Feasibility of using microalgal biomass cultured in domestic wastewater for the removal of chromium pollutants

The feasibility of obtaining and using the biomass of a microalga, Chlorella miniata, from domestic wastewater (DW) cultures for the removal of chromium(III) [Cr(III)] and chromium(VI) [Cr(VI)] was compared with that from commercial Bristol medium (BM). Results showed that Chlorella miniata cultured in DW under 16-8 hours light-dark cycle [DW(16-8)] had similar growth to that in BM [BM(16-8)], but these two biomass had different biochemical compositions, and the former one had lower carbohydrate and higher protein content. When cultured in domestic wastewater, a higher biomass was obtained under continuous illumination [DW(24-0)], and the cells had higher carbohydrate and lower protein concentrations than that of DW(16-8). The spectra of the Fourier transform infrared spectrometer revealed that the functional groups on the surface of the three kinds of biomass--DW(16-8), DW(24-0), and BM(16-8)--were comparable, except an additional peak at 1731 cm(-1) was found in the biomass cultured in domestic wastewater, which was probably the result of bacterial contamination. Although biochemical differences were found among the three kinds of microalgal biomass, similar biosorption performances to chromium pollutants were recorded, with approximately 75% Cr(III) and 100% Cr(VI) removed at equilibrium in Cr(III) and Cr(VI) experiments, respectively, when dead biomass was used as a biosorbent. Therefore, it is possible to culture Chlorella miniata in domestic wastewater and use the biomass for the removal of chromium pollutants.     

活性炭/聚丙烯腈纤维对溶液中的甲基橙染料吸附动力学研究

采用自制添加活性炭的聚丙烯腈纤维为吸附剂,吸附染料甲基橙溶液,考察了活性炭含量、温度及溶液pH值等因素对纤维吸附染料甲基橙吸附量和吸附速率的影响.结果表明,活性炭/聚丙烯腈纤维吸附甲基橙染料符合表观二级动力学方程.吸附过程的限速步骤为甲基橙染料向活性炭/聚丙烯腈纤维中活性炭颗粒内部微孔扩散,自制的活性炭/聚丙烯腈纤维对甲基橙染料具有较大的吸附容量和较快的吸附速率,可作为甲基橙等染料废水治理的理想材料.     

混合耐冷菌群的优化筛选及应用研究

从冬季时污水处理厂曝气池的活性污泥中分离出高生物活性的耐冷细菌和耐冷酵母菌,以低温生活污水为处理对象,分别测定单株菌及混合耐冷菌群有机污染物降解能力.结果表明,共分离出从属于黄杆菌属、假单胞菌属、芽胞杆菌属等的耐冷细菌6株;从属于毕赤酵母菌属、假丝酵母菌属、红酵母菌属等的耐冷酵母菌4株.耐冷菌在5℃条件下具有相对较短的世代时间:9.04～13.11 h.单株耐冷细菌F和耐冷酵母菌AH在5℃条件下的COD去除率分别为64%和83%.混合耐冷菌群经驯化后可较高地去除低温生活污水中的有机污染物,COD去除率可保持在83%～87%.     

支持向量机在城市震后火灾损失预测中的应用

针对地震火灾的复杂性和多变性的特点,在综合分析了各种震后火灾损失预测方法的基础上,提出了基于支持向量机的城市震后火灾损失预测模型。以地震火灾的历史资料为依据,建立学习样本和测试样本,并与BP神经网络预测方法相比较,验证了其可行性,也为其它自然灾害的损失预测提供了简单、有效的方法。     

城镇圩区排涝模数计算方法及其与河道调蓄库容关系研究

农业圩区原有的排涝模数计算方法已不适用于城镇圩区.针对城镇圩区的排涝特殊性,通过分析排涝计算的原理,充分考虑圩区内河道的调蓄能力,得到适应城镇圩区排涝计算的方法.以南京市江宁区为例,对城镇圩区的排涝模数进行计算,得到排涝模数与调蓄库容之间的定量关系.     

厌氧氨氧化颗粒污泥胞外聚合物金属元素特性

为探究厌氧氨氧化颗粒污泥胞外金属元素特性,将厌氧氨氧化颗粒污泥根据粒径筛分为0.5~1.4mm、1.4~2.8mm、>2.8mm 3组,提取不同粒径厌氧氨氧化颗粒污泥胞外聚合物（EPS）,研究EPS金属元素特性.结果表明,蛋白质（PN）是厌氧氨氧化颗粒污泥EPS的主要成分,占EPS含量的84.2%以上.随着粒径的增大,EPS中Na、K、Ca、Mg元素含量均增多,且与EPS中蛋白质含量变化一致.EPS中K、Ca、Mg元素的离子形式占比分别为68.6%、56.2%、94.7%.EPS经过阳离子交换树脂（CER）处理后,0.5~1.4mm、1.4~2.8mm、>2.8mm组EPS Zeta电位分别减小了4.7,7.2,9.1mV,EPS中的金属离子可通过压缩双电层作用促进颗粒污泥的聚集,金属离子对大粒径颗粒污泥EPS Zeta电位的影响幅度更大.     

