LFG控制利用工程基本参数的试验研究

通过深圳市玉龙坑垃圾填埋场的现场抽气试验。本文进行了填埋气本安全控制与回收利用工程基本参数的研究。     

Modeling and simulation of landfill gas production from pretreated MSW landfill simulator

The cumulative landfill gas (LFG) production and its rate were simulated for pretreated municipal solid waste (MSW) landfill using four models namely first order exponential model, modified Gompertz model, single component combined growth and decay model and Gaussian function. Considering the behavior of the pretreated MSW landfill, a new multi component model was based on biochemical processes that occurring in landfilled pretreated MSW. The model was developed on the basis of single component combined growth and decay model using an anaerobic landfill simulator reactor which treats the pretreated MSW. It includes three components of the degradation i.e. quickly degradable, moderately degradable and slowly degradable. Moreover, the developed model was statistically analyzed for its goodness of fit. The results show that the multi components LFG production model is more suitable in comparison to the simulated models and can efficiently be used as a modeling tool for pretreated MSW landfills. The proposed model is likely to give assistance in sizing of LFG collection system, generates speedy results at lower cost, improves cost-benefit analysis and decreases LFG project risk. It also indicates the stabilization of the landfill and helps the managers in the reuse of the landfill space. The proposed model is limited to aerobically pretreated MSW landfill and also requires the values of delay times in LFG productions from moderately and slowly degradable fractions of pretreated MSW.     

Modified landfill gas generation rate model of first-order kinetics and two-stage reaction

This investigation was carried out to establish a new domestic landfill gas (LFG) generation rate model that takes into account the impact of leachate recirculation. The first-order kinetics and two-stage reaction (FKTSR) model of the LFG generation rate includes mechanisms of the nutrient balance for biochemical reaction in two main stages. In this study, the FKTSR model was modified by the introduction of the outflow function and the organic acid conversion coefficient in order to represent the in-situ condition of nutrient loss through leachate. Laboratory experiments were carried out to simulate the impact of leachate recirculation and verify the modified FKTSR model. The model calibration was then calculated by using the experimental data. The results suggested that the new model was in line with the experimental data. The main parameters of the modified FKTSR model, including the LFG production potential (L₀), the reaction rate constant in the first stage (K₁), and the reaction rate constant in the second stage (K₂) of 64.746 L, 0.202 d⁻¹, and 0.338 d⁻¹, respectively, were comparable to the old ones of 42.069 L, 0.231 d⁻¹, and 0.231 d⁻¹. The new model is better able to explain the mechanisms involved in LFG generation.     

危险废物安全填埋场的环境经济分析

遵循国家颁布的《中华人民共和国固体废物污染环境防治》、对工业固体废物中危险废物处理处置技术和方法进行系统研究,推荐采用安全填埋法处置工业危险废物。从环境经济角度论证安全填埋法方案可行性,采用效益费用分析法对实例进行分析,最终得出安全填埋法方案的实用性,可行性结论。     

生活垃圾填埋场填埋气中汞的分布特征

利用Tekran 2537A和Lumex RA-915汞分析仪分别对生活垃圾填埋场排气筒、填埋场内部的气态总汞变化规律进行了分析,结果表明,填埋场排气筒中气态总汞含量呈现明显的昼夜变化规律,白天高于夜间,并于午间达到峰值。气象条件对汞的释放过程有重要影响,光照强度与排气筒中气态总汞含量的相关性明显。受填埋场内部物理、化学、生物作用的影响,填埋场内部填埋气的汞浓度明显高于排气筒中填埋气的汞浓度。填埋场内部气态总汞变化规律为:植被覆盖区域明显低于无植被覆盖区域,表明有效的绿化措施对于控制填埋场汞污染具有重要意义。     

Optimization of methyl orange removal from aqueous solution by response surface methodology using spent tea leaves as adsorbent

The effective disposal of redundant tea waste is crucial to environmental protection and comprehensive utilization of trash resources. In this work, the removal of methyl orange （MO） from aqueous solution using spent tea leaves as the sorbent was investigated in a batch experiment. First, the effects of various parameters such as temperature, adsorption time, dose of spent tea leaves, and initial concentration of MO were investigated. Then, the response surface methodology （RSM）, based on Box- Behnken design, was employed to obtain the optimum adsorption conditions. The optimal conditions could be obtained at an initial concentration of MO of 9.75 mg·L-1, temperature of 35.3℃, contact time of 63.8 min, and an adsorbent dosage 3.90 g· L-1. Under the optimized condi- tions, the maximal removal of MO was 58.2%. The results indicate that spent tea leaves could be used as an effective and economical adsorbent in the removal of MO from aqueous solution.     

