Stabilization and dewatering of wastewater treatment plant sludge using combined bio/Fenton-like oxidation process

Wastewater sludge usually contains large amounts of water and organic materials; therefore, its stabilization and dewatering are of particular importance. The present study aimed to investigate the possibility of sludge stabilization and dewatering from wastewater sludge by bioleaching (Thiobacillus ferrooxidans), Fenton/bioleaching, and bioleaching/Fenton-like processes. To evaluate sludge stabilization and dewatering, specific resistance to filtration (SRF), volatile suspended solids (VSS), total suspended solids (TSS), and soluble chemical oxygen demand (SCOD) were measured. In biological treatment with T. ferrooxidans with Fe²⁺ (2?g?L^?1), 99.75, 33, 37, and 72% reduction were observed in SRF, VSS, TSS, SCOD, respectively, after 2 days. In the combined treatment of Fenton before bioleaching (including Fe²⁺ 2?g?L^?1 and H₂O₂ 1?g?L^?1 with Fenton oxidation for 30?min followed by biological treatment with T. ferrooxidans for 2 days), the reduction rates in TSS, VSS, SCOD, and SRF were 40.18, 40.88, 60.95, and 75.43%, respectively. In treatment with the combined method of bioleaching before Fenton-like oxidation, the removal rates of the aforementioned parameters were 52.5, 54.4, 88, and 99.82%, respectively. In comparison to Fenton oxidation and bioleaching alone, combined biological method of bioleaching/Fenton-like oxidation using a lower dose of H₂O₂ and Fe²⁺ significantly improved sludge dewatering and stabilization.     

Enhancement of biological fermented sludge dewaterability by inoculation of filamentous fungi Mucor circinelloides XY-Z and Penicillium oxalicum LY-1

Abstract

The two filamentous fungi of Mucor circinelloides XY-Z and Penicillium oxalicum LY-1 isolated from citric acid wastewater sludge collectively enhanced sludge dewaterability by 85.83% to achieve the lowest value of normalized sludge specific resistance (SRF) to 6.8?×?10¹¹ m·L/kg·g-TSS. The results showed that 75.77% of slime extracellular polymeric substances (EPS), 42.99% of protein in slime EPS and 60.27% of polysaccharide in LB-EPS were degraded during activated sludge treatment by the two mixed fungi of Mucor circinelloides XY-Z and Penicillium oxalicum LY-1, contributing to the conversion of 64.61% of bound water wrapped in EPS into free water, thereby improving activated sludge dewaterability.     

Conditioning and Dewatering of Phosphorus-Rich Biological Sludge

The conditioning and dewatering of phosphorus-rich biological sludge, obtained from a pilot-scale biological phosphorus removal plant, was investigated. Dual conditioning utilizing a polyampholyte (AC4601) in combination with aluminum chloride (AlCl₃), ferric chloride (FeCl₃), and calcium chloride (CaCl₂) was studied. Capillary suction time (CST) and specific resistance to filtration (SRF) were utilized to assess sludge dewaterability. The dewaterability and removal of dissolved phosphorus from the phosphorus-rich sludge were examined. Compared with conditioning with only AC 4601, dual conditioning by adding 49 kg/ton of AlCl₃ prior to addition of AC4601 resulted in formation of large flocs, better dewaterability, and removal of 50% of soluble phosphorus. Better dewaterability, even larger flocs (> 1 cm), and 75% removal of soluble phosphorus were found when dosage of AlCl₃ increased to 189.2 kg/ton. The use of alumina (Al₂O₃) in combination with AC4601 could achieve equivalent dewaterability. However, only insignificant removal of soluble phosphorus (ca. 10%) was found. Sludge conditioning utilizing FeCl₃ and AC4601 was also very effective. A higher dosage of AC4601 was required and insignificant removal of soluble phosphorus was found when CaCl₂ was used in combination with AC4601. The interactions between hydrolyzed species of trivalent metal ions and polyampholyte contributed to enhanced dewaterability. Precipitates acted as skeleton builder and assisted in dewaterability as well. In addition, the removal of phosphorus was due to its precipitation reactions with metal ions. This study demonstrated an alternative way to condition phosphorus-rich sludge that could control the release of phosphorus from sludge to aqueous phase under anaerobic environment and achieve enhanced dewaterability simultaneously.     

