Enhanced biodegradation of chlorobenzene via combined Fe3+ and Zn2+ based on rhamnolipid solubilisation

Biotrickling filters (BTFs) for hydrophobic chlorobenzene (CB) purification are limited by mass transfer and biodegradation. The CB mass transfer rate could be improved by 150 mg/L rhamnolipids. This study evaluated the combined use of Fe³⁺ and Zn²⁺ to enhance biodegradation in a BTF over 35 day. The effects of these trace elements were analysed under different inlet concentrations (250, 600, 900, and 1200 mg/L) and empty bed residence times (EBRTs; 60, 45, and 32 sec). Batch experiments showed that the promoting effects of Fe³⁺/Zn²⁺ on microbial growth and metabolism were highest for 3 mg/L Fe³⁺ and 2 mg/L Zn²⁺, followed by 2 mg/L Zn²⁺, and lowest at 3 mg/L Fe³⁺. Compared to BTF in the absence of Fe³⁺ and Zn²⁺, the average CB elimination capacity and removal efficiency in the presence of Fe³⁺ and Zn²⁺ increased from 61.54 to 65.79 g/(m³?hr) and from 80.93% to 89.37%, respectively, at an EBRT of 60 sec. The average removal efficiency at EBRTs of 60, 45, and 32 sec increased by 2.89%, 5.63%, and 11.61%, respectively. The chemical composition (proteins (PN), polysaccharides (PS)) and functional groups of the biofilm were analysed at 60, 81, and 95 day. Fe³⁺ and Zn²⁺ significantly enhanced PN and PS secretion, which may have promoted CB adsorption and biodegradation. High-throughput sequencing revealed the promoting effect of Fe³⁺ and Zn²⁺ on bacterial populations. The combination of Fe³⁺ and Zn²⁺ with rhamnolipids was an efficient method for improving CB biodegradation in BTFs.     

Effect of Mn2+ on the phosphorus removal and bioflocculation under anoxic condition

Manganese ion (Mn²⁺) generated from metallurgical, steel making and chemical industries enters sewage treatment plants and affects the sludge activity and flocculation. The effect of Mn²⁺ on the removal of chemical oxygen demand (COD) and total phosphorus (TP) and sludge activity were investigated in anoxic zone of an anaerobic/anoxic/oxic (A²O) process. The compositions and structures of extracellular polymeric substances (EPS) were characterized using three-dimensional excitation emission matrix fluorescence spectroscopy (3D-EEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) to reveal the relationship among Mn²⁺, EPS and sludge flocculation.The results showed that low concentration of Mn²⁺ (<5 mg/L) improved removal efficiencies of COD and TP and increased the activity of alkaline phosphatase, acid phosphatase and dehydrogenase. Meanwhile, the addition of Mn²⁺ increased total EPS, sludge contact angle, Zeta potential and sludge particle size, and thus enhanced sludge flocculation. However, high concentration of Mn²⁺ (>10 mg/L) hindered microbial flocculation and reduced removal efficiencies of the pollutants. When Mn²⁺was 5 mg/L, removal efficiencies of COD and TP reached 65% and 90%, respectively. Sludge flocculation was the best and SVI was 70.56 mL/g. The changes of Mn²⁺ concentration caused deviation of groups’ compositions in LB-EPS and TB-EPS, where the main components were always protein (PN) and polysaccharide (PS). The addition of Mn²⁺ resulted in the degradation of humic acids. However, it did not give rise to significant morphology changes of EPS.     

Mg2+ improves biomass production from soybean wastewater using purple non-sulfur bacteria

Soybean wastewater was used to generate biomass resource by use of purple non-sulfur bacteria (PNSB). This study investigated the enhancement of PNSB cell accumulation in wastewater by Mg²⁺ under the light-anaerobic condition. Results showed that with the optimal Mg²⁺ dosage of 10 mg/L, biomass production was improved by 70% to 3630 mg/L, and biomass yield also was improved by 60%. Chemical Oxygen Demand (COD) removal reached above 86% and hydraulic retention time was shortened from 96 to 72 hr. The mechanism analysis indicated that Mg²⁺ could promote the content of bacteriochlorophyll in photosynthesis because Mg²⁺ is the bacteriochlorophyll active center, and thus improved adenosine triphosphate (ATP) production. An increase of ATP production enhanced the conversion of organic matter in wastewater into PNSB cell materials (biomass yield) and COD removal, leading to more biomass production. With 10 mg/L Mg²⁺, bacteriochlorophyll content and ATP production were improved by 60% and 33% respectively.     

