Synergetic Bioproduction of Short-Chain Fatty Acids from Waste Activated Sludge Intensified by the Combined Use of Potassium Ferrate and Biosurfactants

The synergetic effect and underlying mechanism of potassium ferrate(PF)with tea saponin(TS,a biosurfactant)in producing short chain fatty acids(SCFAs)from anaerobic fermentation of waste activated sludge(WAS)were explored in this work.Experimental results showed that 0.2 g PF(g TSS)^(-1)(total suspended solid)combined with 0.02 g TS(g TSS)^(-1) could further improve SCFAs’production,and the maximum SCFAs content reached 2008.7 mg COD L^(-1),which is 1.2 and 4.5 times higher than those with PF and TS individually added,respectively,and 5.3 times higher than that of blank WAS on Day 12.In the model substrates experiments,the degradation rates of bovine serum albumin and dextran with combination of PF and TS were 41.3%±0.1% and 48.5%±0.06%,respectively,on Day 3,which are lower than those in blank WAS(with degradation rates of 72.3%±0.5%and 90.3%±0.3%).It was revealed that the oxidative effect of PF and the solubilization of TS caused more organic matters to be dissolved out from WAS,providing a large number of biodegradable substances for subsequent SCFAs production.While WAS pretreated with the combination of PF and TS,the relative abundances of Firmicutes increased from 6.4%(blank)to 38.6%,and that of Proteobacteria decreased from 41.8%(blank)to 21.8%.The combination of PF and TS promoted the hydrolysis process of WAS by enriching Firmicutes,and then increased acetic acid production by inhibiting Proteobacteria that consumed SCFAs.Meanwhile,at the genus level,acidogenesis bacteria(e.g.,Proteiniclasticum and Petrimonas)were enriched whereas SCFAs consuming bacteria(e.g.,Dokdonella)were inhibited.

Effects of Potassium Ferrate and Low-Temperature Thermal Hydrolysis Co-Pretreatment on the Hydrolysis and Anaerobic Digestion Process of Waste Activated Sludge

This study evaluated the effect of potassium ferrate(PF)and low-temperature thermal hydrolysis co-pretreatment on the promotion of sludge hydrolysis process and the impact on acid production in the subsequent anaerobic digestion process.The analytical investigations showed that co-pretreatment significantly facilitated the hydrolysis process of the sludge and contributed to the accumulation of short-chain fatty acids(SCFAs).The pretreatment conditions under the optimal leaching of organic matter from sludge were hydrothermal temperature of 75℃,hydrothermal treatment time of 12 h,and PF dosage of 0.25 g g^(−1)TSS(total suspended solids),according to the results of orthogonal experiments.By pretreatment under proper conditions,the removal rate of soluble chemical oxygen demand(SCOD)achieved 71.8%at the end of fermentation and the removal rate of total phosphorus(TP)was 69.1%.The maximum yield of SCFAs was 750.3 mg L^(−1),7.45 times greater than that of the blank group.Based on the analysis of the anaerobic digestion mechanism,it was indicated that the co-pretreatment could destroy the floc structure on the sludge surface and improve organic matter dissolving,resulting in more soluble organic substances for the acidification process.Furthermore,microbial community research revealed that the main cause of enhanced SCFAs generation was an increase in acidogenic bacteria and a reduction of methanogenic bacteria.

Flotation behaviors of chalcopyrite and galena using ferrate(Ⅵ) as a depressant

This paper investigated the effects of potassium ferrate(PF)on the flotation performances of chalcopyrite and galena.The flotation results showed that PF obviously depressed galena,but had little effects on the floatability of chalcopyrite within pH range of 4.0–12.0.Zeta potential tests showed that the addition of PF induced the formation of more amounts of hydrophilic species on the surface of galena under an alkaline environment.Industrial grade O-isopropyl-N-ethyl thionocarbamate(IPETC)chemically adsorbed on the surface of the PF-treated chalcopyrite and galena after its addition.Contact angle measurements showed that with the addition of PF,the contact angle of the galena surface significantly decreased compared with the chalcopyrite surface.Localized electrochemical impedance spectroscopy(LEIS)tests showed that the addition of PF increased the impedance of the galena surface.X-ray photoelectron spectroscopy(XPS)analyses revealed that the formation of hydrophilic species,namely lead sulfite,lead hydroxide and ferric hydroxide,on the galena surface,decreased its floatability in the presence of PF,while the formation of hydrophobic species,namely copper disulfide and elemental sulfur,on the chalcopyrite surface,maintained its floatability.Finally,a descriptive model for the reaction of PF with chalcopyrite and galena was proposed.

