Microstructures and electrochemical behaviors of the friction stir welding dissimilar weld

By using optical microscope, the microstructures of 5083/6082 friction stir welding (FSW) weld and parent materials were analyzed. Meanwhile, at ambient temperature and in 0.2 mol/L NaHS0₃ and 0.6 mol/L NaCl solutionby gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation, the electrochemical behavior of 5083/6082 friction stir welding weld and parent materials were comparatively investigated by gravimetric test, potentiodynamic polarization curve test, electrochemical impedance spectra (EIS) and scanning electron microscope (SEM) observation. The results indicated that at given processing parameters, the anti-corrosion property of the dissimilar weld was superior to those of the 5083 and 6082 parent materials.     

土著微生物修复城市小型湖泊实验研究

利用生物制剂及生物修复技术对鞍山市英泽湖进行了净化治理.研究结果表明,经过8～30 d的生物净化,该湖水中的COD、植物营养元素浓度及浊度都有了大幅度的下降.其中COD降至20 mg/L以下,去除率达到70%以上;氨氮降至0.2 mg/L以下,去除率达97%;总磷降低至0.02 mg/L以下,去除率达到60%以上;浊度...     

高温下好氧污泥接种启动UASB的试验研究

采用高温UASB处理柠檬酸废水,研究利用好氧脱水污泥接种启动高温UASB的可行性。试验结果表明,在温度55℃,HRT为6天的条件下,UASB反应器能降解的柠檬酸废水浓度为10000mg/L,容积负荷为1.67gCOD/(L.d),柠檬酸废水的去除率达到90%以上。     

DELtatox便携式毒性测试仪在Q—TOX和B—TOX两种模式下应用与探讨

随着经济社会的发展,突发性水质污染事故日趋增多。因此能够快速、准确测定水质状况是环境应急监测的一项重要工作。在一起水厂取水口有人投药打鱼事故中,采用DELtatox便携式毒性测试仪在Q—TOX和B—TOX两种模式下快速检测事发地水质,结果表明快速、高效的检测为此次污染事故的成功处置提供了技术支持,为以后类似突发污染事故的应急监测提供了参考。     

我国垃圾分类现状及对策建议

分析目前我国垃圾分类回收中存在的问题,阐述垃圾分类回收处理的必要性和相关对策建议。     

Beyond hypoxia：Occurrence and characteristics of black blooms due to the decomposition of the submerged plant Potamogeton crispus in a shallow lake

Organic matter-induced black blooms(hypoxia and an offensive odor) are a serious ecosystem disasters that have occurred in some large eutrophic shallow lakes in China. In this study, we investigated two separate black blooms that were induced by Potamogeton crispus in Lake Taihu, China. The main physical and chemical characteristics, including color- and odor-related substances, of the black blooms were analyzed. The black blooms were characterized by low dissolved oxygen concentration(close to 0 mg/L), low oxidation-reduction potential, and relatively low pH of overlying water. Notably higher Fe2+and∑S2-were found in the black-bloom waters than in waters not affected by black blooms. The black color of the water may be attributable to the high concentration of these elements, as black FeS was considered to be the main substance causing the black color of blooms in freshwater lakes. Volatile organic sulfur compounds, including dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, were very abundant in the black-bloom waters. The massive anoxic degradation of dead Potamogeton crispus plants released dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide, which were the main odor-causing compounds in the black blooms. The black blooms also induced an increase in ammonium nitrogen and soluble reactive phosphorus levels in the overlying waters. This extreme phenomenon not only heavily influenced the original lake ecosystem but also greatly changed the cycling of Fe, S, and nutrients in the water column.     