FENTON AND FENTON-LIKE AOPs FOR ALUM SLUDGE CONDITIONING: EFFECTIVENESS COMPARISON WITH DIFFERENT Fe2+ AND Fe3+ SALTS

Currently, organic polymers are adopted in alum sludge (aluminum-coagulated drinking water treatment sludge) conditioning. However, there are important concerns regarding the use of these polymers because of the unknown and long-term effects of the potential release of excess polymer to the surrounding environment when the sludge is landfilled. Therefore, as an initial action, this study aimed at investigating alternative chemical conditioning methods and focused mainly on exploiting Fenton (Fe²⁺/H₂O₂) and Fenton-like (Fe³⁺/H₂O₂) reagents as the conditioner. Experiments have been conducted to test the effectiveness of Fenton's reagent (containing the ferrous salts of chloride, sulfate, or oxalate), Fenton-like reagent (containing ferric salts of chloride and sulfate), and the coagulation method using FeCl₃ for alum sludge conditioning at constant hydrogen peroxide and iron salt concentrations of 125 and 20 mg/g DS (dry solids), respectively. The effectiveness on dewaterability of the alum sludge demonstrated that the maximum reduction (%) of SRF (specific resistance to filtration) and CST (capillary suction time) of 74% and 47%, respectively, can be obtained when Fenton's reagent was adopted for sludge conditioning. Such reduction of 64% for SRF and 38% for CST can be achieved when Fenton-like reagents were applied.     

Bioleaching of heavy metals from dewatered sludge by Acidithiobacillus ferrooxidans

The feasibility of bioleaching for removal of heavy metals from dewatered sewage sludge using an iron‐oxidizing bacterium Acidithiobacillus ferrooxidans was investigated. The influence of seven process parameters including cell adaptation, total amount and particle size of the sludge, initial concentrations of Fe²⁺ and At ferrooxidans, and addition of inorganic nutrients and sulfur were evaluated in terms of the solubilization of Zn, Cu and Cr. When sludge‐adapted cells, addition of inorganic nutrients and lower sludge content were involved, higher yields of metal extraction were obtained. However, higher initial concentrations of At ferrooxidans and Fe²⁺, fine particle size of the sludge and S addition did not improve the metals' solubilization during an experimental period of 7 days. As a result of a long‐term (40 days) bioleaching experiment, 42% of Zn (1300–1648 mg kg^?1), 39% of Cu (613–774 mg kg^?1) and 10% of Cr (37–44 mg kg^?1) in the sludge were leached into the solution. The results indicate that a bioleaching process conducted under operationally optimal conditions can be effectively employed for the removal of heavy metals from sewage sludge before land application. Copyright © 2005 Society of Chemical Industry     

NaHCO3-enhanced sewage sludge thin-layer drying: Drying characteristics and kinetics

Drying sewage sludge is a highly energy-extensive process. For this reason, this work seeks to identify a reagent that can enhance the effectiveness of the drying process. In this study, drying experiments of sewage sludge were conducted at drying temperatures ranging from 100 to 160°C. NaHCO₃ was selected as the drying reagent, which was added to the sludge before drying. The thin-layer drying characteristics of the sludge and sludge/NaHCO₃ mixtures were later investigated and compared. Various mathematical models were used to simulate the sludge drying curves. It was found that adding 2 and 6% (wet basis) of NaHCO₃ to the sludge was effective in improving the moisture diffusion during the drying process, whereas the drying rate of the sludge/NaHCO₃ mixtures decreased when the addition of NaHCO₃ was further increased to 10% (wet basis). When the addition ratio was 2%, the increase in the maximum drying rate was the largest. With coefficients of determination (R²) over 0.9999, the modified Midilli model proposed in this study was observed to be the most suitable model to describe thin-layer drying of sludge relative to the other models examined in terms of R², reduced χ², root mean square error, and residual sum of squares. The values of the diffusion coefficients at each temperature were obtained using Fick’s second law of diffusion, which varied from 3.700?×?10^?9 to 1.085?×?10^?8?m²/s over the temperature range (i.e., 100–160°C). The activation energy of moisture diffusion was determined to be 27.57?kJ/mol. Scanning electron microscope images of the dried sludge and sludge/NaHCO₃ mixtures indicated that the porosity of the sludge after drying increased with an increase in the NaHCO₃ addition ratio. Overall, the results suggested that NaHCO₃ is a suitable reagent to improve the drying efficiency of the sludge.     