不同部位梧桐生物质炭对水溶液中镉吸附的机理

为了探究梧桐不同部位废弃物所制备的生物质炭(皮、枝、叶)对Cd²⁺的吸附效率和稳定修复的机理,以此为园林废弃物炭化利用在重金属污染修复方面的应用提供科学依据.利用实验室模拟法,通过高温煅烧法制备梧桐不同部位生物质炭,采用元素分析仪、比表面积及孔隙分析(BET)、X射线衍射仪(XRD)、扫描电镜/能谱(SEM/EDS)及衰减全反射红外光谱(ATR-IR)等技术研究不同反应时间、重金属浓度和溶液初始pH条件下生物质炭对Cd²⁺吸附效果的影响,并运用四步萃取法和脱附实验分析生物质炭上Cd²⁺的吸附形态和稳定性.3种生物质炭都在8 h左右达到吸附平衡,最终吸附量依次为树皮炭>枝条炭>叶片炭;溶液初始浓度为0.5—2 g·L^-1时Cd²⁺的吸附量呈增长趋势,在2.5—3g·L^-1时逐渐平缓;生物质炭Cd²⁺吸附量均随着pH的升高而升高,但在pH值为5—8时,吸附的趋势逐渐平稳;树皮炭的酸溶态和非生物利用态的稳定Cd形态要高于枝条炭和叶片炭;比表面积不是影响梧桐生物质炭吸附Cd²⁺的主要影响因素,吸附动力学,ATR,XRD和重金属形态萃取均证实Cd碳酸盐类矿物生成是主导吸附机理;3种生物质炭的脱附量在4 h后逐渐趋于平衡,其中脱附量最大为叶片炭,最小为树皮炭.梧桐不同部位的初始性质对生物质炭吸附Cd²⁺具有明显的影响,其中梧桐皮具备更高的吸附量和重金属稳定形态,并且相比其他种类生物质炭有明显优势.因此,从吸附效果和生产成本的角度,本研究建议以梧桐皮为主,枝条和叶片为辅的生物质炭对重金属Cd进行修复治理.     

垃圾填埋气对植物生长影响初探

以11种上海常见绿化植物的盆栽幼苗为对象,在上海顾村垃圾填埋场就填埋气对这些植物幼苗生长和生理特征的影响进行了初步分析和比较。研究测定的形态指标和生理指标主要包括：生长势、存活率、株高变化、叶绿素含量和脯氨酸含量。结果表明：1）距离填埋气排放口越近的植物生长越差,存活率越低,株高变矮。2）距离填埋气排放口越近的植物叶绿素含量越小,脯氨酸含量越高。3）狗牙根（Cynodon dactylon）、构树（Broussonetia papyrifera）等植物出现了受害后的恢复性生长,暗示了其对垃圾填埋气良好的适应性,而蚊母树（Distylium racemosum）存活率低且生长势差,暗示了其对垃圾填埋气的极度不适应。本研究的结果可以为在高浓度填埋气环境下对垃圾填埋场进行近自然植被恢复提供一定的研究基础。     

重气连续泄漏扩散的盐水模拟实验

根据相似理论,分析了用盐水模拟方法研究意外泄漏的重气在大气中扩散过程的可行性,通过假设重气为不可压缩气体以及在均匀温度场中扩散等条件,推导出模拟实验的准则数.采用缩比模型的盐水模拟实验,对重气在大气中的扩散速度及浓度变化进行了分析,证实了重气扩散过程中的重力沉降、密度分层以及近源区分叉等现象.实验表明,在满足主导准则数相等的条件下,盐水在清水中的扩散可以较好地再现重气在大气中的扩散特征.     

