Dairy Effluent-Saturated Biochar's Short-Term Effects on Vigna unguiculata and Cynodon dactylon Performance and Soil Properties.

We compared the effects of wood-, manure-, and blend-derived biochar (BC) saturated/unsaturated with dairy effluents on Vigna unguiculata and Cynodon dactylon performance and soil characteristics in a greenhouse pot study. Plant samples were assayed for herbage and root dry weight and N and C percentages. Soil samples were assayed for nutrients, pH, and conductivity. Variance analysis, Tukey's tests, Pearson's correlations, and multiple regression analysis were performed. The performance of C. dactylon was not affected. V. unguiculata's herbage and root production responded negatively to manure BC and 2% of any BC, respectively, which is mainly explained by the conductivity and soil P increase, respectively. When V. unguiculata was grown, BC inclusion decreased NO3-N and increased the soil P content. When C. dactylon was grown, only P was altered (increased) when manure or the blend BC were applied. The soil total C increased as the BC loading rate increased. The application of high BC rates was detrimental for V. unguiculata, but showed a neutral effect for C. dactylon. To improve dairy waste recycling, saturated 1% blend BC and saturated 2% blend or manure BC could be applied to V. unguiculata and C. dactylon, respectively, with no short-term negative impacts. Only wood BC avoided soil P build-up. BC application increased the soil total C, showing potential for C sequestration.

Biochar and Dairy Manure Amendment Effects on Cynodon dactylon Performance and Soil Properties.

Studies have determined the separate effects of biochar (BC) and manure application on forage species and soil, but few examined the effects of BCs made from different feedstock applied along with dairy manure. We compared the effect of wood- and manure-derived feedstock BC as well as dairy manure amendment application on Cynodon dactylon performance and soil properties in sandy loam and clay loam soils in a greenhouse pot study. Plant samples were assayed for herbage and root dry weight as well as herbage and root N and C percent and yield. Soil samples were assayed for macronutrients, micronutrients, metals, pH and conductivity. Data analyses involved variance analysis and Tukey's tests using R in RStudio (the IDE). In general, C. dactylon yields or mineral content were not affected by either manure or BC. However, an increase in the total herbage dry weight (30%) and in herbage N% (55%) was observed for clay loam and sandy loam soil, respectively, due to manure amendment application. There were no alterations in clay loam NO3-N and P due to any treatment; however, in sandy loam, these nutrients were not altered only when wood BC was applied. In sandy loam soil, NO3-N and P increased when manure BC along with dairy manure and when manure BC alone were applied, respectively. Thus, wood BC application should be considered to avoid these nutrient buildups when dairy manure is used as a soil amendment. This research shows a neutral (BC) or positive (dairy manure amendment) impact on C. dactylon performance. BC incorporation increases soil total C, showing potential for C sequestration. Long-term field trials could corroborate plant performance and soil parameters.

Effects of perfluorooctanoic acid and perfluorooctane sulfonic acid on microbial community structure during anaerobic digestion.

Per- and polyfluoroalkyl substances (PFASs) are recalcitrant organic pollutants, which accumulate widely in aquatic and solid matrices. Anaerobic digestion (AD) is one of possible options to manage organic wastes containing PFASs, however, the impacts of different types of PFAS on AD remains unclear. This study aimed to critically investigate the effects of two representative PFAS compounds, i.e., perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), on the AD performance and microbial community structure. 100 mg/L of both PFOA and PFOS considerably inhibited the AD performance and changed the microbial community structure. Especially, PFOA was more toxic to bacterial and archaeal activity than PFOS, which was reflected in AD performance. In addition, the sulfonic acid group in PFOS affected the changes in microbial community structure by inducing abundant sulfate reducing bacteria (i.e., Desulfobacterota). This study provides a significant reference to the response of AD system on different PFAS types and dosage.

Enhanced Escherichia coli removal from stormwater with bermudagrass-derived activated biochar filtration systems.

