Visible-light-induced photocatalytic reduction of Cr(VI) with coupled Bi2O3/TiO2 photocatalyst and the synergistic bisphenol A oxidation

Coupled Bi₂O₃/TiO₂ photocatalysts were fabricated by sol–gel and hydrothermal methods and characterized using various spectroscopy techniques. Photocatalytic reduction of Cr(VI) in aqueous solution, together with the synergistic effect of photodegradation of bisphenol A (BPA), was investigated using these coupled Bi₂O₃/TiO₂ under visible-light irradiation. Coupling of Bi₂O₃ inhibited the phase transformation from anatase to rutile and extended absorption region to visible light. Bi ions did not enter TiO₂ lattice and were more likely to bond with oxygen atoms to form Bi₂O₃ on the surface of TiO₂. Photovoltage signals in visible range revealed the effective interfacial charge transfer between Bi₂O₃ and TiO₂. Two percent Bi₂O₃/TiO₂ exhibited the highest photocatalytic activity of visible-light-induced reduction of Cr(VI). The addition of BPA effectively increased the photocatalytic reduction of Cr(VI). Simultaneously, the presence of Cr(VI) promoted the degradation of BPA, which was demonstrated by the investigation of TOC removal yield and generated intermediates. A possible mechanism of photocatalytic reduction of Cr(VI) and degradation of BPA in Bi₂O₃/TiO₂ system was proposed. The synergistic effect, observed between reduction of Cr(VI) and degradation of BPA, provides beneficial method for environmental remediation and purification of the complex wastewater.     

菇渣作为有机栽培基质好氧改性的实验

研究分别以珍珠岩、菌种、猪粪作为添加料,对菇渣静态垛好氧发酵效果的影响。结果表明,菇渣+猪粪处理50℃以上的高温维持时间更长,挥发性固体(VS)和C/N下降幅度更高,有利于菇渣好氧发酵达到腐熟的状态。堆体内温度出现层次效应,高温发酵阶段下层温度高于中层温度,稳定阶段中层温度高于下层,堆体上层温度始终低于中下层。     

物化-生化组合工艺处理造纸化学品废水的中试研究

针对造纸化学品生产废水具有成分复杂,可生化性差,有机物、NH3-N、Cl-浓度高的特点,采用"初沉池-悬浮生物滤池(A/O)-混凝沉淀池-催化氧化池-硝化滤池"组合工艺对造纸化学品生产废水进行了中试研究,取得很好的处理效果。结果表明,在进水COD为4 832～12 846 mg/L,NH3-N为39～430 mg/L,Cl-为3 200～15 000 mg/L的情况下,处理后出水COD小于500 mg/L,NH3-N小于35 mg/L,主要指标达到污水综合排放标准(GB 8978-1996)三级标准。     

固定化活性污泥实现短程硝化反硝化处理畜禽废水

以畜禽废水为处理对象,通过分别控制水力停留时间(HRT)、溶解氧(DO)、pH值、温度和碳氮比(C/N)等影响亚硝化的主要单因子,以使固定化活性污泥颗粒实现短程硝化反硝化反应,在连续流运行模式下进行废水脱氮实验,实验结果表明,单因子HRT为10 h,溶解氧为4 mg/L,pH值为8.5,温度为30℃,碳氮比为10时,对TN和COD的去除率分别为81.98%、93.79%;87.32%、98.35%;83.82%、93.93%;85%、97%;85.37%、97.28%,达到了理想的去除效果。     

产酸克雷伯氏菌Klebsiella oxytoca对硝基苯及4-氯硝基苯的降解

硝基苯类化合物生物降解菌的筛选及性能研究,是制药、染料等行业废水达标的重要基础。以浓度梯度升高法筛选到一株硝基苯厌氧降解菌Klebsiella oxytoca NBA-1。考察了该菌对氧气的需求,以及在厌氧条件下,温度、pH值、外加葡萄糖及硝基苯初始浓度等环境因子对菌株降解硝基苯能力的影响,并进一步讨论菌株对氯取代硝基苯类化合物的降解情况。结果表明,该菌在厌氧条件下生长比好氧条件下慢,但降解速度更快;厌氧降解硝基苯的最佳pH值和温度和分别为8.3和30~35℃;加入0.3%~0.5%的葡萄糖可促进降解,且对300 mg/L以下的硝基苯均有降解能力;该菌能将4-氯硝基苯转化为4-氯苯胺,并进一步脱氯为苯胺。研究结果可为硝基苯及含氯硝基苯的处理工艺选择提供相关的参考依据。     

