Using catalytic ozonation and biofiltration to decrease the formation of disinfection by-products

The effect of catalytic ozonation in a fluidized bed reactor (FBR) on the formation of individual disinfection by-products (DBPs) was investigated. A biofiltration column was used to evaluate the removal efficiency of biotreatment on DBP precursors. Dissolved organic carbon (DOC), simulated distribution system trihalomethanes (SDS THMs), and six simulated distribution system haloacetic acids (SDS HAA6) were monitored. The source water was polluted by domestic and agricultural effluents. Catalytic ozonation removed the concentration of DOC by 8.2-51.4% depending on the dosage of the catalyst. The decreases of SDS THMs and SDS HAA6 were 41.3-51.2% and 31.7-48.3%, respectively, under the same operating conditions. Biotreatment greatly improved the removal efficiency of DOC and decreased the formation of DBPs. Up to 81.7%, 76.1%, and 81.3% of DOC, SDS THMs precursors, and SDS HAA6 precursors were removed after the catalytic ozonation followed by biofiltration, respectively. The treatment processes also influenced the proportions of individual DBP species. The proportion of bromine-containing species from the SDS THMs and SDS HAA6 increased in water samples after being treated by biofiltration alone, ozonation alone, catalytic ozonation, and catalytic ozonation followed by biofiltration.     

Absolute Configuration of β- and α-Asymmetric Carbons within β-O-4-Structures in Hardwood Lignin

In this study, we investigated the proportion of erythro- and threo-forms of β-O-4-ether structures and their enantiomeric compositions in hardwood lignin by applying the ozonation method to birch wood meal. Optical activity was not substantially observed in either the erythronic or threonic acids obtained as the ozonation products of β-O-4-structures in birch wood meal. The proportions of the four stereoisomeric forms {(αS,βR)-erythro, (αR,βR)-threo, (αS,βS)-threo, and (αR,βS)-erythro forms} were estimated to be 37-38%, 13-14%, 12-13%, and 36-37% based on the yields of erythronic and threonic acids, and on their optical activities. The proportions suggest that the entire components of β-O-4-ether structures in birch wood lignin have R- and S-configurations at the β-carbon in approximately the same quantities {(βR)-β-O-4-structure: (βS)-β-O-4-structure = 50–52:48–50}; i.e., that the β-ether structures are essentially racemic. This estimation implies that, during lignin biosynthesis, an equal number of enantiomeric forms of β-O-4-bonded quinone methides were formed by radical coupling reactions.     

活性炭催化臭氧氧化工艺对焦化废水可生化性的改善

预氧化工艺常用来提高难降解工业废水的可生化性,其中以芬顿、臭氧应用最多。该文对这两种工艺提高煤化工行业焦化废水可生化性的性能做了对比,并提出了活性炭臭氧催化预氧化的改进工艺。试验表明单纯芬顿和臭氧预氧化并不能改善焦化废水的可生化性,而活性炭臭氧催化预氧化可以改善焦化废水的可生化性。经活性炭臭氧催化预氧化的焦化废水,BOD5/COD从0.16增加到0.24,COD去除率从72.5%提高到83.0%。     

可见光下Cu2O/TiO2催化臭氧氧化头孢曲松钠性能研究

抗生素是治疗各种传染病的常用药物,但残留在水环境中的抗生素会对生态系统造成威胁。因此,探索去除水环境中抗生素的有效方法具有重要意义。由于光催化臭氧氧化技术可以高效降解和矿化水体中的污染物,该技术受到广泛关注。本工作通过浸渍-化学还原法制备Cu₂O/TiO₂复合材料并将其作为可见光催化臭氧氧化头孢曲松钠(CRO)的催化剂。利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、比表面积分析仪(BET)和紫外-可见漫反射光谱仪(UV-Vis DRS)对Cu₂O/TiO₂形貌结构和光学性能进行表征,考察了Cu₂O/TiO₂配比、Cu₂O/TiO₂投加量、臭氧浓度、头孢曲松钠初始浓度、溶液初始pH值等因素对可见光催化臭氧氧化头孢曲松钠的影响。结果表明,Cu₂O对TiO₂的掺杂改性使材料孔容和平均孔径增大,能带宽度减小,...     

Dairy Waste Water Treatment by Combining Ozonation and Nanofiltration

Abstract

The aim of this investigation was to examine the applicability of the membrane technique and the effect of preozonation in dairy waste water treatment technology. The best degree of surfactant removal from model anionic surfactant solution by nanofiltration was achieved at 20°C and 40 bar. Investigations on the effects of ozone treatment of the waste water indicated that preozonation decreased the flux and increased the chemical oxygen demand and surfactant removal efficiency. Ozone treatment enhanced the biodegradability of the retentate from 68.8% to 96.4%.     

