吸附-预沉淀MBR工艺处理生活污水及膜污染控制效果

膜污染是限制膜生物反应器（MBR）广泛应用的主要因素之一。针对MBR处理生活污水过程中存在的硝化效果不稳定与膜污染问题,提出了一种新型的MBR系统：通过吸附-预沉淀实现进水中碳氮的分离和单独处理,不仅提高了污染物去除效果,且能够有效控制膜污染。研究结果表明,吸附-预沉淀可以去除进水中约89.7%的有机物,系统出水COD、NH₄⁺-N平均浓度为24 mg/L、0.78 mg/L,去除率分别为95.9%和98.1%。MBR中碳氮比的降低和硝化细菌比例的增加大大降低了MBR内MLSS、EPS和SMP含量,平均浓度分别为5 185 mg/L、41 mg/g MLSS和2.62 mg/g MLSS。在膜通量为4 L/（m²·h）条件下,TMP可稳定保持在20 kPa左右。通过吸附-预沉淀过程可有效控制MBR中的膜污染。     

活性污泥法处理高钙废水中污泥特性的变化

通过单级SBR法处理模拟高钙废水,研究了活性污泥法处理高钙废水的过程中钙离子对COD,MLVSS,MLSS,SVI,污泥增长速率,污泥形态结构及生物相的影响,揭示活性污泥法处理高钙废水的过程中污泥量巨大的原因。采用逐步增加钙离子浓度的方法,检测到在污泥培养期([Ca2+]=0 mg/L),COD去除率为98.1%,MLVSS和MLSS稳定在4 900~5 500mg/L,污泥增长速率为67 mg/(L·d),SVI为55~60 mL/g;在驯化处理期([Ca2+]=120~2 400 mg/L),COD去除率降至87.37%,MLVSS降至2 500 mg/L,MLSS增加至19 300 mg/L,污泥增长速率为212.31 mg/(L·d),SVI降至25 mL/g;在冲击期([Ca2+]=4 000 mg/L),COD去除率降至69.23%,MLVSS降至1 600 mg/L,MLSS迅速增加至24 200 mg/L,污泥增长速率为816.67 mg/(L·d),SVI降至14 mL/g。经显微镜观察发现,污泥絮体由松散变得密实,生物相由钟虫等指示性微生物变为不适应环境的胞囊结构。结果表明,随Ca2+浓度的增加,COD去除率下降,MLSS迅速增加,MLVSS和SVI急剧缩小,说明活性污泥中的活性微生物逐渐减少,而无机物组分逐渐增多;钙离子的加入促使系统碳酸平衡向右移动,使离子状态的钙大部分转化为难降解的碳酸盐,并附着于污泥絮体上,污泥绒粒被压缩,使污泥颗粒密实度及MLSS迅速增加,导致污泥排放量巨大。     

Direct N2O emission from agricultural soils in Poland between 1960 and 2009

Nitrogen fertilization (N) is commonly known as a main source of direct nitrous oxide (N₂O) emission from agricultural soils. An area of 38 % of the total land surface of Poland was covered by agricultural soils in 2009. In this paper, we aimed at analyzing data regarding the land exploitation for 13 selected subareas of Poland between 1960 and 2009. Seven out of the 13 subareas studied are located in the West (area A), and six subareas are located in southeast of Poland (area B). The total area covered by large farms (>20 ha) differed largely, between area A (10.6 %) and area B (0.9 %) in 2009. Both areas varied in terms of the amount of fertilizers used annually, average crop yield and crop structure. Average direct emissions of N₂O from agricultural soils were 1.66 ± 0.09 kg N₂O–N ha^?1 a^?1 for area A, 1.39 ± 0.07 kg N₂O–N ha^?1 a^?1 for area B and 1.46 ± 0.07 kg N₂O–N ha^?1 a^?1 for the whole country between 1960 and 2009.     

The linear accumulation of atmospheric mercury by vegetable and grass leaves: Potential biomonitors for atmospheric mercury pollution

One question in the use of plants as biomonitors for atmospheric mercury (Hg) is to confirm the linear relationships of Hg concentrations between air and leaves. To explore the origin of Hg in the vegetable and grass leaves, open top chambers (OTCs) experiment was conducted to study the relationships of Hg concentrations between air and leaves of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.). The influence of Hg in soil on Hg accumulation in leaves was studied simultaneously by soil Hg-enriched experiment. Hg concentrations in grass and vegetable leaves and roots were measured in both experiments. Results from OTCs experiment showed that Hg concentrations in leaves of the four species were significantly positively correlated with those in air during the growth time (p?<?0.05), while results from soil Hg-enriched experiment indicated that soil-borne Hg had significant influence on Hg accumulation in the roots of each plant (p?<?0.05), and some influence on vegetable leaves (p?<?0.05), but no significant influence on Hg accumulation in grass leaves (p?>?0.05). Thus, Hg in grass leaves is mainly originated from the atmosphere, and grass leaves are more suitable as potential biomonitors for atmospheric Hg pollution. The effect detection limits (EDLs) for the leaves of alfalfa and ryegrass were 15.1 and 22.2 ng g^–1, respectively, and the biological detection limit (BDL) for alfalfa and ryegrass was 3.4 ng m^–3.     

