorption sites being exposed to Cd. The process of adsorption followed pseudo-second-order kinetic model. The mechanism for high adsorption efficiency is attributed to surface complexation of biochar particles with Cd(II) ions. Considering the excellent Cd sorption ability of our present adsorbent, there is heightened scope of using Ipomoea biochar as a new potential sorbent for removal of other toxic elements. [ABSTRACT FROM AUTHOR]

Forest soil, especially temperate forest soil, is a prominent sink of atmospheric methane (CH 4). Biochar has been increasingly applied to enhance CH 4 uptake by soil. However, the effect of biochar size and temperature on CH 4 uptake is still largely unknown. A series of incubation experiments were conducted to examine the single and combined effects of biochar addition and temperature (10 °C, 20 °C, and 30 °C) on CH 4 uptake by temperate forest soil in China. The biochar was classified into three particle sizes (<0.1 mm, 0.1–0.5 mm, and 0.5–1 mm) and two application rates (0.73% and 3.65%, m: m). Results showed that the CH 4 uptake was accelerated with the reduced particle sizes and the increased application rates of biochar. This variation was caused by two factors. Firstly, both the reduced particle sizes and increased application rates of biochar decreased the concentration of inorganic N, which had a negative relationship with CH 4 uptake (P < 0.05). Secondly, the reduced particle sizes and increased application rates of biochar promoted both available phosphorus concentration and pH, and these two factors positively correlated with CH 4 uptake (P < 0.05). The increased temperatures produced a negative effect on CH 4 uptake (P < 0.05) due to the increased concentration of inorganic N after rising temperatures. Furthermore, the combined effect of biochar addition and increasing temperatures on CH 4 uptake was antagonistic owing to the reduced Q 10 value of CH 4 uptake after biochar addition. This research highlights the importance of particle size of biochar on CH 4 uptake. Our results also suggest that the positive effect of biochar addition on CH 4 uptake may be dampened by global warming in the near future. • Fine-grain biochar addition absorbed more CH 4 than coarse-grain biochar. • Increased temperatures reduced soil CH 4 uptake. • Combined effect of biochar addition and temperature was antagonistic. • The antagonistic effect was due to the reduced Q 10 of CH 4 uptake. [ABSTRACT FROM AUTHOR]

Biochar production from manure wastes, including pig manure, could provide a valuable alternative to current waste management practices, while offering an opportunity to improve soil properties and to reduce the risk of contamination derived from the direct application of manure as a soil amendment. Two different biochar samples, produced from pig manure at 300 °C (BPC300) and 500 °C (BPC500) were used to evaluate the impact of biochar amendment on soil enzymatic activity and soil CO 2 emissions. An incubation experiment was designed as follows: selected soil (S) was amended with pig manure (PC) and two pig manure biochars prepared at 300 °C (BPC300) and 500 °C (BPC500) at a rate of 8 wt%. All samples were incubated during 219 days. The results indicated that soil amendment with biochars decreased the carbon mineralization, in contrast to soil amended with the pig manure. Addition of pig manure increased dehydrogenase, phosphomonoesterase and phosphodiesterase activities, while B prepared at 300 °C resulted on a positive effect on dehydrogenase activity. In contrast, B prepared at 500 °C did not exhibit a positive effect on soil enzyme activity. [ABSTRACT FROM AUTHOR]

In the present study, chemically modified biochar (developed from sugarcane bagasse) was used for the nitrate removal from aqueous solution. The physico-chemical properties of modified biochar such as morphology, surface functional groups, elemental composition, cation exchange capacity, anion exchange capacity and surface area were analyzed. The effects of various operational parameters such as solution pH, adsorbent dosage, contact time, initial concentration of nitrate, co-existing anions and temperature were examined on nitrate adsorption by modified biochar. The experimental data were fitted to different adsorption kinetic models (pseudo-first-order, pseudo-second-order, intraparticle diffusion and Avrami models) and adsorption isotherms models (Langmuir, Freundlich, Sips and Dubinin–Raduskovich models). The obtained results showed that the maximum percentage of nitrate adsorption attained at equilibrium pH 4.64, after 60 min of contact time and with an adsorbent dose of 2 g L −1 . In competing anions experiments, carbonate and chloride ions have shown maximum and minimum influence on the adsorption of nitrate by modified biochar sugarcane bagasse. Pseudo-second-order kinetic model and Langmuir isotherm model showed the best fit to the experimental adsorption data. The maximum adsorption capacity of modified biochar for nitrate removal was found to be 28.21 mg g −1 . The values of ΔH ° , ΔG ° and ΔS ° indicated that the nature of adsorption was endothermic, spontaneous and feasible. [ABSTRACT FROM AUTHOR]