Stormwater treatment and reuse can alleviate water pollution and scarcity while current sand filtration systems showed low treatment performance for stormwater. For enhancing E. coli removal in stormwater, this study applied the bermudagrass-derived activated biochars (BCs) in the BC-sand filtration systems for E. coli removal. Compared with the pristine BC (without activation), the FeCl3 and NaOH activations increased the BC carbon content from 68.02% to 71.60% and 81.22% while E. coli removal efficiency increased from 77.60% to 81.16% and 98.68%, respectively. In all BCs, the BC carbon content showed a highly positive correlation with E. coli removal efficiency. The FeCl3 and NaOH activations also led to the enhancement of roughness of BC surface for enhancing E. coli removal by straining (physical entrapment). The main mechanisms for E. coli removal by BC-amended sand column were found to be hydrophobic attraction and straining. Additionally, under 105-107 CFU/mL of E. coli, final E. coli concentration in NaOH activated BC (NaOH-BC) column was one order of magnitude lower than those in pristine BC and FeCl3 activated BC (Fe-BC) columns. The presence of humic acid remarkably lowered the E. coli removal efficiency from 77.60% to 45.38% in pristine BC-amended sand column while slightly lowering the E. coli removal efficiencies from 81.16% and 98.68% to 68.65% and 92.57% in Fe-BC and NaOH-BC-amended sand columns, respectively. Moreover, compared to pristine BC, the activated BCs (Fe-BC and NaOH-BC) also resulted in the lower antibiotics (tetracycline and sulfamethoxazole) concentrations in the effluents from the BC-amended sand columns. Therefore, for the first time, this study indicated NaOH-BC showed high potential for effective treatment of E. coli from stormwater by the BC-amended sand filtration system compared with pristine BC and Fe-BC.

Escherichia coli inactivation in water by sulfate radical-based oxidation process using FeCl3-activated biochar/persulfate system.

Pathogenic microbes in water present great risks to environments, water resources, and human health. In the present study, for the first time, a FeCl3-activated bermudagrass-derived biochar (FA-BC) was applied to activate persulfate (PS) for E. coli inactivation. The PS activation was ascribed to the presence of Fe0 and Fe3O4 on the surface of FA-BC, and SO4·- radicals were proved to be the main role for E. coli inactivation using FA-BC activated PS system (FA-BC/PS). Decreasing the pH (5-9) and increasing the PS concentration (50-300 mg/L), reaction temperature (20-50 °C), and FA-BC dosage (100-500 mg/L) resulted in the enhancement of disinfection efficiency of E. coli using FA-BC/PS. 6.21 log reductions of E. coli were achieved within 20 min under the optimal conditions (500 mg/L FA-BC, 200 mg/L PS, pH 7, and 20 °C with 107 CFU/mL E. coli in DI water). The FA-BC/PS effectively eliminated various initial concentrations of E. coli (105-108 CFU/mL). The E. coli inactivation rate decreased from 0.1426 min-1 to 0.0883, 0.1268 min-1, and 0.1093 min-1 with the presence of 10 mg/L humic acid, 100 mg/L Cl-, and 100 mg/L HCO3-, respectively. In addition, after three cycles of disinfection tests using FA-BC/PS, the E. coli inactivation rate only slightly decreased from 0.1426 to 0.1288 min-1. The FA-BC/PS also effectively removed the E. coli in real stormwater with a 99.2 % inactivation efficiency within 180 min. The FA-BC/PS in fixed-bed column tests revealed the continuous and high inactivation of E. coli in water. Increasing the FA-BC amount (1.5 %-5 %) and PS concentration (50-200 mg/L) and decreasing the flow rate (2-4 mL/min) caused the lower E. coli concentration in effluent. Therefore, the FA-BC/PS can be considered as a promising and efficient technique for water disinfection.

FeCl3-activated biochar catalyst for heterogeneous Fenton oxidation of antibiotic sulfamethoxazole in water.

