Dynamic Leaching Research Articles

Effect of Fe-based substance on Cr leaching behavior in hazardous waste incineration fly ash after thermal treatment.

This study investigated the influence of the interaction between Fe-based substances and thermal treatment parameters on the leaching behavior of Cr in hazardous waste incineration fly ash (HWIFA) after thermal treatment. The results revealed that the interaction between the addition of Fe-based substance and the thermal treatment parameters and their effects on static and dynamic leaching behaviors of Cr had significant differences when Fe2O3, Fe3O4, and Fe were added, respectively. Specifically, when Fe2O3 or Fe was added, the thermal treatment temperature was the most significant factor affecting the static leaching of Cr in thermal treated HWIFA, and the interaction effect of other factors was not significant. The most important influence on the dynamic leaching behavior of Cr was the interaction between the thermal treatment temperature and the addition of Fe2O3. Different from the addition of Fe2O3, the effect of the addition of Fe3O4 on the static leaching of Cr in thermal treated HWIFA was more significant than that of thermal treatment temperature; meanwhile, the interaction between the thermal treatment temperature and the addition of Fe3O4 was also significant. However, when Fe3O4 was added, the effect of interaction between factors on the dynamic leaching of Cr in thermal treated HWIFA was consistent with that when Fe2O3 was added.

Long-Term Leaching Effects on CaO-Modified Iron Silicate Slag

Granulated iron silicate slag, a by-product of pyrometallurgical copper extraction, has excellent properties for construction applications. Slag modification with CaO enhances the application properties regarding pozzolanic reactivity, potentially extending slag use in the future. The slags’ short-term leaching behavior has already been investigated with promising results, while the long-term leaching effects are less studied. Therefore, this study aims to determine the long-term leaching effects on CaO-modified iron silicate slags. The CaO-modifications were conducted during full-scale slag treatment operation. The slags were characterized and leached, and the remaining slags were investigated regarding the formation of secondary phases. The long-term leaching of main and trace elements was determined over 30 days using a dynamic leaching method corresponding to an extended time period. The leaching tests showed increased leaching of the main slag elements (Si, Ca). Zn and Cu showed peak leaching after four days of leaching, and the leaching of As and Sb decreased with the increasing CaO content in the samples. After dynamic leaching, secondary phases formed on the Cu-containing inclusions on the sample surfaces. Independent of the CaO content, the leaching of Cu was increased when subjected to external acidic and oxidating conditions using static pH titration at pH 5 in dilute nitric acid.

Transformation and leaching behavior of Pb in hazardous waste incineration fly ash after thermal treatment with addition of Fe2O3

This study investigated the leaching behavior of Pb in hazardous waste incineration fly ash (HWIFA) after adding Fe2O3 thermal treatment and revealed the leaching mechanism of Pb from the perspective of phase transformation. The static leaching results showed that at 600 °C-1300 °C, with the addition of Fe2O3 increased, the Pb leaching toxicity continued to decrease. The dynamic results indicated that as the thermal treatment temperature was higher than 1100 °C, the addition of Fe2O3 can effectively inhibit the dynamic leaching of Pb in HWIFA. Meanwhile, the inhibition effect was not very closely related to the amount of Fe2O3. The addition of Fe2O3 can react with PbO to form PbFe12O19, which has a better stability. The appearance of PbFe12O19 was the main reason for adding Fe2O3 to enhanced the immobilization of Pb. However, the amount of Fe2O3 should be carefully controlled to avoid an excessive reducible fraction of Pb in the thermal treated HWIFA, which will affect the long-term stability of Pb.

Ultrasonic-assisted preparation of interlaced layered hydrotalcite (U–Fe/Al-LDH) for high-efficiency removal of Cr(VI): Enhancing adsorption-coupled reduction capacity and stability