Biochar (BC) application for improving soil quality and carbon sequestration has generated great interest for scientists and policy makers. BC can influence soil organic carbon (SOC) mineralization through priming effects. Positive, negative or no priming effects on C mineralization has been observed following BC additions to soils. However, uncertainty still remains about the influence of biochar on SOC mineralization in the coastal wetland soils of the Yellow River Delta, China. Therefore, a five months of incubation experiment using the coastal wetland soil was conducted to investigate the effects of adding BC produced from peanut shell at 350 °C on SOC mineralization at the rates of 0% (0%BC), 0.1% (0.1%BC), 1% (1%BC) and 3% (3%BC) (w/w). BC addition increased the cumulative CO 2 emissions, indicating that the cumulative SOC mineralization was enhanced in the coastal soil by BC application. However, the increased C mineralized only accounted for 1.71%, 0.32% and 0.17% of the BC-C added in the 0.1%BC, 1%BC and 3%BC treatments, respectively. Moreover, the experimental values of SOC mineralization was much lower than that of the theoretical values in both 1%BC and 3%BC treatments, indicating that a negative priming effect occurred. This may be explained by two reasons: (1) the conversion process of SOC to dissolved inorganic C (DIC) was accelerated by BC addition, which was confirmed by SEM image; (2) the amounts of available C substrate and microorganisms decreased via the sorption of labile organic C (LOC) and microorganisms onto BC. These results suggest that BC application will enhance soil C storage in the salinized wetland soils. [ABSTRACT FROM AUTHOR]

Analyzing the fractionation of cadmium (Cd) and lead (Pb) could provide key information to identify how wheat straw biochar (WBC) affects the bioavailability of Cd and Pb in contaminated soils. The fractionations of Cd and Pb were extracted from amended paddy soil according to the approach by European Community Bureau of Reference (BCR). Total Cd and Pb concentrations in contaminated paddy soil were decreased by 7.5–23.3% and 3.7–19.8% with WBC application during five years, respectively. The Cd was distributed primarily in the exchangeable (∼50%) and carbonate (>30%) fractions, and Pb was the mainly carbonate-bound fraction (∼70%). The exchangeable fractions concentration of Cd and Pb were significantly decreased by 8.0–44.6% and 14.2–50.3% during five years. The residual fractions were increased by 4.0–32.4% (Cd) and 14.9–39.6% (Pb). The percentage of exchangeable Cd fractions decreased by 1.2–6.9%, but the incensements of 1.7–7.2% and 1.3–2.2% were observed in carbonate and residual fractions for Cd. Similarly, the percentage of exchangeable Pb fractions decreased by 0.3–1.6%, though the carbonate and residual fraction were increased by 1.2–2.9% and 1.4–12.2%. The changes of Cd and Pb fractions were mainly due to the abundant functional groups and complex structures in WBC, which could improve soil microstructure and increase soil pH and soil organic matter. [ABSTRACT FROM AUTHOR]

Abstracts Wheat straw biochars produced at 400 and 700 °C (BC400 and BC700) were used to investigate their effects on the growth of Vallisneria spiralis and the dissipation of phenanthrene and pyrene in sediments. Biochar amendment inhibited the growth of V. spiralis to some extent at the end of 54-day experiment, and the inhibition was stronger by BC700 than by BC400. In unplanted sediments, PAH dissipation was significantly retarded by BC400 but slightly increased by BC700 although bioavailable fraction of the contaminants extracted by butanol was more significantly reduced by the addition of BC700. It is possible that the contaminants sorbed to BC700 are still bioavailable to bacteria. Planting V. spiralis significantly enhanced the dissipation of phenanthrene and pyrene in biochar-unamended sediments, but showed only small effect on the dissipation in biochar-amended sediments. Moreover, redox potential was much higher in planted sediments than in unplanted sediments no matter whether the biochars were amended or not, suggesting that oxygen is not the limiting factor for the degradation in biochar-amended sediments. [ABSTRACT FROM AUTHOR]

The present investigation emphasizes the feasibility of chemically modified N-biochar (CMNB) as a potential sorbent for the removal of a non-steroidal and anti-inflammatory drug ibuprofen from contaminated water. N-biochar engineered from precursor Parthenium hysterophorus was treated with NaOH for surface modification. The biosorptive uptake of ibuprofen onto CMNB was studied for the solid–liquid phase characteristics of ibuprofen–water system by a series of batch sorption experiments over the influence of different process parameters viz. adsorbent dose (0.05 g–3 g), speed of agitation (80–240 rpm), contact time (15 min–240 min), pH (2–10), initial ibuprofen concentration (5–100 ppm) and temperature (293–308 K). The maximum adsorptive removal percentage of ibuprofen onto CMNB was found to be more than 99% at adsorbent dose of 20 g L −1 , agitation speed 160 rpm, pH 2, initial ibuprofen concentration 20 mg L −1 , equilibrium time 120 min and temperature 20°C. The equilibrium adsorption data was well fitted into the Langmuir isotherm model. Kinetic data suggested that the adsorption of ibuprofen onto CMNB follows the pseudo second order kinetics. The probable mechanistic adsorptive behavior of CMNB was well supported by different analytical techniques viz. SEM, FTIR, BET, pH PZC , XRD. Out of six process parameters studied in batch process, three parameters such as dose, agitation speed and pH were chosen for optimization of ibuprofen removal employing central composite design (CCD) approach of response surface methodology (RSM). The same experimental matrix was used in artificial neural network (ANN) for the comparative analysis of ibuprofen removal. Results of this study revealed that CMNB could be a cost-effective and efficient adsorbent for the removal of ibuprofen from aqueous solution. [ABSTRACT FROM AUTHOR]

