污泥的高温微好氧消化-厌氧消化工艺研究

城市污泥含有大量有机物和病原菌,需要稳定化处理.采用新型工艺高温微好氧与中温厌氧两级消化工艺(ATMD-MAD)处理城市污泥,与全程厌氧消化工艺(MAD)相比,不仅回收能源气体甲烷,而且缩短稳定化停留时间.55℃高温微好氧消化停留时间为2 d,后接35℃中温厌氧消化共运行24 d.结果表明,在ATMD-MAD系统中污泥的挥发性悬浮固体VSS去除率能在22 d时达到污泥稳定化要求的40%以上.ATMD-MAD工艺的单位VSS甲烷产量最高为496 mL/g VSS高于MAD工艺.在消化的前14天,可溶性挥发有机酸VFA在ATMD-MAD系统中的总量比MAD高出20%;在消化的第2天,ATMD-MAD系统中可溶性COD(SCOD)高出MAD工艺43.8%.ORP的变化反映了ATMD-MAD工艺保持了较好的厌氧状态,消化开始时的头2天限量曝气并没有给厌氧带来冲击.     

烟秸杆生物碳对铬(Ⅵ)废水的吸附动力学和热力学

以农业废弃物烟秸杆为原料,以KH2PO4为活化剂,制备了烟秸杆生物碳(简称TSC500),通过静态吸附实验研究了TSC500对含Cr(Ⅵ)废水的吸附性能。采用比表面积分析仪对TSC500进行了测试,实验考察了pH值、吸附剂用量、吸附时间、Cr(Ⅵ)初始浓度和温度对Cr(Ⅵ)吸附的影响,深入研究了TSC500对Cr(Ⅵ)的吸附行为。结果表明,在pH=3、温度313 K条件下,0.2 g TSC500吸附100 mg/L Cr(Ⅵ),去除率和吸附容量分别达到91.32%和45.66 mg/g,Langmuir和Freundlich比Temkin等温模型更好地拟合吸附实验数据;准一级和准二级动力学模型均能较好地描述该吸附行为,相关系数高达0.99;计算得到热力学参数ΔGθ、ΔHθ和ΔSθ值表明该吸附过程为自发吸热过程。     

Carbon dioxide adsorption behaviors of aluminum-pillared montmorillonite-supported alkaline earth metals

The Al-pillared montmorillonite-supported alkaline earth metal 5M/Al-PILC(PILC = pillared clay, M = Mg, Ca, Sr, and Ba) and x Mg/Al-PILC( x = 1, 3, 5, and 7 wt.%) samples were prepared using an impregnation method. Physical properties of the materials were determined by means of X-ray diffraction(XRD) and N₂ adsorption-desorption, and their CO₂ adsorption behaviors were investigated using the thermogravimetric analyzer(TG), CO₂ temperatureprogrammed desorption(CO...     

4种矿物质载体对硝化微生物富集培养的影响

硝化微生物具有附着生长的特性,载体筛选是其高效富集培养的关键。该研究选取钠基膨润土、钙基膨润土、碳酸钙和硅藻土共4种矿物质作为载体进行硝化微生物富集培养,在其结构特征分析的基础上,研究不同矿物质对硝化微生物氨氧化速率和亚硝酸盐氧化速率的影响,筛选出最佳矿物质载体并进行不同投加比试验(空白、1%、2%、3%、4%),明确硝化微生物富集培养的最佳矿物质载体及投加比。结果表明,4种矿物质均显著提高氨氧化速率和亚硝酸盐氧化速率,较对照组分别增加81.9%～192.8%和93.2%～155.6%;其中,投加硅藻土后氨氧化速率和亚硝酸盐氧化速率均为最高,较对照组分别增加192.8%和155.6%;不同硅藻土投加比例均显著增加氨氧化速率和亚硝酸盐氧化速率,较对照组分别增加121.1%～262%和101.2%～216%;尽管比氨氧化速率和比亚硝酸盐氧化速率随着投加比的增加依次降低32%～59.1%和36.7%～60.8%,但4%投加比处理效果仍为最佳,富集培养过程中硝化微生物的增长符合逻辑斯蒂增长模型,其对载体的利用率随硅藻土投加比的增大而降低。     

Effects of sludge age on anaerobic acidification of waste activated sludge: Volatile fatty acids production and phosphorus release

Effects of sludge age on volatile fatty acids (VFAs) production and Phosphorus (P) release during anaerobic acidification of waste activated sludge (WAS) were investigated. Sequencing batch reactors (SBR) fed with simulating domestic sewage were applied to produce WAS of different sludge ages, and batch tests were used for anaerobic acidification. The maximum dissolved total organic carbon, release of  ${\text{PO}}_4^{3+}?\mathrm{P}$, and accumulation of acetate (C2), propionate (C3), butyrate (C4), and valerate (C5) decreased by 56.2%, 55.8%, 52.6%, 43.7%, 82.4% and 84.8%, respectively, as the sludge age of WAS increased from 5 to 40 days. Limited degradation of protein played a dominating role in decreasing DTOC and VFAs production. Moreover, the increase in molecular weight of organics and organic nitrogen content in the supernatant after acidification suggested that the refractory protein in WAS increased as sludge age extended. Although the production of C2, C3, C4, and C5 from WAS decreased as the sludge age increased, the proportions of C2 and C3 in VFAs increased, which might be due to the declined production of C5 from protein and the faded genus Dechlorobacter. Keeping sludge age of WAS at a relatively low level (<10 days) is more appropriate for anaerobic acidification of WAS as internal carbon sources and P resource.     

Working mechanism and experimental study of dual-diameter and bi-speed composite drilling tool

ABSTRACT

As oil and gas production gradually shifts to deep and ultra-deep formations, the pressure and complexity of stratum is increased and drilling efficiency is decreased. Based on this, a Dual-diameter and bi-speed composite drilling method that can realize the different depth, diameter, and rotate speed coupling using only hole-bottom power is proposed in this paper. And a Dual-diameter and bi-speed composite drilling tool is designed, processed, and carried out to complete the field experiment. The tool is connected by a two-stage screw to make the rotate speed of a pilot bit higher than that of the reaming bit to increase the rate of penetration. And a concave bottom hole is formed so that the ground stress is released and the drillability of rock is lifted. Based on the introduction of the speed-up mechanism of the tool, the numerical analysis of the drilling performance of the tool with different diameter ratios and rotate-velocity combinations is completed. The experimental data showed that the Dual-diameter and bi-speed composite drilling method can obviously increase the rate of penetration and drilling efficiency, and also help to reduce the risk of stick-slip and prolong the service life of the drill bit.     

Improved overall water splitting for hydrogen production on aluminium-doped SrTiO3 photocatalyst via tuned surface band bending

Environmental Chemistry Letters - Future carbon neutrality and the energy crisis are calling for advanced methods to produce sustainable fuels such as hydrogen production by photocatalytic water...     

Hyperaccumulating potential of Bidens pilosa L. for Cd and elucidation of its translocation behavior based on cell membrane permeability

Environmental Science and Pollution Research - Phytoremediation with the use of hyperaccumulating plant species to remove excess trace metals from contaminated soil and water is considered a...     

水中典型内分泌干扰物双酚A的去除技术研究进展

水中双酚A的生物毒性作用,以及其对动物和人体内分泌系统的干扰影响已引起国内外研究人员的广泛关注。通过对水体中双酚A的来源和污染特征的分析,综述了目前对水中双酚A去除技术的研究进展,指出膜分离技术将成为水中双酚A去除技术的主要研究发展方向。