易腐有机垃圾单级高固体厌氧消化实验研究

在中温(35～37℃)条件下,对连续式单级高固体厌氧消化反应器处理易腐有机垃圾进行了试验研究,连续试验时间达半年以上.结果表明,系统稳定运行时,在进料TS为24.79%、VS为23.06%的情况下,单位体积反应器产气效率最高达到3.69L/(L·d),易腐有机垃圾的产气能力(以VS计)为746.33 L/kg,有机负荷(以VS计)达到4.94 kg/(m3·d),水力停留时间47 d,此时期处理效果理想;试验启动之初易发生酸化,其抑制情况严重,出现0产气,经碱性溶液调节后情况得到较好解决;反应进行至80 d后产气速率降至最高速率的一半以下,推断是氨氮浓度超过2000mg/L而产生氨氮抑制,经过投加化学药剂和调节进料C/N抑制情况得到缓解.     

规模化猪场原水氨氮对厌氧微生物活性的影响

通过厌氧毒性测定试验,研究模拟废水及猪场原水氨氮对厌氧微生物活性的影响。结果表明,模拟废水氨氮对厌氧颗粒污泥产甲烷活性的影响具有多重性,当氨氮浓度低于400mg/L时,表现为促进产甲烷作用。当氨氮浓度为800mg/L时,开始表现为抑制产甲烷作用,并且随着氨氮浓度的升高,抑制作用增强。猪场原水在进水浓度下均表现为抑制作用。模拟废水50%抑制浓度为1900.1mg/L,猪场原水50%抑制浓度为1725.9mg/L;在相同的抑制程度下,模拟废水氨氮浓度均高于猪场原水,平均相差594.1mg/L。     

Degradation and detoxification of microcystin-LR in drinking water by sequential use of UV and ozone

Microcystins (MCs) produced by cyanobacteria are strong hepatotoxins and classified as possible carcinogens.MCs pose a considerable threat to human health through tainted drinking and surface waters.Herein filtrated water from a waterworks in Harbin,China,was spiked with microcystin-LR (MC-LR) extracted from a toxic scum of microcystis aeruginosa,and the spiked sample waters were treated using UV irradiation with consequent ozonation process (UV/O3),compared with ozonation at a dose range commonly applied in water treatment plants,UV irradiation at 254 nm and UV irradiation combined with ozonation (UV+O3),respectively.The remaining of toxins were analyzed using high-performance liquid chromatography and also determined using a protein phosphatase type 2A inhibition assay,which was utilized to evaluate the reduction in toxicity.Results indicated that in comparison to other three processes (O3,UV,and UV+O3),UV/O 3 process could effectively decrease both the concentration and toxicity of MC-LR at 100 μg/L level after 5 min UV irradiation with consequent 5 min ozonation at 0.2 mg/L (below 1 μg/L),while 0.5 mg/L ozone dose was required for the level below 0.1 μg/L.The addition of an UV treatment step to the existing treatment train may induce significant transformation of micropollutants and breaks down the natural organic matters into moieties unfavorable for ozone decomposition,stabilizing the ozone residual.These findings suggested that sequential use of UV and ozone may be a suitable method for the removal of these potentially hazardous microcystins from drinking water.     

Sugar receptor response of the food-canal taste sensilla in a nectar-feeding swallowtail butterfly, Papilio xuthus

The feeding behavior in nectar-feeding insects is triggered by a sugar-receptor response in contact chemosensilla. The contact chemosensilla are distributed not only on tarsi and the outside of the proboscis but also on the inside of the food canal in Lepidoptera. Although the chemosensilla inside the food canal are assumed to detect sweet taste during the passage of nectar through the food canal, their electrophysiological function has received little attention. In the nectar-feeding Asian swallowtail butterfly, Papilio xuthus (Lepidoptera: Papilionidae), we found 15- to 30-μm-long sensilla neatly lined up along the inside galea wall, which forms the food canal in the proboscis. The receptor neurons of these sensilla responded to sucrose. We hypothesized that starch and sucrose compete with each other for a taste receptor site on the sensilla. When we added starch and sucrose to the food-canal sensilla, the electrophysiological responses of food-canal sensilla were inhibited in parallel with the food-sucking behavior of the butterflies. These results suggest that the food-canal sensilla are involved in the behavioral control of nectar-sucking in this butterfly species.     

PAN dust explosion inhibition mechanisms of NaHCO3 and Al(OH)3

We investigate the PAN dust explosion inhibition behaviors of NaHCO₃ and Al(OH)₃ in a 20 L spherical explosion system and a transparent pipe explosion propagation test system. The results show that, in the standard 20 L spherical explosion system, the highest PAN dust explosion concentration is 500 g/m³, the maximum explosion pressure is 0.661 MPa, and the maximum explosion pressure increase rate is 31.64 MPa/s; adding 50% NaHCO₃ and 60% Al(OH)₃ can totally inhibit PAN dust explosion. In the DN0.15 m transparent pipe explosion propagation test system, for 500 g/m³ PAN dust, the initial explosion flame velocity is 102 m/s, the initial pressure is 0.46 MPa, and the initial temperature is 967 °C; adding 60% NaHCO₃ and 70% Al(OH)₃ can totally inhibit PAN dust explosion flames. Through FTIR and TG analyses, we obtain the explosion products and pyrolysis patterns of the explosion products of PAN dust, NaHCO₃, and Al(OH)₃. On this basis, we also summarize the PAN dust explosion inhibition mechanisms of NaHCO₃ and Al(OH)₃.     