Cr(VI) contamination in aquatic systems has been a challenge for environmental science researchers. To environmental-friendly, stable, and efficiently remove Cr (VI), a novel layered double hydroxide was prepared through the ultrasonic-assisted co-precipitation method. The ultrasonic-assisted step prevented the Fe2+ oxidation, improved the morphology and performance, and finally, the adsorption-coupled reduction capacity and stability were enhanced. By adding U–Fe/Al-LDH (1.0 g/L) for Cr(VI) (100 mg/L), the removal rate reached 82.24%. The removal data were well fitted by the pseudo-second-order kinetic and Langmuir isotherm model. Using U–Fe/Al-LDH can be performed over a wide pH range (2–10), with a theoretical maximum removal capacity of 118.65 mg/g. The Cr(VI) with high toxicity was adsorbed and reduced to low-toxicity Cr(III). In the final phase, stable Cr(III) complex precipitates were generated. After 30 days, the dynamic leaching amounts of total Cr in used U–Fe/Al-LDH-2 were 0.1052 mg/L. Combined with the results of the influence experiment of coexisting anions and oxidants and the SO42− release experiment, the stability of the removal effect and the safety of U–Fe/Al-LDH were proved. In conclusion, U–Fe/Al-LDH-2 is a promising remediation agent and a feasible Cr(VI) removal method for the practical remediation.

Heavy metal release and acid generation during the oxidation of sulfide waste rock induced by ferric iron

As aby-product of waste rock from sulfide ore, Fe3+ is one of the important factors that promote acid production and heavy metals release from waste rock pile fields. In this paper, the dynamic leaching tests were conducted to investigate the behavior of acid generation and heavy metal release from the sulfide waste rock of Dexing copper mine under different Fe3+ concentrations. The Sulphur content in the waste rock samples was 3.56 % and the net acid production potential (NAPP) reached 47.95 kg·t−1 H2SO4. Under the oxidation of 600 mg·L-1 Fe3+, the pH value of the leaching system decreased to 5.53, which is 1.85 units lower than that of the control check group (CK). However, the quantity of SO42- in the leachate was reduced by 41.81 % compared to the CK group, as the jarosite precipitation was more likely to form under high Fe3+ conditions. The oxidation of Fe3+ effectively accelerated the release of heavy metals from the waste rock. In addition, the heavy metals release quantity gradually increased with the increase of the Fe3+ concentration, with the maximum release quantities of Cu, Pb, Zn, and As of 569.69, 333.75, 222.69, and 31.11 μg·kg−1, respectively, which increased by 27.66 %-129.60 % compared to the CK group. The release of SO42-, Cu, Pb, and Zn was controlled by the combined internal diffusion and the chemical reaction, while the release of As was best fitted to the interfacial chemical reaction-controlled model. The SEM analysis showed that the waste rock near the top of the column was strongly corroded, resulting in the increase of the specific surface area of the waste stone by 24.48 %. The re-precipitation reaction of heavy metals mainly occurred near the bottom of the leaching column. Leaching under Fe3+ oxidation caused a decrease in the proportion of residual heavy metals in the waste rock, which will lead to the easier release of heavy metals.

Insight into functional microorganisms in wet-dry conversion to alleviate the toxicity of chromium fractions in red soil.

Soil contamination with potentially toxic element such as chromium (Cr) poses a threat to the environment and human health. The environmental toxicity of Cr is related not only to the total Cr content but also to the distribution of Cr fractions. In this study, laboratory simulation experiments were conducted to explore the characteristics of Cr fractions and responses of the functional microbial community during dynamic leaching and static drying processes. The results showed that acid-soluble Cr and reducible Cr transformed into other relatively stable fractions under dry conditions, and ammonium nitrogen promoted the transformation. Nitrate-nitrogen was significantly positively correlated with Cr fractions in the wet stage (p < 0.05), while ammonium nitrogen showed the same relation in the dry process. Analysis of the microbial community showed that the bacterial and fungal genera Flavihumibacter, Altererythrobacter, Methylobacillus, Flavisolibacter, Lysobacter, and Cladosporium were related to the Cr fractions (acid-soluble Cr, reducible Cr, and oxidizable Cr) under wet conditions, while the microbial genera Ellin6067, MND1, and Ramlibacter were related to Cr fractions under dry conditions. Moreover, the proliferation of the functional microbial genera Methylobacillus, Ellin6067, and MND1 related to Cr fractions in the wet–dry conversion process alleviated the environmental toxicity of Cr. These findings provide useful information for the remediation of Cr-contaminated soils by monitoring the distribution fractions of Cr and the functional microbial community under wet–dry conditions.