Systematic Analysis of the Biochemical Characteristics of Activated Sludge During Ozonation for Lowering of Biomass Production

Properties of activated sludge during ozonation were analyzed. The structure and surface characteristics altered with the increase of ozone dosage. At low ozone dosage, the floc structure was completely dismantled. Floc fragments reformed through reflocculation at an ozone dosage greater than 0.20 g O₃·g^?1 mixed liquor suspended solids (MLSS). Inactivation of microorganisms in the activated sludge mixture was caused by ozonation. Microbial growth decreased by up to 65% compared to the control. Simultaneously, 92.5% of nucleotide and 97.4% of protein in microbial cells of the sludge were released. Organic substance, nitrogen and phosphorus were released from the sludge during the ozonation process. The initial value of soluble chemical oxygen demand (SCOD) was 72 mg·L^?1. When the ozone dosage was 0.12 g O₃·g^?1 MLSS, the value of SCOD rapidly reached 925 mg·L^?1, increased by almost 12-fold. Simultaneously, 54.7% of MLSS was reduced. The composition of MLSS was changed, indicating that the inner water of cells and volatile organic substance decreased during the ozonation process.     

Assessment of solid retention time of a temperature phased anaerobic digestion system on performance and final sludge characteristics

BACKGROUND: This paper describes the results obtained during the thermophilic/mesophilic temperature phased anaerobic digestion (TPAD) of sewage sludge on a pilot scale. The aim of this research study was not only to optimize the anaerobic digestion process, but also to obtain a digested sludge suitable for agricultural applications according to the legal requirements. RESULTS: Four TPAD assays were carried out: 5/15, 3/15, 3/12 and 3/9 (days/days of solid retention time) with a specific methane production (expressed as LCH₄ g^?1 VS_destroyed) of 0.77, 0.83, 0.66 and 0.20, respectively. TPAD 3/15 and 3/12 reached pathogen concentrations of less than 1000 MPN g^?1 TS (faecal colifoms) and 3 MPN per 4 g TS (Salmonella spp.); therefore, these digested sludges can be considered Class A biosolids, according to the US Environmental Protection Agency. Concentrations of heavy metals rose after the anaerobic digestion of mixed sludge, but the final values were always below the limits required by legal regulations. CONCLUSION: TPAD 3/15 is the best option in terms of organic matter removal, CH₄ generation, and process stability. TPAD 3/12 obtained the best final dewaterability and pathogen reduction and in general, showed much better results than those obtained by anaerobic mesophilic control (15 days of SRT). Copyright © 2012 Society of Chemical Industry     

Ozonolysis Post-Treatment of Anaerobically Digested Distillery Wastewater Effluent