The combined application of biochar (BC) and chemical fertilizer (CF) increased crop and essential oil yield in two successive years (2013 and 2014) in basil ( Ocimum basilicum ). Organic carbon (OC) content increased under both: BC and BC mixed with CF treatments. The increase in OC ranged from 5.55% to 29.26% in the first year and 2.73–30.58% in the second year, respectively. Addition of biochar also led to increase in the soil microbial biomass carbon and soil microbial biomass nitrogen, suggesting that the higher concentration of biochar promotes the overall microorganism population. Soil dehydrogenase enzyme activity was 27% higher over the control in BC treatment. In the second harvest (2014), the urease activity increased from 7.4% to 39% in BC + CF treatment. Essential oil constituents (aroma compounds) did not change in biochar amended pots. The results show that the amendment of biochar with chemical fertilizer offers an appropriate alternative strategy to achieve higher crop productivity and essential oil yield in basil without compromising the aroma quality of the oil. Strategic addition of biochar in fertilizer regime has the concomitant advantage of enriching soil fertility for long-term sustainable agriculture with potential to reduce chemical fertilizer inputs. [ABSTRACT FROM AUTHOR]

The obtained results showed that the addition of biochar to the mixture of sewage sludge and wheat straw prior to composting facilitated the growth and reproduction of Eisenia fetida during laboratory vermicomposting of this mixture. After 4 weeks of vermicomposting the average number of produced cocoons in the mixtures amended with biochar increased by 13% for SS + ST + 4%B and 66% for SS + ST + 8%B. Also, the number of juvenile earthworms was higher in the mixtures amended with biochar. However, the total weight of earthworms declined with the depletion of organic matter after 18 weeks of the experiment. Amending sewage sludge mixtures with biochar for vermicomposting resulted in higher reproduction rates, and thus could allow faster and more efficient conversion of sewage sludge into vermicompost. [ABSTRACT FROM AUTHOR]

This study aims to investigate the impacts of pH, inorganic fractions and dissolved organic carbon (DOC) on pentachlorophenol (PCP) adsorption on reed biochars prepared by pyrolysis temperatures ranging from 300 °C to 600 °C, as well as illustrating the adsorption mechanisms. The adsorption capacities for PCP on acid-washed reed biochars were higher than that of original reed biochars. The dedication of neutral PCP molecules (PCP 0 ) and ionized PCP species (PCP − ) to the overall adsorption at pH 3.0–12.0 was calculated. The relative contribution of PCP 0 was above 53.4% at pH 3.0–5.0, and PCP − was dominant for adsorption at pH 6.0–12.0 with the contributions of 43.2%-100%. The inorganic fractions in the biochars present the negligible or negative effect on PCP adsorption due to its high hydrophilic. The water extractable DOC decreased the adsorption capacity of PCP on reed biochars. The isotherms of PCP adsorption on reed biochars were well described by Freundlich model, and the adsorption mechanisms were mainly interpreted as π–π and hydrophobic interactions. These observations are helpful for exploiting reed biochars as engineered absorbents to remove PCP from aqueous solution. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the best absorbent for cadmium (Cd) present in aqueous solutions. Among the selected absorbents ( n = 22), peanut husk biochar (PHB) was the best absorbent for Cd and its adsorption reached to equilibrium within 12 h. In this study, the optimum conditions observed for Cd adsorption were pH 5.0, an initial Cd concentration of 200 mg L −1 , a PHB dosage of 40 g L −1 , and room temperature. The Cd removal efficiency of the tested biochar reached to 99.9% at these optimum conditions. EDX analysis confirmed that Cd was adsorbed onto PHB more than onto PHs. It is concluded that PHB can be used as a good remediating material for removal of Cd from contaminated environmental matrixes. [ABSTRACT FROM AUTHOR]

Pot experiments were conducted to investigate the impact of biomass amendments (biochar, compost and nutrient solution) and chemical amendments (Ethylenediaminetetraacetic acid (EDTA) and Igepal CA-720) on the phytoremediation of soil co-contaminated with organic and metal contaminants by Helianthus annuus (sunflower) and Avena sativa (oat plant). Mixed contaminated soil was prepared by mixing clean soil with naphthalene, phenanthrene, lead (Pb), cadmium (Cd), and chromium (Cr). To study the biomass amendments, soil was amended with biochar, compost, or a nutrient solution. To study chemical amendments, plants raised in contaminated soils were amended with a solution of EDTA, Igepal CA-720 or both. The combination of biomass and chemical amendments were studied by treating composted soil with either EDTA or Igepal CA-720. The results showed that the biochar and compost amendments improved the growth characteristics and biomass of the plants. Growth improvement was best observed for sunflower plants in composted soil. Average maximum plant height of sunflower in contaminated soil was increased by 115% with the addition of compost. Cd and Pb removal was best in the presence of biochar and compost amendments, but Cr removal was unaffected by the use of amendments. The best removal rate was observed for Pb by oat plant in compost amended soil, with average final Pb concentration decreased by 57.8% with the addition of compost to soil. Nutrient solution amendment did not improve the removal of the metal contamination from the soil. The overall growth and biomass were less for plants grown in soil that was treated with chemical amendments. A combination of compost and chemical amendments also did not provide positive results on the plant growth or contaminant dissipation. Polycyclic aromatic hydrocarbon (PAH) degradation improved in the presence of all of the amendments studied. The results suggest that biochar and compost amendments can improve the plant growth characteristics and enhance phytoremediation of mixed contaminated soils. [ABSTRACT FROM AUTHOR]