Experimental Simulation Study of Mine Water Acidification under the Action of Pyrite

The discharge of acidic water has become an environmental issue of great concern worldwide. In order to investigate the characteristics and mechanism of acidic water induced by pyrite in sulfur-rich mines, indoor static precipitation and dynamic leaching simulation experiments were carried out under the conditions of pyrite content, rock particle size, media combination, and ambient temperature. At the same time, this paper used the gray correlation method to quantitatively analyze the influencing factors. The results showed that the degree of groundwater acidification was negatively correlated with the rock particle size and temperature and positively correlated with the pyrite content. The quantitative analysis of the effect of each factor on acid mine drainage pH was pyrite content &gt; temperature &gt; rock size. When considering different media conditions, the combined effect of the three media on reducing the acidification degree of mine water was limestone &gt; gangue &gt; coal. In addition, dynamic leaching and static soaking have different effects on the acidification of the mine water, with the latter acidifying more rapidly. It is also concluded that although pyrite enrichment was the main controlling factor affecting the acidification of mine water in nature, complexation of trivalent iron ions adsorbed in the formation was more likely to be the main causal mechanism for the rapid acidification of mine water in coal mining areas.

Effects of oyster shell powder on leaching characteristics of nutrients in low-fertility latosol in South China.

In this study, we analyzed the effect of oyster shell powder of different proportions on the nutrient leaching characteristics of latosol using an indoor soil column simulation test. Based on the optimized fertilizer application amount, we assessed five different amounts of oyster shell powder (0% (control, CK), 0.1% (T1), 0.2% (T2), 0.4% (T3), and 0.8% (T4)) and analyzed the intermittent and dynamic leaching characteristics of nutrients in the soil samples. The results indicated that the loss of nutrients in urea, superphosphate, and potassium chloride (due to leaching) increased linearly with the amount of fertilizer. By adding oyster shell powder, the leaching loss reduced by 23.90-57.25% for ammonium nitrogen, 6.31-10.07% for phosphorus, and 17.08-26.58% for potassium. However, the leaching loss for nitrate nitrogen increased by 2.5-5.8 times. In addition, the application of oyster shell powder to latosol provided acid adjustment and water retention enhancement, which increased the pH value of the soil by 3.77 (from pH 4.15 to 7.92) and reduced water loss by 2.52%. Thus, the application of oyster shell powder can reduce the acidity of the surface soil and retain water and fertilizer to a certain extent.

Leaching of Copper Contained in Waste Printed Circuit Boards, Using the Thiosulfate-Oxygen System: A Kinetic Approach.

The present work is related to the treatment of crushed waste of printed circuit boards (WPCBs) from electrical and electronic devices (WEEE), carrying out the recovery of copper in solution. In the first stage, the studied material was characterized by AAS, SEM-EDS, and XRD. The results revealed significantly high amounts of copper (744.42 mg/g), compared with the rest of the metals present in the sample, mainly iron and zinc. In the second stage of the work, alkali dynamic leaching experiments were carried out in the medium, evaluating important kinetic variables in order to verify the controlling step of the system and adjust the data to a kinetic model. According to the results obtained from the various experimental tests executed, it was found that in the studied system of , the leaching of copper was preferably adjusted to the model of spherical particles with a shrinking core finding a mixed chemical–diffusive control, with values of Ea = 25.78 kJ/mol and n = 0.22 (for the leaching reagent), indicating that the reaction was controlled by the oxygen transport to the solid–liquid interface and also by the chemical reaction in the surface of particles, obtaining up to 99.82% copper in solution.

Study on dynamic adsorption characteristics of broken coal gangue to heavy metal ions under leaching condition and its cleaner mechanism to mine water

The underground reservoir of a coal mine can store and purify mine water. The high salinity ions in the underground reservoir of a coal mine can be removed by the adsorption with gangue block, and the high salinity mine water can be purified in the flow process of the underground reservoir of a coal mine. Through the dynamic leaching experiments, the effects of gangue gradation, ion concentration and ion sort of displacement fluid on the dynamic adsorption characteristics of gangue were studied, the leaching laws of Ca2+, K+, Mg2+ ions were obtained. The results show that (1) the smaller the average particle size of the gangue in the leaching column, the better the adsorption effect of the leaching column on Ca2+, the higher the removal rate of Ca2+. (2) Mg2+ has a relatively strong promoting effect on the dissolution of K+ and Ca2+, and K+ also has a relatively strong promoting effect on the dissolution of Mg2+. (3) The higher the concentration of Ca2+ in the displacement fluid, the more significant the promoting effect of Ca2+ on the dissolution of Mg2+ and K+, and the greater the dissolution mass of Mg2+ and K+ in unit time. (4) There are two different types of adsorption sites for Ca2+ on the surface of gangue. When the concentration is low, Ca2+ is adsorbed by the first adsorption site. When the concentration is high, Ca2+ is adsorbed by the second adsorption site. The research results can provide theoretical reference and data support for the in-depth understanding of the water purification mechanism and engineering design of underground reservoir in a coal mine.