填充床电化学反应器催化氧化法降解苯酚工艺条件的优化

采用填充床电化学反应器,以Na2SO4为支持电解质,分别以IrO2-Ta2O5/Ti和PbO2/Ti为阳极,以Ti板为阴极催化氧化降解苯酚。考察了电流密度和进水流量对废水COD去除率、平均电流效率(ACE)和电耗(Esp)的影响。实验结果表明:PbO2/Ti阳极电催化氧化苯酚的效率高于IrO2-Ta2O5/Ti阳极,且PbO2/Ti阳极有更高的ACE和更低的Esp;在以PbO2/Ti为阳极、电流密度为100 A/m2、进水流量为0.8 L/h的条件下,COD去除率最高为90.59%,ACE较高,Esp较低。     

K+对肝素钠废水厌氧生物处理中污泥性能的影响

以肝素钠生产废水为研究对象,研究了不同盐浓度下K+对厌氧污泥性能的影响。实验结果表明:在ρ(NaCl)小于8000mg/L的低盐浓度条件下,K+对污泥的解抑作用不明显;在ρ(NaCl)大于16000mg/L的高盐浓度条件下,K+对污泥表现出解抑作用。ρ(NaCl)为24000mg/L、K+加入量为60mg/L时,COD去除率、产气量和甲烷体积分数相比空白对照组分别提高了17.1%、43.3%和71.8%,氨化率变化不大,均在32%左右。     

Effects of submerged macrophytes on the abundance and community composition of ammonia-oxidizing prokaryotes in a eutrophic lake

Abundances and community compositions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) in unvegetated sediment and the rhizosphere sediments of three submerged macrophytes (Ceratophyllum demersum, Vallisneria spinulosa, and Potamogeton crispus) were investigated in a large, eutrophic freshwater lake, Lake Taihu. Abundances of archaeal ammonia monooxygenase alpha-subunit (amoA) gene (from 6.56?×?10⁶ copies to 1.06?×?10⁷ copies per gram of dry sediment) were higher than those of bacterial amoA (from 6.13?×?10⁵ to 3.21?×?10⁶ copies per gram of dry sediment) in all samples. Submerged macrophytes exhibited no significant effect on the abundance and diversity of archaeal amoA gene. C. demersum and V. spinulosa increased the abundance and diversity of bacterial amoA gene in their rhizosphere sediment. However, the diversity of bacterial amoA gene in the rhizosphere sediments of P. crispus was decreased. The data obtained in this study would be helpful to elucidate the roles of submerged macrophytes involved in the nitrogen cycling of eutrophic lake ecosystems.     

城市污水处理系统进水水质对曝气池微生物种群结构的影响

以芜湖市天门山污水处理厂为例,研究城市污水处理系统进水水质对曝气池活性污泥微生物种群结构的影响。采集多个曝气池活性污泥样品进行DNA提取和聚合酶链式反应(PCR)扩增,对采样期间进水主要水质指标进行测定,运用变性梯度凝胶电泳(DGGE)技术分析各活性污泥样品DNA的PCR扩增产物,采用非加权组平均(UPGMA)聚类法分析活性污泥样品的DGGE图谱,选择基于线性模型的冗余分析(RDA)对影响微生物种群结构的水质理化因子进行排序。分析结果表明,污水处理系统处理效果整体比较稳定,COD的去除率在62.3%～97.0%,NH3-N的去除率在81.6%～96.4%,TP的去除率在95.3%～99.7%,系统出水均能达到设计要求。微生物种群结构不稳定,随着进水水质的变化呈现出动态变化过程。其中,BOD5与微生物种群结构的关联度最高。由此得出,系统功能稳定的污水处理厂污泥中微生物的种群结构仍会存在一定变化。     

亚甲基蓝在污泥活性炭上的吸附

以剩余污泥为原料,氯化锌为活化剂制备污泥活性炭。研究了初始pH值、吸附温度及离子强度对污泥活性炭吸附亚甲基蓝效果的影响。采用高分辨电子扫描电镜(SEM)和氮吸脱附曲线对污泥活性炭进行了表征。结果表明,随着pH值的升高,吸附量增大,碱性条件下最好。在15～55℃的范围内,亚甲基蓝的吸附量先增加后降低,温度为35℃时吸附量达到最大值。加入氯化钠后的污泥活性炭的吸附能力变弱,但随着离子强度的增大,变弱的强度减少。污泥活性炭以中孔为主和污泥活性炭具有不规则结构,预示着污泥活性炭较高的吸附能力。污泥活性炭对亚甲基蓝的吸附符合Lang-muir等温吸附方程。污泥壳活性炭对亚甲基蓝的吸附符合二级反应动力学方程反应特征。