Potential Of Biochar And Humic Substances For Phytoremediation Of Trace Metals In Oil Sands Process Affected Water.

Oil sands process affected water (OSPW) is produced during bitumen extraction and typically contains high concentrations of trace metals. Constructed wetlands have emerged as a cost effective and green technology for the treatment of metals in wastewaters. Whether the addition of amendments to constructed wetlands can improve metal removal efficiency is unknown. We investigated the synergistic effects of carbon based amendments and wetland plant species in removal of arsenic, cadmium, cobalt, chromium, copper, nickel, and selenium from OSPW. Three native wetland species (Carex aquatilis, Juncus balticus, Scirpus validus) and two amendments (canola straw biochar, nano humus) were investigated in constructed wetland mesocosms over 60 days. Amendment effect on metal removal efficiency was not significant, while plant species effect was. Phytoremediation resulted in removal efficiencies of 78.61 to 96.31 % for arsenic, cadmium, and cobalt. Carex aquatilis had the highest removal efficiencies for all metals. Amendments alone performed well in removing some metals and were comparable to phytoremediation for cadmium, cobalt, copper, and nickel. Metals were primarily distributed in roots with negligible translocation to shoots. Our work provides insights into the role of plants and amendments during metal remediation and their complex interactions in constructed treatment wetlands.

Synergistic effects of coal waste derived humic substances and inorganic fertilizer as soil amendments for barley in sandy soil.

Increasing pressures on land resources requires increased land use efficiency. Over 900 million ha of sandy soils throughout the world are extensively used for agricultural crop production, most requiring nutrient inputs. Although use of humic substances together with inorganic fertilizer as soil amendments has been introduced, their synergistic effects on plant growth in sandy soils are not well addressed. We assessed the efficacy of a lignite waste derived humic substance on barley (Hordeum vulgare L.) growth, with and without inorganic fertilizer. Ten treatments were applied to sandy soils, comprising sole application of the humic product at four rates (NH1, NH2, NH3, NH4), sole application of fertilizer (F), and their combinations (F + NH1, F + NH2, F + NH3, F + NH4). Synergistic effects of nano humus and fertilizer were more notable than the corresponding sole application, particularly on plant biomass and seed production. Combined application with inorganic fertilizer increased root biomass by 92 % (0.1 g per plant), shoot biomass by 80 % (0.5 g per plant), root length by 24 % (3.6 cm), and seed production by 38 % (5 seeds per head) averagely relative to the untreated control, suggesting a strong synergistic effect. The increased seed production was particularly important from an agricultural perspective. Four application rates of nano humus all showed beneficial effects on barley growth with no significant differences. The most distinct positive effect of the humic product as a sole application was on root growth. Our study confirmed that a lignite waste derived humic product, nano humus, together with fertilizer may be an effective soil amendment to enhance agricultural plant growth in sandy soil regions.

Phosphogypsum impacts on soil chemical properties and vegetation tissue following reclamation.

Phosphogypsum (PG) is a by-product of phosphorus fertilizer that is typically stacked near production sites. Phosphogypsum contains trace elements and naturally occurring radioactive materials which may be hazardous to the surrounding environment. Phosphogypsum stack reclamation typically involves placing a soil cap and seeding grass to create a barrier for reducing environmental impacts; using woody species is uncommon. This study used three soil treatments with grass and woody species to determine whether mixing PG with soil affects soil chemical properties, and metal and radionuclide concentrations in tissue. None of the elements in soil was above Canadian guidelines for industrial land use. Aluminum, beryllium, chromium, copper, iron, magnesium, manganese, nickel, and vanadium were significantly higher in both study and reference sites than in pure PG; cadmium, calcium, fluoride, and strontium were significantly higher in pure PG. There was a poor correlation between soil and plant concentrations for most elements indicating trace elements were not in a bioavailable form. Trace elemental concentrations in plant tissue generally differed significantly with vegetation type but not within similar species. Trace elements and isotopes in PG were not high enough to affect plant growth. Among the isotopes, 222Ra emissions differed significantly with vegetation covers; activity of 226Ra in pure PG was above Canadian guidelines, but lower in vegetation tissue. This study suggests 15 cm soil mixed with PG can be used for PG stack revegetation when fast-growing Salix and Populus species are used in reclamation.