Effect of Fe2O3 on the leaching behavior of Cr in hazardous waste incineration fly ash after thermal treatment

The effect of Fe2O3 on the leaching behavior of Cr in hazardous waste incineration fly ash (HWFA) after thermal treatment was investigated. Addition of Fe2O3 could inhibit the static leaching behavior of Cr at most temperature conditions: the maximum reduction in leaching was 98.3% at 1200 °C. Long-term dynamic leaching behavior of Cr could be inhibited when using a thermal treatment temperature of 1200 °C and proportion of Fe2O3 exceeding 14.3%. At 1200 °C, Fe2O3 reacted strongly with the hazardous fraction of Cr in HWFA to form a stable chromite (Fe+2Cr2O4). The study results illustrate that the leaching behavior of Cr in HWFA after thermal treatment is affected by addition of Fe2O3 and treatment temperature. Adding Fe2O3 could effectively control the static and dynamic leaching behavior of Cr in HWFA after thermal treatment at 1200 °C, but excessive Fe2O3 addition accelerated dynamic leaching rate of Cr in HWFA after thermal treatment at 1100 °C.

Research of heavy metals leaching from sediments after feritization processing of galvanic sludge

Possibility of environmental safety increasing for industrial enterprises as a result of resource-saving technology implementation for processing galvanic sludge is considered. An experimental study of stability for sediments after ferritization processing of galvanic sludge and exhausted technological solutions was carried out. As a result of dynamic leaching of heavy metal ions, the immobilization properties of sediments were determined, which were obtained at different technological parameters of the ferritization process. It is shown that the level of immobilization of heavy metals in ferritic sediments has significantly higher values in comparison with sediments of traditional wastewater neutralization. It was found, that the precipitate obtained at following key parameters of reaction mixture for the ferritization process: the total concentration of heavy metal ions 10.41 g/dm3; ratio of concentrations of iron ions to total concentration of other heavy metals ions 4/1 and pH value of 10.5, is characterized by the highest degree of immobilization of heavy metals in the sediments of 99.96% mass. Using the results of a complete factorial experiment, regression equation for the leaching of heavy metal ions (iron, nickel, copper and zinc) from ferrite sediments was obtained: ratio of iron concentrations to the total concentration of other heavy metals and the pH value of reaction mixture. The adequacy of coefficients of regression equations was evaluated according to the criteria of Student and Fisher, which with 95% reliability correspond to the experimental results of the study. The proposed calculation algorithm provides an opportunity to increase efficiency and automation of ferritization process. Subsequent use of the research results will allow to implement reliable utilization of ferritized galvanic waste by application them into the row materials for obtaining alkaline cements for special purposes.

Leaching efficiency and plant growth response in an integrated use of saline water for coastal saline soil reclamation

AbstractA field experiment was carried out to evaluate an integrated use of saline water for saline soil reclamation around Bohai Bay in China. A landscape shrub (Caryopteris × clandonensis 'Worcester Gold') was cultivated and irrigated with five water salinities (ECi): 0.8, 3.1, 4.7, 6.3, and 7.8 dS m−1. Drip irrigation was scheduled by evolving soil matric potential thresholds of −5, −10, −15, and −20 kPa in 4 years. A gravel‐sand layer as subsurface drainage was installed at 1.0 m depth. After 4 years, the extremely saline soil (ECe of 27.8 dS m−1) for 0–1.0 m depth was reclaimed to moderately saline soil (ECe of 4.1–7.2 dS m−1). The decreases in survival rate, growth, and shoot dry weight of the plants as increasing ECi were observed. To achieve a relative survival rate of &gt;50%, the ECi thresholds for plants were 7.8, 6.9, 5.5, and 5.3 dS m−1 for the 4 years, respectively. The quantificationally estimating root zone drainage and salt leaching efficiency indicated that more efficient salt leaching offered by ECi up to 3.1 dS m−1 in comparison with freshwater with ECi of 0.8 dS m−1 and less efficiency occurred at ECi &gt; 6.3 dS m−1. The plants strongly responded to the different soil water and salinity regime in the dynamic leaching process, as thus it is recommended to use an inter‐seasonal evolving matric potential threshold of −10 kPa for dry season of the third year, −15 kPa for rainy season and following dry season for providing optimized soil water and salinity condition.

