Photocatalytic ozonation-based degradation of phenol by ZnO—TiO_(2)nanocomposites in spinning disk reactor

Spinning disk reactor(SDR)has emerged as a novel process intensification photocatalytic reactor,and it has higher mass transfer efficiency and photon utilization for the degradation of toxic organic pollutants by advanced oxidation processes(AOPs).In this study,ZnO—TiO_(2)nanocomposites were prepared by solgel method,and coated on the disk of SDR by impregnation-pull-drying-calcination method.The performance of catalyst was characterized by X-ray diffraction,scanning electron microscope,X-ray photoelectron spectroscopy,photoluminescence and ultraviolet—visible diffuse reflectance spectroscopy.Photocatalytic ozonation in SDR was used to remove phenol,and various factors on degradation effect were studied in detail.The results showed that the rate of degradation and mineralization reached 100%and 83.4%under UV light irradiation after 50 min,compared with photocatalysis and ozonation,the removal rate increased by 69.3%and 34.7%,and mineralization rate increased by 56.7%and 62.9%,which indicated that the coupling of photocatalysis and ozonation had a synergistic effect.The radical capture experiments demonstrated that the active species such as photogenerated holes(h^(+)),hydroxyl radicals(·OH),superoxide radical(·O_(2)-)were responsible for phenol degradation,and·OH played a leading role in the degradation process,while h+and·O_(2)^(-)played a non-leading role.

Heterogeneous catalytic ozonation by amorphous boron for degradation of atrazine in water

As one of the most promising and practical advanced oxidation processes(AOPs),the catalytic ozonation is triggered by the active components of catalyst,which are usually derived from metals or metal oxides.To avoid the metal pollution from catalyst,here the amorphous boron(A-boron)is used as a metalfree catalyst for catalytic ozonation to produce free radicals for effective degradation of atrazine(ATZ),the world-widely used herbicide and also a widespread pollutant in environment.A-boron exhibits an outstanding performance for catalytic ozonation to remove ATZ from water.As A-boron is introduced into ozonation,the degradation efficiency in 10 min is promoted to 97.1%,much higher than that of 15.1%under ozonation.The mechanism is that the B-B bonds and internal suboxide B in A-boron serve as the main active sites to donate electrons to accelerate ozone decomposition to produce reactive oxygen species(ROS),including·O_(2)^(-)and^(1)O_(2),and further enhance ATZ degradation via ROS reactions.Moreover,the A-boron is still highly active with a degradation efficiency of ATZ over 95%in 10 min even after four successive cycles.This work shows A-boron could be an alternative for the active components of metal or metal oxide in catalytic ozonation.

Treatment of coking wastewater using oxic-anoxic-oxic process followed by coagulation and ozonation

An oxic-anoxic-oxic(O-A-O)system followed by coagulation and ozonation processes was used to study the treatment of coking wastewater.In the O-A-O process,the removals of NH4+-N,total nitrogen and COD were 91.5-93.3%,91.3-92.6%and 89.1-93.8%,respectively when employing hydraulic residence times of 60 h for the biochemical system.High removal of NH4+-N was obtained due to the placement of an aerobic tank in front of A-O system which can mitigate the inhibitory effect of toxic compounds in coking wastewater on nitrifying bacteria.Addition of methanol into the anoxic reactor greatly increased the removal of total nitrogen,indicating that denitrifiers can hardly use organic compounds in coking wastewater as carbon source for denitrification.COD values of the effluent from the O-A-O system were still higher than 260 mg/L even with a prolonged time of 160 h mainly due to the high refractory properties of residual compounds in the effluent.The subsequent coagulation and ozonation processes resulted in the COD removal of 91.5%-93.3%and reduced the relative abundance of large molecular weight(MW)organics(>1 kDa)from 55.8%to 20.93%with the ozone,PAC and PAM dosages of 100,150 and 4 mg/L respectively.Under these conditions,the COD value and concentration of polycyclic aromatic hydrocarbons in the final effluent were less than 80 and 0.05 mg/L,respectively,which meet the requirement of the Chinese emission standard.These results indicate that the combined technology of O-A-O process,coagulation and ozonation is a reliable way for the treatment of coking wastewater.

