基于数值仿真-响应表面法的二沉池优化研究

以长沙市某污水处理厂二沉池为例,采用多相流混合物模型与k-ε湍流模型结合对辐流式二沉池内速度场和污泥浓度场进行了数值模拟.以出水口悬浮物浓度(SS)为响应目标,对影响二沉池沉淀效果的3个影响因素(进水口流速、颗粒污泥粒径、挡板的淹没深度)进行中心复合设计(central composite design,CCD),并经响应表面法分析得到影响出水SS的二次回归模型,确定了二沉池沉降的最佳条件:进水口流速为0.03m·s-1,颗粒污泥粒径为220.41μm,挡板的淹没深度为3.45m,采用数值仿真模拟实验得到出水口悬浮物浓度值为2.4mg·L-1,较优化之前的仿真结果一周平均值6.7mg·L-1相比,其处理效率提高了64.2%.采用数值仿真和响应表面法结合对二沉池工艺条件进行优化研究,可以加速寻优过程,是工艺优化的辅助工具.     

水泥混凝处理模拟染料废水及其循环再生利用的研究

以常见的CA-70铝酸盐水泥、32.5R硅酸盐水泥、白水泥作为混凝剂,处理活性艳蓝X-BR模拟染料废水。在测定模拟废水在混凝过程中有机物含量以及pH值变化的基础上,探讨了以水泥替代传统混凝剂的可行性。依据水泥水化产物的性质,采用高温煅烧方法使混凝剂再生,实现了其循环使用的目的。研究结果表明:水泥作为混凝剂,在水化过程中能形成具有良好混凝性能的形态,对模拟染料废水中活性艳蓝X-BR去除率达90%以上,且通过高温再生后,可重复使用10次以上,出水均达到纺织染整工业水污染物排放标准。混凝污泥的沉淀性能良好,便于稳定化处理。     

Topsoil dichlorodiphenyltrichloroethane and polychlorinated biphenyl concentrations and sources along an urban-rural gradient in the Yellow River Delta

The Yellow River Delta (YRD) is a typical agricultural and petrochemical industrial area of China. To assess the current status of soil dichlorodiphenyltrichloroethane (DDT) and polychlorinated biphenyls (PCB) residues, topsoil samples (0-15 cm) (n = 82) were collected in Bincheng District, at the geographic center of the YRD. The total concentrations of six DDT homologues were within 3.3-3819 μg/kg, with a mean concentration of 191 μg/kg, showing significant increase along urban-rural gradient. Soil concentrations of seven indicator PCBs in the area ranged from non-detectable to 87.0 μg/kg, dominated by heavily chlorinated PCBs (PCB-101 and -118). Soil PCBs concentrations were significantly greater in urban than suburban and rural areas. Principal component and multiple linear regression analysis suggest that 86.4% of soil DDTs originate from past DDT usage, and 13.6% originate from dicofol application. Soil PCBs most likely originate from the petrochemical industry (77.1%), municipal solid waste disposal (16.5%), local commercial PCB homologues usage (5.2%), and long-range atmospheric deposition (1.2%). In general, soil DDTs pollution was classified as low level, and mean PCBs concentrations were below the severe contamination classification range. Because PCB-118 is a dioxin-like congener, monitoring and remediation is advised to assess and reduce negative environmental and human health effects from soil DDTs and dioxin-like congeners in the study area.     

铁炭微电解组合工艺处理大蒜切片废水研究

采用铁炭微电解技术为核心工艺的混凝-铁炭微电解-强化电解组合工艺对大蒜切片废水进行处理,主要研究了铁炭微电解的运行参数,包括曝气与否、废水pH值、反应时间、铁炭质量比、铁水质量比对COD去除效果的影响。结果表明:经过组合工艺处理后,废水刺鼻的气味完全消除,浊度去除率达100%,ρ(COD)值由13050mg/L降至878mg/L,去除率达93.3%,BOD5/COD(B/C)值由0.10提高到0.46,废水的可生化性显著提高。     

辽宁徐大堡海域浮游动物多样性及群落结构的季节变化

于2009年春季(5月)、夏季(8月)、秋季(10月)、冬季(12月),在辽宁徐大堡海域共开展四个航次的现场监测,进行浮游动物群落结构、优势种及其季节演替、特征种的丰度及时空分布(包括优势种、鱼卵和仔稚鱼等)以及物种多样性的时空分布等研究。结果表明:研究海域浮游动物的种类数及物种多样性,夏季最高,春季和秋季次之,冬季最低。浮游动物优势种主要属于广温广盐类群和近岸暖温类群,优势种及其群落组成的季节演替较明显。浮游动物优势种的丰度,春、夏季较高,秋、冬季较低;水温的季节变化及沿岸水的输入是该海域浮游动物群落结构及丰度时空变化的主导因素。     

腹泻性贝类毒素大田软海绵酸液态芯片检测方法的建立

利用间接竞争法免疫学原理,以自制的大田软海绵酸(okadaic acid,OA)与卵清白蛋白(ovalbumin,OVA)的偶联物OA-OVA包覆微球为载体,同时自制生物化抗OA单克隆抗体,利用液态芯片(Luminex Xmap 200TM)系统建立OA液态芯片定量检测方法;同时测定了方法的灵敏性和特异性,并对贝类模拟样本进行了测试。结果显示:液态芯片法对OA的检测线性范围为0.2～63μg/L,最低检测值为0.129μg/L,均优于酶联免疫吸附法;除与DTX-1的交叉反应率为54.2%外,与其他几种用于检测的贝类毒素没有任何交叉现象;在加标浓度为6.25～400μg/L时,回收率为84.96%～90.35%,变异系数为3.20%～6.59%。因此,该方法可满足海产品中贝类样品OA限量标准检测。     