多维气相色谱分离TCDDs和PCBs

本文描述用多维气相色谱(SE-54柱/FFAP柱)和FID/ECD并行检测系统分析TCDDs和PCBs的方法。经SE-54柱切割的目的部分立即进入FFAP柱分离,中间不需用冷捕集技术。结果表明,该方法是选择检测复杂环境样品中痕量毒物的有效方法。     

气相色谱-质谱联用法在线观测大气中的氢氟碳化物和全氟化碳

利用组装的气相色谱-质谱联用系统(GC-MS)同时测定大气中6种氢氟碳化物(HFCs)和4种全氟化碳(PFCs),空气样品采样的时间分辨率120 min,精度范围0.15%—3.11%,准确度范围-1.52%—0.63%.对2011年2月在北京上甸子站的实验观测结果进行分析,获得HFC-23、HFC-32、HFC-134a、HFC-143a、HFC-125、HFC-152a、CF4、PFC-116、PFC-218、PFC-318的本底和非本底浓度,表明该系统适用于大气中HFCs和PFCs浓度在线观测.     

垃圾填埋场的甲烷减排及覆盖层甲烷氧化研究进展

温室效应导致的全球变暖是备受瞩目的环境问题之一,其中垃圾填埋场产生填埋气是全球温室气体的重要来源。文章从垃圾填埋场的CH4产生、CH4减排技术和覆盖层CH4氧化行为及其影响因素等方面对国内外研究现状进行总结,为全面认识垃圾填埋场的CH4减排提供参考。目前,填埋场CH4减排技术包括填埋层原位减排、资源化利用和末端控制技术等,其中准好氧填埋技术和生物覆盖层甲烷氧化技术是适合我国现阶段大量中小型填埋场CH4减排要求的技术。填埋场覆盖层的特性如温度、含水率、有机质含量、pH值、孔隙率、CH4/O2比、植被和无机氮等都会影响其甲烷氧化能力,是填埋场覆盖层甲烷氧化能力研究和调控的主要参数。     

Reaction mechanism of arsenic capture by a calcium-based sorbent during the combustion of arsenic-contaminated biomass: A pilot-scale experience

Pilot-scale combustion is required to treat arsenic-enriched biomass in China. CaO addition to arsenic-enriched biomass reduces arsenic emission. CaO captures arsenic via chemical adsorption to form Ca₃(AsO₄)₂. Large quantities of contaminated biomass due to phytoremediation were disposed through combustion in low-income rural regions of China. This process provided a solution to reduce waste volume and disposal cost. Pilot-scale combustion trials were conducted for in site disposal at phytoremediation sites. The reaction mechanism of arsenic capture during pilot-scale combustion should be determined to control the arsenic emission in flue gas. This study investigated three Pteris vittata L. biomass with a disposal capacity of 600 kg/d and different arsenic concentrations from three sites in China. The arsenic concentration in flue gas was greater than that of the national standard in the trial with no emission control, and the arsenic concentration in biomass was 486 mg/kg. CaO addition notably reduced arsenic emission in flue gas, and absorption was efficient when CaO was mixed with biomass at 10% of the total weight. For the trial with 10% CaO addition, arsenic recovery from ash reached 76%, which is an ~8-fold increase compared with the control. Synchrotron radiation analysis confirmed that calcium arsenate is the dominant reaction product.     

VOCs走航监测:技术方法与案例应用

挥发性有机物(VOCs)来源广泛、组成复杂,是臭氧(O3)和二次有机气溶胶(SOA)的重要前体物,且其中一些组分对人体健康存在潜在威胁。VOCs的主要排放方式包括点源、面源和无组织源排放,排放过程具有瞬时性,难以控制和监测。与传统的离线监测和在线监测相比,走航监测技术具有监测范围大、响应快速、机动性强的特点,但中国VOCs的走航监测研究还鲜有报道。该研究通过使用装载了单质谱分析仪与便携式气相色谱-质谱联用仪(GC-MS)的走航车对珠三角沿海城市某工业集聚区进行VOCs走航监测,走航过程中对环境空气中的TVOCs进行快速监测并对TVOCs质量浓度高值点进行采样及VOCs组分的成分和浓度分析。该次走航共监测到32种优控污染因子和CW加油(加气)站、JH加油站、G空调电器生产企业的两器车间及南门货场等多个TVOCs质量浓度高值点,并通过分析进一步判断VOCs排放源。结合监测结果和实地调研推断:加油站的VOCs高值主要来源于油气挥发及机动车尾气排放;G空调企业的VOCs高值则主要来源于两器车间的喷涂、烘干、洗网工序及厂区内的机动车尾气排放。尽管VOCs走航监测技术目前还存在一定不足,该方法的应用能够为掌握区域VOCs污染现状及分布特征提供新的技术手段,为实现VOCs精细化管控提供新的思路。     