One-step FeCl3-mediated pyrolysis/activation was developed for preparation of bermudagrass (BG)-derived FeCl3-activated biochars (FA-BCs) from bermudagrass (BG) as a heterogenous Fenton catalyst for heterogeneous Fenton oxidation of sulfamethoxazole (SMX) in water. The FA-BC prepared at the FeCl3 to BG mass ratio of 2 (FA-BC) exhibited higher adsorption and Fenton oxidation of SMX than other mass ratios of the FeCl3 to BG. FA-BC presented the great surface area (835 m2/g) and high SMX adsorption capacity (195 mg SMX/g BC), which was higher than various BCs in the previous studies. Additionally, the surface of FA-BC was attached with Fe2O3, Fe0, and Fe3O4 after the FeCl3 activation. Under the optimal conditions for Fenton reaction (SMX concentration, 100 mg/L; loading of FA-BC, 0.1 g/L; dose of H2O2, 200 mg/L; temperature, 20 °C; pH 3; reaction time, 12 h), SMX and COD removal efficiencies reached 99.94% and 65.19%, respectively. Increasing reaction temperature from 20 to 50 °C significantly improved the SMX oxidation rate from 0.46 to 1.04 h-1. The HO· radicals were proved to play a major role during the Fenton oxidation of SMX. In addition, the SMX solution treated by Fenton oxidation showed much less toxicity than the initial SMX solution. Additionally, the reusability tests of FA-BC indicated that 89.58% removal efficiency for SMX was still achieved after 3 cycles of Fenton oxidation under the optimal conditions. Furthermore, FA-BC can also efficiently remove SMX from the dairy wastewater. Therefore, FA-BC showed a high potential to eliminate aqueous SMX through adsorption and heterogeneous Fenton oxidation.

Enhanced removal of antibiotic resistance genes and human bacterial pathogens during anaerobic digestion of dairy manure via addition of manure biochar.

In this study, the response of antibiotic resistance genes (ARGs), mobile gene elements (intI1), and human bacterial pathogens (HBPs) to addition of manure biochar (1-10 g/L) was studied in anaerobic digestion (AD) at 20-55 °C for treating dairy manure. Twelve ARGs comprising five tetracycline resistance genes, two sulfonamide resistance genes, two macrolide resistance genes, three ß-lactam antibiotic resistance genes, and intI1 were analyzed by quantitative PCR. High-throughput sequencing data were matched against a database of putative 538 HBPs. Significant removal of ARGs (except for tetO and ermB) and intI1 was observed in all the samples. Manure biochar resulted in significant removal of ARGs and HBPs; however, negative effects were also observed in some conditions. This is the first study to provide to explore the fates of ARGs and HBPs by adding manure biochar to AD.

Sustainable use of Ca(OH)2 modified biochar for phosphorus recovery and tetracycline removal from water.

To prevent possible secondary pollution from phosphorus-loaded biochar (BC) in agricultural systems, this study investigated the sustainable use of Ca(OH)2 modified wood biochars (Ca-BCs) for P recovery while significantly lowering the tetracycline (TC) adsorption onto Ca-BCs. Ca-BCs were prepared via calcination of mixtures of Ca(OH)2 and wood BC under 100-500 °C for removing P and TC from water. Compared to the pristine BC (without Ca(OH)2 modification), Ca-BC100 (Ca-BC prepared at 100 °C) showed a significant increase of P adsorption capacity from 4.00 to 138.70 mg/g due to reactive interaction between P and Ca(OH)2 on Ca-BC while decrease of TC adsorption capacity from 62.17 to 20.86 mg/g owing to decrease of surface area from 260.50 to 120.26 m2/g. Batch adsorption tests implied that the P adsorption on Ca-BC100 would occur mainly via electrostatic attraction (pH > 2.1) and formation of hydroxylapatite (Ca5(PO4)3(OH)) between phosphate and Ca(OH)2. In addition, Ca-BC100 reacted with TC via electrostatic attraction (pH > 7.6), complexation, hydrogen bond, and π-π interactions. P and TC adsorption onto Ca-BC100 was a chemical, endothermic, and spontaneous process. The dynamic adsorption experiments using a fixed bed column filled with Ca-BC100 indicated that Ca-BC100 could continuously and effectively remove P and TC from water. Ca-BC100 also effectively lowered P and COD in the dairy wastewater. Under the environmentally relevant conditions, continuous treatment of water containing P and TC using the pristine BC followed by Ca-BC100 showed the pristine BC removed 96% of TC and only 6% of P from water while Ca-BC100 made high recovery of P (94% of P) with negligible TC. Therefore, Ca-BC100 could be used for effective recovery of P with negligible TC from wastewater, and then applied to agricultural systems as a sustainable and safe P-rich biofertilizer.

