Reaction of ortho-methoxybenzoic acid with the water disinfecting agents ozone, chlorine and sodium hypochlorite

Ozone, chlorine and sodium hypochlorite are commonly used as disinfecting agents for drinking water production. The reaction pathways of ozonation and chlorination of o-methoxybenzoic acid in aqueous solution were studied using gas chromatography-mass spectrometry (GC-MS) and high pressure liquid chromatography (HPLC). The results show that less than 1% of o-methoxybenzoic acid remains in reaction. The final major products using ozone oxidation are oxalic and glyoxalic acids. Phenols appear only at insufficient ozone levels. Sodium hypochlorite leads to higher levels of primary products. Molecular chlorine leads to the formation of higher amounts of polychlorinated derivatives. Model experiments allow to propose schemes of o-methoxybenzoic acid transformation under the conditions simulating water treatment processes.     

Waste activated sludge hydrolysis and acidification: A comparison between sodium hydroxide and steel slag addition

Alkaline treatment with steel slag and NaOH addition were investigated under different pH conditions for the fermentation of waste activated sludge. Better performance was achieved in steel slag addition scenarios for both sludge hydrolysis and acidification. More solubilization of organic matters and much production of higher VFA (volatile fatty acid) in a shorter time can be achieved at pH 10 when adjusted by steel slag. Higher enzyme activities were also observed in steel slag addition scenarios under the same pH conditions. Phosphorus concentration in the supernatant increased with fermentation time and pH in NaOH addition scenarios, while in contrast most phosphorus was released and captured by steel slag simultaneously in steel slag addition scenarios. These results suggest that steel slag can be used as a substitute for NaOH in sludge alkaline treatment.     

十二烷基苯磺酸钠的微生物降解

从长期受十二烷基苯磺酸钠(sodiumdodecylbenzenesulfonate,SDBS)污染的土壤中,筛选到3株对SDBS降解能力很强的细菌,分别为荧光假单胞杆菌(PseudomonasfluorescensP-11)、芽孢杆菌(Bacilussp.B-24)、气单胞菌(Aeromanassp.A-2)。3株细菌均属中温细菌,最适生长温度为30℃,最适生长pH为7.0,在低浓度SDBS中生长比在高浓度中生长好。在选定的最适条件下,测定了3株菌对SDBS的降解能力,在含40mg/LSDBS的培养基上,于28℃生长72h,SDBS的降解率均超过95%,其中P-11达100%。      

用于生物降解酚类毒物的固定化细胞性能改进的研究

在获得了一种耐酚能力达915mg/L的菌种的基础上,进一步研究了以海藻酸钠包埋法制得的该菌种固定化细胞的性能。同时,采用了2种方法,即添加硅藻土和用己二胺-戊二醛对固定化细胞表面进行化学处理,使固定化细胞的机械强度,降酚活性,稳定性均得到了提高。实验证明这2种方法都有令人满意的效果。      

Characteristics of a bioxalate chelating extraction process for removal of chromium,copper and arsenic from treated wood

The disposal of wood waste treated with chromated copper arsenate (CCA) is a problem in many countries. We have proposed a novel chelating extraction technique for CCA-treated wood using bioxalate, a solution of oxalic acid containing sufficient sodium hydroxide to adjust the pH to 3.2, which is an effective way to obtain an extraction efficiency of 90% for chromium, copper, and arsenic. The purpose of the present study was to investigate the characteristics of bioxalate extraction of CCA-treated wood. Extractions of CCA-treated western hemlock chips with solutions of bioxalate, oxalic acid, and sodium hydroxide were carried out. The use of bioxalate was confirmed as the most effective extraction technique for chromium, copper and arsenic, with an efficiency of 90%. Extraction with simple oxalic acid was ineffective for copper (less than 40% extraction efficiency), but effective for chromium and arsenic, with 90% efficiency. Sodium hydroxide showed a similar tendency, being ineffective for chromium and copper (less than 20% extraction efficiency), but relatively effective for arsenic (around 70–80% efficiency). We also discovered an interesting phenomenon whereby the addition of sodium hydroxide to a simple oxalic acid solution during the oxalic acid extraction progress resulted in dramatically increased extraction efficiency for copper, chromium and arsenic, up to 90%. Although oxalic acid was ineffective for copper extraction, the addition of sodium hydroxide during the oxalic acid extraction process rendered it effective.     