The crop biomass treatment is the challenging issue in the intensive agricultural area and the catalyst has the potential to solve this problem. This preliminary study examined the response of the corn straw biochar treatment to the catalytic pyrolysis and applications of catalyst to the sustainable agricultural with cost savings. The surface morphology of corn straw after pyrolysis was compared with the electron microscope scanned images. The pyrolytic characteristics and kinetics of corn straw were studied using a thermogravimetric analyser from ambient temperature to 900 °C under a nitrogen atmosphere at heating rates of 10, 20, 30 and 40 °C min −1 . The mass loss and the rate of mass loss curves derived from the pyrolysis of corn straw biochar and the biochar with the addition of 5% (wt.%) ammonium dihydrogen phosphate (ADP) catalyst. The pyrolysis process was consisted of three distinct stages, and impact of catalyst on the temperature distribution was distinguished. The catalytic pyrolysis process was mainly categorised by removal of water including free water and combined water, decomposition of hemicellulose, cellulose and lignin; and carbonisation. With the increase of pyrolysis rate, the maximum weight loss temperature shifted to lower temperatures. The kinetic process characteristics of corn straw biochar at three levels of ADP addition and four kinds of temperature were calculated. The activation energies and pre-exponential factors of the pyrolysis process were calculated by the Flynn–Wall–Ozawa method, modified Coats–Redfern model-free method and Kissinger method. The detailed information of kinetic parameters also helped to improve the biomass pyrolysis process. The analysis demonstrated that the ADP had a catalytic effect on the pyrolysis behaviour of biomass and was able to reduce the activation energy of biomass pyrolysis. Therefore, the catalyst can improve the pyrolysis process and have great potential to increase crop residue treatment efficiency, especially in the intensive agricultural area. [ABSTRACT FROM AUTHOR]

Biochar is an organic amendment with good effects on soil properties but its influence on Cd fractionation and growth of vegetable crops (e.g. Chinese cabbage) and field crops (e.g. maize) is still restricted. A pot experiment was conducted to investigate the effect of biochar derived from bamboo residues (pyrolyzed at temperature of 400 °C) at four levels (0%, 0.5%, 1% and 1.5%) on Cd solubility and bioavailability, and plant growth in a loamy soil artificially contaminated with Cd at three rates (0, 5 and 50 mg kg −1 ). The soil was strongly acidic (pH = 4.63) with low organic carbon content (1.064 g kg −1 ). Chinese cabbage and maize were used as indicator plants in this investigation. Addition of babmboo biochar significantly increased soil pH, electrical conductivity (EC), organic carbon (SOC), and cation exchange capacity (CEC). Concentrations of Cd in CaCl 2 and DTPA extractions decreased due to the increase of biochar rates but there were no alterations noticed in total concentrations of Cd in the soil. The acid soluble/exchangeable Cd decreased by 3.35–3.88 times, but the reducible and oxidizable fractions of Cd increased by 1.95–1.96 times and 1.91–2.14 times, respectively, after harvesting cabbage and maize plants in the presence of 1.5% biochar. Changes of soil properties, especially pH could be used as a good reason to illustrate the immobilization of Cd in biochar treated soils. The increase of biochar rates from 0% to 1.5% enhanced the growth of cabbage by 64.23%, 47.31% and 34.93%, and maize by 50.78%, 32.83% and 29.68% in soils treated with Cd at 0, 5 and 50 mg kg −1 , respectively. Using biochar at a dose of 1.5% diminished concentrations of Cd in cabbage shoots by 4.71–2.29 times and in maize shoots by 5.17–2.68 times, respectively. Our results suggested that bamboo biochar had positive residual effects on maize after the harvest of cabbage. Finally, bamboo biochar, especially at its highest rate (1.5%) could be recommended as a safe amendment in the immobilization of Cd in contaminated agricultural soils and then reduced its threat on the food chain and human health. [ABSTRACT FROM AUTHOR]

Engineered denitrifying environments, such as constructed wetland, biofilters or bioreactors have been increasingly recognized as an efficient means to improve water quality via facilitated denitrification. These environments function by providing a carbon substrate that serves as an energy source for microbial denitrifiers to utilize during denitrification. However, under sulfate (SO 4 2− ) reducing redox potentials, methane (CH 4 ), hydrogen sulfide (H 2 S) and methyl mercury production can result. Amorphous ferric hydroxide (Fe(OH) 3 ) has been shown to poise soil systems above the redox potential (E h ) of microbial SO 4 2 reduction. This mineral was added in a denitrification column experiment in order to assess the ability of amorphous Fe(OH) 3 to prevent or mitigate microbiological SO 4 2− reduction. Given biochar’s ability to enhance microbial activity, this experiment was also designed to determine whether biochar enhances microbiological SO 4 2− and NO 3 − − N reduction, as well as mitigate N 2 O emissions. Four denitrification substrate mixtures were evaluated in a laboratory column experiment: woodchips only (WC), woodchips + 15% (v/v) sand (Sand), woodchips + 15%(v/v) hardwood 26 mesh biochar (Biochar) and woodchips + 15%(v/v) hardwood 26 mesh biochar + 15 % (v/v) amorphous Fe(OH) 3 (Fe). Columns were sampled for NO 3 − − N, N 2 O and SO 4 2− at an initial interval of 3 hrs gradually decreasing to 12 h over a 120 h sampling period. Analysis of the data show that Biochar enhanced SO 4 2− reduction (to sulfide) by 85% compared to the initial concentration while Fe largely prevented SO 4 2− reduction, displaying a 18% reduction, which was not statistically significant. These results indicated that Fe(OH) 3 addition significantly mitigated SO 4 2− reduction. Similar to Fe, the Sand column exhibited lower microbially reduced SO 4 2 than Biochar, at 20%, but this schema resulted in significantly higher N 2 O production. The WC treatment reduced SO 4 2 by 47%, but also produced more N 2 O than other treatments. As expected, both treatments with biochar (Biochar and Fe) accelerated NO 3 − − N removal while reducing the production of N 2 O, and there was no discernable difference between the two, indicating that the addition of Fe(OH) 3 to the system does not negatively impact performance. These results indicate that biochar, while enhancing denitrification, significantly increases microbiological reduction of SO 4 2− , a precursor to methyl mercury production in. Thus, methyl mercury production may increase with increased biochar addition unless amorphous Fe(OH) 3 is added to the substrate matrix. [ABSTRACT FROM AUTHOR]

