Reaction mechanism and metal ion transformation in photocatalytic ozonation of phenol and oxalic acid with Ag+/TiO2

Photocatalytic ozonation of phenol and oxalic acid （OA） was conducted with a Ag^＋/TiO2 catalyst and different pathways were found for the degradation of different compounds. Ag^＋ greatly promoted the photocatalytic degradation of contaminants due to its role as an electron scavenger. It also accelerated the removal rate of OA in ozonation and the simultaneous process for its complex reaction with oxalate. Phenol could be degraded both in direct ozonation and photolysis, but the TOC removal rates were much higher in the simultaneous processes due to the oxidation of hydroxyl radicals resulting from synergetic effects. The sequence of photo-illumination and ozone exposure in the combined process showed quite different effects in phenol degradation and TOC removal. The synergetic effects in different combined processes were found to be highly related to the properties of the target pollutants. The color change of the solution and TEM result confirmed that Ag＋ was easily reduced and deposited on the surface of Tit2 under photo-illumination, and dissolved again into solution in the presence of ozone. This simple cycle of enrichment and distribution of Ag^＋ can greatly benefit the design of advanced oxidation processes, in which the sequences of ozone and photo-illumination can be varied according to the needs for catalyst recycling and the different properties of pollutants.     

改良UNITANK工艺在东鄱污水处理厂的应用分析

介绍了改良UNTIANK工艺在东鄱污水处理厂的应用情况,对比传统UNITANK工艺与改良UNTIANK工艺在除磷脱氮方面的去除效果,并讨论改良UNITANK工艺的结构、运行方式、工艺特点及存在问题,得出相关结论。     

Nitrogen mass balance in a constructed wetland treating piggery wastewater effluent

The nitrogen changes and the nitrogen mass balance in a free water surface flow constructed wetland （CW） using the four-year monitoring data from 2008 to 2012 were estimated. The CW was composed of six cells in series that include the first settling basin （Cell 1）, aeration pond （Cell 2）, deep marsh （Cell 3）, shallow marsh （Cell 4）, deep marsh （Cell 5） and final settling basin （Cell 6）. Analysis revealed that the NH4＋-N concentration decreased because of ammonification which was then followed by nitrification. The NO4＋-N and NO4＋-N were also further reduced by means of microbial activities and plant uptake during photosynthesis. The average nitrogen concentration at the influent was 37,819 kg/year and approximately 45% of that amount exited the CW in the effluent. The denitrification amounted to 34% of the net nitrogen input, whereas the accretion of sediment was only 7%. The biomass uptake of plants was able to retain only 1% of total nitrogen load. In order to improve the nutrient removal by plant uptake, plant coverage in four cells （i.e., Cells 1, 3, 4 and 5） could be increased.     

制备工艺对La改性湿式氧化催化剂活性和稳定性的影响

采用CWAO(催化湿式空气氧化)法处理甲基橙模拟印染废水,以过量浸渍法制备催化剂,以水样COD Cr去除率和脱色率表征催化剂的活性,以催化剂使用后处理出水中溶出的金属离子质量浓度表征催化剂的稳定性.结果表明,多组分催化剂的金属组分构成为Cu、Fe、La,m(Cu)∶m(Fe)∶m(La)为1∶1∶2,35℃下动态共浸渍8 h,450℃下焙烧3 h,由此制备得到Cu-Fe-La/FSC催化剂.应用该催化剂,以CWAO法处理模拟印染废水,废水COD Cr去除率和脱色率可分别达到79.1%和98.9%,催化剂的活性较高;使用该催化剂处理后的废水中Cu、Fe、La、Al的溶出量(以ρ计)分别为6.1、2.4、2.2、3.2 mg/L,说明金属元素的溶出量较低,催化剂的稳定性较高.     