垃圾焚烧模拟烟气中镉的动态吸附实验

在生活垃圾焚烧烟气模拟净化实验中,采用氯化镉作为气态重金属的发生源,模拟改性钙基吸附剂对重金属的动态吸附,并对重金属入口浓度、吸附温度、吸附剂投加量以及烟气组分等因素进行研究,结果表明:(1)反应温度对镉的去除有一定的影响,温度升高,去除率下降;(2)钙基吸附剂对Cd的去除率随着Cd入口浓度的增加而降低;(3)吸附剂投加量增加,去除率随之增加,但当加入量达到100g以上时,去除率不再变化;(4)HCl气体的存在能促进Cd的吸附,SO_2气体的存在则抑制Cd的吸附;(5)随着吸附质CdCl_2初始浓度的增加,钙基吸附剂的吸附量逐渐增加并趋向平衡,且与活性炭相当.     

环丙沙星在亚高山草甸不同深度土壤上的吸附及其影响因素

兽用抗菌药物环丙沙星(CIP,ciprofloxacin)的大量使用引发了人们的广泛关注.文章研究了CIP在亚高山草甸土剖面土壤上的吸附动力学、吸附热力学和pH、有机质含量、阳离子交换量等因素对吸附的影响,以揭示CIP在亚高山草甸土上的吸附机制,为CIP的生态风险评价提供一定的依据.结果表明,CIP在亚高山草甸土上的吸...     

EDU对臭氧胁迫下菠菜急性伤害症状和光合特性的影响

如何减轻近地层臭氧(O3)体积分数持续升高对作物的影响是污染生态学研究的热点之一。运用改进的开顶式气室(open-top chambers,OTCs)装置,对嘉兴尖叶、嘉兴圆叶和荷兰35三种菠菜(Spinacia oleracea L.)进行连续5 d,每天8 h的臭氧急性暴露处理,且在暴露前24 h喷施300 mg.L-1质量浓度抗氧化剂ethylenediurea(EDU),研究EDU对臭氧胁迫下菠菜急性伤害症状及光合特性的影响。结果表明:(1)菠菜暴露于高体积分数O3时,叶片出现失水干枯、坏死斑等急性伤害症状,光合色素含量、气体交换参数和光响应参数显著降低,且下降幅度和暴露体积分数呈正相关。(2)菠菜经EDU处理后,光合特性参数明显提高。对O3和EDU作双因子分析发现,随着臭氧体积分数升高,EDU对叶片气体交换参数的影响显著,而对其他参数的影响不明显。由此可见,尽管EDU的防护作用对高体积分数的O3胁迫是有限的,但喷施EDU仍能有效减轻O3对植物的伤害,这对缓解农田生态系统O3污染灾害有积极意义。     

企业循环经济发展的探讨

阐述了循环经济的概念;认为现代企业管理应当由原来的企业经济系统管理向企业生态与经济的复合系统管理转变,实行企业循环经济管理;企业应当把资源循环利用和环境保护纳入企业总体的创新、开发和经营的战略中去,建立“绿色技术”体系和“绿色营销”体系,实行全过程控制。     

地下水中铵态氮的迁移转化过程

铵态氮进入地下水的主要途径是土壤淋失,通过室内土柱淋滤实验研究铵态氮在土壤中的迁移转化过程,测定不同时间和不同深度土壤中铵态氮及其转化物硝态氮和亚硝态氮的浓度变化,分析了影响铵态氮迁移转化的因素。实验表明：在土壤饱和、持续淋滤条件下,土柱中随采样深度的增加,铵态氮穿透时间延长,依次滞后;通过硝化能力分析,土柱上层发生了轻微的硝化反应,土柱底部发生了反硝化反应,导致硝态氮的浓度衰减。研究认为在铵态氮的迁移转化过程中,当入渗铵态氮浓度较低时,影响铵态氮迁移转化的显著因素是土壤对铵态氮的吸附;当入渗铵态氮浓度较大时,影响铵态氮迁移转化的显著因素是生物作用导致的铵态氮的硝化,以及土壤的渗透系数、弥散度等因素。