Recycle of Wastewater from Lead-Zinc Sulfide Ore Flo-tation Process by Ozone/BAC Technology

Lead-zinc sulphide ore contains lead sulphide (galena), and zinc sulphide (sphalerite). In the first flotation stage, galena is rendered hydrophobic with an organic collector such as xanthate, while sphalerite is kept from floating by depressants, and in the second flotation stage, activator was used to activated zinc flotation. Since the organic regent used are different in the two flotation stage, wastewater from the second zinc flotation stage can’t be directly recycled to the first lead flotation stage. Wastewater from flotation process for concentrating lead-zinc sulphide ore often containing organic compounds such as diethyldithiocarbamate(DDTC), xanthate, terpenic oil(2# oil) and thionocarbamate esters (Z-200), are environmentally hazardous. Their removal from contaminated water and the reuse of the water is one of the main challenges facing lead-zinc sulphide ore processing plants. In this study, synthetic wastewater containing DDTC, xanthate, 2# oil and Z-200 at concentrations ranging from 21 to 42 mg/L was fed into an Ozone/Biological activated carbon (BAC) reactor. Analyses of the effluent indicated a chemical oxygen demand (COD) removal over 86.21% and Total organic carbon (TOC) removal over 90.00% were achieved under Hydraulic retention time (HRT) of 4h and O3 feeding concentration of 33.3mg/L. The effluent was further recycled to the lab scale lead concentrating process and no significant difference was found in compare with fresh water. Furthermore, lead-zinc sulphide mineral concentrating process was carried out at lab scale. The produced wastewater was treated by Ozone/BAC reactor at O3 feeding concentration of 16.7mg/L and HRT of 4h. The effluent analysis showed that TOC removal was 74.58%. This effluent was recycled to the lab scale lead-zinc sulphide mineral concentrating process and the recovery of lead was not affected. The results showed that by using Ozone/BAC technology, the lead-zinc sulphide mineral processing wastewater could be recycled.

Identification of resistant pharmaceuticals in ozonation using QSAR modeling and their fate in electro-peroxone process

The abatements of 89 pharmaceuticals in secondary effluent by ozonation and the electro-peroxone(E-peroxone)process were investigated.Based on the results,a quantitative structure-activity relationship(QSAR)model was developed to explore relationship between chemical structure of pharmaceuticals and their oxidation rates by ozone.The orthogonal projection to latent structure(OPLS)method was used to identify relevant chemical descriptors of the pharmaceuticals,from large number of descriptors,for model development.The resulting QSAR model,based on 44 molecular descriptors related to the ozone reactivity of the pharmaceuticals,showed high goodness of fit(R^(2)=0.963)and predictive power(Q^(2)=0.84).After validation,the model was used to predict second-order rate constants of 491 pharmaceuticals of special concern(k_(O_(3)))including the 89 studied experimentally.The predicted k_(O_(3))values and experimentally determined pseudo-first order rate constants of the pharmaceuticals’abatement during ozonation(k_(OZ))and the E-peroxone process(k_(EP))were then used to assess effects of switching from ozonation to the E-peroxone process on removal of these pharmaceuticals.The results indicate that the E-peroxone process could accelerate the abatement of pharmaceuticals with relatively low ozone reactivity(k_(O_(3))<∼10^(2)M^(−1)⋅s^(−1))than ozonation(3–10 min versus 5–20 min).The validated QSAR model predicted 66 pharmaceuticals to be highly O_(3)-resistant.The developed QSAR model may be used to estimate the ozone reactivity of pharmaceuticals of diverse chemistry and thus predict their fate in ozone-based processes.

AO+芬顿反应池+BAC组合工艺处理电厂循环外排水的应用

某电厂循环外排水主要来源于电厂循环水系统中凝汽器不断循环,使机组降温的水。有可生化性较差、有机物浓度较低、硬度较大等特点,某电厂的综合污水处理厂采用AO+芬顿反应池+BAC组合工艺处理此污水,出水水质执行《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A排放标准,结果显示,AO+芬顿反应池+BAC组合工艺能使出水稳定达到标准。

Mechanism of Formation of the Ozone Valley over the Tibetan Plateau in Summer-Transport and Chemical Process of Ozone

With the 3D chemical transport model OSLO CTM2, the valley of total column ozone over the Tibetan Plateau in summer is reproduced. The results show that when the ozone valley occurs and develops, the transport process plays the main part in the ozone reduction, but the chemical process partly compensates for the transport process. In the dynamic transport process of ozone, the horizontal transport process plays the main part in the ozone reduction in May, but brings about the ozone increase in June and July. The vertical advective process gradually takes the main role in the ozone reduction in June and July. The effect of convective activities rises gradually so that this effect cannot be overlooked in July, as its magnitude is comparable to that of the net changes. The effect of the gaseous chemical process brings about ozone increases which are more than the net changes sometimes, so the chemical effect is also important.