Performance of constructed floating wetlands in a cold climate waste stabilization pond.

Effectiveness of constructed floating wetlands (CFWs) is largely unknown for wastewater treatment in cold climates. An operational-scale CFW system was retrofitted into a municipal waste stabilization pond in Alberta, Canada. During the first year (Study I), insignificant performance was recorded for water quality parameters, although phyto-uptake of elements was evident. In Study II, doubling of the CFW area and addition of underneath aeration promoted plant uptake of elements, including nutrients and metals, following significant pollutant reduction in the water; 83 % of chemical oxygen demand, 80 % of carbonaceous biochemical oxygen demand, 67 % of total suspended solids, and 48 % of total Kjeldhal nitrogen. A mesocosm study, conducted in parallel to the pilot scale field study, confirmed the impact of both vegetation and aeration on water quality improvement. The phytoremediation potential was linked to accumulation within plant shoot and root biomass and was confirmed by mass balance. Bacterial community analyses reflected that heterotrophic nitrification, aerobic denitrification, complete denitrification, organic matter decomposition, and methylotrophy were dominant mechanisms in the CFW, likely resulting in successful transformation of organics and nutrients. CFWs appear to be a viable ecotechnology to treat municipal wastewater in Alberta; however, larger and aerated CFW systems are recommended to achieve maximum remediation. The study aligns with the United Nations Environment Program to scale up restoration of degraded ecosystems, and to improve conditions for water supply and biodiversity following recognition of 2021-2030 as the Decade on Ecosystem Restoration.

Application timing optimization of lignite-derived humic substances for three agricultural plant species and soil fertility.

Coal is mined for energy generation around the world, producing large amounts of waste and extensive disturbances to the environment. Post-mining lands with sandy soils to be reclaimed for agricultural uses are very challenging. The use of humic substances such as soil amendments has been discussed, although little information is available regarding application timing in the field. We conducted a field experiment over two consecutive growing seasons on a former coal mine in China, to investigate soil and vegetation response to a lignite-derived humic product called "nano humus" and to determine optimal application timing. Three economically valuable agricultural species, alfalfa (Medicago sativa L.), barley (Hordeum vulgare L.), and sea buckthorn (Hippophae rhamnoides L.), were used for this study. The benefits of the humic product on soil properties and plant growth under field conditions were expressed after 2 yr of application. A single application at the beginning of each growing season provided better results than splitting into two applications, with no impact of duration (months) between applications. A single application significantly increased soil available phosphorus by 63% and potassium by 96% relative to the control; it significantly enhanced total biomass of alfalfa by 749%, barley by 250%, and sea buckthorn by 147%. Our findings provided important practical implications for using a humic material as a soil amendment in coal mine reclamation, with potential applications in other agricultural and reclamation scenarios.

Effects of nitric acid modification on hydrochar's combustion, fuel and thermal properties are dependent on feedstock type.

Elevated metal (e.g., alkali metals) and ash contents can negatively impact the use of biomass-derived solid fuels, including hydrochars, in clean energy generation. The effects of nitric acid modification on those and other properties (combustion, fuel and thermal) were studied for hydrochars produced at three temperatures from four feedstocks. Through side-chain oxidation and surface protonation, nitric acid significantly leached metals from pristine hydrochars to a maximum of five order and increased their burnout temperature by 9-41%, but its effect on ash content, gross calorific values and ignition temperature depended on feedstock type and carbonization temperature. Ignition temperature increased by > 2 times for modified manure pellet hydrochar produced at 300 °C. The combustion characteristics index for the hydrochars was above the minimum benchmark (2 × 10-7 %2 min-2 °C-3) for a typical solid fuel. Therefore, nitric acid can effectively improve hydrochar's combustion and fuel properties and reduce slagging in industrial boilers.