Coating zirconium oxide-nanocomposite with humic acid for recovery of mercury and chromium in hazardous waste of chemical oxygen demand test

Hazardous waste of chemical oxygen demand (COD) test (HW_COD) is one of the most common laboratory wastewaters, containing large amounts of H₂SO₄ and highly toxic Cr³⁺ and Hg²⁺. Current treatment methods suffered from incomplete removal of Cr³⁺ and high-cost. Herein, a humic acid-coated zirconium oxide-resin nanocomposite (HA-HZO-201) was fabricated for efficient recovery of Cr³⁺ and Hg²⁺ in HW_COD. The synthesized HA-HZO-201 shows excellent tolerance to wide pH range (1–5) and high salinity (3.5 mol/L NaCl), as well as adsorption capacity for Cr³⁺ (37.5 mg/g) and Hg²⁺ (121.3 mg/g). After treating with HA-HZO-201 by using a fixed-bed adsorption procedure, the final Cr³⁺ and Hg²⁺ concentrations in HW_COD decreased to 0.28 and 0.02 mg/L, respectively. In addition, the HA-HZO-201 can be regenerated by desorption and recovery of Cr³⁺ and Hg²⁺ using HNO₃ and thiourea as eluents, respectively. After 5 cycles of adsorption/desorption, the removal efficiencies still reach up to 86.0% for Cr³⁺ and 89.7% for Hg²⁺, indicating an excellent regeneration of HA-HZO-201. We hope this work open new opportunities for treatment of HW_COD with high-efficiency and low-cost.     

Cd2+ removal from wastewater by sulfate reducing bacteria with an anaerobic fluidized bed reactor

A process of treatment for containing Cd²⁺ wastewater by sulfate reducing bacteria with upflow anaerobic fluidized bed reactor has been studied. When the concentration of COD and Cd²⁺ in the influent were 270 5mg/L and 100mg/L respectively and hydraulic retention time was 4 hours, the removal rate of COD and Cd²⁺ were higher than 73 8% and 99 8% respectively. The reactor can treat as high as 1000mg/L of concentration of Cd²⁺ . The highest removal velocity rate of Cd²⁺ reached 2999 1mg/(L·d). And the possible relationship between sulfate reducing bacteria and methanogenic bacteria was discussed.     

New insight into scale inhibition during tea brewing: Ca2+/Mg2+ complexing and alkalinity consumption

Scale not only affects the taste and color of water, but also increases the risks of osteoporosis and cardiovascular diseases associated with drinking it. As a popular beverage, tea is rich many substances that have considerable potential for scale inhibition, including protein, tea polyphenols and organic acids. In this study, the effect of tea brewing on scale formation was explored. It was found that the proteins, catechins and organic acids in tea leaves could be released when the green tea was brewed in water with sufficient hardness and alkalinity. The tea-released protein was able to provide carboxyl groups to chelate with calcium ions (Ca²⁺), preventing the Ca²⁺ from reacting with the carbonate ions (CO₃²⁻). The B rings of catechins were another important structure in the complexation of Ca²⁺ and magnesium ions (Mg²⁺). The carboxyl and hydroxyl groups on the organic acids was able to form five-membered chelating rings with Ca²⁺ and Mg²⁺, resulting in a significant decrease in Ca²⁺ from 100.0 to 60.0 mg/L. Additionally, the hydrogen ions (H⁺) provided by the organic acids consumed and decreased the alkalinity of the water from 250.0 to 131.4 mg/L, leading to a remarkable reduction in pH from 8.93 to 7.73. It further prevented the bicarbonate (HCO₃⁻) from producing CO₃²⁻ when the water was heated. The reaction of the tea constituents with the hardness and alkalinity inhibited the formation of scale, leading to a significant decrease in turbidity from 10.6 to 1.4 NTU. Overall, this study provides information to help build towards an understanding of the scale inhibition properties of tea and the prospects of tea for anti-scaling in industrial applications.     