Most countries in the South Pacific rely on traditional soak pits which transfers wastewater down through the unsaturated carbonate sand sediment profile with little nutrient attenuation. With surface nutrients having an almost direct path to groundwater, this may have consequences for the sustainability of subsurface water reserves. This study examined the long-term removal and production of wastewater nutrients (including greenhouse gases) in tropical sediments and materials under different saturation regimes. The study showed that unsaturated carbonate sands alone are not an effective means of reducing nutrient loads to groundwater. There was no significant difference in removal rates of total dissolved nitrogen (TN) and phosphorus (TP) in unsaturated carbonate sand columns and columns amended with coconut husk and basalt sediment. Doubling of the effluent flow rate resulted in no significant decrease in the TN removal rate, but did halve the TP removal rate. The addition of a biochar filter to the unsaturated carbonate sand columns increased TN removal from ∼8% to ∼42%. The TN removal rate in the wastewater-saturated treatments (662.1 ± 49.4 mg m −3 day −1 ) was approximately six times higher than the unsaturated treatments (110.2 ± 27.2 mg m −3 day −1 ). TN removal in the fully saturated columns increased from 63% to 95% after the addition of an external carbon source (glucose). Higher nitrous oxide (N 2 O) and methane (CH 4 ) concentrations in partially saturated columns and at the surface of the fully saturated columns were likely due to partial coupled nitrifier denitrification. The addition of basalt sediments to carbonate sands increased the total phosphorous removal from 72% to 95%. Sampling of groundwater below an in situ wastewater treatment system showed an almost complete removal of TN and TP within two meters of the aquifer surface, even with limited bioavailable carbon to facilitate denitrification. Modelling of NO 3 − and N 2 concentrations for an idealized treatment system indicated reduced NO 3 − concentrations may be due to a combination of dilution with high volumes of groundwater (∼45% of removal at the farthest sampling point from the system) and denitrification. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the performance of sludge biochar compared to unprocessed wastewater sludge on production of Coolatai grass ( Hyparrhenia hirta) as a potential forage and energy crop species. Pot trials were conducted to determine the nutritive quality and yield of Coolatai grass using chromosol soil amended with wastewater sludge and sludge biochar. The application of biochar combined with fertiliser was found to have the highest effect on the yield producing more than double of the plant dry matter comparing to unamended chromosol soil conditions. The combination of biochar and fertiliser treatment also increased some of the important chemical characteristics of Coolatai grass, such as the metabolisable energy and crude protein composition compared to control, wastewater sludge and fertiliser treatments. [ABSTRACT FROM AUTHOR]

Soil applicable biochar has been prepared from bark of Leucaena leucocephala wood which is a waste generated during its pulping and papermaking process. The slow pyrolysis process adopted for this purpose has been modelled and optimized employing central composite design and desirability function under response surface methodology taking temperature (308–592 °C) and time (35–205 min) as independent variable while yield, loss on ignition, stable organic matter, oxidisable carbon and carbon liability index as dependent variable. L. leucocephala bark was characterized in terms of proximate analysis (moisture 4.90%, ash 7.20%, fixed carbon 18.10%, volatile matter 69.80%), elemental analysis (carbon 45.78%, hydrogen 10.67%, nitrogen 1.77%, oxygen 32.08%, sulphur 0.09%), lignocellulosic composition (holocellulose 45.86%, hemicellulose 15.01%, lignin 34.75%) and compared with a wide range of feedstocks to find its suitability towards biochar production. The optimum pyrolysis temperature and residence time were found to be 350 °C and 60 min respectively which gave biochar yield 53.16%, loss on ignition 88.17%, oxidisable carbon 28.82%, stable organic matter 38.48%, and carbon liability index 0.32. The biochar produced at optimum conditions were characterized by proximate analysis (moisture 0.65%, ash 11.83%, fixed carbon 40.2%, volatile matter 47.57%) and elemental analysis (carbon 62.91%, hydrogen 3.12%, nitrogen 2.65%, oxygen 20.74%, sulphur 0.05%). The O/C ratio of 0.25 and H/C ratio of 0.60 confirmed its life between 100–1000 years and appropriateness for soil application as well as carbon sequestration. [ABSTRACT FROM AUTHOR]