Effect of soil capping depth on phosphogypsum stack revegetation.

Phosphogypsum is a by-product of the phosphorus fertilizer production process and is typically stacked at the production sites. These stacks can potentially pose environmental hazards, which can be substantially reduced through reclamation by capping with soil and revegetation upon decommissioning. We conducted a study on a phosphogypsum stack using five soil capping depths (8, 15, 30, 46, 91 cm), an uncapped treatment, and five vegetation treatments (monocultures of four grass species Agrostis stolonifera L., Festuca ovina L., Deschampsia caespitosa (L.) Beauv., Agropyron trachycaulum (Link) Malte ex H.F. Lewis and one mix of the four species with Trifolium hybridum L.) to assess plant growth, health, rooting characteristics, and trace element uptake. Cobalt and nickel concentrations in plant tissue from plots with ≥ 15 cm soil capping were within ranges found at reference sites, whereas fluorine was three times elevated. Vegetation cover was significantly greater on capped than uncapped plots, being greatest for Agropyron trachycaulum (26%) and Festuca ovina (26%). Capping depths ≥ 15 cm had greater cover, biomass, and healthy plants than the 8 cm cover. Soil water content was similar in the 15-46 cm capping depth, with the lowest in the 91-cm caps. Fluorine, cobalt, and nickel were elevated in select plant tissue samples on the research plots relative to references, and cap depth affected tissue fluorine and cobalt concentrations but not nickel. Concentrations of these trace elements were lower than maximum tolerable levels for animal consumption. From this 5-year study, Agropyron trachycaulum and Festuca ovina and a soil cover depth of ≥ 15 cm are recommended for reclamation of phosphogypsum stacks.

Soil amendment with a humic substance and arbuscular mycorrhizal Fungi enhance coal mine reclamation.

Coal mine sites covered by sandy soils often have low nutrient and high heavy metal concentrations, making reclamation for agricultural uses challenging. Although the combined use of humic substances and soil biota has generated considerable research interest, little information is available regarding their synergistic effects. In a two year field study, we assessed the effects of sole and combined applications of a humic substance product called nano humus (150 g/m2 in soils), arbuscular mycorrhizal fungi (250 g inocula/m2 in soils), and fertilizer (37 g/m2 in soils) on soil chemical properties, soil heavy metals, and growth of alfalfa (Medicago ruthenica L.) and barley (Hordeum vulgare L.). Application of arbuscular mycorrhizal fungi with nano humus exhibited greatest effects in year two. Relative to untreated soils, they increased soil cation exchange capacity by 38%, total organic carbon by 36%, and available nitrogen, phosphorus, and potassium by 20 to 92%; they reduced concentrations of soil cadmium by 25% and of arsenic by 9%. Mycorrhizal colonization rate and soil heavy metal concentrations were significantly negatively correlated, suggesting an inhibition effect of metals on colonization. The combination of arbuscular mycorrhizal fungi and nano humus showed greatest impact on root and shoot biomass of alfalfa, which increased 18 and 12 times, respectively. Barley responded most positively to combinations of arbuscular mycorrhizal fungi, nano humus, and fertilizer; root biomass increased 4 times, and shoot biomass and seed production increased 3 times. Combined applications generally provided greater benefits than sole applications, which could be a useful practice in heavy metal contaminated reclamation sites.

Biomonitoring and assessment of airborne fluoride using Lolium perenne near a phosphate fertilizer production facility.