利用淀粉/PCL共混物作为反硝化固体碳源和生物膜载体的研究

以双螺杆挤出机制备了淀粉聚己内酯(PCL,polycaprolactone)共混物(SPCL5),研究了其浸出性能及吸水性能,并在序批试验中研究了其作为反硝化固体碳源和生物膜载体的特性。结果表明,SPCL5颗粒前3 d浸出的有机物浓度较高,随后逐渐降至1.31 mgL。SPCL5颗粒吸水率在1 d左右达到饱和,约为30.97%。SPCL5可作为固体碳源用于去除低碳氮比(CN)水中的硝酸盐。以活性污泥接种时,SPCL5颗粒在1 d后就有显著的脱氮效果。驯化结束后,SPCL5颗粒的平均反硝化速率(以N计)为0.020 8 mg(g·h)。剪切力是影响反硝化速率的重要因素,转速从70 rmin提高至140 rmin时,平均反硝化速率提升近1倍,达到0.040 3 mg(g·h)。进水NO3-N浓度为15~50 mgL时对反硝化速率无显著影响,反硝化为零级反应。红外光谱结果表明利用后的共混物中淀粉和PCL均发生了降解。     

辽河保护区七星湿地表层水与间隙水中氮的时空分布

将大型人工湿地工程技术应用于支流河口,可以有效减轻干流污染物负荷。研究了辽河流域典型支流河口湿地的营养盐迁移转化特征。利用2012年5—7月的采样监测数据分析辽河保护区七星湿地表层水和间隙水中不同形态氮的时空分布规律。结果表明,氨氮浓度为表层水小于间隙水,而硝氮和亚硝氮浓度为表层水高于间隙水;氨氮、硝氮以及亚硝氮浓度随空间的变化趋势均体现为支流河入口处浓度较高,湿地中部及出口处浓度明显降低。水体氨氮浓度表现出随时间推移呈逐渐下降的趋势,硝氮和亚硝氮浓度呈现波动。七星湿地3个月内的氨氮总去除量为1.99 t。     

钦州湾无机氮入海通量及其富营养化症状分析

根据对环钦州湾区域的入海河流、直排海污染源及养殖废水无机氮入海通量的估算,2011年钦州湾无机氮入海通量约为7 655 t,其中入海河流无机氮入海通量占总量的96.4%,直排海污染源次之。入海无机氮占钦州湾无机氮总量的比重为36.7%,说明钦州湾已属中等强度人为影响海域。根据对钦州湾富营养化症状——叶绿素a含量的分析,钦州湾富营养化症状不明显,钦州湾整体的富营养化程度较低。因而仅以营养盐含量评价目标海域的富营养化程度,易失之偏颇,宜结合富营养化症状来判断目标海域的富营养化程度。     

低碳高氮污水处理应用技术研究

针对碳氮比小于7的污水,其碳源不能满足硝化与反硝化的要求这一问题,通过改变SBR工艺的运行方式、调解工艺参数等技术手段,使其能够达标处理此类工业废水,并通过某淀粉厂的工程实例进行了验证:采用改良的SBR工艺可以对低碳高氮污水进行有效的处理。     

上海某饮用水源地不同形态氮的时空分布研究

在2010~2012年进行的上海某水源地水质监测资料的基础上,应用纳氏试剂分光光度法等分析方法研究该水源地2011年1~10月总氮、氨氮、硝酸盐氮、亚硝酸盐氮等不同形态的氮素在水体中的空间分布规律及时间变化规律。并就其氮的来源、迁移转化机理和对氮的迁移转化有较大影响的因素进行研究和分析,得出该水库水体中各种形态氮以硝酸盐氮为主,平均占总氮的71.6%,氨氮及亚硝酸盐氮各占总氮的4.39%及0.95%;水体中的温度、光照条件、溶解氧、点位位置分布、水深等是影响各氮形态含量与分布的重要环境因子。     

SBR法处理低C/N污水的工程应用——以某基地污水处理站改造工程为例

低C/N污水的生化处理过程中,由于碳源不足,不能满足硝化和反硝化的要求,造成出水NH3-N超标。采用SBR工艺对某基地污水处理站厌氧处理后的低C/N污水进行改造,处理后出水COD去除率达到97%以上,NH3-N去除率达到93%以上。