Thermally enhanced adsorption and persulfate oxidation-driven regeneration on FeCl3-activated biochar for removal of microcystin-LR in water.

In this study, a cyclic process of adsorption and persulfate (PS) oxidation-driven regeneration using FeCl3-activated biochar (FA-BC) was suggested as a novel remediation process to remove microcystin-LR (MC-LR) from water. For enhancing overall treatment efficiency and cost effectiveness, the impacts of temperature on adsorption and PS oxidation-driven regeneration were investigated. The increase of temperature resulted in the increase of MC-LR adsorption rate on FA-BC due to the enhanced MC-LR diffusivity in water. Moreover, the MC-LR oxidation and PS reaction rates during the PS regeneration on FA-BC were remarkably improved by factors of 3.4 and 3.5 with increasing temperature from 20 °C to 50 °C. Both diffusion and desorption of MC-LR from FA-BC were thought to be the key factors for controlling the MC-LR oxidation rate during the PS regeneration of MC-LR. In addition, the decrease of pH (from 10 to 4) and increase of PS concentration (from 100 to 400 mg/L) enhanced the regeneration efficiency for MC-LR-spent FA-BC. The four cycles of adsorption-PS regeneration (200 mg/L PS, pH 6, and 50 °C) resulted in 92.81% regeneration efficiency in DI water and 82.89% in lake water. However, the four cycles of adsorption-PS regeneration led to the reduction of surface area (from 835 to 413 m2/g), oxidation of carbon surface and slight reduction of Fe0 on FA-BC. In overall, the cyclic adsorption-PS regeneration at higher temperature could provide practical reuse of FA-BC for cost-effective treatment of aqueous MC-LR.

Effects of Mechanical Refining on Anaerobic Digestion of Dairy Manure.

Mechanical refining (MR) is a cost-effective pretreatment in biochemical conversion processes that is employed to overcome biomass recalcitrance. This work studied the effects of MR on biogas and methane produced by the anaerobic digestion (AD) of dairy manure. The cumulative gas volume and yield from the AD of manure refined at 6k revolutions increased by 33.7 and 7.7% for methane and by 32.0 and 6.4% for biogas, respectively, compared to the unrefined manure. This enhancement was reached by increasing manure solubilization, reducing particle size, and achieving external fibrillation and internal delamination of fibers in manure. However, the highly refined manure (subjected to 60k revolutions) exhibited methane and biogas yields that were reduced by 9.5 and 1.5%, respectively. This decrease was observed because the pore structure was ruptured, and finely ground manure particles were aggregated together at high revolutions (60k), thereby inhibiting the release of organic matter from the manure. Therefore, this study indicates that the MR for pretreatment of dairy manure could have great potential for significantly enhancing AD of dairy manure. Further studies will include optimization of conditions of mechanical refining (i.e., mechanical intensity, process time), a continuous AD of dairy manure pretreated by the MR, and scale-up with cost evaluation.

Adsorption and regeneration on iron-activated biochar for removal of microcystin-LR.