鼠尾藻对养殖水体净化的围隔试验

通过围隔实验研究鼠尾藻对N、P的吸收速率。在秋冬季围隔实验中,围隔体积为1 040 L,藻体密度分为低、中、高三个密度组。鼠尾藻对P的平均吸收速率:低密度组为0.19μmol/[g(dw)·d],中密度组为0.15μmol/[g(dw)·d],高密度组为0.09μmol/[g(dw)·d];对N的平均吸收速率:低密度组为3.65μmol/[g(dw)·d],中密度组为2.50μmol/[g(dw)·d],高密度组为1.47μmol/[g(dw)·d];在春夏季围隔实验中,鼠尾藻对P的平均吸收速率:低密度组为0.64μmol/[g(dw)·d],高密度组为0.45μmol/[g(dw)·d];对N的平均吸收速率:低密度组为2.70μmol/[g(dw)·d],高密度组为1.88μmol/[g(dw)·d]。结果表明,在相同密度条件下,鼠尾藻春夏季对P的吸收速率是秋冬季的4倍;对N的吸收速率,春夏季比秋冬季略高。     

基于人体健康风险的水污染事件遗传性致癌物安全浓度研究

确定水污染事件中遗传性致癌物短期暴露安全浓度,是目前我国水环境管理中急需解决的问题.在假设遗传性致癌物暴露剂量与致癌风险呈线性相关的前提下,提出了水体中遗传性致癌物安全浓度计算流程,建立了采用遗传性致癌物终生暴露安全浓度计算短期暴露安全浓度的方法.在我国2000～2010年间发生的60起水污染事故中,特征污染物为砷的水污染事件为6起,占总污染事件比例为10%,这一结果表明砷为我国水污染事件中高发的特征污染物.根据水污染事件遗传性致癌物短期暴露安全浓度计算方法,得出砷短期暴露安全浓度为0.5 mg.L-1,表明该方法在水污染事件应急管理中具有一定的可行性.     

低分子有机酸强化植物修复重金属污染土壤的作用与机制

植物修复是利用植物的物理、化学作用去除污染土壤中重金属的技术方法,可以减少二次污染物的产生,具有经济可行性.低分子有机酸（LMWOAs）具有生物降解性和环境友好性,在重金属污染土壤植物修复中具有较强的应用潜力.综述了LMWOAs在植物修复中的作用机制,主要包括：①调控根茎叶发育,增加植物生物量,强化植物富集效果;②增强光合作用,提升植物抗性,提高对重金属的耐受能力;③改变根际土壤性质,提高根际微生物活性,促进对重金属的吸收;④改变重金属形态,减轻重金属毒性,提高转运效率.最后阐述了LMWOAs强化植物修复重金属污染土壤的优缺点及应用,提出了LMWOAs在重金属污染土壤植物修复中的研究方向,这对LMWOAs在未来植物修复中的研究和应用具有科学意义.     

Effects of iron oxide nanoparticles on phenotype and metabolite changes in hemp clones (Cannabis sativa L.)

● Fe₃O₄ NPs increased the biomass and chlorophyll content of hemp clones. ● Fe₃O₄ NPs penetrated and were internalized by root cells. ● Fe₃O₄ NPs induced the alteration of metabolite profiles in hemp leaves. ● The psychoactive compound THC in hemp leaves was significantly down-regulated. We investigated the effect of iron oxide nanoparticles (Fe₃O₄ NPs, ~17 nm in size) on the phenotype and metabolite changes in hemp (Cannabis sativa L.), an annual crop distributed worldwide. Hemp clones were grown in hydroponic cultures with Fe₃O₄ NPs (50, 100, 200, or 500 mg/L) for four weeks. TEM and ICP-MS were used to determine Fe₃O₄ NPs uptake and translocation. LC-MS-based metabolomics was employed to explore the deep insight into the effect of Fe₃O₄ NPs on hemp plants. The results revealed that plant growth enhanced gradually with increasing concentrations of given NPs up to 200 mg/L, which improved the fresh weight and dry weight by 36.13% and 74.68%, respectively, compared to the control. Even at a high dose (500 mg/L), Fe₃O₄ NPs promoted plant growth, including increased biomass and tissue length. NPs significantly increased the iron and chlorophyll content in plant tissues Increased catalase activity and reduced hydrogen peroxide content in hemp leaves suggested that the Fe₃O₄ NPs activated the defense system. TEM showed that NPs were abundantly attached to the cell wall and dispersed throughout the root cells. Metabolomics revealed that Fe₃O₄ NPs induced metabolic reprogramming in hemp leaves, including the up-regulation of carbohydrates and organic acids, and down-regulation of antioxidants, especially tetrahydrocannabinol (THC). The significantly up-regulated metabolites, including peonidin and 2-hydroxycinnamic acid, could be involved in photosynthesis in hemp plants. These results demonstrate the potential of Fe₃O₄ NPs for promoting hemp growth and decreasing the THC content at low doses.