Lignocellulosic crop residue biomass, in surplus, is of vital importance due to its multifaceted utilization potential on- and off-site to agricultural systems; therefore, its management is essential for sustainable agriculture. The malpractice of open crop residue burning leading to the brown cloud phenomenon and contributing significantly to atmospheric heterogeneity through enhanced gaseous and particulate emissions is of greater off-late concern. Available traditional crop residue management (CRM) technologies have not achieved wider adaptation; therefore, recently thermochemical conversion has been foreseen as an interesting tool for potential CRM under changing climate scenario. Biochar, a by-product of thermochemical processes, has been evaluated as a potential soil ameliorant and C sequestration agent. As soil ameliorant, it improves soil basic properties directly along with subdued release of greenhouse gases from agroecosystems, provides adsorption surface to agrochemicals and improves essential nutrient dynamics. Since the potential benefits of biochar in soil are governed by initial pyrolysis conditions and soil types; therefore, its wider utilization potential as suitable tool in sustainable agriculture and climate change mitigation needs to be critically analyzed before its specific recommendation to an agroecosystem. The present review provides a critical insight on current research on various aspects, particularly ecological, of crop residue biochar starting from the feedstock sources, pyrolysis conditions and changes after application. Additionally, a brief account is given on the agronomic relevance and major constraints of biochar amendment as an ecological engineering tool for sustainable agriculture. After reviewing various aspects of crop residue as feedstock, we recommend its use as a blend, rather than sole use, along with several other lignocellulosic materials under pyrolysis process as well as ameliorating agent. [ABSTRACT FROM AUTHOR]

Due to the high content of PAHs in biochars, their utilisation in agriculture is questioned. However, in the literature there is a lack of evidence whether and what amount of PAHs in biochar may create a threat to living organisms. The objective of the study was to determine the effect of PAHs on various biochars toxicity towards Vibrio fischeri , Daphnia magna and Lepidium sativum . The study was conducted on three biochars obtained from miscanthus (BCM), willow (BCW) and wheat straw (BCS). PAHs were removed from the biochars by drying at temperatures of 100 °C, 200 °C and 300 °C. Depending on the kind of biochar, drying at temperature of 100 °C caused PAH content reduction at the level of 33.8–88.1%. Increase of the drying temperature (to 200 °C and 300 °C) caused total reduction of PAHs within 24 h. PAH removal from the biochar that had their highest content (BCM) caused total reduction of its toxicity. In the case of the other biochars (BCS and BCW), in which lower content of PAHs was observed relative to biochar BCM, no correlation was noted between the level of removal of PAHs and their toxicity. [ABSTRACT FROM AUTHOR]

Slow pyrolysis corn stover biochar was prepared at 500 °C in an ingeniously developed reactor. Biooil was also collected. Corn stover biochar was magnetized by mixing aqueous biochar suspension with aqueous Fe 3+ /Fe 2+ solution, followed by NaOH treatment. Corn stover biochar (CSBC) and magnetic corn stover biochar (MCSBC) were characterized by pHzpc, S BET , X-ray, FT-IR, SEM, SEM-EDX, TEM, EDXRF and Raman analyses. Magnetic moment of MCSBC was also measured. Both the biochars were utilized for fluoride removal to replace the existing commercially available costly adsorbents. Maximum fluoride removal was achieved at pH 2.0. Adsorption studies were carried out at 25, 35 and 45 °C. Fluoride removal on CSBC and MCSBC was decreased with rise in temperature [CSBC: Q 0 25 = 6.42 mg/g; Q 0 35 = 5.17 mg/g; Q 0 25 = 4.99 mg/g and MCSBC: Q 0 25 = 4.11 mg/g; Q 0 35 = 3.45 mg/g; Q 0 25 = 3.41 mg/g]. Pseudo-first order kinetics best fit the fluoride adsorption data. Both biochars successfully remediated fluoride from contaminated ground water. [ABSTRACT FROM AUTHOR]

Biochar has been widely used in soil improvement and bioretention cells because of its low carbon content, easy preparation, environmental protection, and excellent performance. This study reviews the element composition, morphological structure, adsorption, hydrophobicity, and water-retention capacity of biochar applications in bioretention. The review focused on biochar's water-retention capacity, its influence on the water permeability of fillers, and its capacity to remove contaminants such as nitrogen, phosphorus, organic compounds, pathogenic microorganisms, and heavy metals in bioretention cells. This review summarizes the potential application of biochar-modified fillers, biochar-modified bioretention, and related problems, to guide the modification and application of biochar as a bioretention filler. [Display omitted] • The physical and chemical properties of biochar and its application in soil improvement are summarized. • Mechanisms of improving the water holding capacity and water conductivity of bioretention cell by biochar is analyzed. • The effect of biochar modified filler on the removal efficiency of pollutants in rainwater is analyzed. • Deficiencies of biochar modified bioretention cell in current research are proposed to provide ideas for future research. [ABSTRACT FROM AUTHOR]