Airborne fluoride emission is an environmental concern. There is a lack of knowledge in determining factors influencing internal fluoride accumulation in plant tissue. The aim of this study was to improve understanding of how temporal, spatial and physiological factors influence internal fluoride accumulation. Lolium perenne L. (perennial rye grass) was used as a bioindicator and exposed in 52 sites in 2015 and 11 sites in 2016 surrounding the emission source. Biomass was harvested for fluoride analysis. A biomonitoring system was developed to standardize greenhouse cultivation, field exposure, and plant harvest. Results show that relatively cooler weather may promote internal fluoride accumulation of perennial rye grass over time. Distance from the source and exposure time significantly influenced internal fluoride accumulation. Internal fluoride concentrations decreased exponentially with distance from the source, with a sharp drop within 500 m. Generally, fluoride accumulation increased with days of exposure. It peaked after 81 days of exposure in 2015 and 110 days in 2016. Plant age had no significant impact on fluoride accumulation. Biomonitoring can be a cost effective approach for detecting long term environmental impacts of airborne pollution. The method in this research can be applied in various point source air pollution scenarios to assess emission impacts on biota and to aid in land use management.

Pristine and engineered biochar for the removal of contaminants co-existing in several types of industrial wastewaters: A critical review.

Biochar has been widely studied as an adsorbent for the removal of contaminants from wastewater due to its unique characteristics, such as having a large surface area, well-distributed pores and high abundance of surface functional groups. Critical review of the literature was performed to understand the state of research in utilizing biochars for industrial wastewater remediation with emphasis on pollutants that co-exist in wastewater from several industrial activities, such as textile, pharmaceutical and mining industries. Such pollutants include organic (such as synthetic dyes, phenolic compounds) and inorganic contaminants (such as cadmium, lead). Multiple correspondence analyses suggest that through batch equilibrium, columns or constructed wetlands, researchers have used mechanistic modelling of isotherms, kinetics, and thermodynamics to evaluate contaminant removal in either synthetic or real industrial wastewaters. The removal of organic and inorganic contaminants in wastewater by biochar follows several mechanisms: precipitation, surface complexation, ion exchange, cation-π interaction, and electrostatic attraction. Biochar production and modifications promote good adsorption capacity for those pollutants because biochar properties stemming from production were linked to specific adsorption mechanisms, such as hydrophobic and electrostatic interactions. For instance, adsorption capacity of malachite green ranged from 30.2 to 4066.9 mg g-1 depending on feedstock type, pyrolysis temperature, and chemical modifications. Pyrolyzing biomass at above 500 °C might improve biochar quality to target co-existing pollutants. Treating biochars with acids can also improve pollutant removal, except that the contribution of precipitation is reduced for potentially toxic elements. Studies on artificial intelligence and machine learning are still in their infancy in wastewater remediation with biochars. Meanwhile, a framework for integrating artificial intelligence and machine learning into biochar wastewater remediation systems is proposed. The reutilization and disposal of spent biochar and the contaminant release from spent biochar are important areas that need to be further studied.

Feedstock type drives surface property, demineralization and element leaching of nitric acid-activated biochars more than pyrolysis temperature.

Nitric acid activation (NA-A) effects on the surface properties, mineral phases and element compositions of biochars produced from four feedstocks at three temperatures were evaluated. NA-A increased biochar thermal stability, but its effect on ash content and surface area was feedstock-dependent, with ash content in manure pellet biochars less affected due to a high quartz content. Apart from the manure pellet biochars and the sawdust biochar produced at 400 °C, NA-A decreased the surface area of biochars by up to 100% due to reduced pore volume. Nitric acid significantly leached elements such as potassium from biochars due to protonation and their reactions with several mineral phases, such as sylvite, on the biochars (p < 0.05). This study shows that mineral phases and element compositions of nitric acid-activated biochars were driven more by the feedstock type than the pyrolysis temperature and the derived biochars would be poor adsorbents.

Effects of dust deposition from diamond mining on subarctic plant communities and barren-ground caribou forage.