ABSTRACT

In this study, the ozonolysis of real anaerobically digested distillery wastewater (DWW) was carried out. The effect of operating parameters, such as pH, initial concentration, and ozone dosage, on the efficiency of ozone utilization, color removal, and sludge solubilization was studied. The highest ozone utilization of 99% was observed at the highest initial concentration (COD of 3000 mg/L) and lowest ozone flowrate (22.5 mg O₃/L/min), but with a very low color reduction of 20%, after 60 minutes of ozonolysis. To achieve a higher color reduction >80% and at ozone utilization >95%, the DWW had to be diluted twice (COD 1500 mg/L), and the flowrate doubled to 45 mg O₃/L/min. The reduction in color signified the oxidation of the color causing biorecalcitrant aromatic melanoidin compounds. This was confirmed by the 47% reduction in ultraviolet absorbance at 254 nm indicating the breakdown of the complex aromatic compounds into low molecular weight organics. Moreover, increases in average oxidation state from ?0.6 to ?0.2 suggested a decline in aromaticity and formation of easily biodegradable aliphatic compounds. The ozonolysis process was found to follow the first-order reaction kinetic model with the highest rate constant of 0.0326 min^?1 obtained. A reduction in suspended COD by 88% indicated solubilization of the sludge contained in the effluent.     

Effect of acetic acid on lipid accumulation by glucose‐fed activated sludge cultures

BACKGROUND: The effect of acetic acid, a lignocellulose hydrolysis by‐product, on lipid accumulation by activated sludge cultures grown on glucose was investigated. This was done to assess the possible application of lignocellulose as low‐cost and renewable fermentation substrates for biofuel feedstock production. RESULTS: Biomass yield was reduced by around 54% at a 2 g L^?1 acetic acid dosage but was increased by around 18% at 10 g L^?1 acetic acid dosage relative to the control run. The final gravimetric lipid contents at 2 and 10 g L^?1 acetic acid levels were 12.5 ± 0.7% and 8.8 ± 3.2% w/w, respectively, which were lower than the control (17.8 ± 2.8% w/w). However, biodiesel yields from activated sludge grown with acetic acid (5.6 ± 0.6% w/w for 2 g L^?1 acetic acid and 4.2 ± 3.0% w/w for 10 g L^?1 acetic acid) were higher than in raw activated sludge (1–2% w/w). The fatty acid profiles of the accumulated lipids were similar with conventional plant oil biodiesel feedstocks. CONCLUSIONS: Acetic acid enhanced biomass production by activated sludge at high levels but reduced lipid production. Further studies are needed to enhance acetic acid utilization by activated sludge microorganisms for lipid biosynthesis. Copyright © 2011 Society of Chemical Industry     

Structural Analysis and Dewatering Characteristics of Waste Sludge from WWTP MBR

Abstract

A pilot‐scale UF membrane bioreactor (MBR) of 1 m³/day capacity was set up in an industrial wastewater treatment plant to evaluate its performance. This study mainly focused on testing the dewaterability and structural analysis of MBR sludge. MBR had 14% reduction of excess sludge production in relative to the conventional activated sludge process (CAS sludge). For dewatering, MBR sludge had comparable dewaterability with the CAS sludge but required nearly 20% less flocculant to reach the highest filterability χ and lowest specific filtration resistance (SRF). This could reduce the cost for running the dewatering facilities and final disposal. Meanwhile the chemical and morphological analyses on MBR sludge exhibited lower EPS (exocellular polymeric substances) content, slightly smaller flocs and more compact morphology. Additionally, to estimate the appropriate polyelectrolyte dose prior to dewatering, we measured the hysteresis loop area of the sludge rheogram (shear stress vs. shear rate) using a co‐axial cylinder viscometer. For both sludges, the area dramatically increased at some critical flocculant dosage and then plateaued off. The critical dosage, though not optimal, still led to an acceptable dewatering performance for the sludge.     

Effect of coagulation on palm oil mill effluent and subsequent treatment of coagulated sludge by anaerobic digestion