Co-metabolic and biochar-promoted biodegradation of mixed PAHs by highly efficient microbial consortium QY1

Polycyclic aromatic hydrocarbons (PAHs), typical representatives of the persistent organic pollutants (POPs), have become ubiquitous in the environment. In this study, a novel microbial consortium QY1 that performed outstanding PAHs-degrading capacity has been enriched. The degradation characteristics of single and mixed PAHs treated with QY1 were studied, and the effect of biochar on biodegradation of mixed PAHs and the potential of biochar in PAHs-heavy metal combined pollution bioremediation were also investigated. Results showed that, in single substrate system, QY1 degraded 94.5% of 500 mg/L phenanthrene (PHE) and 17.8% of 10 mg/L pyrene (PYR) after 7 days, while in PHE-PYR mixture system, the biodegradation efficiencies of PHE (500 mg/L) and PYR (10 mg/L) reached 94.0% and 96.2%, respectively, since PHE served as co-metabolic substrate to have significantly improved PYR biodegradation. Notably, with the cooperation of biochar, the biodegradations of PHE and PYR were greatly accelerated. Further, biochar could reduce the adverse impact of heavy metals (Cd²⁺, Cu²⁺, Cr₂O₇^2?) on PYR biodegradation remarkably. The sequencing analysis revealed that Methylobacterium, Burkholderia and Stenotrophomonas were the dominant genera of QY1 in almost all treatments, indicating that these genera might play key roles in PAHs biodegradation. Overall, this study provided new insights into the efficient bioremediation of PAHs-contaminated site.     

Photoproducts of tetracycline and oxytetracycline involving self-sensitized oxidation in aqueous solutions: Effects of Ca2+ and Mg2+

Tetracyclines constitute one of the most important antibiotic families and represent a classic example of phototoxicity. The photoproducts of tetracyclines and their parent compounds have potentially adverse effects on natural ecosystem. In this study, the self-sensitized oxidation products of tetracycline (TC) and oxytetracycline (OTC) were determined and the effects of Ca²⁺ and Mg²⁺on self-sensitized degradation were investigated. The Ca²⁺ and Mg²⁺ in the natural water sample accounted for enhancement (pH 7.3) and inhibition (pH 9.0) of photodegradation of TC and OTC due to the formation of metal-ions complexes. The formation of Mg²⁺ complexes was unfavorable for the photodegradation of the tetracyclines at both pH values. In contrast, the Ca²⁺ complexes facilitated the attack of singlet oxygen (¹O₂) arising from self-sensitization at pH 7.3 and enhanced TC photodegradation. For the first time, self-sensitized oxidation products of TC and OTC were verified by quenching experiments and detected by LC/ESI-DAD-MS. The products had a nominal mass 14 Da higher than the parent drugs (designated M+14), which resulted from the ¹O₂ attack of the dimethylamino group on the C-4 atom of the tetracyclines. The presence of Ca²⁺ and Mg²⁺ also affected the generation of M+14 due to the formation of metal-ions complexes with TC and OTC. The findings suggest that the metal-ion complexation has significant impact on the self-sensitized oxidation processes and the photoproducts of tetracyclines.     

Aminobenzenesulfonamide functionalized SBA-15 nanoporous molecular sieve: A new and promising adsorbent for preconcentration of lead and copper ions

A rapid method for the extraction and monitoring of nanogram level of Pb²⁺ and Cu²⁺ ions using uniform silanized mesopor (SBA-15) functionalized with aminobenzenesulfonamide groups and flame atomic absorption spectrometry (FAAS) is presented. Aminobenzenesulfonamide functionalized SBA-15 was synthesized according to procedure in the literature and the presence of organic groups in the silica framework was demonstrated by FT-IR spectra. The functionalized product showed the BET surface area 110 m²/g and pore diameter 5.1 nm, based on adsorption-desorption of N₂ at 77 K. The effect of several variables such as (amount of adsorbent, stirring time, pH and presence of other ions in the medium) has been studied. Lead and copper were completely extracted at pH greater than 3 after stirring for 10 min. The maximum capacity of the adsorbent was found to be 191.3 ± 1.4 and 155.0 ± 1.0 μg of lead and copper ions/mg functionalized SBA-15, respectively. The preconcentration factor of the method was found to be 200. The detection limit of the technique was 3.4 and 0.4 ng/mL for Pb²⁺ and Cu²⁺, respectively. The applications of this methodology for real samples were examined by various water type, black tea and pepper samples.     