Dust produced from mining has the potential to reduce plant cover, alter plant communities, and increase metal concentrations in vegetation-changes that may affect the amount, type, and quality of forage for barren-ground caribou (Rangifer tarandus groenlandicus). We quantified dust deposition from Diavik Diamond Mine (Northwest Territories, Canada) and investigated the changes on forage quality, type, and quantity for caribou. From 2002 to 2016, dust deposition was measured, and vegetation cover and richness were assessed in permanent plots established adjacent to the mine and in reference areas 1-6 km from the mine. Lichen was collected from areas up to 100 km from the mine to determine metal concentrations. Dust deposition rapidly decreased within 4 km of the mine. Plant communities adjacent to the mine (within 500 m) had disproportionately increased cover of vascular plants and decreased bryophyte and lichen cover. Lichen sampled within 4 km from the mine had greater metal concentrations than those sampled farther afield. Concentrations of Al in lichen collected within 40 km of the mine exceeded safe exposure limits for consumption, assuming lichen comprised 100% of caribou diet. We conclude that dust deposition from mining is altering adjacent vegetation communities but that such changes to forage are unlikely to cause negative effects to caribou due to reduced lichen intake in summer and autumn, their migratory nature, and avoidance of mine-influenced areas. However, minimization and reclamation of mine-related disturbances will be important for maintaining sufficient quality forage and available habitat or space in caribou ranges.

Biochar heavy metal removal in aqueous solution depends on feedstock type and pyrolysis purging gas.

The effectiveness of biochar as a sorptive material to remove contaminants, particularly heavy metals, from water is dependent on biomass type and pyrolysis condition. Biochars were produced from pulp mill sludge (PMS) and rice straw (RS) with nitrogen (N2) or carbon dioxide (CO2) as the purging gas. The sorptive capacity of the biochars for cadmium(II), copper(II), nickel(II) and lead(II) was studied. The heavy metal adsorption capacity was mainly affected by biomass type, with biochars adsorption capacities higher for lead(II) (109.9-256.4 mg g-1) than for nickel(II) (40.2-64.1 mg g-1), cadmium(II) (29.5-42.7 mg g-1) and copper(II) (18.5-39.4 mg g-1) based on the Langmuir adsorption model. The highest lead(II) adsorption capacities for PMS and RS biochars were 256.4 and 133.3 mg g-1, respectively, when generated using N2 as the purging gas. The corresponding lead(II) adsorption capacities were 250.0 and 109.9 mg g-1, respectively, when generated using CO2 as the purging gas. According to the intraparticle diffusion model, 30-62% of heavy metal adsorption was achieved in 1 h; film diffusion was the rate-dominating step, whereas pore diffusion was a rate-limiting step. Ion exchange and complexation between heavy metals and biochar surface functional groups such as carbonyl and hydroxyl groups were effective mechanisms for heavy metal sorption from the aqueous solution. We conclude that proper selection of both the feedstock type and the purging gas is important in designing biochars for the effective removal of potentially toxic metals from wastewater.

Carbonization temperature and feedstock type interactively affect chemical, fuel, and surface properties of hydrochars.

The hydrothermal carbonization (HTC) process that converts wet/dry biomass to hydrochars (for use as solid fuels or adsorbents) needs to be optimized. We investigated the interactive effects of feedstock type and HTC temperature on chemical, fuel, and surface properties of hydrochars produced from lignocellulosic (canola straw, sawdust and wheat straw) and non-lignocellulosic feedstocks (manure pellet) at 180, 240 and 300 °C. Increased HTC temperature decreased hydrochar yield and surface functional group abundance, but increased hydrochar thermal stability due to increased devolatilization and carbonization. Hydrochar surface area ranged from 1.76 to 30.59 m2g-1, much lower than those of commercially available activated carbon. Lignocellulosic and non-lignocellulosic feedstocks were distinctly affected by HTC temperature due to variable carbonization from ashing. Hydrochars produced from lignocellulosic biomass at 240 and 300 °C resembled high-volatile bituminous coal. Hydrochars should be designed for specific applications such as fuels by selecting specific feedstock types and carbonization conditions.