A new effluent treatment scheme is proposed for treating palm oil mill effluent based on coagulation and anaerobic digestion of coagulated sludge. The effectiveness of anionic (N9901) and cationic (N9907) polyelectrolytes manufactured by NALCO (Malaysia) was evaluated both as coagulant and coagulant aid. The results showed that the anionic and cationic polyelectrolytes were best suited as a coagulant aid, and the cationic polyelectrolyte showed better performance than the anionic polyelectrolyte. For an influent chemical oxygen demand (COD) concentration of 59 700 mg L^?1 at an alum dosage of 1700 mg L^?1, the residual COD, suspended solid removal, sludge volume and pH were found to be 39 665 mg L^?1, 87%, 260 mL L^?1 and 6.3, respectively. For the above influent COD and alum dosage with the addition of 2 mg L^?1 of cationic polyelectrolyte as coagulant aid, the results were 30 870 mg L^?1, 90%, 240 mL L^?1 and 6.2, respectively. The sludge resulting from the coagulation process using alum as coagulant and cationic polyelectrolyte as coagulant aid was tested for its digestibility in an anaerobic digester. The quantity of biogas generated per gram of volatile solids (VS) destroyed at a loading rate of 26.7 ± 0.5 and 35.2 ± 0.4 g VS L^?1 d^?1 was found to be 0.68 and 0.72 L g^?1 VS destroyed. The anaerobic biomass when subjected to varying alum dosage in the coagulated palm oil sludge did not exhibit inhibition as the digester performance was in conformity with the regular treatment process Copyright © 2006 Society of Chemical Industry     

Effects of butyric acid stress on anaerobic sludge for hydrogen production from kitchen wastes

BACKGROUND: Anaerobic digestion is an alternative technology to achieve the dual benefits of hydrogen production and waste stabilization from kitchen wastes. In this work, the butyric acid stress on anaerobic sludge was investigated in order to improve the tolerance of sludge against organic acids, and to enhance hydrogen accumulation. RESULTS: The tolerance of butyric acid in anaerobic sludge increased with the stress concentration, however, it decreased at concentrations greater than of 4.0 g L^?1. The maximum hydrogen yield reached 63.72 mL g^?1 VS at 4.0 g L^?1 stress, representing an increase of 114% compared with the control group. The concentration of volatile solids (VS) of the sludge and SCOD increased steadily with time up to 20 h. At 4.0 g L^?1 butyric acid stress, the maximum activity of β‐glucosidase, BAA‐hydrolysing protease and dehydrogenase enzyme were 14912.1 µmol PNP g^?1 TS h^?1, 134.14 µmol NH₄‐N g^?1 TS h^?1 and 7316.42 µg TF g^?1 TS h^?1, which were 2.78, 1.90 and 2.01 times that of the control, respectively. CONCLUSIONS: The feasibility of butyric acid stress on anaerobic sludge to increase hydrogen production from kitchen wastes was demonstrated. Remarkably, 4.0 g L^?1 butyric acid stress was found to be favorable for improving the tolerance of butyric acid in sludge as well as hydrogen yield in the experiment. Copyright © 2010 Society of Chemical Industry     

Comparison of thermo‐oxidative treatments for the anaerobic digestion of sewage sludge

BACKGROUND: In this study, various thermo‐oxidative treatments were examined and compared with the aim of overcoming the disadvantages of thermal treatment and enhancing the anaerobic digestion of sewage sludge. RESULTS: Oxygen, hydrogen peroxide and ozone were selected as oxidant, accompanied with the addition of either acid (HCl) or alkali (Na₂CO₃) for oxygen. The temperature and duration were fixed at 170 °C and 1 h, respectively. Anaerobically digested sludge was used as the substrate, to see the effects on the refractory part of sewage sludge. A batch methanogenesis test using 120 mL serum bottles was run at 35 °C for 20 days, and methane production, solids reduction, dewaterability and color intensity were measured. As the strength of the oxidants was increased, methane production tended to decrease, whereas solids reduction was increased. The dewaterability of the sludges and the color in the filtrates became worse for thermo‐oxidative treatment with oxygen and alkali. On the other hand, the dewaterability was improved significantly and color generation was restricted the most for the thermo‐oxidative treatment with oxygen and acid. CONCLUSION: Lowering the pH of thermo‐oxidative treatment is advantageous with respect to the dewaterability and color generation of digested sludge. Based on evaluation of the overall performance, thermo‐oxidative treatment with acid is considered the best among the thermo‐oxidative treatments examined. Copyright © 2008 Society of Chemical Industry     

