酸化冲击对低pH厌氧发酵系统性能的影响

为了研究酸化冲击对厌氧发酵有机废水能源回收系统的影响,利用自制的厌氧内循环反应器（anaerobic internal circulation reactor,AICR）,以模拟糖蜜废水为底物,逐步提高进水容积负荷以模拟高容积负荷下出现的酸化冲击。研究了反应器酸化前后运行参数,并利用高通量测序检测了酸化后系统微生物群落结构。结果表明：酸化会导致颗粒污泥解体,产气速率和COD去除率下降,产甲烷活性严重抑制,同时发酵类型也发生转变。反应器酸化以后,发酵类型从丁酸型发酵类型转变为混合酸发酵类型,在进水负荷不变的情况下,总产气速率下降约50%,从2 100 mmol·（L·d）-1下降至1 056 mmol·（L·d）-1。酸化后的系统中,非产氢发酵细菌为优势细菌（54.7%）,而产氢细菌所占比例较少（37.3%）,未检测到产甲烷细菌。     

TiO2、BiVO4、Cu2O光催化降解低浓度甲醛

比较研究了3种（TiO2,BiVO4,Cu2O）光催化剂对低浓度甲醛的降解过程,拟通过结构分析（晶粒尺寸、比表面积、禁带宽度）和实验评价其性能优劣,优选出光催化性能较好的材料。通过结构分析和降解甲醛实验发现,甲醛初始浓度较低时,BiVO4降解率优于其他,随甲醛浓度增加,催化剂降解率均呈上升趋势,TiO2-1（T-1）、TiO2-2（T-2）降解率增加显著。随环境湿度增大,降解率先上升后下降,BiVO4-1（B-1）、BiVO4-2（B-2）降解率下降的较为缓慢。同一物质当晶粒尺寸越小比表面积越大,其降解率越好。T-2比B-1有更好的稳定性。分析认为在较低甲醛浓度时,决定光催化降解率的主要因素是催化剂的表面反应速率。随着甲醛初始浓度的增加,吸附脱附成为主要限制步骤。随环境湿度增加,甲醛降解率先上升后下降,具有较小比表面积的BiVO4降解甲醛效率下降不显著。连续的工作产生甲醛分解副产物,不易堵塞具有大比表面积的T-2的活性位点,所以T-2有更好的稳定性。     

Effects of butachlor on microbial populations and enzyme activities in paddy soil

This paper reports the influences of the herbicide butachlor (n-butoxymethlchloro -2', 6'-diethylacetnilide) on microbial populations, respiration, nitrogen fixation and nitrification, and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil. The results showed that the number of actinomycetes declined significantly after the application of butachlor at different concentrations ranging from 5.5 microg g(-1) to 22.0 microg g(-1) dried soil, while that of bacteria and fungi increased. Fungi were easily affected by butachlor compared to the bacteria. The growth of fungi was retarded by butachlor at higher concentrations. Butachlor however, stimulated the growth of anaerobic hydrolytic fermentative bacteria, sulfate-reducing bacteria (SRB) and denitrifying bacteria. The increased concentration of butachlor applied resulted in the higher number of SRB. Butachlor inhibited the growth of hydrogen-producing acetogenic bacteria. The effect of butachlor varied on methane-producing bacteria (MPB) at different concentrations. Butachlor at the concentration of 1.0 microg g(-1) dried soil or less than this concentration accelerated the growth of MPB, while at 22.0 microg g(-1) dried soil showed an inhibition. Butachlor enhanced the activity of dehydrogenase at increasing concentrations. The soil dehydrogenase showed the highest activity on the 16th day after application of 22.0 microg g(-1) dried soil of butachlor. The hydrogen peroxidase could be stimulated by butachlor. The soil respiration was depressed during the period from several days to more than 20 days, depending on concentrations of butachlor applied. Both the nitrogen fixation and nitrification were stimulated in the beginning but reduced greatly afterwards in paddy soil.     

铁还原菌作用下含镉聚合硫酸铁絮体中铁还原与镉释放规律及其影响因素

选取Shewanella oneidensis MR-1为供试铁还原菌,旨在研究MR-1在还原含Cd聚合硫酸铁絮体过程中,絮体中Fe（Ⅲ）还原、Cd释放规律及影响因素。结果表明,扰动可促进絮体中Fe（Ⅲ）还原及Cd释放;絮体中Cd的添加使得Fe（Ⅲ）还原过程中产生的二次矿物主要物相由磁铁矿转变为针铁矿,且Cd浓度的增加导致Fe（Ⅲ）还原率逐渐降低,Cd释放率也逐渐降低;絮体中Fe浓度的逐渐增大同样使得Fe（Ⅲ）还原率逐渐降低,Cd释放率则先增大后减小;腐殖质类模型物质蒽醌-2,6-二磺酸钠的添加可提高絮体中Fe（Ⅲ）的还原率,进而促进Cd的释放。对同一体系或不同体系间的Fe（Ⅲ）还原率及Cd释放率进行线性拟合,结果发现较大的Fe（Ⅲ）还原率能够导致絮体中Cd的更多释放,从而对环境造成更大的危害。     

纳米ZnO/PS薄膜的制备及光降解性能

利用纳米ZnO与聚苯乙烯(PS)高速共混法制备了一种在紫外光下具有自降解性能的复合薄膜.分析表明,经过KH570处理的纳米ZnO与PS通过化学键的方式桥联在一起.TG分析表明,复合薄膜的耐热性较PS有所提高;SEM图像显示0.5 wt％ ZnO在PS薄膜表面分布均匀,经过UV照射后薄膜表面出现光腐蚀现象.复合薄膜紫外光自降解实验表明:0.5 wt％ ZnO/PS薄膜在15W的紫外灯照射下,15d的自降解率为3.715％.     