Degradation of 2,4-dichlorophenoxyacetic acid in water by ozonehydrogen peroxide process

This study reports an investigation into the degradation of 2,4-dichlorophenoxyacetic acid in bubble contactor column by O2/H2O2 process, which is widely used as a principal advanced oxidation process. The degradation of 2,4-dichlorophenoxyacetic acid was studied under different H202/O3 molar ratio and pH value. Meanwhile, TOC removal was investigated both in distilled water and tap water. The influences of ozone transfer and consumed hydrogen peroxide were also discussed. The degradation products and oxidation intermediates were identified by GC-MS and LC-MS. A possible reaction mechanism was thus proposed.

Controlling of crustacean zooplankton reproduction in biological activated carbon (BAC) filters by strengthen operation and management of conventional process

To counter the mass reproduction and penetration of crustacean zooplankton in Biological Activated Carbon(BAC)filters which may result in the presence of organisms in potable water and water pollution,this paper analyzed the factors affecting organisms' reproduction in BAC filters.A comparative study was performed on the density and composition of crustacean zooplankton of the concerned water treatment units of two advanced water plants(Plant A and B)which with the same raw water and the same treatment technique in southern China.The results obtained show that the crustaceans' density and composition was very different between the sand filtered water of Plant A and Plant B.which Harpacticoida bred sharply in the sediment tanks and penetrated sand filter into BAC filters was the primary reason of crustaceans reproduce in BAC filters of Plant A.For prevention of the organisms reproduction in BAC,some strengthen measures was taken including pre-chlorination,cleaning coagulation tanks and sediment tanks completely,increasing sludge disposal frequency to stop organisms enter BAC filters,and the finished water quality was improved and enhanced.

基于新有机污染物风险控制的UV/H_(2)O_(2)-BAC深度处理技术优化与应用

《生活饮用水卫生标准》(GB 5749-2022)新国标的颁布实施对饮用水高效净化提出了新的挑战。现状常规与深度处理工艺对新污染物去除能力有限,紫外/过氧化氢-生物活性炭(UV/H_(2)O_(2)-BAC)组合工艺是一种可行的饮用水深度处理技术。文中提出了UV/H_(2)O_(2)-BAC工艺组成、设计要点,并与O_(3)-BAC工艺进行技术经济对比分析,结合UV高级氧化技术中试研究结果及实际工程应用案例,总结评估了UV高级氧化深度处理工艺的运行效果及运行管理要求,以期为水厂深度工艺选择提供可行的工程技术方案。

无机催化剂对O_(3)-BAC工艺出水降解效果研究

针对O_(3)工艺降解效率低下、出水可生化性低的问题,在连续流O_(3)-BAC组合工艺中投加无机催化剂,对某工业园区污水处理厂MBR出水进行降解试验,研究了无机催化剂对O_(3)段废水COD、UV_(254)和TOC的降解效果提升影响,以及其出水对BAC段COD的降解效果提升影响。结果表明,在相同的反应条件下,无机催化剂对组合工艺O_(3)段和BAC段处理效果都有较大提升,最优条件下O_(3)段的COD、UV_(254)、TOC的降解率分别为23.5%、41%和43.2%,BAC段COD降解率为39.3%;BAC段微生物Shannon指数、聚类单元数和Chao指数分别上升了1.9、87、40.7。Ca、Al复合催化剂降解效果要优于分别以Ca和Al为单组分的催化剂。结果表明无机催化剂可明显提升O_(3)-BAC组合工艺处理效果。

