Iron improving bio-char derived from microalgae on removal of tetracycline from aqueous system

Novel magnetic carbonaceous bio-char was hydrothermal prepared from microalgae under different loadings of iron and its structures and surface chemistry were characterized with Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and nitrogen adsorption-desorption isotherm (BET). The morphology of bio-char changed from sheet to particle as iron loading increased and its surface area also increased. When 3.0 g of dried microalgae and 6.0 mmol iron salt ((NH₄)₂SO₄·FeSO₄·6H₂O) were mixed and treated, the obtained bio-char possessing the highest amount of oxygen-containing functional groups resulted in the best adsorption performance on tetracycline (TC). This adsorption process was fitted to Langmuir adsorption isotherm and the maximum adsorption capacity was 95.86 mg/g, which is higher than other bio-char reported. The iron loading contributed to the higher adsorption capacity of bio-char, which may be due to three factors, the high surface area, more hydrogen bonding, and bridging effects of the structural Fe for TC. Our data suggest that bio-char may have more important role in stabilization of pollutants in the environment.     

镍渣的重金属浸出特性

在分析镍渣的矿物相组成和重金属元素含量的基础上,鉴定了镍渣样品的浸出毒性,并考察了pH、液固比和浸出时间等条件对镍渣样中铬、铅、铜和锌等重金属浸出特性的影响。结果表明,镍渣中的重金属总量约为渣样的0.9%,且铬、铜和锌的含量较高,需进行安全管理。实验所用镍渣样品为第Ⅰ类一般工业固体废物。在强酸条件下镍渣中重金属浸出浓度较大,pH3后浸出浓度显著降低;液固比40 L/kg时,镍渣中重金属不断溶出,液固比40 L/kg后,浸出达到饱和,浸出浓度趋于平衡;随着浸出时间的增加,重金属离子的浸出浓度先增加后减少,但由于各重金属性质不同,各重金属达到最大浸出浓度的时间不同。     

光催化氧化处理低浓度含醇废水实验

室内实验了TiO2紫外光催化氧化处理废水中的低浓度甲醇。通过对TiO2催化剂活性及添加方式、溶液pH、紫外光强与催化剂加量等参数优化,在TiO2加入浓度为300mg/L和120 W紫外灯照射条件下,对6.8L甲醇浓度为2.77%的低浓度含醇废水持续处理70min后,废水中的甲醇去除率可达98.31%。该实验为进一步处理低浓度含醇废水提供了方法依据。     

Influence of root-exudates concentration on pyrene degradation and soil microbial characteristics in pyrene contaminated soil

The effect of ryegrass (Lolium perenne L.) root-exudates concentration on pyrene degradation and the microbial ecological characteristics in the pyrene contaminated soil was investigated by simulating a gradually reducing concentration of root exudates with the distance away from root surface in the rhizosphere. Results showed that, after the root-exudates were added 15 d, the pyrene residue in contaminated soil responded nonlinearly in the soils with the same pyrene contaminated level as the added root-exudates concentration increased, which decreased first and increased latter with the increase of the added root-exudates concentration. The lowest pyrene concentration appeared when the root exudates concentration of 32.75 mg kg(-1) total organic carbon (TOC) was added. At the same time, changes of microbial biomass carbon (MBC, C(mic)) and microbial quotient (C(mic)/C(org)) were opposite to the trend of pyrene degradation as the added root-exudates concentration increased. Phospholipid fatty acid (PLFA) analysis revealed that bacteria was the dominating microbial community in pyrene contaminated soil, and the changing trends of pyrene degradation and bacteria number were the same. The changing trend of endoenzyme-dehydrogenase activity was in accordance with that of soil microbe, indicating which could reflect the quantitative characteristic of detoxification to pyrene by soil microbe. The changes in the soils microbial community and corresponding microbial biochemistry characteristics were the ecological mechanism influencing pyrene degradation with increasing concentration of the added root-exudates in the pyrene contaminated soil.     

活性污泥的耐盐驯化培养

以某污水处理厂二沉池好氧污泥为接种污泥,采用逐步提高盐度和稳定盐度2种方法对活性污泥进行耐盐性驯化培养,考察驯化结果表明,前一种方法更有利于耐盐菌的培养。对比不同盐度情况下各项指标的去除效果得出:本实验污泥适宜盐度为1%。使用稳定进水盐度的方法,出水指标及各指标的去除率均低于逐步提高盐度法,且镜检结果表明大量微生物死亡。     