无机调理剂与表面活性剂联合调理对污泥脱水性能的影响

研究了CaO、PAFC联合表面活性剂预处理对污泥脱水性能的影响。以污泥滤饼含水率和比阻（SRF）作为评价污泥脱水性能的指标,通过测定污泥调理过程中胞外聚合物（EPS）含量、Zeta电位的变化来阐明污泥脱水性能的变化。实验结果表明,十二烷基二甲基苄基氯化铵（1227）的加入导致上清液中EPS含量发生变化,有效降低了SRF和滤饼含水率,提高污泥脱水性能。CaO、PAFC和表面活性剂的联合调理污泥比单独使用表面活性剂的效果更好,CaO、PAFC的投加不仅改善污泥脱水性能,并有助于减少表面活性剂的用量。污泥上清液中EPS及其各组分含量与污泥滤饼含水率、SRF均有较高的相关性,对污泥的脱水性能有重要贡献。实验中确定的最佳污泥调理条件是CaO投加量为66.67 mg·（g DS）^-1、PAFC投加量为33.33 mg·（g DS）^-1和表面活性剂投加量为56.25 mg·（g DS）^-1,污泥滤饼含水率和SRF分别降至69.41%、0.294×10¹³ m·kg^-1。     

Enhanced lipid and biodiesel production from glucose‐fed activated sludge: Kinetics and microbial community analysis

An innovative approach to increase biofuel feedstock lipid yields from municipal sewage sludge via manipulation of carbon‐to‐nitrogen (C:N) ratio and glucose loading in activated sludge bioreactors was investigated. Sludge lipid and fatty acid methyl ester (biodiesel) yields (% cell dry weight, CDW) were enhanced via cultivation in activated sludge bioreactors operated at high initial C:N ratio (≥40:1) and glucose loading (≥40 g L^?1). Under C:N 70, 60 g L^?1 glucose loading, a maximum of 17.5 ± 3.9 and 10.2 ± 2.0% CDW lipid and biodiesel yields, respectively, were achieved after 7 d of cultivation. The cultured sludge lipids contained mostly C₁₆? C₁₈ fatty acids, with oleic acid consistently accounting for 40–50% of the total fatty acids. Microbial composition in activated sludge exposed to C:N 70 shifted toward specific gammaproteobacteria, suggesting their relevance in lipid production in wastewater microbiota and potential value in biofuel synthesis applications. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Effect of temperature and bulking agents on deep bio-drying of high-solid anaerobically digested sludge

Abstract

The effect of temperature and bulking agents, namely sawdust (SD), wheat bran (WB), and wheat straw (WS), on bio-drying of high-solid anaerobically digested sludge (ADS) was evaluated. A mixture of dewatered ADS with municipal sludge compost product (CP) and different bulking agents was loaded into a 180-L pilot-scale reactor. Intermittent aeration of 12?L min^?1 with 20?min run/40?min stop was adopted during the whole bio-drying process. After 18 to 21?days of bio-drying, volatile solids (VS) in the trials with SD, WB, and WS degraded at a rate of 86.6, 284.3, and 344.2?g kg^?1 initial VS, respectively. The matrix with easier biodegradable WB and WS achieved faster and higher water removal at a rate of 692.7 to 764.2?g kg^?1 initial water, and a higher temperature cumulation of 373 to 427?°C·d. Approximately 70% of the bio-generated heat consumed for water evaporation. In the trials with WB and WS, the matrix moisture content decreased to below 39%, and the weight declined by above 48%. Water removal and VS degradation contributed to 85.2?±?3.4% and 14.8?±?3.4% of the total weight loss, respectively. The residual WB in bio-dried products (BP) caused low germination index (GI), indicating possible phytotoxic effects in soils. WS was determined to be the best agent with significantly higher GI and lower cost compared to WB, implying promising land utilization potential of BP.     