Mercury uptake and effects on growth in Jatropha curcas

The use of metal-accumulating plants for the phytoremediation of contaminated soils is gaining more attention. Mercury(Hg)-contaminated soils from historical gold mines represent a potential risk to human health and the environment. Therefore, Jatropha curcas plant, that has shown its tolerance to these environments, is a species of particular interest to implement phytoremediation techniques in gold mining sites. In this work, the behavior of J. curcas was assessed in different hydroponic cultures fortified with Hg at concentrations of 5, 10, 20, 40, and 80 μg Hg/mL(T5, T10, T20, T40 and T80, respectively). After exposure,plant growth, net photosynthesis, leaf area, and Hg accumulation were determined and variables such as net Hg uptake, effective Hg accumulation, translocation and bioaccumulation factors were calculated. Accumulation of Hg in root and leaf tissues increased with respect to the Hg concentrations in the hydroponic culture, with statistically significant differences(p 0.05) among treatments. Moreover, Hg concentration in roots was 7 and 12-fold higher in average than in plant leaves and shoots, respectively. Many effects were found in the development of plants, especially related with loss of biomass and leaf area,with significant growth inhibition related to control values( 50% with treatment T5).Moreover, percentage of inhibition was even higher( 60%) with same treatment for net photosynthesis. Finally, it should be highlighted that for T40 and T80 treatments, plant growth and photosynthesis were almost completely depleted(88%–95%).     

Growth inhibition and oxidative damage of Microcystis aeruginosa induced by crude extract of Sagittaria trifolia tubers

Aquatic macrophytes are considered to be promising in controlling harmful cyanobacterial blooms. In this research, an aqueous extract of Sagittaria trifolia tubers was prepared to study its inhibitory effect on Microcystis aeruginosa in the laboratory. Several physiological indices of M. aeruginosa, in response to the environmental stress, were analyzed. Results showed that S. trifolia tuber aqueous extract significantly inhibited the growth of M. aeruginosa in a concentration-dependent way. The highest inhibition rate reached 90% after 6 day treatment. The Chlorophyll-a concentration of M. aeruginosa cells decreased from 343.1 to314.2 μg/L in the treatment group. The activities of superoxide dismutase and peroxidase and the content of reduced glutathione in M. aeruginosa cells initially increased as a response to the oxidative stress posed by S. trifolia tuber aqueous extract, but then decreased as time prolonged. The lipid peroxidation damage of the cyanobacterial cell membranes was reflected by the malondialdehyde level, which was notably higher in the treatment group compared with the controls. It was concluded that the oxidative damage of M. aeruginosa induced by S.trifolia tuber aqueous extract might be one of the mechanisms for the inhibitory effects.     

两种粒径氧化镍纳米颗粒对小球藻(Chlorella vulgaris)的生物毒性

采用藻类生物毒性测试方法(OECD201)研究了两种粒径氧化镍(NiO)纳米颗粒对小球藻(Chlorella vulgaris)的生物毒性.发现纳米颗粒的毒性与其尺度有关,7 nm NiO的毒性大于20 nm NiO,二者72 h EC50分别为18.01和74.64mgNiO/L.利用扫描电子显微镜(SEM)观察了对...     

镍对厌氧消化过程的抑制作用研究

采用混合式厌氧反应器,以酒糟废水为基质,在相同条件的不同反应器中每日加入不同浓度的镍离子（以硝酸镍形式加入）,研究不同浓度的镍离子对厌氧体系的抑制作用,以及体系中溶解态的镍离子含量与抑制程度的关系。结果表明,日加入镍量低于３６．４ｍｇ／Ｌ时,对体系无影响;在４０－６０ｍｇ／Ｌ时,产生轻微的抑制;超过８０ｍｇ／Ｌ时,对体系造成严重的抑制。当体系中溶解态镍离子浓度低于２．５ｍｇ／Ｌ时,体系不受影响。厌     

水溶性有机物对土壤中菲的生态毒性影响

采用生物培养和物理化学试验,研究了水溶性有机物(DOM)对土壤中phe生态毒性的影响.结果表明,本研究所用DOM均具有表面活性;小麦根phe毒害的敏感区间为0～200mg/kg,200mg/kg是土壤中phe的50%小麦根伸长抑制率浓度.DOM的存在会降低phe的生态毒性,但是降低程度与其疏水性馏分含量和表面活性有关,且phe生态毒性的降低程度随DOM浓度的增大而增大.本研究的结果说明DOM能减轻土壤中phe的生态毒性.