介质阻挡放电对湖泊水华蓝藻的去除

采用介质阻挡放电等离子体技术去除太湖水华蓝藻,考察了放电输出功率、空气流速、添加剂(异丙醇、腐植酸)等对蓝藻去除的影响。结果表明,介质阻挡放电能去除太湖水华蓝藻,放电功率100 W,空气流速1.0 L/min,放电18min,在光照强度2 000 lx和25℃下培养4 d,初始叶绿素a浓度为9.58 mg/L藻液中蓝藻去除率达87.8%。增加放电输出功率和空气流速能提高蓝藻的去除效率;腐植酸促进了介质阻挡放电对蓝藻的去除;而异丙醇添加剂抑制了介质阻挡放电的作用。放电处理后,蓝藻细胞内类胡萝卜素含量、SOD活性、MDA含量发生明显变化,介质阻挡放电破坏了蓝藻细胞内含物。     

Effect of ambient-level gas-phase peroxides on foliar injury, growth, and net photosynthesis in Japanese radish (Raphanus sativus)

To investigate the effects of ambient-level gas-phase peroxides concurrent with O₃ on foliar injury, photosynthesis, and biomass in herbaceous plants, we exposed Japanese radish (Raphanus sativus) to clean air, 50 ppb O₃, 100 ppb O₃, and 2-3 ppb peroxides + 50 ppb O₃ in outdoor chambers. Compared with exposure to 100 ppb O₃, exposure to 2-3 ppb peroxides + 50 ppb O₃ induced greater damage in foliar injury, net photosynthetic rates and biomass; the pattern of foliar injury and the cause of net photosynthetic rate reduction also differed from those occurring with O₃ exposure alone. These results indicate for the first time that sub-ppb peroxides + 50 ppb O₃ can cause more severe damage to plants than 100 ppb O₃, and that not only O₃, but also peroxides, could be contributing to the herbaceous plant damage and forest decline observed in Japan's air-polluted urban and remote mountains areas.     

ASBBR-二级SBBR-化学除磷组合工艺处理榨菜腌制废水

针对榨菜腌制废水高盐高氮磷高有机物浓度的特征,提出"厌氧序批式生物膜反应器(ASBBR)-二级序批式生物膜反应器(SBBR)-化学除磷"组合处理工艺,在前期对组合工艺中单元工艺的关键工况参数研究的基础上,考察组合工艺的处理效能。实验结果表明,采用该组合工艺,可使进水COD、NH4+-N、TN及PO43--P分别为10 000、345、550和38.5mg/L的榨菜腌制废水,处理出水COD、NH4+-N、TN及PO43--P分别达到93.6、12.3、18和0.1 mg/L,去除率分别为99.1%、96.4%、96.7%和99.9%,出水达到污水综合排放一级标准。     

Quantitative evaluation of environmental risks of flotation tailings from hydrothermal sulfidation–flotation process

Floatation tailings (FT) are the main by-products of the hydrothermal sulfidation–flotation process. FT (FT₁ and FT₂) were obtained by treating two different neutralization sludges (NS) (NS₁ and NS₂). This paper quantitatively evaluated the environmental risks of heavy metals (Zn, Cd, Cu, Pb, and As) in FT versus NS. The total concentration and leaching rates (R ₂) of heavy metals in FT were much lower than those in NS, demonstrating that the hydrothermal sulfidation–flotation process was able to effectively suppress the mobility and leachability of heavy metals. The BCR-three sequence leaching procedure of FT confirmed that all metals were transformed into more stable forms (residue and oxidizable forms) than were found that in NS. The potential ecological risk index indicated that the overall risks caused by heavy metals decreased significantly from 6627.59 and 7229.67 (very serious risk) in NS₁ and NS₂, respectively, to 80.26 and 76.27 (low risk) in FT₁ and FT₂, respectively. According to the risk assessment code, none of the heavy metals in FT posed significant risk to the natural environment except Zn (with low risk). In general, the risk of heavy metals in FT had been well controlled.     

Biotreatment of chromite ore processing residue by Pannonibacter phragmitetus BB

Chromite ore processing residues (COPR) is the source of the Cr(VI) contamination in the environment. Pannonibacter phragmitetus BB was used to treat two different types of COPRs in this research. The water-soluble Cr(VI) of COPR A and B is 3,982.9 and 1,181.4 mg/kg, respectively. In the column biotreatment process, P. phragmitetus BB can reduce Cr(VI) in the leachate to an undetectable level at the flow rate of 1 and 2 ml/min. In the direct biotreatment process, Cr(VI) in the liquid supernatant of COPR A and B decreased from 265 and 200 mg/l to 145 and 40 mg/kg after 240 h of incubation. In one-step and two-step biotreatment processes, Cr(VI) in the liquid supernatant of both COPRs can be reduced to an undetectable level. The toxicity characteristic leaching procedure results indicate that the Cr(VI) concentration of treated COPR A (3.48 mg/l) is lower than the identification standards for hazardous wastes of China (5 mg/l) (GB 5085.6-2007). The information obtained in this study has significance for the application of P. phragmitetus BB to remediate COPR contamination.