三维电极法深度处理维生素生产废水

采用三维电极法对维生素废水进行深度处理,分别以钛涂钌铱板、铁板和不锈钢板作为电极阳极,石墨板作为电极阴极,柱状活性炭作为粒子电极,结果表明,当以钛涂钌铱板作为阳极,以粒径为1 mm的柱状活性炭作为粒子电极时电解效果最好,COD和色度去除率最高。实验选择电解电压、电极板间距、电解时间和初始pH值作为主要影响因素进行正交实验,实验研究证明,各因素的影响大小为电解电压>电极板间距>电解时间>初始pH值,得到的最佳参数组合分别为:电解电压为10 V,电极板间距为8 cm,电解时间为20 min,初始pH值为4,得到COD和色度最大去除率分别为59.5%和93.57%。     

Quantitative evaluation of environmental risks of flotation tailings from hydrothermal sulfidation–flotation process

Floatation tailings (FT) are the main by-products of the hydrothermal sulfidation–flotation process. FT (FT₁ and FT₂) were obtained by treating two different neutralization sludges (NS) (NS₁ and NS₂). This paper quantitatively evaluated the environmental risks of heavy metals (Zn, Cd, Cu, Pb, and As) in FT versus NS. The total concentration and leaching rates (R ₂) of heavy metals in FT were much lower than those in NS, demonstrating that the hydrothermal sulfidation–flotation process was able to effectively suppress the mobility and leachability of heavy metals. The BCR-three sequence leaching procedure of FT confirmed that all metals were transformed into more stable forms (residue and oxidizable forms) than were found that in NS. The potential ecological risk index indicated that the overall risks caused by heavy metals decreased significantly from 6627.59 and 7229.67 (very serious risk) in NS₁ and NS₂, respectively, to 80.26 and 76.27 (low risk) in FT₁ and FT₂, respectively. According to the risk assessment code, none of the heavy metals in FT posed significant risk to the natural environment except Zn (with low risk). In general, the risk of heavy metals in FT had been well controlled.     

不同流量分配比对多级A/O工艺去除有机物及脱氮的影响

采用三级A/O工艺分段进水工艺处理低碳源生活污水,考察了进水流量分配比对系统去除有机物、硝化反硝化能力以及去除TN的影响。通过对水质指标沿程监测结果表明,不同流量分配比(4∶3∶3,5∶3∶2,6∶3∶1)对系统去除有机物及硝化效率影响不大,出水COD、氨氮分别均在30 mg/L、1 mg/L以下。但反硝化效果受流量分配比的影响较大,在流量比为5∶3∶2时,有效利用原水中碳源进行反硝化,反硝化效果最好。在流量比为5∶3∶2的情况下,TN出水为5.7 mg/L去除率为82.9%,优于流量分配比为6∶3∶1和4∶3∶3时的脱氮效果。总体而言,分段进水工艺在对碳源的有效利用及能耗节省方面优于单点进水。     

Polybrominated diphenyl ethers in house dust in Singapore

The use of polybrominated diphenyl ethers (PBDEs) as flame retardants in Singapore is not strictly regulated; therefore these compounds can be readily found in furniture, electronic devices, and building materials. This study was the first of its kind to be conducted in Singapore to measure concentrations of PBDEs in house dust. Samples were collected from 31 homes in various locations across the island-state of Singapore, and a total eight PBDEs congeners were measured. PBDEs were detected in all 31 dust samples and the number of BDE congener detected per home ranged between 3 and 8. The most abundant BDE congeners found were BDE 47, 99 and 209, with a median value of 20 ng g(-1) dust, 24 ng g(-1) dust and 1000 ng g(-1) dust, respectively. BDE 209 contributed 88% to the median of all the congeners, and BDE 47 and 99 contributed 1.8% and 3.5%, respectively. Different congener profiles were observed between this and studies conducted elsewhere, which is consistent with the use of different commercial PBDE around the world. No significant correlations between PBDE dust levels and residential characteristics (number of TVs and computers, floor area or flooring material) were observed. The daily intake of PBDEs via the inhalation pathway was estimated. House dust may be regarded as the most important exposure route of PBDEs for children.     

Rhodobacter sp. NP25b菌株缺氧降解壬基酚聚氧乙烯醚的研究

从城市污水处理厂活性污泥中分离得到一株能够在缺氧条件下以壬基酚聚氧乙烯醚(NPEOs)为惟一碳源和能源生长的菌株NP25b.经生理生化鉴定和16S rRNA基因序列分析,该菌株属于红细菌属(Rhodobacter sp.),对该菌株降解NPEOs的特性进行了研究.结果表明,在缺氧条件下,菌株NP25b在7 d内对初始底物浓度为400 mg/L NPEOs的降解率可达84%.利用液相色谱-质谱(LC-MS)和气相色谱-质谱(GC-MS)对NPEOs降解中间产物进行了分析,结果表明,主要降解产物为短链NPEOs和壬基酚聚氧乙烯醚乙酸(NPECs),其中包括具有较强内分泌干扰效应的NP1EO.该菌株能够代谢含有疏水基团的聚氧乙烯醚类表面活性剂,例如辛基酚聚氧乙烯醚和脂肪醇聚氧乙烯醚.推测菌株NP25b降解NPEOs是通过乙氧基(EO)链末端氧化后逐步切割完成的.