Insights into the mechanism of the deterioration of mainstream partial nitritation/anammox under low residual ammonium

Residual ammonium is a critical parameter affecting the stability of mainstream partial nitritation/anammox (PN/A), but the underlying mechanism remains unclear. In this study, mainstream PN/A was established and operated with progressively decreasing residual ammonium. PN/A deteriorated as the residual ammonium decreased to below 5 mg/L, and this was paralleled by a significant loss in anammox activity in situ and an increasing nitrite oxidation rate. Further analysis revealed that the low-ammonium condition directly decreased anammox activity in situ via two distinct mechanisms. First, anammox bacteria were located in the inner layer of the granular sludge, and thus were disadvantageous when competing for ammonium with ammonium-oxidizing bacteria (AOB) in the outer layer. Second, the complete ammonia oxidizer (comammox) was enriched at low residual ammonium concentrations because of its high ammonium affinity. Both AOB and comammox presented kinetic advantages over anammox bacteria. At high residual ammonium concentrations, nitrite-oxidizing bacteria (NOB) were effectively suppressed, even when their maximum activity was high due to competition for nitrite with anammox bacteria. At low residual ammonium concentrations, the decrease in anammox activity in situ led to an increase in nitrite availability for nitrite oxidation, facilitating the activation of NOB despite the dissolved oxygen limitation (0.15–0.35 mg/L) for NOB persisting throughout the operation. Therefore, the deterioration of mainstream PN/A at low residual ammonium was primarily triggered by a decline in anammox activity in situ. This study provides novel insights into the optimized design of mainstream PN/As in engineering applications.     

江宁开发区污水处理厂二期调试运行

江宁开发区污水处理厂建设规模为4万m^3／d，分两期建成，采用氧化沟处理工艺，污泥处理采用不经消化的带式脱水工艺。在此主要叙述了各工艺构筑物的设备配置、功能、设计参数及二期工程的试运行情况。     

磺酰脲类除草剂的残留分析

磺酰脲类除草剂是一类新型超高效除草剂，大约包括２Ｖ化合物，已被广泛用于禾谷作物防除阔叶杂草以及某些禾本科杂草，该类除草剂在环境中的残留浓度〈１μｇ．ｋｇ＾－１水平。常规的分析方法包括生物鉴定，酶免疫分析，气相色谱法和高效液相色谱法（ＨＰＬＣ）、ＨＰＬＣ／ＭＳ联用后，可以准确测定复杂环境样中磺酰脲类除草剂的痕量残留。     

锅炉烟气脱硫技术发展综述

在调查研究的基础上，论述国内外烟道气脱硫技术的发展与前景，提出开发生产适合我国国情的烟气脱硫技术势在必行。还简要介绍了最为普遍的石灰／石灰石法脱硫基本原理。     

内蒙古巴彦淖尔市乌拉特中旗生态环境恶化的根源及其对策

通过对乌拉特中旗近20年来农牧业生产发展情况、气象环境质量状况等多方面调查，总结出乌拉特中旗生态环境恶化的根源，按照“围封轮牧，划区禁牧，舍饲养牧，移民休牧”的指导思想，并对如何改善乌拉特中旗生态环境提出具体的对策和措施。     

用水基表面活性剂乳液回收废白土中蜡的界面张力研究

通过测定液体与废白土粉末之间的接触角及液体与蜡之间的液液界面张力，对水基表面活性剂乳液的溶剂及配方进行了优选，得到最佳的水基面活性剂乳液的组成为：质量分数０．２％的十二烷基苯磺酸钠＋体积分数为２．５％的乙醇＋体积分数为２５％的混合烃（正己烷＋苯，等体积）＋体积分数为７２．５％的水。实验证明，用该水基表面活性剂乳液处理废白土，蜡的回收率可达８０％，同时不破坏白土的颗粒结构。     

一种新型滑动集电材料的研制及性能研究

利用粉末冶金 /挤压的方法制作了一种新型的Cu C滑动集电材料 ,并对该材料的机械物理、摩擦磨损性能进行了检测 ,结果证明该材料具有较高的抗拉强度、适中的表面硬度、较低的电阻率、优良的摩擦磨损性能 ,是一种较为优良的电力机车滑板材料。其性能测试结果和铁道部标准要求相比 ,优于铁道部标准要求。     

半干法喷射烟气脱硫试验研究

介绍了半干法喷射烟气脱硫试验 ,研究了钙硫比、雾化水量、进口SO2 浓度、湿度等主要因素对脱硫率的影响规律 ,对布袋除尘器的辅助脱硫也进行了研究。结果将有助于改进半干法脱硫技术 ,并为进一步的工业应用提供了参考数据。     

Photodegradation of acetochlor in water and UV photoproducts identified by mass spectrometry

The sunlight photodegradation half-lives of 20 mg/L acetochlor were 151, 154 and 169 days in de-ionized water, river water and paddy water, respectively. When exposed to ultraviolet (UV) light, acetochlor in aqueous solution was rapidly degraded. The half-lives were7.1, 10.1, and 11.5 min in de-ionized water, river water and paddy water, respectively. Photopreduets of acetochlor were identified by gas chromatography/mass spectrometry(GC/MS) and found at least twelve photoproducts resulted from dechlorination with subsequent hydrtrxylation and cyclization processes. The chemical structures of ten photoproducts were presumed on the basis of mass spectrum interpretation and literature data. Photoproducts are identified as 2-ethyl-6-methylaniline; N, N-diethylaniline ; 4, 8-dimethyl-2-oxo- 1,2,3,4- tetrahydroquino-line; 2-oxo-N-(2-ethyl-6-methylphenyl)-N-(ethoxymethyl) acetamide; N-(ethoxymethyl)-2‘-ethyl-6‘-methylformanilide; 1-hydroxyaeetyl-2-ethoxyl-7-ethylind ole; 8-ethyl-l-ethoxymethyl-2-oxo-1, 2, 3, 4-tetrahydroquinoline; 4, 8-dimethyl-l-ethoxymethyl-2-oxo-1, 2, 3, 4-tetrahydroquinoline; 2-hydroxy-2‘-ethyl-6‘-methyl-N-(ethoxymethyl) acetanilide and a compound related to acetochlor. The other two photoproducts were detected by GC/MS although their chemical structure was unknown.     

45,X/46,XY chromosome mosaicism detected by midtrimester amniocentesis in amniocyte clones

Amniocyte clones from a mid-trimester pregnancy disclosed 45,X/46,XY sex chromosome mosaicism. Because of the uncertainty concerning the phenotype of the fetus, the parents elected to terminate the pregnancy. Mixed (asymmetrical) gonadal dysgenesis was not found. The fetus appeared to have a normal male uro-genital system. No malformations of any type were detected, although as expected, the fetus did have 45,X/46,XY mosaicism.