Highly efficient P uptake by Fe3O4 loaded amorphous Zr-La (carbonate) oxides: Electrostatic attraction, inner-sphere complexation and oxygen vacancies acceleration effect

Bimetallic oxides composites have received an increasing attention as promising adsorbents for aqueous phosphate (P) removal in recent years. In this study, a novel magnetic composite MZLCO was prepared by hybridizing amorphous Zr-La (carbonate) oxides (ZLCO) with nano-Fe₃O₄ through a one-pot solvothermal method for efficient phosphate adsorption. Our optimum sample of MZLCO-45 exhibited a high Langmuir maximum adsorption capacity of 96.16 mg P/g and performed well even at low phosphate concentration. The phosphate adsorption kinetics by MZLCO-45 fitted well with the pseudo-second-order model, and the adsorption capacity could reach 79% of the ultimate value within the first 60 min. The phosphate adsorption process was highly pH-dependent, and MZLCO-45 performed well over a wide pH range of 2.0-8.0. Moreover, MZLCO-45 showed a strong selectivity to phosphate in the presence of competing ions (Cl⁻, NO₃⁻, SO₄²⁻, HCO₃⁻, Ca²⁺, and Mg²⁺) and a good reusability using the eluent of NaOH/NaCl mixture, then 64% adsorption capacity remained after ten recycles. The initial 2.0 mg P/L in municipal wastewater and surface water could be efficiently reduced to below 0.1mg P/L by 0.07 g/L MZLCO-45, and the phosphate removal efficiencies were 95.7% and 96.21%, respectively. Phosphate adsorption mechanisms by MZLCO-45 could be attributed to electrostatic attraction and the inner-sphere complexation via ligand exchange forming Zr/La-O-P, -OH and CO₃²⁻ groups on MZLCO-45 surface played important roles in the ligand exchange process. The existence of oxygen vacancies could accelerate the phosphate absorption rate of the MZLCO-45 composites.     

Fe2+和Fe3+在4-氯酚光化学反应中性质的相似性

研究在光照条件下,２０ｍｇ／ｌ４－氯酚＋１ｍｇ／ＬＦｅ＾２＋（体系Ａ）和２０ｇ／Ｌ４－氯酚＋１ｍｇＦｅ＾３＋（体系Ｂ）中Ｆｅ＾２＋和Ｆｅ＾３＋的浓度变化,通过离子色谱手段,在体系Ａ中能够同时检测出Ｆｅ＾２＋,在体系Ｂ中亦能够同时检测到Ｆｅ＾２＋,故Ｆｅ＾２＋和Ｆｅ＾２＋在４－氯酚光化学反应中的性质,表现出相似性。     

纳米伊/蒙黏土对水体中重金属的吸附去除效果

为明确纳米伊/蒙黏土(下称伊/蒙黏土)作为修复材料在去除水体重金属方面的应用潜力,研究了伊/蒙黏土对水体中Ni2+、Cu2+和Cd2+的去除效果与吸附规律,并通过小麦水培试验分析伊/蒙黏土降低水体重金属在小麦地上部分的累积和缓解重金属对小麦的毒害效应等效果. 结果表明:伊/蒙黏土可以吸附去除水体中的Ni2+、Cu2+和Cd2+,当水体中ρ(Ni2+)、ρ(Cu2+)和ρ(Cd2+)分别为5、10、2 mg/L时,添加2%(以w计)的伊/蒙黏土对3种重金属的去除率均达到95%以上. 伊/蒙黏土对重金属的吸附等温线符合Langmuir方程,对Ni2+、Cu2+和Cd2+的理论最大吸附量分别为2.13、8.52和1.56 mg/g. 在培养液中添加2%伊/蒙黏土可降低小麦对Ni2+、Cu2+和Cd2+的累积富集,缓解重金属对小麦生长的毒害效应. 研究显示,纳米伊/蒙黏土可有效去除水体中的Ni2+、Cu2+和Cd2+,并缓解其对小麦的毒性,因此其在修复水体重金属污染、恢复水环境生态功能方面具有潜在的应用前景.      