Removal of anionic azo dye from aqueous solution via an adsorption–photosensitized regeneration process on a TiO2 surface

Textile dye effluents are typically characterized by strong color and recalcitrance, even at very low concentration. The process of enrichment of anionic azo dye on the surface of TiO₂ fibers followed by photosensitization degradation under ambient air conditions was extensively investigated. Adsorption isotherms and zeta potentials were used to describe the “dye/TiO₂ surface” interface, taking into account the effects of pH on the nature and population of the surface groups on the TiO₂ fibers. The extent of the photocatalytic degradation of dye on TiO₂ surface was determined by FTIR. N₂ adsorption isotherms and optical spectra were employed to investigate the effect of photosensitization. The adsorption of dyes on the TiO₂ surface occurs via electrostatic attraction through the formation of single- or multidentate-coordinated surface complexes. Almost complete photobleaching of the absorption band at 534 nm is achieved in ~4 h. Dye-sensitized TiO₂ fiber could absorb part of the visible light spectrum (λ?<?600 nm). Interfacial electron transfer can potentially alter the degradation efficiency. The regenerated TiO₂ fiber could be reused for subsequent decolorization without a decline in adsorption efficiency compared with freshly prepared TiO₂ samples, which may be attributed to preservation of the hierarchical pore structure and restoration of the original surface properties. In summary, we propose an efficient “adsorption–photoregeneration–reuse” process applying TiO₂ fibers for the degradation of dyes in water.     

活性红BF-3BN脱色菌群的构建及特性研究

采用梯度压力式驯化法,从河南某印染厂的活性污泥中富集筛选一组活性红BF-3BN高效脱色菌群AR1。经菌株分离和16S rDNA测序分析,确定菌群内微生物分别归属Clostridium sp.、Pseudomonas sp.和Shewtnella sp.等3个属。染料脱色实验结果表明,在活性红BF-3BN起始浓度为200...     

Mg-Al水滑石对偶氮染料活性艳红X-3B的脱色性能研究

采用共沉淀法合成出一系列镁铝摩尔比不同的碳酸根型水滑石（LDHs）,经500℃高温煅烧制备出镁铝复合氧化物CLDH,并用X-射线、红外光谱对它们进行表征。考查了吸附剂投加量、反应时间、初始pH值等因素对LDHs和CLDH处理阴离子染料活性艳红X-3B模拟废水效果的影响,并对吸附机理进行探讨。实验结果表明：以镁铝摩尔比为3∶1时制得的水滑石对活性艳红X-3B溶液的脱色效果最好。水滑石LDHs及其焙烧产物CLDH对活性艳红X-3B染料均具有较好的吸附性能,最佳反应时间分别为60 min和30 min;在较宽的pH范围内二者的脱色性能稳定,且CLDH对该染料的吸附效果要优于LDHs。LDHs及CLDH对活性艳红X-3B的吸附结果符合Langmuir吸附等温式,25℃下饱和吸附量分别为263.77 mg/g和875.23 mg/g。LDHs及CLDH的吸附机理分别为离子交换和层状结构重建。饱和吸附后的CLDH用高温热解法再生,吸附性能良好,随再生次数增多,脱色率下降。     

Photolysis of Enrofloxacin in aqueous systems under simulated sunlight irradiation: Kinetics, mechanism and toxicity of photolysis products

Photolysis of Enro in water was investigated under simulated sunlight irradiation using a Xenon lamp. The results showed that Enro photolysis followed apparent first-order kinetics. Increasing Enro concentration from 5.0 to 40.0 mg L⁻¹ led to the decrease of the photolysis rate constant from 1.6 × 10⁻² to 3.0 × 10⁻³ min⁻¹. Compared with the acidic and basic conditions, the photolysis rate was faster at neutral condition. Both of nitrate and humic acid can markedly decrease the photolysis rate of Enro because they can competitively absorb photons with Enro. The electron spin resonance and reactive oxygen species scavenging experiments indicated that Enro underwent self-sensitized photooxidation via OH and ¹O₂. After irradiation for 90 min, only 13.1% reduction of TOC occurred in spite of fast photolysis of 58.9% of Enro, indicating that Enro was transformed into intermediates without complete mineralization. The photolysis of Enro involved three main pathways: decarboxylation, defluorination, and piperazinyl N⁴-dealkylation. The bioluminescence inhibition rate using Vibrio fischeri increased to 67.2% at 60 min and then decreased to 56.9% at 90 min, indicative of the generation of some more toxic intermediates than Enro and then the degradation of the intermediates. The results will help us understand fundamental mechanisms of Enro photolysis and provide insight into the potential fate and transformation of Enro in surface waters.     

Quantification of net carbon flux from plastic greenhouse vegetable cultivation: a full carbon cycle analysis

Plastic greenhouse vegetable cultivation (PGVC) has played a vital role in increasing incomes of farmers and expanded dramatically in last several decades. However, carbon budget after conversion from conventional vegetable cultivation (CVC) to PGVC has been poorly quantified. A full carbon cycle analysis was used to estimate the net carbon flux from PGVC systems based on the combination of data from both field observations and literatures. Carbon fixation was evaluated at two pre-selected locations in China. Results suggest that: (1) the carbon sink of PGVC is 1.21 and 1.23 Mg C ha⁻¹ yr⁻¹ for temperate and subtropical area, respectively; (2) the conversion from CVC to PGVC could substantially enhance carbon sink potential by 8.6 times in the temperate area and by 1.3 times in the subtropical area; (3) the expansion of PGVC usage could enhance the potential carbon sink of arable land in China overall.     

低温对MBBR、SBR深度处理废水出水水质的影响

比较了低温和常温下移动床生物膜反应器(MBBR)与 SBR 深度处理低浓度废水的出水水质,研究了低温对反应器出水 COD、运行温度、DO、出水 pH、出水蛋白质质量浓度的影响.实验结果表明:相同曝气和环境温度条件下,MBBR 比 SBR 的运行温度高 0.5-1.5 ℃,受环境温度影响更小;与常温相比,低温反应器内 D...