Study on degradation mechanism of aniline solution by potassium ferrate

研究了高铁酸钾投加量、初始pH及苯胺初始浓度对苯胺降解效果的影响。结果表明，苯胺废水的COD去除率照高铁酸钾投加量和苯胺初始浓度的增大而升高，而初始pH对COD去除率影响不明显。对高铁酸钾降解苯胺废水后的产物进行了气相色谱／质谱（GC／MS）分析，在此基础上详细探讨了高铁酸钾降解苯胺的机制。

Oxidative Desulfurization of Model Sulfur Compound by Potassium Ferrate in the Presence of Phosphomolybdic Acid Catalyst

In this work, the removal of thiophene from simulated oil has been studied by using the adsorption, extraction and oxidation/adsorption methods, respectively. In the adsorptive desulfurization process, different commercial adsorbents were used to eliminate thiophene at ambient pressure and mild temperature, and the results showed that carbon powder had the best adsorption ability. In the extractive desulfurization process, the best desulfurization result was obtained when DMF is used. In the oxidative/adsorptive desulfurization procedure using synthesized potassium ferrate as the oxidant and phosphomolybdic acid solution as the catalyst, thiophene was oxidized and removed from hydrocarbons in combination with active carbon adsorption, and the residual sulfur content of simulated oil could be reduced to 15.3mg/L from the original level of 200mg/L, with the desulfurization rate reaching 92.3%.

Treatment of Phenol-Contaminated Soil by Potassium Ferrate Based on pH Control

This study aims to optimize the treatment of phenol-contaminated soil by potassium ferrate. Variations in pH value can accurately reflect the state and reaction status of the entire treatment process. Therefore, the pH value could be an important variable for optimizing the reaction conditions and achieving the automatic control of the process. About 99.89% of phenol was removed after 10 min of the pH-contxolled reaction at a rotational speed of 40-70 r/min, with the initial phenol concentration equating to 10.0 g/kg and the total water consumption reaching 2.72 L （at a soil/water ratio of 1：0.68）. The test results could provide a basis for practical application of automatic reaction control by pH value.

Preparation of Potassium Ferrate (VI) via β-Fe_2O_3

β-Fe2O3·H2O is prepared by reacting FeCl3, K2CO3, an oxidizing agent HIO4 and a metal chelating agent K3PO4 at 65~ 70℃. The prepared β-Fe2O3' H2O is introduced into the mixture of KOH, KOCl and a ferrate stabilizer KI, and reacted at room temperature for 5 h to produce a ferrate-containing cake. The cake is dried to give a water-free dried potassium ferrate (VI).

Effects of operating conditions on iron(hydr)oxides evolution and ciprofloxacin degradation in potassium ferrate-ozone stepwise oxidation system

In this study,a stepwise oxidation system of potassium ferrate(K_(2)FeO_(4))combined with ozone(O+3)was used to degrade ciprofloxacin(CIP).The effects of pH and pre-oxidation time of K_(2)FeO_(4) on the evolution of K_(2)FeO_(4) reduction products(iron(hydr)oxides)and CIP degradation were investigated.It was found that in addition to its own oxidation capacity,K_(2)FeO_(4) can also influence the treatment effect of CIP by changing the catalyst content.The presence of iron(hydr)oxides effectively enhanced the mineralization rate of CIP by catalyzing ozonation.The pH value can influence the content and types of the components with catalytic ozonation effect in iron(hydr)oxides.The K_(2)FeO_(4) pre-oxidation stage can produce more iron(hydr)oxides with catalytic components for subsequent ozonation,but the evolution of iron(hydr)oxides components was influenced by O_(3) treatment.It can also avoid the waste of oxidation capacity owing to the oxidation of iron(hydr)oxides by O_(3) and free radicals.The intermediate degradation products were identified by Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR-MS).Besides,the degradation pathways were proposed.Among the degradation products of CIP,the product with broken quinolone ring structure only appeared in the stepwise oxidation system.