金盆水库沉积物铁锰释放规律

针对分层型水库周期性厌氧问题,金盆水库利用人工强制混合充氧技术补充底部水体溶解氧,抑制沉积物中还原性污染物的释放.但受水库地形地貌的影响,人工强制混合充氧效率存在一定差异性,在曝气系统运行结束后部分较深区域上覆水体溶解氧迅速耗竭,导致污染物的再次释放.为探究铁锰在该条件下的释放规律及扩散强度,选取主库区代表性采样点,对沉积物间隙水及上覆水溶解态铁锰浓度分布进行测定,并计算沉积物-水界面处溶解态铁锰的扩散通量.结果表明,人工强制混合充氧结束后地势较低区域底部水体迅速进入厌氧状态,导致大量溶解态锰释放进入上覆水体,浓度最高达0.42mg·L~(-1);而地势较高区域底部水体短暂进入缺氧状态,之后溶解氧浓度迅速回升,因此底部溶解态锰浓度升高幅度较小,浓度最高为0.17mg·L~(-1).沉积物间隙水-上覆水铁锰浓度分布结果表明,由于铁锰氧化还原电位的差异,溶解态锰相较于铁在厌氧条件下更容易释放进入上覆水体,且不断在表层沉积物及上覆水体中积聚,而溶解态铁的释放不仅受溶解氧的抑制,还受锰氧化物等其他氧化剂的抑制.由扩散通量计算可知,人工强制混合充氧结束后溶解态锰的扩散通量有降低趋势.由质量平衡计算可知,溶解态锰在厌氧层中的积聚不仅与扩散通量有关,还与沉降通量、厌氧层厚度有关,因此厌氧层中铁锰的生物地球化学循环作用有待进一步的研究.     

Distribution of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in surface water and sediments from Baiyangdian Lake in North China

Persistent organochlorine compounds, including hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and polychlorinated biphenyls (PCBs) were analyzed in surface water and sediments from Baiyangdian Lake, North China. Total concentrations of HCHs, DDTs and PCBs in surface water were in the range of 3.13-10.60, 4.05-20.59 and 19.46-131.62 ng/L, respectively, and total concentrations of HCHs, DDTs and PCBs in sediments were 1.75-5.70, 0.91-6.48 and 5.96-29.61 ng/g dry weight, respectively. Among the groups of HCHs (sum of α-HCH, β-HCH, γ-HCH and δ-HCH) and DDTs (sum of DDT, DDD and DDE), the predominance of β-HCH, DDE and DDD in water and sediment samples was clearly observed. This observation suggested that β-HCH was resistant to biodegradation and the DDTs had been transformed to its metabolites, DDE and DDD. For PCBs, penta-, hexa- and hepta-chlorinated congeners were the most abundant compounds in the both phases. Furthermore, the partitioning of chlorinated compounds between sediment and water was investigated to understand their transport and fates in aquatic ecosystems. The results indicated that average logs of organic carbon-normalized sediment-water partition coefficients (logK_oc') for OCPs varied between 3.20 and 5.53, and for PCBs, logK_oc' values ranged from 3.19 to 5.57. The observed logK_oc' was lower than their equilibrium logK_oc predicted from linear model, which may be attributed to the solubility enhancement effect of colloidal matter in water phase and the disequilibrium between sediment and water.     

Mn1-yNiyOx的制备及其催化燃烧甲苯性能的研究

通过水热共沉淀法制备了Mn_1-yNi_yO_x复合氧化物催化剂(y=0.1~0.5),考察掺杂Ni对Mn基氧化物在甲苯燃烧中的影响,在获得最优锰镍比例后,对其热稳定性与耐久性进行测试,然后通过XRD、N₂吸脱附、SEM、H₂-TPR以及XPS对其物理结构和氧化还原性能进行表征.结果表明,Mn和Ni在甲苯吸附和活化中产生相互作用,生成更多的Mn⁴⁺以及表面吸附氧,提供大量的反应活性位点,增强了催化氧化性能.Mn_0.8Ni_0.2O_x在甲苯催化燃烧中表现出的催化性能最好,其热稳定性与耐久性也表现优异,与MnO_x在甲苯催化燃烧中相比,其T₅₀、T₉₀分别下降12和11 ℃,在238℃即可将甲苯完全氧化,并且碳平衡值约为99%,无二次污染产生,该研究成果可为挥发性有机化合物(VOCs)催化燃烧提供更好的方式和材料.