Effect of heavy metals and phenol on bacterial decolourisation and COD reduction of sucrose-aspartic acid Maillard product

Melanodins are amino-carbonyl complex, predominantly present in sugarcane molasses based distillery wastewater as major source of colourant. The microbial decolourisation of melanoidin is a challenge due to its binding property with other co-pollutants of distillery waste. Results revealed that the presence of Zn2+ (2.00-20.00 mg/L) in melanoidin solution (1200 mg/L) stimulated the bacterial growth and sucrose-aspartic acid Maillard product (SAA) decolourisation as compared to control, while Fe 3+ and Mn2+ at the same concentration inhibited the process. However, the presence of phenol (100 mg/L) along with Zn2+ , Fe3+ and Mn2+ suppressed the bacterial growth, SAA decolourisation and MnP activity. The shrinkage and reduced number of bacterial cell count at higher concentration of heavy metals in presence of phenol was also observed under scanning electron microscope.     

Adsorption of heavy metal ions from aqueous solution by carboxylated cellulose nanocrystals

A novel nanoadsorbent for the removal of heavy metal ions is reported.Cotton was first hydrolyzed to obtain cellulose nanocrystals(CNCs).CNCs were then chemically modified with succinic anhydride to obtain SCNCs.The sodic nanoadsorbent(NaSCNCs) was further prepared by treatment of SCNCs with saturated NaHCO 3 aqueous solution.Batch experiments were carried out with SCNCs and NaSCNCs for the removal of Pb 2+ and Cd 2+.The effects of contact time,pH,initial adsorption concentration,coexisting ions and the regeneration performance were investigated.Kinetic studies showed that the adsorption equilibrium time of Pb 2+ and Cd 2+ was reached within 150 min on SCNCs and 5 min on NaSCNCs.The adsorption capacities of Pb 2+ and Cd 2+ on SCNCs and NaSCNCs increased with increasing pH.The adsorption isotherm was well fitted by the Langmuir model.The maximum adsorption capacities of SCNCs and NaSCNCs for Pb 2+ and Cd 2+ were 367.6 mg/g,259.7 mg/g and 465.1 mg/g,344.8 mg/g,respectively.SCNCs and NaSCNCs showed high selectivity and interference resistance from coexisting ions for the adsorption of Pb 2+.NaSCNCs could be efficiently regenerated with a mild saturated NaCl solution with no loss of capacity after two recycles.The adsorption mechanisms of SCNCs and NaSCNCs were discussed.     

铜和锌离子对真鲷幼鱼组织酶活性的影响

研究水中Ｃｕ＾２＋、Ｚｎ＾２＋对真鲷幼鱼组织ＣＡＴ、ＧＰＴ、胃蛋白酶活性的影响。结果表明：真鲷幼鱼暴露于不同浓度Ｃｕ＾２＋（０．５、０．７５、１．５ｍｇ／Ｌ）、Ｚｎ＾２＋（１、２、４ｍｇ／Ｌ）海水中４ｄ后,Ｃｕ＾２＋、Ｚｎ＾２＋对鳃,肝脏ＣＡＴ,胃蛋白酶有抑制作用。     

云南鹤庆西山岩溶地下水主要离子雨季和旱季对比及来源分析

鹤庆西山岩溶地下水是当地居民的主要生活用水来源,本文综合运用统计学分析方法对地下水主离子的雨季和旱季变化特征及其来源进行了研究。结果表明,研究区岩溶地下水主要补给来源为大气降水,TDS介于113.3~180.76mg/L属弱矿化度水,总硬度(Ca2++Mg2+)介于38~53 mg/L之间属于极软水。HCO-3和(Ca2++Mg2+)分别占主要阴阳离子的79.6%~95.5%和75%~94%,按照O.A.阿列金分类法研究区水质为HCO3-Ca·Mg型水。Ca2+、Mg2+、Cl-、SO2-4及HCO-3均未出现季节性变化,Na+与NO-3为丰水期枯水期,K+出现异常为丰水期枯水期。参照我国及世界卫生组织饮用水标准,锰矿黑龙潭泉受人为活动的影响较大,不宜长期饮用;其他地区主要离子浓度不会对人体产生危害。     

