Effect of Mn2+ on the phosphorus removal and bioflocculation under anoxic condition

Manganese ion (Mn²⁺) generated from metallurgical, steel making and chemical industries enters sewage treatment plants and affects the sludge activity and flocculation. The effect of Mn²⁺ on the removal of chemical oxygen demand (COD) and total phosphorus (TP) and sludge activity were investigated in anoxic zone of an anaerobic/anoxic/oxic (A²O) process. The compositions and structures of extracellular polymeric substances (EPS) were characterized using three-dimensional excitation emission matrix fluorescence spectroscopy (3D-EEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) to reveal the relationship among Mn²⁺, EPS and sludge flocculation.The results showed that low concentration of Mn²⁺ (<5 mg/L) improved removal efficiencies of COD and TP and increased the activity of alkaline phosphatase, acid phosphatase and dehydrogenase. Meanwhile, the addition of Mn²⁺ increased total EPS, sludge contact angle, Zeta potential and sludge particle size, and thus enhanced sludge flocculation. However, high concentration of Mn²⁺ (>10 mg/L) hindered microbial flocculation and reduced removal efficiencies of the pollutants. When Mn²⁺was 5 mg/L, removal efficiencies of COD and TP reached 65% and 90%, respectively. Sludge flocculation was the best and SVI was 70.56 mL/g. The changes of Mn²⁺ concentration caused deviation of groups’ compositions in LB-EPS and TB-EPS, where the main components were always protein (PN) and polysaccharide (PS). The addition of Mn²⁺ resulted in the degradation of humic acids. However, it did not give rise to significant morphology changes of EPS.     

基于生物有效性的农田土壤磷素组分特征及其影响因素分析

适宜的磷素分级方法是研究磷素组分特征与评价其有效性的关键.以磷素的化学与生物活化特点,采用改进的生物有效性的磷素分级方法,应用其研究不同土地利用方式下旱地土与水田土中磷素组分与有效磷（Olsen-P）的关系,并分析环境因子对磷组分的影响.磷素分级方法将磷素分为4个组分：①自由扩散或根际截留的磷（CaCl₂-P）;②有机酸活化和无机弱结合磷（Citrate-P）;③系列酶矿化的有机磷（Enzyme-P）;④潜在活化的无机磷库（HCl-P）.结果表明,旱地土及水田土4种磷素组分含量均表现为：HCl-P > Citrate-P>Enzyme-P > CaCl₂-P,且旱地土各磷组分均显著高于水田土.Olsen-P与各磷素组分均呈显著正相关,表明各磷素组分对有效磷都有贡献.具体表现为：在旱地土中,Olsen-P与CaCl₂-P和Enzyme-P相关性较高（R²=0.359;R²=0.386）;在水田土中,Olsen-P与Citrate-P相关性较高（R²=0.788）,说明旱地土中有效磷主要来自土壤自由扩散的无机磷和易矿化的有机磷部分,而水田土中有效磷主要来自弱酸活化的无机磷.冗余分析结果表明,磷素组分主要受土壤pH和黏粒含量的影响,指示在农业生产活动中,可通过调节土壤pH值,提高土壤有效磷含量.     

Seasonal variations in the concentration and removal of nonylphenol ethoxylates from the wastewater of a sewage treatment plant

In this study, we investigated the occurrence and fate of nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO) in a full scale sewage treatment plant, which applied an Anaerobic/Oxic process. Concentrations of NP, NP1EO and NP2EO in the wastewater were measured during the period spanning a whole year. The results showed remarkable seasonal variation in the concentrations of the compounds. The NPnEO compounds were most abundant in winter, with the total concentrations of influent NP, NP1EO and NP2EO ranging from 3900 to 7000 ng/L, 4000 to 4800 ng/L and 5200 to 7200 ng/L, respectively. Regarding the total removal efficiencies of the three types of short-chain NPnEO compounds, different trends were exhibited according to different seasons. The average removal efficiency of NP for the different seasons ranked as follows: winter > summer > autumn > spring; NP2EO concentrations decreased as follows: summer > autumn > winter > spring, while NP1EO concentrations reduced according to: spring > summer > autumn > winter. We also investigated the contribution ratio of individual treatment units in the A/O process, with the findings suggesting that the anaerobic treatment unit plays an important role in the elimination of short-chain NPnEOs from the wastewater.     