Response of three native grass species on dry tailings reclamation substrate amended with petroleum coke.

Surface mining around the world has produced large quantities of waste materials with ecological impacts. Oil sands mining in Canada generates large volumes of petroleum coke and tailings every year, which are stockpiled in the mining areas and must be reclaimed through capping or used in reclamation substrates. A greenhouse study was conducted to determine whether substrates of various mixes of dry tailings (DT), tailings sand (TS), and peat mineral mix (PMM) with coke amendment would support emergence and growth of three grass species commonly used in land reclamation. After 16 wk in the greenhouse, plant performance varied with substrate and amendment. Treatment with DT/TS/PMM (50:25:25) with 40% coke had greatest cover, biomass, and density and the best plant health. Plant growth was inhibited in treatments with DT (100%) and coke (100%) due to high concentrations of hydrocarbons, undesirable exchangeable ions, and salinity that restricted soil water retention (gravimetric water content, hydraulic conductivity) relative to treatments with PMM. Agrostis scabra Willd. and Festuca saximontana. showed poor growth or did not survive on DT and DT/TS with coke. Elymus trachycaulus (Link) Gould ex Shinners performed better in all DT mixes and performed the best in DT/TS/PMM with 40% coke. Results from this study indicate that mixing with PMM could improve the reclamation potential of DT and coke.

Lead(II) adsorption on microwave-pyrolyzed biochars and hydrochars depends on feedstock type and production temperature.

Adsorption of lead(II) using carbon-rich chars is an environmentally sustainable approach to remediate lead(II) pollution in industrial wastewater. We studied mechanisms for lead(II) adsorption from synthetic wastewater by biochars produced by microwave-assisted pyrolysis and hydrochars by hydrothermal carbonization at three temperatures using four feedstocks. Lead(II) adsorption was highest (165 mg g-1) for canola straw biochar produced at 500 °C. Except for chars derived from sawdust, biochars outperformed hydrochars for lead(II) adsorption due to changes in solution pH driven by char pH. As char production temperature increased, lead(II) adsorption decreased in hydrochar mainly due to interaction with aromatic carbon but increased in biochar due to precipitation as hydrocerussite and lead oxide phosphate. Lead(II) adsorption also occurred via surface complexation and cation-á´¨ interaction, as the data fitted well to Freundlich, Langmuir and Temkin models, and the pseudo-first and pseudo-second order kinetic models, depending on feedstock type and production temperature. More than 80% of lead(II) adsorption occurred in the first 3 h for both types of chars; with a few exceptions, adsorption continued for almost 24 h. We conclude that production method, production temperature and feedstock type are crucial factors to consider in designing chars as adsorbents for removing lead(II) from wastewater.

Feather keratin derived sorbents for the treatment of wastewater produced during energy generation processes.

Water dependency of energy generation systems including renewable energy resources pollute water. Efforts are being made to control energy-related water pollution. Here in, eight keratin derived biopolymers were developed to sequester the toxic trace elements from synthetic wastewater. Chemical modifications of biopolymers affect their physical and chemical characteristics, hence, enhance the sorption of contaminants from wastewaters. KBP-I (processed chicken feathers), KBP-II (acid modified), KBP-III & KBP-IV (modified with ionic liquids), KBP-V (amine modified), KBP-VI & KBP-VII (POSS modified) and KBP-VIII (sodium sulfite modified) were characterised for their surface morphology, structural integrity, functional group changes, crystallinity behaviour, surface area and pore size distribution using different analytical techniques. Developed biopolymers were then tested against synthetic wastewater spiked with nine transition and redox sensitive elements (100 µg L-1 each). Among the eight biopolymers, KBP-I removed 87-93% of As and Cd, KBP-IV removed 80-85% of Cu and VV, KBP-V removed 60-90% of Co, Ni and Zn, whereas KBP-VI removed 95% of CrVI. The developed keratin biopolymers show prospects to effectively treat the metals contaminated wastewater.