高铁酸钾-过硫酸钠降解萘的效能及机理研究

为了绿色且高效地治理多环芳烃萘污染地下水,采用高铁酸钾-过硫酸钠体系降解萘,考察高铁酸钾和过硫酸钠的摩尔比、pH值和温度对萘降解效果的影响,并探究反应动力学和降解机理。研究显示,当温度为25℃,pH值为5.0,高铁酸钾和过硫酸钠的摩尔比为1∶2时,在50 min时萘最佳降解率为82.3%。采用一级反应动力学方程对萘的降解曲线进行拟合,发现其反应速率k为0.0302 min^(-1),远高于高铁酸钾体系的0.0074 min^(-1)和过硫酸钠体系的0.0034 min^(-1)的总和,表明高铁酸钾-过硫酸钠体系存在协同作用。通过对高铁酸钾-过硫酸钠体系中Fe(Ⅱ)和Fe(Ⅲ)质量浓度变化测定,显示该体系可以活化过硫酸钠且Fe(Ⅱ)和Fe(Ⅲ)质量浓度变化与萘的降解试验结果吻合。采用自由基猝灭试验和电子顺磁共振(Electron Paramagnetic Resonance,EPR)技术探究高铁酸钾-过硫酸钠体系中的活性氧化物种,发现羟基自由基(·OH)和硫酸根自由基(·SO_(4)^(-))都参与了萘的降解过程。采用气相色谱-质谱联用仪(Gas Chromatography and Mass Spectrometry,GC-MS)分析确定了3种萘的中间产物,并提出了一种可能的降解途径。研究发现,萘在降解过程中可被转化为低毒或无毒物质,表明高铁酸钾-过硫酸钠体系对萘的降解是一个渐进降低毒性的过程,可以有效降低环境风险。总之,高铁酸钾-过硫酸钠联合体系作为一种高效的清洁技术,可为治理多环芳烃萘污染地下水提供一定的理论指导。

高铁酸盐体系中高价铁氧中间体对双酚A的降解研究

以典型内分泌干扰物双酚A(BPA)为目标污染物,研究了高铁酸钾[Fe(Ⅵ)]对其的去除效果及机理。通过高效液相色谱仪、离子色谱仪等手段考察了pH、Fe(Ⅵ)投加量和共存离子等因素对BPA去除效果的影响。结果表明,在pH为8.0、Fe(Ⅵ)与BPA浓度比为30∶1时,反应10 min后BPA的降解率达到81.5%。Cl^(-)、SO_4^(2-)、NO^(-)_(3)、HCO^(-)_(3)等共存阴离子未影响Fe(Ⅵ)体系的氧化能力,但Ca^(2+)和Mg^(2+)因加速了Fe(Ⅵ)自分解而抑制了BPA降解。通过淬灭实验对体系中的活性氧物种进行识别,Fe(Ⅵ)及其高价铁氧中间体Fe(Ⅴ)/Fe(Ⅳ)在氧化BPA中起主导作用。在实际水体(自来水、市政二级出水和地下水)中,Fe(Ⅵ)氧化体系对BPA的降解未受到明显影响,证实其具有较高的环境适应性。

电解法制备高铁酸钾及对Sb(Ⅲ)去除效能的研究

实验采用电解法制备高铁酸钾固体,采用XRD、SEM及分光光度法进行表征和纯度分析,证明了纯度可达90%以上。采用K2FeO4对水体中Sb(Ⅲ)进行降解去除,实验表明,在溶液pH=5,Sb(Ⅲ)初始浓度为2?mg/L时,投加K2FeO4为50?mg/L为最优投加量。通过K2FeO4及分解产物在不同pH值下对Sb(Ⅲ)、Sb(Ⅴ)去除实验,发现K2FeO4主要通过分解产物即絮凝、吸附作用对Sb(Ⅲ)去除,去除率在90%以上,且受pH值影响小。通过K2FeO4除Sb(Ⅲ)沉淀物的XPS、FTIR表征分析,证明了Sb(Ⅲ)可以有效的被K2FeO4去除。