二硫代氨基甲酸盐絮凝处理模拟油田聚合物驱采油废水的效果研究

在碱性条件下,端氨基聚醚Jeffamine-T403与二硫化碳反应合成了二硫代氨基甲酸盐型絮凝剂DTC(T403).考察了DTC(T403)对模拟聚合物驱采油废水的絮凝除油性能,研究了DTC(T403)、水解聚丙烯酰胺(HPAM)、Fe2+和Fe3+的投加量以及pH值对除油效果的影响.结果发现,DTC(T403)与Fe2+络合形成的网状螯合物通过网捕作用取得良好的絮凝除油效果;HPAM的存在影响絮凝除油效果;在同时投加Fe2+和DTC(T403)且二者的投加量分别为10mg/L和25mg/L的条件下,HPAM含量在0～900mg/L范围和含油量约300mg/L的模拟水样经絮凝处理后其含油量均可降到10mg/L以下.DTC(T403)的絮凝除油效果受pH値的影响,在pH7.5条件下可取得良好的除油效果.DTC(T403)适用于含Fe2+的聚合物驱采油废水的处理.     

Decontamination of alachlor herbicide wastewater by a continuous dosing mode ultrasound/Fe2+/H2O2 process

We used a ultrasound/Fe2+/H2O2 process in continuous dosing mode to degrade the alachlor.Experimental results indicated that lower pH levels enhanced the degradation and mineralization of alachlor. The maximum alachlor degradation(initial alachlor concentration of 50 mg/L) was as high as 100% at pH 3 with ultrasound of 100 Watts, 20 mg/L of Fe2+, 2 mg/min of H2O2 and 20℃ within60 min reaction combined with 46.8% total organic carbon removal. Higher reaction temperatures inhibited the degradation of alachlor. Adequate dosages of Fe2+and H2O2 in ultrasound/Fe2+/H2O2process not only enhance the degradation efficiency of alachlor but also save the operational cost than the sole ultrasound or Fenton process. A continuous dosing mode ultrasound/Fe2+/H2O2 process was proven as an effective method to degrade the alachlor.     

镉对大鼠肾皮质结合反应的影响

通过体内和体外试验分别研究了镉对肾皮质微粒体谷胱甘肽转移酶(GST)及游离肾近曲小管细胞中葡萄糖醛酸(GA)结合反应的影响.结果表明:(1)体外试验中,在10~(-7)—10~(-3)mol/L浓度范围内,镉可抑制肾皮质微粒休GST活力;(2)体内腹腔注射CdCl_2(2.4mg/kg,连续3天)后,大鼠肾皮质GST活力无明显改变;(3)按同样方式腹腔注射CdCl_2后,可降低游离肾近曲小管细胞中GA和7-羟基香豆素(7-HC)的结合反应;(4)体外试验中,低浓度镉(10~(-7)mol/L)可使肾皮质细胞中GA和7-HC的结合反应增强,而在10~(-6)—10~(-2)mol/L浓度范围内,镉可降低GA和7-HC的结合反应.     

Cadmium removal from wastewater by sponge iron sphere prepared by charcoal direct reduction

Sponge iron sphere (SIS), made of concentrated iron powder and possessed high activity and intension, was prepared through the process of palletizing, roasting and direct reduction by charcoal. The sponge iron sphere could remove most of Cd²⁺ from wastewater. The results showed the Cd²⁺ removal followed the first order reaction. Initial pH value played an important role in Cd²⁺ removal. With original initial pH, Cd²⁺ removal decreased to the minimum and then increased slightly with the rising of original concentration. The removal rate constant was ?0.1263 and ?0.0711 h^?1, respectively, under the Cd²⁺ concentration of 50 and 200 mg/L. When the initial pH was adjusted to 3.0, the removal rate constant could increase to ?9.896 and ?4.351 h^?1, respectively. The removal percentage almost reached to 100% when Cd²⁺ concentration was below 100 mg/L. While Cd²⁺ concentration was above 100 mg/L, Cd²⁺ removal percentage decreased slightly. In dynamic experiments, the column filled with sponge iron sphere exhibited favorable permeability. There was no sphere pulverization and conglutination between spheres. In contrast to the static state experiments, the Cd²⁺ removal percentage in dynamic state experiment was lower, and the removal Cd²⁺ quantity was 1.749 mg/g.