Simultaneous sulfide and acetate oxidation under denitrifying conditions using an inverse fluidized bed reactor

BACKGROUND: Simultaneous removal of sulfur, nitrogen and carbon compounds from wastewaters is a commercially important biological process. The objective was to evaluate the influence of the CH₃COO^?/NO₃^? molar ratio on the sulfide oxidation process using an inverse fluidized bed reactor (IFBR). RESULTS: Three molar ratios of CH₃COO^?/NO₃^? (0.85, 0.72 and 0.62) with a constant S^2?/NO₃^? molar ratio of 0.13 were evaluated. At a CH₃COO^?/NO₃^? molar ratio of 0.85, the nitrate, acetate and sulfide removal efficiencies were approximately 100%. The N₂ yield (g N₂ g^?1 NO₃^?‐N consumed) was 0.81. Acetate was mineralized, resulting in a yield of 0.65 g inorganic‐C g^?1 CH₃COO^?‐C consumed. Sulfide was partially oxidized to S⁰, and 71% of the S^2? consumed was recovered as elemental sulfur by a settler installed in the IFBR. At a CH₃COO^?/NO₃^? molar ratio of 0.72, the efficiencies of nitrate, acetate and sulfide consumption were of 100%, with N₂ and inorganic‐C yields of 0.84 and 0.69, respectively. The sulfide was recovered as sulfate instead of S⁰, with a yield of 0.92 g SO₄^2?‐S g^?1 S^2? consumed. CONCLUSIONS: The CH₃COO^?/NO₃^? molar ratio was shown to be an important parameter that can be used to control the fate of sulfide oxidation to either S⁰ or sulfate. In this study, the potential of denitrification for the simultaneous removal of organic matter, sulfide and nitrate from wastewaters was demonstrated, obtaining CO₂, S⁰ and N₂ as the major end products. Copyright © 2008 Society of Chemical Industry     

Solvent extraction and separation of rare earths from chloride media using α-aminophosphonic acid extractant HEHAMP

Solvent extraction and separation of rare earths (REs: La ~ Lu, plus Y and Sc) by a novel synthesized extractant, (2-ethylhexylamino)methyl phosphonic acid mono-2-ethylhexyl ester (HEHAMP, abbreviated as H₂A₂), were investigated in chloride medium. The favorable separation factors (SFs) between adjacent heavy REs suggested that HEHAMP has a better separation performance than P507. The extracted complex of trivalent REs was determined to be REClH₂A₄ by the slope analysis method. Thermodynamic parameters (ΔH, ΔG, and ΔS) of Lu were calculated as 7.47 kJ mol^?1, ?6.05 kJ mol^?1, and 45.4 J mol^?1 K^?1 at 298.15 K, respectively, which indicate that the extraction reaction of Lu is an endothermic process. The loading capacity of 30% (v/v) HEHAMP toward Lu(III), Yb(III), and Y(III) was about 15.17 g Lu₂O₃/L, 14.46 g Yb₂O₃/L, and 12.64 g Y₂O₃/L, respectively. HCl is the most efficient stripping acid, and 92% of the loaded Yb(III) can be stripped by one-stage stripping with 2 mol/L HCl.     

Development of a Green Process for the Preparation of Antioxidant and Pigment-Enriched Extracts from Winery Solid Wastes Using Response Surface Methodology and Kinetics

Red grape pomace (RGP), an abundant wine industry solid waste, was used for the recovery of polyphenols and anthocyanin pigments, using ultrasound-assisted extraction and water/glycerol mixtures as the solvent. Glycerol concentration (C_gl) and liquid-to-solid ratio (R_L/S) were first optimized by implementing Box?Behnken experimental design and the process was further studied through kinetics. The optimal conditions were found to be C_gl = 90% (w/v) and R_L/S = 90 mL g^?1, and under these conditions the extraction of total polyphenols (TP) and total pigments (TPm) obeyed first-order kinetics. Maximum diffusivity (D_e) values were 4.22 × 10^?12 and 12.59 × 10^?12 m² s^?1, for TP and TPm, respectively, and the corresponding activation energies were (E_a) 13.94 and 8.22 kJ mol^?1.