气象要素与前体物排放对中国区域性臭氧污染的影响

2022年9月,中国出现了多次区域性臭氧污染过程,污染较重的区域主要集中于华南与华北。全国339个城市中,共出现了1844天次的臭氧超标情况,其中重度污染3天次(均出现在珠三角)、中度污染123天次、轻度污染1718天次。中国华北与华南等地长期处于台风外围下沉气流影响区,容易出现持续干燥少雨、风速偏低、气温持续偏高的气象特征,有利于臭氧的生成与积累,是造成该时期臭氧污染过程持续时间长、影响范围广、污染程度重的重要原因。臭氧超标天数较多的城市一般具有较高的NO_(2)浓度与挥发性有机化合物臭氧生成潜势(OFP),其中NO_(2)一般在30μg/m^(3)左右、OFP一般超过100μg/m^(3),通过相关性分析与多元线性回归方法,得出区域性臭氧污染受NO_(2)影响更显著的结论。可见,当前中国华南与华北等地臭氧前体物排放量仍较大,在不利气象条件下,臭氧前体物累积加剧了臭氧污染。

陶瓷膜在饮用水处理中的应用现状

水是人类生存所必需的资源。近年来,我国的饮用水水质标准不断提高。为了满足更高的标准,自来水厂开始使用膜过滤技术取代传统过滤技术。作为一种先进的水处理技术,膜过滤技术已经在各个领域得到广泛应用。与有机膜相比,陶瓷膜具有化学性能稳定、耐酸碱、热稳定性好、机械强度高、回收率高、使用寿命长等优点,在饮用水领域有更广阔的应用前景。本文旨在阐述陶瓷膜的结构特点和过滤机理,并探讨陶瓷膜在饮用水处理中的研究进展。通过对陶瓷膜饮用水处理工艺进行分析,发现原水经过混凝、吸附、臭氧氧化预处理后,陶瓷膜的过滤性能有明显的提升。文章还分析了陶瓷膜的抗污染性能,并强调了其在维护成本方面的优势。最后,对优化陶瓷膜成本、多元陶瓷膜集成工艺和陶瓷膜大规模运行成本估算等未来研究方向进行了展望。

O_3/BAC工艺应用于城市污水深度处理

为使再生水适合不同用途,对经过混凝沉淀和砂滤处理的再生水进行了臭氧—生物活性炭的深度处理。在臭氧消耗量和反应时间分别为5mg/L和10min,BAC空床停留时间(EBCT)为10min的条件下,臭氧—生物活性炭工艺对CODMn、DOC、UV254和色度平均去除率为32.4%、29.2%、48.6%和80.1%,出水CODMn、DOC、UV254和色度的平均值分别为3.3mg/L、4.0mg/L、0.05cm-1和2.0倍;臭氧生物活性炭工艺出水SDI<4,从而满足了反渗透系统的进水要求。

O_3/BAC对氯化消毒副产物的控制作用

采用臭氧化—生物活性炭 (O3/BAC)深度处理工艺去除水中消毒副产物前质的试验结果表明 ,该工艺能够有效去除水中消毒副产物前质 ,可控制氯化消毒副产物的生成 ,其中主臭氧化对三卤甲烷前质和卤乙酸前质均具有很好的去除效果 ,生物活性炭对卤乙酸前质表现出较好的去除效果 ,但对三卤甲烷前质的去除效果有限 ;藻类、有机物等在滤层的累积使得砂滤池在同一工作周期中的不同阶段对水中三卤甲烷前质的去除效果有所不同 ,因而需要合理设置砂滤池的反冲洗周期。臭氧化—生物活性炭工艺充分发挥了臭氧化和生物活性炭两种技术的优点 ,并相互促进和补充 。

预臭氧-BAC工艺处理微污染原水参数优化与有机物去除特性

采用中试装置研究了预臭氧-生物活性炭工艺对长江南京段微污染原水有机物的去除特性,考察了臭氧投加量和臭氧接触时间对预臭氧氧化、砂滤及生物活性炭单元中DOC、BDOC、CODMn、UV254和微量有机污染物去除的影响。结果表明当臭氧投加量为3 mg/L、臭氧接触时间为10 min时,预臭氧氧化单元中DOC、CODMn和UV254的去除率分别达到19%、31%和78%,BDOC增长了33%;砂滤单元四种指标的去除率分别为25%、52%、42%和44%,而生物活性炭滤柱对四种污染物指标的去除率分别为46%、83%、52%和20%,高于常规处理工艺。整个工艺对三种微量有机物(1,2,4-三氯苯、DMP和DEHP)的去除率也分别达到了60%、68.6%和68.8%。与未投加臭氧相比,臭氧的投加有效促进了砂滤和生物活性炭对有机污染物的去除。采用预臭氧-生物活性炭工艺处理微污染长江原水,有效提高了有机污染物的去除效果,可保障出水水质安全。