Fuel, thermal and surface properties of microwave-pyrolyzed biochars depend on feedstock type and pyrolysis temperature.

We evaluated the fuel, thermal and surface properties of twelve biochars produced from three lignocellulosic (canola straw, sawdust, wheat straw) and one non-lignocellulosic feedstock (manure pellet) pyrolyzed at three temperatures using a microwave. Regardless of feedstock type, increasing pyrolysis temperature progressively reduced the abundance of -OH functional group and yield, but increased pH and thermal stability of biochar. Gross calorific values (GCV), carbon stability, and degree of aromaticity of biochars derived from lignocellulosic feedstocks increased with increasing temperature due to decreased elemental oxygen content. However, high ash content in the non-lignocellulosic feedstock retarded its thermal degradation, producing biochars with low GCV. The specific surface area of biochars was low, with the highest value of 43 m2 g-1 achieved for sawdust biochar produced at 500 °C. We conclude that the fuel, thermal, and surface properties of the biochars were dependent on the feedstock type and pyrolysis temperature.

Biochar surface complexation and Ni(II), Cu(II), and Cd(II) adsorption in aqueous solutions depend on feedstock type.

Biochar is a promising material for efficient removal of toxic metals from wastewater to meet standards for discharge into surface water. We characterized adsorption behaviour of willow (Salix alba) wood (WW) and cattle manure (CM) and their biochars, willow wood biochar (WWB) and cattle manure biochar (CMB), and elucidated the mechanisms for the removal of Ni(II), Cu(II) and Cd(II) from aqueous solutions. The kinetic adsorption suggests that the adsorption of Ni(II), Cu(II) and Cd(II) by feedstock and their biochars was controlled by mass transport, and chemisorption also played a role in the adsorption process. The Elovich model also well described the adsorption kinetics for WW and CM (R2 > 0.92), indicating that heterogeneous diffusion was the mechanism. The Sips isotherm model fitted best (R2 > 0.98) for Ni(II), Cu(II) and Cd(II) adsorption by the feedstocks and their biochars, indicating that both monolayer and multilayer adsorption played roles on the heterogeneous surfaces of the four adsorbents. The WWB had a higher while the CMB had a lower adsorption capacity than their respective feedstock due to the presence of abundant -COOH functional group on WWB surface to interact with Ni(II), Cu(II) and Cd(II) to form surface complexes. The higher specific surface area and lower pH of point of zero charge (PZC) of WWB were other contributing factors for its greater removal capacity. Therefore, we conclude that proper feedstocks need to be selected to produce biochars that are efficient for the removal of toxic metals from wastewater.

Perspectives on environmental impacts and a land reclamation strategy for solar and wind energy systems.

Global energy demands and environmental concerns are a driving force for use of alternative, sustainable and clean energy sources. Solar and wind are among the most promising sources and have been developing steadily in recent years. However, these energy developments are not free of adverse environmental consequences, which require appropriate reclamation procedures. The environmental issues caused by solar and wind plants were reviewed in this paper by summarizing existing studies and synthesizing the principles that could underlie development of reclamation practices. The major environmental drawback of solar and wind energy plants are bird mortality, biodiversity, and habitat loss; noise; visual impact; and hazardous chemicals used in solar panels. Available mitigation measures to minimize these adverse environmental impacts, and appropriate reclamation protocol for the disturbed ecosystems, including key research needs are discussed. We include socio-economic perspectives of solar and wind energy, such as policy related to re-powering initiatives, decommissioning, and reclamation liability. The intent of this paper is to provide current perspectives on environmental issues associated with solar and wind energy development, strategies to mitigate environmental impacts, and potential reclamation practices to solar and wind energy planners and developers.