Novel iron activated biochars (FA-BCs) were prepared via simultaneous pyrolysis and activation of FeCl3-pretreated bermudagrass (BG) for removing microcystin-LR (MC-LR) in aqueous solution. Compared to the raw BC (without activation), the surface area and adsorption capacity of FA-BC at iron impregnation ratio of 2 (2 g FeCl3/g BG) were enhanced from 86 m2/g and 0.76 mg/g to 835 m2/g and 9.00 mg/g. Moreover, FA-BC possessed various iron oxides at its surface which provided the catalytic capacity for regeneration of MC-LR spent FA-BC and magnetic separation after the MC-LR adsorption. Possible mechanisms for the MC-LR adsorption onto FA-BC would include electrostatic attraction, π+-π, hydrogen bond, and hydrophobic interactions. The detailed adsorption studies indicated mainly chemisorption and intra-particle diffusion limitation would participate in the adsorption process. The thermal regeneration at 300 °C kept high regeneration efficiency (99-100%) for the MC-LR spent FA-BC during four cycles of adsorption-regeneration. In addition, the high regeneration efficiency (close to 100%) was also achieved by persulfate oxidation-driven regeneration. FA-BC also exhibited high adsorption capacity for the MC-LR from the real lake water to meet the MC-LR concentration below 1 µg/L as a safe guideline suggested by WHO.

Iron-activated bermudagrass-derived biochar for adsorption of aqueous sulfamethoxazole: Effects of iron impregnation ratio on biochar properties, adsorption, and regeneration.

This work focused on the impacts of FeCl3 impregnation ratio on the properties of FeCl3-activated bermudagrass (BG)-derived biochars (IA-BCs), adsorption of sulfamethoxazole (SMX) onto IA-BCs and regeneration of SMX-spent IA-BC. Compared with the control BC (85.82 m2/g), IA-BCs made via pyrolysis with FeCl3 to BG mass ratio between 1 and 3 (1-3 g FeCl3/g BG) resulted in significantly enhancing surface area (1014-1035 m2/g), hydrophobicity, Fe content in IA-BCs (3.87-7.27%), and graphitized carbon. The properties of IA-BCs supported magnetic separation and higher adsorption (32-265 mg SMX/g BC) than the control BC (6-14 mg SMX/g BC) at various pH. Adsorption experiments indicated various adsorption mechanisms between SMX and IA-BCs via π-π EDA, hydrophobic interactions, and hydrogen bond with intraparticle diffusion limitation. The adsorption was also found to be spontaneous and exothermic. The IA-BC made at FeCl3 to BG mass ratio of 2 (IA-BC2.0) showed the maximum adsorption capacity for SMX (253 mg SMX/g BC) calculated from Langmuir isotherm model. Additionally, both NaOH desorption and thermal oxidation showed effective regeneration of SMX-saturated IA-BC2.0 over multiple cycles. After three cycles of adsorption-regeneration, 64% and 62% of regeneration efficiencies were still achieved under thermal treatment at 300 °C and desorption with 0.1 M NaOH solution, respectively, indicating a cost-efficient adsorbent for the elimination of SMX in water.

Facile and Economical Functionalized Hay Biochar with Dairy Effluent for Adsorption of Tetracycline.

The present study reports a novel hay biochar functionalized with dairy effluent for enhanced tetracycline (TC) adsorption in the aqueous phase for the first time. The enrichment of hay (i.e., alfalfa) with dairy effluent led to significant accumulation of cationic metals during biochar production. The dairy effluent-functionalized alfalfa biochar (DEAF-BC) possessed strong crystallization (i.e., CaCO3), functional groups (i.e., CO3 2-, C-O stretching), and high surface area (334 m2/g) related to TC adsorption. Therefore, DEAF-BC showed higher TC adsorption capacity (835.7 mg/g) than that of the alfalfa biochar (94.5 mg/g). The adsorption isotherm and kinetic results for the DEAF-BC were correlated with the Freundlich, pseudo-second-order, and intraparticle diffusion models for TC. For the TC adsorption onto DEAF-BC, the thermodynamic analysis implied a spontaneous and endothermic process. Possible mechanisms would include metal complexation, hydrogen bonding, van der Waals forces, and π-π interaction.