Effects of oil sands process-affected waters and naphthenic acids on yellow perch (Perca flavescens) and Japanese medaka (Orizias latipes) embryonic development

Syncrude Canada Ltd. is currently developing environmentally acceptable oil sands process-affected water management methods as part of their land reclamation strategy. Surface waters of the “wet landscape” reclamation option characteristically have elevated concentrations of sodium sulphate and naphthenic acids (NAs), with low levels of PAHs. The following experiment compared early-life stage responses of yellow perch (Perca flavescens) to those of Japanese medaka (Oryzias latipes) when exposed to Mildred Lake settling basin (MLSB) surface water and a commercial sodium naphthenate (Na-NA) standard. Perch eggs were fertilized and incubated in: 100%, 50%, 20%, 4%, 0.8%, and 0.16% dilutions of MLSB water, as well as 20, 10, 5, 2.5, and 1.25 mg/l solutions of the commercial standard. Medaka embryos were exposed to the same treatments, post-fertilization. Both species demonstrated an increase in the incidence of deformity, and a decrease in length at hatch as NA concentrations increased. MLSB surface water contained higher levels of NAs than the commercial standard, however, showed consistently higher NA threshold effect concentrations for both species. Significant differences between the MLSB water and the Na-NA standard suggest that they contain NA congeners with different toxicity, or other compounds such as PAHs. Species differences in thresholds could be explained by the difference in developmental stage in which the exposures were initiated.     

关于使用硫代硫酸钠溶液省略标定过程的讨论

通过实验证明使用低浓度的硫代硫酸的钠标液时,可用已配制标定好的硫代硫酸钠标准贮备液直接稀释使用,不需重新标定。此法切实可行,完全能满足样品分析的要求,既省时省力,又节约试剂,值得推广。     

燃烧器偏转-火焰原子吸收法测定水中钾钠钙镁

对采用燃烧器偏转-火焰原子吸收法测定水中钾、钠、钙、镁的仪器条件及灵敏度、检出限、测定下限、精密度、准确度进行了研究。发现该方法在没有铯盐及镧盐加入的情况下,曲线线性好、灵敏度高、精密度好、准确度高,能够满足实际分析的需要。     

The influence of reducing conditions on the dissolution of a Mn-rich slag from pyrometallurgical recycling of alkaline batteries

The redox potential (Eh) is a key parameter for controlling the release of elements from solid materials. Nevertheless, this parameter is seldom taken into account during risk assessment studies within any regulatory framework. We studied the incidence of redox changes to the solid materials using two batch procedures: i) a gradient of redox conditions obtained using sodium ascorbate solutions at various concentrations; ii) N₂ bubbling in water. These experiments were performed on two Mn-rich slag samples coming from a pyrometallurgical plant that recycles alkaline batteries. Both samples differed slightly in their chemical composition and solid characterization (i.e. presence of Mn oxide) and presented different behaviours. The present study focused on the release of the main slag elements (i.e. Mn and Si) chosen as indicators of the dissolution of primary silicate phases. Solid phase analyses (SEM-EDS and XRD) were coupled with the monitoring of elements in leachates in order to understand their behaviour and the mechanisms involved. The results indicated that the solid composition plays an important role in the release mechanisms. The presence of Mn oxide enhanced the mobilization of Mn in the greatest reducing conditions (−320 ± 5 mV/SHE), to the extent that 42% of the total Mn was leached. This demonstrated the significance in studying the solid phases (using SEM-EDS and XRD) before and after any leaching experiment. From a laboratory practice point of view, it was easier to use sodium ascorbate and allowed, in our case, greater reducing conditions to be reached.     

Comparison of UV and UV-LED activated sodium percarbonate for the degradation of O-desmethylvenlafaxine

As an active metabolite of venlafaxine and emerging antidepressant, O-desmethylvenlafaxine (ODVEN) was widely detected in different water bodies, which caused potential harm to human health and environmental safety. In this study, the comparative work on the ODVEN degradation by UV (254 nm) and UV-LED (275 nm) activated sodium percarbonate (SPC) systems was systematically performed. The higher removal rate of ODVEN can be achieved under UV-LED direct photolysis (14.99%) than UV direct photolysis (4.57%) due to the higher values of photolysis coefficient at the wavelength 275 nm. Significant synergistic effects were observed in the UV/SPC (80.38%) and UV-LED/SPC (53.57%) systems and the former exhibited better performance for the elimination of ODVEN. The degradation of ODVEN all followed the pseudo-first-order kinetics well in these processes, and the pseudo-first-order rate constant (k_obs) increased with increasing SPC concentration. Radicals quenching experiments demonstrated that both ·OH and CO₃·⁻ were involved in the degradation of ODVEN and the second-order rate constant of ODVEN with CO₃·⁻ (1.58 × 10⁸ (mol/L)⁻¹ sec⁻¹) was reported for the first time based on competitive kinetic method. The introduction of HA, Cl⁻, NO₃⁻ and HCO₃⁻ inhibited the ODVEN degradation to varying degrees in the both processes. According to quantum chemical calculation, radical addition at the ortho-position of the phenolic hydroxyl group was confirmed to be the main reaction pathways for the oxidation of ODVEN by ·OH. In addition, the oxidation of ODVEN may involve the demethylation, H-abstraction, OH-addition and C-N bond cleavage. Eventually, the UV-LED/SPC process was considered to be more cost-effective compared to the UV/SPC process, although the UV/SPC process possessed a higher removal rate of ODVEN.