适合我国国情的烟气脱硫技术探讨

本文总结了几种在国内燃煤电厂主要应用开发的脱硫技术,并对不同烟气脱硫技术的主要特点、示范工程及其优缺点作了简单评述。在此基础上,结合我国环境政策分析了发展脱硫技术的关键问题,对未来我国火电厂烟气脱硫技术的发展提出了建议。     

污水处理厂中污水臭气除臭技术的研究与应用

污水处理厂中恶臭气体污染已成为环境污染的重大问题,除臭技术的研究与应用已经成为一个热点。通过介绍处理厂中污水臭气的来源、成分以及对人体的危害,详细分析了各种除臭技术的发展历程,并比较了各自的优缺点,展望了其发展的趋势与应用领域。通过各种除臭技术的比选,最终确定污水处理厂臭气除臭形式采用生物滤池法,最终满足污染物排放标准的要求。展望了今后的研究方向是寻找研究新型的、高效的、环保的除臭技术。     

乡村景观园林问题分析

为加强乡村景观园林建设和保护,分析了乡村景观园林技术改革、设计建筑水平提升、研究意识提升等问题.乡村园林景观是我国园林文化的重要组成部分,对乡村园林进行研究,能够深化对园林文化的认识,从思想上树立建设乡村园林的意识,对乡村园林进行技术层面分析,找到建造技术方面存在的问题,探究建设水平提升对园林建筑发展的重要作用,促进乡...     

威海市土地利用规划对生态环境的影响

新一轮土地利用总体规划修编（2006年-2020年）要求深入分析资源供给、环境容量等限制因素,研究土地利用方式、空间布局对生态环境的影响,提出环境友好型土地利用模式;研究提出有利于环境保护和生态建设的土地利用调控指标和空间管制措施。本文在分析了威海市土地利用现状特点、生态环境状况的基础上,分析了威海市土地利用环境承载力,探讨土地利用规划对生态环境的影响,对合理调整土地利用结构和布局,科学地安排土地利用规划有着十分重要的意义。     

三亚市风景资源生态敏感性及保护初探

从可持续发展的角度,分析了三亚市海陆自然体系生态完整性和旅游资源单体的生态敏感性,根据区域所具有的承载力和风景资源的生态功能,对典型滨海型旅游景观资源的开发提出了具体保护建议。     

不同类型污泥对Cr(VI)的吸附及其影响因素

城市污水厂污泥产生量大且成分复杂,如何实现它的资源化利用已越来越受人们的关注.本研究以生活污水厂和工业废水厂的污泥为吸附剂,研究了其对Cr6 的吸附特性;并以4种挥发份含量不同的污泥为对象,探求污泥挥发份含量与Cr6 吸附量之间的关系.结果表明:两污水厂污泥对Cr6 的吸附量随着pH的降低而增大;Cr6 在两种污泥中的最佳吸附时间均为15 min.另挥发份含量越高的污泥对Cr6 的吸附率越高,由此表明污泥中挥发份含量对Cr6 的吸附有重要的影响.     

Landscape dynamitic change in Mu Us Desert derived from Landsat TM data

Landscpae ecology emphasizes large areas and ecological effects of the spatial patterning of ecosystem.Recent developments in landscape ecology emphasized the important relationship between spatial patterns and many ecological processes.Quantitative methods in landscape ecology link spatial patterns and ecological processes at broad spatial and temporal scales.In turn the increased attention on temoral change of ecosystem has highlighted the need for quantitative methods that can analyze patterns.This research applies quantitative methods-change detection to assess the ecosystem temporal change in the arid and semiarid area.Remote sensing offers the temporal change of ecosystem on landscape characteristics.