应用Illumina MiSeq高通量测序技术解析O_3-BAC饮用水处理过程细菌多样性变化

采用Illumina MiSeq高通量测序技术,对臭氧-生物活性炭水处理工艺过程各单元出水中细菌多样性及丰度进行研究,测序获得196 809条16S r DNA基因序列,归类为38个门,522个属。各样品中细菌多样性分析结果表明:在各处理单元出水中细菌群落具有高度多样性,预臭氧和臭氧氧化处理对水体中细菌多样性及丰度的影响最大,可杀灭一部分属的细菌,可合理控制臭氧浓度杀灭部分耐氯菌;絮凝沉淀和沙滤单元处理对水体中细菌多样性具有恢复效果,使水体中细菌种属进一步增多;在生物活性炭滤池处理后,细菌多样性增加,丰度分布更为均匀,对后期消毒工艺提出了更高的要求。

臭氧处理对晚熟柑橘的采后贮藏品质变化及杀菌效果分析

针对柑橘采后贮藏期间存在品质下降及腐坏的问题,该研究以晚熟柑橘为试验材料探讨不同臭氧处理时间对其采后贮藏保鲜效果。结果表明,持续25 d每日固定浓度不同时间的臭氧处理对晚熟柑橘品质有显著影响:臭氧每日处理1 min能显著降低柑橘失重率,贮藏25 d仅为CK组的59.90%;每日处理10 min可较好维持柑橘可溶性固形物(TSS)含量,贮藏结束时为9.20%;臭氧处理可延缓柑橘Vc含量的下降,显著抑制多酚氧化酶(PPO)、超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性,降低柑橘果皮表面微生物数量,但臭氧处理时间对柑橘硬度、可滴定酸(TA)含量、固酸比没有显著影响;每日处理1、10、20和40 min可抑制柑橘丙二醛(MDA)含量的增加,提升过氧化物酶(POD)活性,每日处理40 min还可显著提升柑橘总多酚含量(TPC)和总黄酮含量(TFC);主成分分析臭氧每日处理10和40 min柑橘综合品质较佳,从经济性和安全性方面考虑,臭氧每日处理10 min可作为晚熟柑橘采后贮藏期间的适宜保鲜手段。

上向流O_3-BAC工艺处理微污染湖泊水研究

以我国华东地区某湖泊水为原水,进行中试规模的上向流臭氧生物活性炭(O3—BAC)工艺研究,考察该工艺去除水中有机物的能力,以及工艺出水的生物稳定性和化学安全性。研究结果表明:该工艺能有效去除有机物、氨氮和消毒副产物前体物,同时能提高出水的生物稳定性。该工艺出水CODMn、UV254和DOC的平均值分别为2.31mg/L、0.034cm-1和1.76mg/L,平均去除率为53.4%、67.3%和65.1%;三卤甲烷,卤乙酸和亚硝胺类副产物生成潜能的平均去除率分别为50.3%,59%和96.6%;AOC平均去除率为54.5%;工艺出水BDOC仅为0.56mg/L;且出水未检出BrO3-。因此,O3—BAC工艺适合处理该湖泊水且出水水质安全。

O_3—BAC工艺处理微污染地表水的试验研究

采用预臭氧—曝气生物活性炭滤池(O_3—BAC)工艺处理低碳源的北运河通州段原水,探讨了该系统的主要工艺参数与各项污染物去除效果的相关性。研究结果表明,臭氧的投加对提高COD_(Cr)和NH_3—N的去除效果均有促进作用,且在投加量3 mg/L、接触时间30 min时臭氧利用效率最高;在此投加量和接触时间、回流比1:1时,COD_(Cr)和NH_3—N的去除率分别可达42%和94.3%,均高于回流比为0.5:1时,而TN去除率为13.4%,有所降低,投加外碳源和降低好氧单元气水比可使之升高;系统对UV_(254)去除率达到38.8%,其中臭氧接触单元去除率为18.66%,由臭氧氧化特性推断,原水中大分子有机物以芳香族化合物为主。