Enhanced struvite recovery from wastewater using a novel cone-inserted fluidized bed reactor

The feasibility of struvite recovery at low （12.5 mg/L） and high （120 mg[L） phosphorus concentrations was studied by constructing a novel fluidized bed reactor with cones （FBRwc） and without cones （FBRwoc）. The crystallization process was continuously operated for 133 days under different hydraulic retention times （HRT = 1-10 hr）, pH （7.5-10）, and molar ratios of Mg/P （0.75-1.75）, N/P （1-10） and Ca/Mg （0-2）. The optimum operating conditions of HRT, pH, Mg/P and N/P molar ratios were found to be 2 hr, 9, 1.25, and 7.5, respectively. Under these optimum conditions, the phosphorus precipitation efficiencies of FBRwc were 93% for low and 98% for high phosphorus influent; however, the efficiencies were 78% and 81% for FBRwoc, respectively. Due to crystal losses at each junction （17%-31%）, the crystal recovery efficiency of FBRwoc was relatively low （47%-65%） for both influent concentrations. However, the losses were minimal in FBRwc, which showed 75% and 92% crystal recovery for low and high phosphorus concentrations, respectively. At low calcium concentration, crystal chemical analysis showed the product to be pure struvite （〉 99%）. The scanning electron microscope and X-ray diffraction results further confirmed that the crystal recovered from FBRwc contained pure struvite, which could be considered a high quality fertilizer. Except HRT, all parameters （pH, Mg/P, N/P and Ca/Mg） were found to be influencing factors for FBRwc performance. Overall, inserting cones in each part of the reactor played a significant role in enhancing struvite recovery from a wide range of phosphorus-containing wastewater.     

Removal of phosphate from wastewater using alkaline residue

Alkaline residue(AR) was found to be an efficient adsorbent for phosphate removal from wastewater. The kinetic and equilibrium of phosphate removal were investigated to evaluate the performance of modified alkaline residue. After treatment by NaOH(AR-NaOH), removal performance was significantly improved, while removal performance was almost completely lost after treatment by HCl(AR-HCl). The kinetics of the removal process by all adsorbents was well characterized by the pseudo second-order model. The Langmuir model exhibited the best correlation for AR-HCl, while AR was effectively described by Freundlich model. Both models were well fitted to AR-NaOH. The maximum adsorption capacities calculated from Langmuir equation were in following manner: AR-NaOH AR AR-HCl. Phosphate removal by alkaline residue was pH dependent process. Mechanisms for phosphate removal mainly involved adsorption and precipitation, varied with equilibrium pH of solution. For AR-HCl, the acid equilibrium pH( 6.0) was unfavorable for the formation of Ca-P precipitate, with adsorption as the key mechanism for phosphate removal. In contrast, for AR and ARNaOH, precipitation was the dominant mechanism for phosphate removal, due to the incrase on pH( 8.0) after phosphate removal. The results of both XRD and SEM analysis confirmed CaHPO4·2H2O formation after phosphate removal by AR and AR-NaOH.     

Arsenic removal from groundwater by acclimated sludge under autohydrogenotrophic conditions

Arsenic in the environment is attracting increasing attention due to its chronic health effects. Although arsenite(As(III)) is generally more mobile and more toxic than arsenate(As(V)), reducing As(V) to As(III) may still be a means for decontamination, because As(III) can be removed from solution by precipitation with sulfide or by adsorption or complexation with other metal sulfides. The performance of As(V) bio-reduction under autohydrogenotrophic conditions was investigated with batch experiments. The results showed that As(V) reduction was a biochemical process while both acclimated sludge and hydrogen were essential. Most of the reduced arsenic remained in a soluble form, although 20% was removed with no addition of sulfate, while 82% was removed when sulfate was reduced to sulfide. The results demonstrated that the reduced arsenic was re-sequestered in the precipitates, probably as arsenic sulfides. Kinetic analysis showed that pseudo first-order kinetics described the bio-reduction process better than pseudo second-order. In particular, the influences of pH and temperature on As(V) reduction by acclimated sludge under autohydrogenotrophic conditions and total soluble As removal were examined. The reduction process was highly sensitive to both pH and temperature, with the optimum ranges of pH 6.5–7.0 and 30–40°C respectively. Furthermore, Arrhenius modeling results for the temperature effect indicated that the As(V) reduction trend was systematic. Total soluble As removal was consistent with the trend of As(V) reduction.     

普光气田含硫污水尾气处理工艺应用与优化

针对中国石化普光气田产出水属于典型的含硫污水,密闭处理系统中产生大量高含硫尾气,论述了尾气处理工艺中存在的问题,优化了单一的生物除硫、活性炭吸附工艺,增加了一级碱洗、氧化除硫工艺,实现尾气达标排放。