Study on the mechanism and kinetics of manganese release from waste manganese ore waste rock under rainfall leaching

Manganese released from the piled manganese ore wastes is a great threat to the local ecosystem and human health. The mechanism and dynamic characteristics of manganese release from the manganese ore wastes were studied based on the static and dynamic experiments. The concentration of manganese in the leaching solution under the intensive state is twice that resulted from the static state; the manganese release from the waste rock increased with the increase of the solid-liquid ratio and reached 922.3 mg/L when the solid-liquid ratio was 1:5. When the particle size of waste rock was less than 180 μm, the release amount of manganese was the largest and reached 491.3 mg/L. When the pH was 7 and the rainfall intensity was 80 mL/h, the increase of leaching time contributed to the rapidly decreased amount of manganese released, and the leaching process reached equilibrium gradually. The cumulative release of manganese increased with the increase of rainfall duration. In the dynamic leaching process, the change of pH and EC of the leachate had nothing to do with the initial pH of leaching agent but has a close relationship with the hydrolysis of minerals in waste. According to the experimental results, it was found that the double constant equation model fitted the kinetic process of release process better. The purpose of this study was to provide a scientific basis for the assessment and control of manganese pollution in soil and groundwater in manganese mining area.

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

The role of natural organic matter in the silver release from sludge generated from coagulation of wastewater spiked with silver nanoparticles

Sludge is an integral part in the migration pathway of silver nanoparticles (AgNPs) from manufacture to the terrestrial environment. However, the detailed information on the role of natural organic matters (NOMs) remains limited. In this study, the sludge generated from coagulation of wastewater spiked with AgNPs (denoted as sludgeC-AgNPs) was taken as the model. Effects of humic acid (HA), alginate (AA) and bovine serum albumin (BSA) on the release amount, dynamics and speciation of silver from the sludgeC-AgNPs were investigated by a series of leaching experiments. The results showed that HA, AA and BSA in the leaching solution could enhance the silver release from the sludgeC-AgNPs. The concentrations of the dissolved and colloidal silver in the BSA solution were the highest at the initial stage of dynamic leaching. The controlling step of the silver release was internal diffusion in the HA and AA solution, while the release of dissolved silver was controlled by both chemical reaction and internal diffusion in the BSA solution. In addition, the released colloidal silver fractions in the BSA solution contained more particles with size >50 nm compared with the HA and AA solutions. The results suggested that the properties of NOMs may be the key factor affecting the transfer of AgNPs from the sludge to the terrestrial environment.

Ecotoxicological evaluation of construction products: inter-laboratory test with DSLT and percolation test eluates in an aquatic biotest battery

BackgroundA European inter-laboratory test with 29 participating laboratories investigated whether a battery of four ecotoxicological tests is suitable for assessing the environmental compatibility of construction products. For this purpose, a construction product was investigated with the dynamic surface leaching test (DIN CEN/TS 16637-2) and the percolation test (DIN CEN/TS 16637-3). The eluates were produced centrally by one laboratory and were tested by the participants using the following biotests: algae test (ISO 8692), acute daphnia test (ISO 6341), luminescent bacteria test (DIN EN ISO 11348), and fish egg test (DIN EN ISO 15088). As toxicity measures, EC50 and LID values were calculated.ResultsToxic effects of the eluates were detected by all four biotests. The bacteria test was by far the most sensitive, followed by the algae test and the daphnia test; the fish egg test was the least sensitive for eluates of both leaching tests. The toxicity level of the eluates was very high in the bacteria, daphnia, and algae test, with lowest ineffective dilution values of LID = 70 to LID = 13,000 and corresponding EC50 values around or even below 1 volume percent. The reproducibility (approximated by interlaboratory variability) of the biotests was good (< 53%) to very good (< 20%), regardless of the toxicity level of the eluates. The reproducibility of the algae test was up to 80%, and thus still acceptable.ConclusionIt can be confirmed that the combination of leaching and ecotoxicity tests is suitable to characterize with sufficient reproducibility the environmental impact posed by the release of hazardous substances from construction products.