超声波-高铁酸钾联合处理间甲酚废水的研究

采用超声波-高铁酸钾联合法处理间甲酚废水,和单独使用高铁酸钾氧化间甲酚废水进行对比,发现在相同的高铁酸钾投加量0.8 g/L的条件下,联合法处理间甲酚废水的效果优于单独高铁酸钾法,间甲酚去除率增加接近20%。联合法处理0.1 g/L间甲酚废水时,最佳反应条件是:高铁酸钾投加量0.8 g/L,间甲酚废水溶液pH值为8,反应时间为50 min,此时间甲酚去除率为89.1%。联合法对间甲酚废水溶液pH值的兼容性较高,在pH值为7~9内,间甲酚去除率均达到87%以上。

高铁酸盐及其联用工艺在水处理中应用综述

综述了高铁酸钾的相关特性以及其在水处理应用中的研究现状,并对其在应用中所展现的优缺点进行解析,重点介绍为克服高铁酸钾单独应用中所出现的缺陷,高铁酸钾与其他技术联用的研究进展。分析了各种高铁酸钾联用技术对于水中污染物的降解原理,并对于国内外水中污染物的研究报道进行了系统的梳理,最后对高铁酸钾联用技术在未来水环境治理中的发展进行展望。

高铁酸钾与过氧化氢联用对水体中氟苯尼考的降解作用

[目的]考察高铁酸钾与过氧化氢联用对水体中氟苯尼考的降解效果。[方法]以高铁酸钾与氟苯尼考的摩尔比、过氧化氢与高铁酸钾的摩尔比、反应体系的pH值以及反应时间作为考察因素,设计4因素5水平正交试验,采用高效液相色谱法测定氟苯尼考浓度,以氟苯尼考降解率作为指标,筛选最佳降解条件。[结果]通过正交试验获得的最佳降解条件:高铁酸钾与氟苯尼考的摩尔比为45∶1、过氧化氢与高铁酸钾的摩尔比为1∶1、反应体系的pH值为7、反应时间为45 min。[结论]高铁酸钾与过氧化氢联用可有效降解水体中的氟苯尼考。

高铁酸钾处理垃圾填埋场渗滤液废水的实验研究

对高铁酸钾处理垃圾填埋场渗滤液废水方法进行研究和探讨,实验结果表明,高铁酸钾处理效果受K_(2)Fe O_(4)掺加量、处理反应时间、初始p H影响。渗滤液废水中的UV_(254)、COD_(cr)去除率随着K_(2)Fe O_(4)掺加量的增加而升高,高铁酸钾掺加量为3.0 g/L时,两项指标的去除率最高且不再上升;0~10 min内,UV_(254)去除率升高迅速,10 min后反应基本完成;p H=5时,UV_(254)、COD_(cr)两项指标去除率最高,分别可达到48.9%、50.8%。该处理方式反应后p H都会有一定程度的升高,终止条件为弱碱性时,可大大高氢氧化铁的絮凝效果。

基于RBF神经网络模型对污泥减量优化的研究

研究了温度、pH值、反应时间、高铁酸钾投加量等因素对污泥溶胞效果和分解效果的影响,并通过建立RBF神经网络模型对实验进行优化。研究结果表明,温度为60℃、反应时间为2~4 h、pH值为12、高铁酸钾投加量5.5mg/(gSS)的条件下,污泥减量处理效果显著且较为经济。此外,RBF神经网络模型计算的污泥溶胞率、污泥分解率值与实验得出的结果,两者相对误差均小于5%,验证了该模型的良好拟合性。