In constructed wetlands for wastewater treatment, plants contribute to nutrient removal. However, plant species differ in their ability to tolerate high nutrient loads and accumulate nutrients in biomass. Growth and nutrient accumulation were investigated in two subtropical/tropical plants: melaleuca trees (Melaleuca quinquenervia) and lemongrass (Cymbopogon citratus). These were planted in 240 L mesocosms containing sand media and biochar (0 to 25% by volume). The mesocosms were loaded with tertiary effluent for 4 months, secondary clarified wastewater (SCW) for 8 months and finally septage for 9 months, a total cumulative load of 1060gN m −2 and 320gP m −2. Plant growth, including stem height and girth for melaleuca and leaf regrowth for lemongrass were monitored. Growth rates were higher (0.48 cm/day stem height; 2.22 cm/day leaf regrowth) when irrigated with septage, compared to SCW (0.32 cm/day stem height; 1.14 cm/day leaf regrowth). Plants were harvested at the end of the experiment and the biomass and nutrient content in each part determined. Both melaleuca and lemongrass had very high N and P tissue content: melaleuca leaves 23 mg/gN, 2 mg/gP; roots15mg/gN, 2.1 mg/gP; lemongrass leaves 18 mg/gN,2.2gP; roots 9.5 mg/gN, 2 mg/gP. Annual biomass and nutrient accumulation per plant was 486 g; 5.72 gN; 0.89 gP for melaleuca trees and 180 g; 2.54 gN; 0.39gP for lemongrass, a total nutrient accumulation of 33 g m −2 N and 5 g m −2 P/annum. Plant uptake accounted for 8.6%TN and 4.5%TP of load retained. Biochar amendments did not enhance growth rate nor increase N and P biomass. We postulate that effluent nutrient loads provided adequate nutrients for plant growth even in pure sand media. • Melaleuca and lemongrass were able to tolerate high nutrient loads. • Both plants had high N and P plant tissue content maximising nutrient uptake. • As a woody plant Melaleuca had high biomass and nutrient bioaccumulation. • Plant biomass and nutrient bioaccumulation in lemongrass was low compared to other herbaceous species. • Biochar additions to sand media did not increase plant growth, nutrient content, nor N and P biomass. [ABSTRACT FROM AUTHOR]

Soil in embankments is often amended with several additives for supporting the vegetation growth on the side slopes. Biochar, a stable, nutrient loaded and moisture retentive material, could be amended to the embankment soils. The positive impacts of biochar on soil properties, soil water and nutrient retention, microbial activity and growth of crops are well established. However, the load-bearing capacity of biochar-amended soil which is utmost important for a material to be used in embankment is rarely reported in literature. The present study aims to investigate the shear strength and load-bearing capacity of biochar-amended soil for application in embankments. For assessing the shear strength and load-bearing capacity, California bearing ratio (CBR) and direct shear tests were conducted on bare and 5%, 10% and 15% (w /w) biochar-amended silty sand and pure sand. The results revealed that the biochar amendment decreased the dry unit weight (6–19%), and increased the shear strength (cohesion (c) and angle of internal friction (ϕ)) and load-bearing capacity of both the soils by 22–228% and 17–89% respectively. Further, the biochar amendment improved the vegetation root (34–108%) and shoot (29–157%) mass, ensuring the enhanced stability and protection (erosion). Thus, the results suggest the application of biochar-amended soil in embankments, however future field-scale trials are needed before application. [ABSTRACT FROM AUTHOR]

The wheat straw biochar has well pronounced effects on the coastal saline-alkali soil remediation/health. The soil water content in saline-alkali soil increased by 12.4–16.6% (2014), 18.1–63.4% (2015), 23.9–42.6% (2016) with 0, 20, 40, and 60 t ha−1 application of wheat straw biochar. The different chemical properties like pH, CEC (cation exchange capacity) and SOM (soil organic matter) ranged between 0.2 and 3.1, 6.7–82.0% and 12.6–139.6%, respectively with biochar application during three years of field experiment. The TSS (total soluble salt) of different biochar treatments in the soil decreased by 15.9–23.7% (2014), 28.6–54.6% (2015), 11.7–42.2% (2016) compared with control. The exchangeable/soluble cations like Calcium (Ca), Magnesium (Mg), chlorine (Cl) and Sodium (Na) concentration showed the similar trend as that of TSS. The soil soluble potassium (K) concentration significantly increased by 82.5–233.1% (2014), 65.3–228.2% (2015), 19.2–233.8% (2016) compared with control, which mainly originated from biochar. The wheat straw biochar application improves the coastal saline-alkali soil health and environment, which promoted the crop growth. The biochar amendment improved the soil properties with decrease in the salt concentration that showed biochar potential to improve/remediate the saline alkali soil. [Display omitted] [ABSTRACT FROM AUTHOR]

In the present investigation, the effect of biochar incorporation into high sulphur mine rejects on buffering of the acid production was assessed. For this, kinetic experiments on pure mine rejects ( L MR ) and biochar amended mine rejects ( L MRBC ) were performed for 720 h. Leachate samples were collected at 0, 20, 40, 60, 168, 336, 504 and 720 h and characterized. Results revealed that incorporation of biochar inhibited the acid production rate (from 10.4 kg/Mt/h to 3.81 kg/Mt/h) and enhanced the alkali consumption (from 9.7 kg/Mt/h to 13.9 kg/Mt/h). Biochar was capable to neutralize all the acid produced. As a neutralizing agent, Mg 2+ dominated over Ca 2+ . The efficiency of biochar to reduce the rate of acid production may be due to either the reduction in Fe 3+ concentration or production of reduced sulphur compounds in reducing conditions of biochar. This is also supported by molar sulphur to iron ratio of leachate water. Principal component analysis applied on the data revealed that biochar altered the salt and carbon dissolution processes of mine rejects. It inhibits the acid production and accelerates the alkali releasing. [ABSTRACT FROM AUTHOR]