The effect of compaction and microbial activity on the quantity and release rate of water-soluble organic matter from bentonites

Swelling bentonites, planned to be installed around spent nuclear fuel canisters made of copper/cast iron in geological repositories, contain organic matter. Organic matter can act as substrates for microorganisms, such as sulfate-reducing microorganisms (SRM), which produce sulfide, a copper corrosion agent. Thus, it is important to study the quantity and release rate of organic matter from bentonites. In this study, the soluble organic matter (sOM) quantity of three bentonites (Wyoming, Indian, and Bulgarian) determined by dynamic leaching assays was originally 85, 16 and >163 mg kg−1, respectively. To assess the effect of simulated repository conditions on the quantity and release rate of bentonite sOM, the original bentonites were compacted to an average dry density of 1314–1368 kg m−3 and connected to sand layers in anaerobic cell systems. The sand layers were either inoculated or uninoculated with microorganisms. Afterwards, the cells were operated on for 12–15 months. As shown by postmortem dynamic leaching assays, the bentonite sOM quantities either increased (Indian and Bulgarian) or decreased (Wyoming) relative to the initial sOM quantities in original bentonites. The release rate of sOM increased in all bentonites in comparison with the original bentonites, and the increase was higher for the bentonites of the inoculated cells than for the uninoculated cells. The findings suggest that the interaction of the microorganisms with the bentonites increased the quantity and/or release rate of the bentonite sOM. Compaction of the bentonites, leading to changes in the mineral size and microstructure of bentonites, was also hypothesized to affect the amount of sOM released. Additional processes (e.g., diffusive transport) might also be relevant for the release of sOM from bentonites, but they were beyond the scope of this study. The present study represents an advance in the understanding of the effect of different possible repository conditions on the quantity and role of bentonite sOM as a source of substrates for the microbial community, especially considering the sulfide-producing SRM.

Characteristics of leaching of heavy metals from low-sulfur coal gangue under different conditions

Coal gangue is the main pollution source of mining areas. When coal gangue is stacked and recycled, the heavy metal elements contained in it are released by natural weathering and leaching, which causes damage to the surrounding ecological environment. In this study, the leaching and precipitation characteristics of heavy metals in low-sulfur coal gangue under different environmental conditions were simulated by indoor dynamic leaching experiments, which provided a theoretical basis for environmental restoration of the mining area. The conclusions are as follows: higher heavy metal content in low-sulfur coal gangue is associated with greater, leaching of heavy metals; acidic conditions promote the release of heavy metals in low-sulfur coal gangue; and more precipitation is associated with better release of heavy metals from the low-sulfur coal gangue.

USEPA LEAF methods for characterizing phosphorus and potentially toxic elements in raw and thermally treated sewage sludge

Biologically available phosphorus supports plant growth but can also cause environmental contamination. Sequential extraction methods, such as Hedley fractionation, are the most widely used to assess available phosphorus from solids. However, such methods exhibit numerous deficiencies. The USEPA Leaching Environmental Assessment Framework (LEAF) is a tiered system developed to evaluate releases of Potentially Toxic Elements (PTEs) from solids. This study compared the Hedley fractionation method to the LEAF pH-dependent, parallel batch tests (Method 1313) and dynamic leaching column test (Method 1314) to assess the bioavailability of phosphorus. The three methods were applied to wastewater treatment plant sludge before and after thermal treatment. Both methods revealed similar qualitative trends, namely that thermal treatment transformed phosphorus into less immediately available forms. However, the Hedley and LEAF methods were inconsistent in the forms and amounts of available phosphorus recovered from the solids. The Hedley method left 40% of phosphorus unextracted from sludge and 20% from ash, suggesting that it may be less appropriate for organic materials. Moreover, only 2 of the 6 Hedley phosphorus pools were within environmentally relevant pH conditions. Furthermore, the Hedley method overpredicted the readily available phosphorus. In contrast, the LEAF methods allowed for a more detailed analysis of phosphorus availability - while simultaneously assessing PTEs - across a controlled pH range. Moreover, LEAF used simpler procedures and provided more easily interpreted results. Thus, LEAF facilitates more robust and valuable assessment of organic and inorganic solids being considered for land application.