Ozonation of complex industrial park wastewater: effects on the change of wastewater characteristics

BACKGROUND: Ozonation of complex industrial park wastewater was carried out in a semi‐batch reactor. The variation of wastewater characteristics was evaluated based on the analysis of 5‐day biochemical oxygen demand (BOD₅) concentration, BOD₅/chemical oxygen demand (COD) ratio, COD fractionation, and dissolved organic carbon (DOC) molecular size distribution before and after ozonation. RESULTS: The experimental results indicated that low efficiency of COD removal with increasing tendency of BOD₅ concentration generally appeared after ozonation. Also, the BOD₅/COD ratio increased from an initial of 0.27 to a maximum of 0.38. The COD fractionation tests revealed that most of the inert soluble COD was transformed to biodegradable soluble COD at 30 min of reaction time. Additionally, the DOC molecular size distribution tests showed that the fraction larger than 500 kDa was significantly decreased and the fraction smaller than 2 kDa was increased when the reaction time was prolonged to 240 min. CONCLUSION: This study verified that partial oxidation of the complex industrial park wastewater by ozonation could enhance wastewater biodegradability. The biodegradability enhancement was primarily because the inert soluble COD fraction was converted to the biodegradable soluble COD and the high molecular weight fraction of DOC was shifted toward the low molecular weight fraction. Copyright © 2009 Society of Chemical Industry     

The Effect of Ozonation on Particle Removal in Drinking-Water Treatment

The effect of the introduction of additional process stages in a surface-water treatment plant was studied in order to investigate how particle removal could be optimized. Particle counting is considered to be a useful indicator of treatment performance. This paper is based on results which were obtained from trials on a water-treatment plant treating surface water; these consisted of a combination of modifications to existing full-scale plant and a specially constructed pilot plant.     

Efficient ozonation of reverse osmosis concentrates from petroleum refinery wastewater using composite metal oxideloaded alumina

Novel Mn–Fe–Mg-and Mn–Fe–Ce-loaded alumina(Mn–Fe–Mg/Al_2O_3 and Mn–Fe–Ce/Al_2O_3) were developed to catalytically ozonate reverse osmosis concentrates generated from petroleum refinery wastewaters(PRW-ROC). Highly dispersed 100–300-nm deposits of composite multivalent metal oxides of Mn(Mn~(2+)), Mn~(3+),and Mn~(4+), Fe(Fe~(2+))and Fe~(3+) and Mg(Mg~(2+)), or Ce(Ce~(4+)) were achieved on Al_2O_3 supports. The developed Mn–Fe–Mg/Al_2O_3 and Mn–Fe–Ce/Al_2O_3 exhibited higher catalytic activity during the ozonation of PRW-ROC than Mn–Fe/Al_2O_3, Mn/Al_2O-3, Fe/Al_2O_3, and Al_2O_3. Chemical oxygen demand removal by Mn–Fe–Mg/Al_2O_3-or Mn–Fe–Ce/Al_2O_3-catalyzed ozonation increased by 23.9% and23.2%, respectively, in comparison with single ozonation.Mn–Fe–Mg/Al_2O_3 and Mn–Fe–Ce/Al_2O_3 notably promoted áOH generation and áOH-mediated oxidation. This study demonstrated the potential use of composite metal oxide-loaded Al_2O_3 in advanced treatment of bio-recalcitrant wastewaters.     

Effect of biological and chemical oxidation on the removal of estrogenic compounds (NP and BPA) from wastewater: an integrated assessment procedure

A major source of the wide presence of EDCs (Endocrine Disrupting Compounds) in water bodies is represented by direct/indirect discharge of sewage. Recent scientific literature reports data about their trace concentration in water, sediments and aquatic organisms, as well as removal efficiencies of different wastewater treatment schemes. Despite the availability of a huge amount of data, some doubts still persist due to the difficulty in evaluating synergistic effects of trace pollutants in complex matrices. In this paper, an integrated assessment procedure was used, based on chemical and biological analyses, in order to compare the performance of two full scale biological wastewater treatment plants (either equipped with conventional settling tanks or with an ultrafiltration membrane unit) and tertiary ozonation (pilot scale).Nonylphenol and bisphenol A were chosen as model EDCs, together with the parent compounds mono- and di-ethoxylated nonylphenol (quantified by means of GC-MS). Water estrogenic activity was evaluated by applying the human breast cancer MCF-7 based reporter gene assay. Process parameters (e.g., sludge age, temperature) and conventional pollutants (e.g., COD, suspended solids) were also measured during monitoring campaigns.Conventional activated sludge achieved satisfactory removal of both analytes and estrogenicity. A further reduction of biological activity was exerted by MBR (Membrane Biological Reactor) as well as ozonation; the latter contributed also to decrease EDC concentrations.     

淮安经济开发区水厂臭氧生物活性炭深度处理工艺设计

淮安经济开发区水厂总规模为20×104 m3/d,一期工程为10×104 m3/d,是目前苏北地区规模最大的具有深度处理工艺的新建水厂项目。针对水源水质条件和现行的生活饮用水水质标准,在参考并借鉴类似水厂成功经验的基础上采用了预臭氧/折板絮凝平流沉淀/后臭氧/微絮凝/上向流活性炭吸附/石英砂过滤/消毒处理工艺。介绍了该工程的工艺选择、参数确定及主要处理构筑物的工艺设计。