Practitioners of ecological restoration must increasingly consider likely impacts of climate change, requiring reassessment of limits to ecological recovery and persistence. Overcoming soil nutrient enrichment and exotic invasions are common restoration targets in mesic ecosystems, but in a drying climate, the focus may shift towards more fundamental ecosystem functions such as capacity to capture and store water. We investigated opportunities for enhancing the climate-resilience of restoration efforts in temperate grassy eucalypt woodlands, by evaluating benefits after two years of soil amelioration techniques in characteristic sites that had become compacted and nutrient-depleted as a result of past land use. Our goal was to restore soil biophysical functioning without exacerbating exotic invasion. High C:N soil amendments including a green-waste biochar and a mixed-size green-waste mulch facilitated recovery of soil biophysical attributes within two years. Both led to lower bulk density, softer soil surfaces, occasionally higher soil moisture and better persistence of a sown, large-seeded native forb. Biochar also led to improved water infiltration and total C, while mulch led to higher labile C and higher microbial and invertebrate activity (but limited establishment of small-seeded forbs). Benefits were achieved without promoting exotic species, and for attributes with comparable reference data, benefits after two years were on average 25% of that required to reach reference condition. By contrast, P fertilization promoted exotic species at the expense of native grasses, with minimal improvement to soil biophysical condition after two years. Potential benefits of re-introducing a native C 4 grass were not evident within the experimental timeframe. We conclude that bulky, high C:N soil amendments have the potential to facilitate recovery of functions associated with soil water availability and hence resilience to a drying climate. However, longer-term evaluation is needed to assess whether benefits reflect once-off small increments, or transitions across ecological thresholds that will facilitate ongoing improvement towards reference condition. [ABSTRACT FROM AUTHOR]

Green roofs are increasingly being built to manage stormwater runoff in cities. Water-retention additives such as biochar could be a useful way of increasing substrate water holding capacity (WHC) and therefore stormwater retention without increasing substrate weight loading. If this also increases plant available water (PAW), plant selection could be expanded to species with higher water use, further reducing stormwater runoff by drying substrates after rain. We examined the effects of adding one type of green waste biochar (0, 10, 20, 30 and 40%, v/v) to two scoria-based substrates (with or without added organic matter) on WHC, bulk density, PAW and days taken to reach permanent wilting point (PWP). Biochar significantly improved WHC, increasing with greater additions of biochar. Increased water was also plant available, with 30% biochar increasing PAW by 16% (scoria with organic matter) and PWP by 2 days in both substrates. Biochar did not affect plant growth or biomass allocation. Application of 30% biochar was optimal for PAW and delaying PWP. However, as 40% biochar significantly increased WHC, this rate will likely be optimal for stormwater retention, with an additional 2.3 cm rainfall/cm area retained in 10 cm deep substrates. Biochar also significantly reduced bulk density, substrates with 40% biochar could have an additional 1.5 cm/m 2 of depth compared to the same weight as scoria only, further increasing PAW and rainfall retention. Consequently, in this study, biochar addition makes green roof substrates lighter and improves plant water supply; potentially expanding plant selection in dry climates and improving their stormwater retention. [ABSTRACT FROM AUTHOR]

The presented research included laboratory scale composting of sewage sludge and woodchips mixtures amended with biochar in 45 L reactor system conducted for 16 days. The effect of biochar amendment on ammonia emission was investigated. The addition of biochar reduced significantly volatilization of ammonia during the first week of the process. Also, the addition of biochar increased temperature and organic matter decomposition. [ABSTRACT FROM AUTHOR]

Highlights: [•] The mechanism for biochar application was first investigated. [•] Effects of biochar on P sorption were highly influenced by soil acidity. [•] Biochar increased the Ca-bounded P the Al-retained P. [•] Biochar improved P availability by P sorption and desorption capacities of the soils. [Copyright &y& Elsevier]

To study the effects of wheat straw and its biochar on carbon mineralization in saline soil, we investigated the changes of carbon (C) mineralization rate with different carbon sources under constant moisture (CM) and drying–rewetting (DW) cycles in a homoeothermic incubator. Six treatments including control (C), wheat straw (S+W), 300°C wheat straw biochar (S+C1), 600°C wheat straw biochar (S+C2), double 300°C wheat straw biochar (S+2C1) and combination of wheat straw and its biochar (S+W+C1) were evaluated in the present study. Application wheat straw to the soil resulted in the higher release of CO2 than that of the treatment of S+C1 and S+C2. However, the CO2 release of S+W+C1 treatment was lower as compared to wheat straw alone, which can be ascribed to the higher adsorption of biochar for organic matter. Rewetting the dried treatments caused higher release of CO2 than that of CM, but the cumulative C mineralization of DW was less than that of CM in all treatments. The extent of reduction between DW and CM was less pronounced in S+2C1 and S+W+C1 especially with increasing DW cycles. The results suggested that the flush of mineralized C in rewetting period can be partly compensate for the reduction of mineralized C during the drying period. The fact can be explained by the good adjustability of “r-strategist” microbes in rewetting period and the provision of better physical habitats by biochar. In general, the stress of DW cycles on saline soils could be effectively reduced with biochar application especially with low charred temperature biochar. [ABSTRACT FROM AUTHOR]