Chemical Activation of Forage Grass-Derived Biochar for Treatment of Aqueous Antibiotic Sulfamethoxazole.

Chemically activated forage Bermudagrass-derived biochar (A-BC) was produced, characterized, and utilized for adsorption of sulfamethoxazole (SMX) in water for the first time. After NaOH activation, A-BC showed a higher surface area (1991.59 m2/g) and maximum adsorption capacity for SMX (425 mg SMX/g BC) than those of various biochars and commercial activated carbons. The detailed analysis for adsorption of SMX onto A-BC indicated the efficient sorption of SMX through π-π EDA and hydrophobic and hydrogen bond interactions. Additionally, the adsorption of SMX on A-BC was limited by pore and liquid film diffusions. The SMX adsorption on A-BC was found to be endothermic and spontaneous from thermodynamic studies. Furthermore, the highly efficient regeneration of SMX-saturated A-BC over multiple cycles was achieved by NaOH-driven desorption, indicating that the adsorption of SMX onto A-BC would have high potential for cost-effective solution for elimination of SMX from water.

Adsorption behavior of tetracycline onto Spirulina sp. (microalgae)-derived biochars produced at different temperatures.

We evaluated the production of Spirulina sp. (microalgae)-derived biochars (SPAL-BCs) at different pyrolysis temperatures for the removal of an emerging water contaminant, tetracycline (TC). Physicochemical properties of SPAL-BCs were characterized and related with their capacity to adsorb TC. Increasing pyrolysis temperatures led to higher aromaticity, higher hydrophobicity, and higher specific surface area. In particular, SPAL-BC750 possessed the highest hydrophobicity, various strong crystallizations (i.e., calcite, hydroxyapatite, and rhenanite) and functional groups (i.e., CH2, CN, CO, and CO32-), which may be associated with high TC adsorption. SPAL-BC750 also presented the highest TC adsorption capacity (132.8 mg TC/g biochar) via batch experimentation because of hydrophobic, π-π interactions, functional groups, and metal complexation. The best fitting isotherm and kinetic models of TC adsorption by SPAL-BC750 were the Langmuir and pseudo-first order models, respectively. SPAL-BCs obtained as a by-product of pyrolysis may be an economical and potentially valuable adsorbent for aqueous antibiotic removal.

Removal of Fluoride from Water Using a Calcium-Modified Dairy Manure-Derived Biochar.

This study investigated the removal of fluoride from water using a calcium-modified dairy manure-derived biochar (Ca-DM500). The Ca-DM500 showed a 3.82 - 8.86 times higher removal of fluoride from water than the original (uncoated) manure-derived biochar (DM500). This is primarily attributed to strong precipitation/complexation between fluoride and calcium. The Freundlich and Redlich-Peterson sorption isotherm models better described the experimental data than the Langmuir model. Additionally, the removal kinetics were well described by the intraparticle diffusion model. The Ca-DM500 showed high reactivity per unit surface area [0.0001, 0.03, 0.16 mg F per m2 for Douglas fir-derived biochar (DF-BC), DM500. and Ca-DM500, respectively] for retention of fluoride reflecting the importance of surface complexation. The copresence of anions reduced removal by Ca-DM500 in the order SO 4 2 - ≈ PO 4 3 - > NO 3 - . The sorption behavior of fluoride in a continuous fixed-bed column was consistent with the Thomas model. Column studies demonstrated that the Ca-DM500 shows a strong affinity for fluoride, a low release potential, and a stable (unreduced) removal capacity through regeneration and reuse cycles.

Engineered biochar from agricultural waste for removal of tetracycline in water.