高铁酸钾降解隧道施工废水中苯酚的效能研究

采用高铁酸钾对两种隧道施工废水中的苯酚、COD、氨氮(NH3-N)进行去除,并分别研究高铁酸钾浓度、温度、pH、时间和苯酚浓度对苯酚去除效果的影响。采用纳氏比色法、分光光度法、高效液相色谱法对废水中的NH3-N、COD、苯酚浓度进行测定;通过设计砂柱实验,模拟真实的地下水环境系统下处理苯酚污染的地下水。结果表明:高铁酸钾去除含苯酚的隧道施工废水效果较好;施工废水中的苯酚降解随高铁酸钾的投加量增加而增加、随温度的升高而降低;施工废水中的苯酚降解在酸性条件下效果较好,随着pH的增加效果降低;同时,高铁酸钾对含苯酚的隧道施工废水中的COD、氨氮(NH3-N)去除也有一定效果。通过淬灭实验探究反应当中的产生的自由基类别。

醋酸钠和次氯酸钠对高铁酸钾溶液稳定性的影响

基于分光光度法研究了醋酸钠和次氯酸钠对高铁酸钾溶液稳定性的影响。对于1 mmol/L的高铁酸钾溶液,在25℃和pH值12的环境中,醋酸钠能提高其稳定性,当醋酸钠浓度达到10 mmol/L时,高铁酸钾的稳定性最好,静置10 h高铁酸钾的留存率约79%;为验证醋酸钠在高铁酸钾分解有机物的反应中是否仍具有稳定高铁酸钾的作用,以降解苯酚为例,当醋酸钠与高铁酸钾摩尔比为51时,苯酚的降解率达到最高值88.9%。次氯酸钠对高铁酸钾的稳定性影响实验结果显示,次氯酸钠可以提高高铁酸钾稳定性,次氯酸钠耗尽前,高铁酸钾留存率接近100%。

原水预处理中高铁酸钾及其改良技术应用研究进展

近年来高铁酸钾(K_(2)FeO_(4))作为一种绿色水处理剂在原水预处理中发挥着重要作用。K_(2)FeO_(4)可以有效地去除水中各种有机及无机污染物,并且不会产生二次污染,污染物的去除效果与药剂投加量、pH、反应时间等因素有关。K_(2)FeO_(4)具有选择性氧化以及不稳定等不足,因此,发展了K_(2)FeO_(4)的强化技术与联用技术。结合近几年国内外的研究现状,分析了K_(2)FeO_(4)联用技术与强化技术的优势与局限性,其中Fe(Ⅲ)与K_(2)FeO_(4)作用明显,有效提高污染物去除率的同时减少了水处理过程中K_(2)FeO_(4)的用量,大幅降低了处理成本,应用前景广阔。

应用物种敏感性分布评价高铁酸钾对淡水水产养殖生物的生态风险

高铁酸钾作为水质改良剂,在水产行业中已经被广泛使用,但高铁酸钾使用的安全性与淡水水产养殖生物基准值一直不明确。利用物种敏感度分布法(species sensitivity distribution,SSD)来推导高铁酸钾淡水水产养殖生物基准值,评价高铁酸钾对淡水水产养殖生物的生态风险,通过急性毒性试验法获取高铁酸钾对14种淡水水生生物的急性毒性值;选取6种拟合模型来拟合毒性数据,通过比较回归系数和残差平方和来确定拟合优度最佳的模型;推导高铁酸钾对不同类生物的5%危害浓度HC 5阈值(hazardous concentration for 5%the species)以及高铁酸钾淡水水产养殖生物及淡水水生生物基准值;结合SSD模型计算高铁酸钾对淡水水产养殖生物的潜在影响比例(potentially affected fraction,PAF)。结果显示,Sigmoid模型拟合优度最佳,高铁酸钾对全部淡水水生生物的安全基准值为6.82 mg·L^(-1),对水产养殖生物的安全基准值为9.53 mg·L^(-1);日常水产养殖高铁酸钾使用的浓度值所对应PAF值为0,生态风险低。研究结果可为高铁酸钾淡水水产养殖生物基准值制定以及安全使用提供科学依据以及理论指导。