For the first time the present study investigated the production, characterization and application of engineered biochar derived from alfalfa hays for removal of tetracycline (TC) in water. The NaOH activation of alfalfa-derived raw biochar (BCR) made significant increase in surface area (796.50 m2/g) and pore volume (0.087 cm3/g). The NaOH-activated BC (BCA) showed much higher adsorption capacity for TC (Qm = 302.37 mg/g) than BCR, but comparable to the commercial activated carbon (Calgon F400). The detailed analyses of the kinetic and isotherm studies suggested the strong chemisorptive interactions between TC and BCA via multiple mechanisms. In addition, intraparticle diffusion was considered as the major limitation for the adsorption of TC onto BCA. Furthermore, the fixed bed experiments revealed that BCA could be a promising adsorbent for treating large volume of TC-contaminated water in columns.

A novel hay-derived biochar for removal of tetracyclines in water.

The biochars derived from alfalfa (AF) and bermudagrass (BG), the abundant grass hays to cows, were prepared, characterized and used for removal of tetracycline (TC) in water. The alfalfa-derived biochar (AF-BC) has exhibited outstanding TC adsorption capacity (372 mg/g), which was about 8-fold higher than that of bermudagrass-derived biochar (BG-BC). In addition, the TC adsorption capacity of AF-BC was comparable with those of the commercial activated carbons under the same conditions. The surface structure, chemistry and high ash contents of AF-BC suggested the hydrogen bonding, electrostatic interactions and surface complexation between AF-BC and TC. Furthermore, hydroxyapatite (HAP; Ca5(PO4)3OH) and calcite (CaCO3) on the surface of AF-BC may also contribute to adsorption of TC via surface complexation, hydrogen bonding and electrostatic interactions. The alkaline desorption-driven regeneration of TC-spent AF-BC led to effective adsorption-desorption for multiple cycles, which indicated AF-BC could be a cost-effective adsorbent for TC in water and wastewater.

Additional reduction of antibiotic resistance genes and human bacterial pathogens via thermophilic aerobic digestion of anaerobically digested sludge.

Thermophilic aerobic digestion (TAD) was applied to further reduce ARGs and heavy metal resistance genes (HMRGs) as well as class 1 integrons (intI1) in sludge from anaerobic digestion (AnD). Unlike after AnD, there was no enrichment of ARGs, HMRGs and intI1 after TAD. Residual gene fractions of intI1 and total ARGs (sum of targeted ARGs) were 0.03 and 0.08, respectively. Two kinetic models (Collins-Selleck and first-order) described the decay patterns of targeted genes, revealing rapid removal of intI1 during TAD. After TAD, the relative abundance of human bacterial pathogens (HBPs) and the numbers of HBPs species decreased to approximately 68% and 64% compared to anaerobically digested sludge, respectively. Thus, TAD, subsequent to AnD, may possess high potential for reducing biological risks resulting from ARGs, HMRGs, intI1 and HBPs in sewage sludge.

Effects of pyrolysis temperature on the physicochemical properties of alfalfa-derived biochar for the adsorption of bisphenol A and sulfamethoxazole in water.

The present study reports alfalfa (one of most abundant hays in U.S)-derived biochar for effective removal of emerging contaminants in water for the first time. The physicochemical properties of alfalfa-derived biochar (AF-BC) made at various pyrolysis temperatures were investigated, and correlated with the adsorption of bisphenol A (BPA) and sulfamethoxazole (SMX) in water. The increase in pyrolysis temperatures from 350 °C to 650 °C for the pyrolysis of AF led to a drastic increase in surface area and carbonization with the loss of functional groups. The AF-derived biochar made at 650 °C showed much higher adsorption capacities for BPA and SMX than those made at 350-550 °C, mainly owing to the hydrophobic and π-π interactions supported by its high surface area and degree of carbonization. The adsorption isotherms fitted the Freundlich for BPA and Temkin models for SMX well, respectively. The adsorption capacities of AF 650 for BPA and SMX were higher than those of other biochars but lower than those of commercial activated carbon. The pH-dependent desorption for AF 650 showed high efficiency for SMX, but low efficiency for BPA indicating needs for alternative regeneration methods for BPA.