一株降解微囊藻毒素的缺陷短波单胞菌的分离鉴定及降解特性研究

从太湖水华腐烂蓝藻中筛选出一株能够降解MC-LR的细菌,将其编号为Q3.经形态、生理生化及16S rRNA基因序列分析鉴定为缺陷短波单胞菌(Brevundimonas diminuta).研究发现,在实验条件下该菌能以MC-LR为唯一碳源和氮源生长;7 d内可将初始浓度为0.96 mg·L-1的MC-LR降解为0.37 mg·L-1,降解效率达到61.5%.同时,本研究首次发现缺陷短波单胞菌能够降解藻毒素,并且在此菌种中扩增出了降解过程的关键基因mlr A,推测该菌可能与已报道的Sphingomonas sp.ACM-3962等菌具有相同的降解机制.     

Aeration optimization through operation at low dissolved oxygen concentrations: Evaluation of oxygen mass transfer dynamics in different activated sludge systems

In wastewater treatment plants(WWTPs)using the activated sludge process,two methods are widely used to improve aeration efficiency — use of high-efficiency aeration devices and optimizing the aeration control strategy. Aeration efficiency is closely linked to sludge characteristics(such as concentrations of mixed liquor suspended solids(MLSS)and microbial communities)and operating conditions(such as air flow rate and operational dissolved oxygen(DO)concentrations). Moreover,operational DO is closely linked to effluent quality. This study,which is in reference to WWTP discharge class A Chinese standard effluent criteria,determined the growth kinetics parameters of nitrifiers at different DO levels in small-scale tests. Results showed that the activated sludge system could meet effluent criteria when DO was as low as 0.3 mg/L,and that nitrifier communities cultivated under low DO conditions had higher oxygen affinity than those cultivated under high DO conditions,as indicated by the oxygen half-saturation constant and nitrification ability. Based on nitrifier growth kinetics and on the oxygen mass transfer dynamic model(determined using different air flow rate(Q′_(air))and mixed liquor volatile suspended solids(MLVSS)values),theoretical analysis indicated limited potential for energy saving by improving aeration diffuser performance when the activated sludge system had low oxygen consumption; however,operating at low DO and low MLVSS could significantly reduce energy consumption. Finally,a control strategy coupling sludge retention time and MLVSS to minimize the DO level was discussed,which is critical to appropriate setting of the oxygen point and to the operation of low DO treatment technology.     

Rate of hexabromocyclododecane decomposition and production of brominated polycyclic aromatic hydrocarbons during combustion in a pilot-scale incinerator

Here, we examined the incineration of extruded polystyrene containing hexabromocyclododecane(HBCD) in a pilot-scale incinerator under various combustion temperatures(800–950℃) and flue gas residence times(2–8 sec). Rates of HBCD decomposition ranged from 99.996%(800℃, 2 sec) to 99.9999%(950℃, 8 sec); the decomposition of HBCD, except during the initial stage of combustion(flue gas residence time 2 sec), followed a pseudo-first-order kinetics model. An Arrhenius plot revealed that the activation energy and frequency factor of the decomposition of HBCD by combustion were 14.2 kJ/mol and 1.69 sec~(-1),respectively. During combustion, 11 brominated polycyclic aromatic hydrocarbons(BrPAHs)were detected as unintentional by-products. Of the 11 BrPAHs detected, 2-bromoanthracene and 1-bromopyrene were detected at the highest concentrations. The mutagenic and carcinogenic BrPAHs 1,5-dibromoanthracene and 1-bromopyrene were most frequently detected in the flue gases analyzed. The total concentration of BrPAHs exponentially increased(range,87.8–2,040,000 ng/m~3) with increasing flue gas residence time. Results from a qualitative analysis using gas chromatography/high-resolution mass spectrometry suggest that bromofluorene and bromopyrene(or fluoranthene) congeners were also produced during the combustion.     

Spatio-temporal variation of landfill gas in pilot-scale semi-aerobic and anaerobic landfills over 5 years

Variation of CH₄, CO₂, and O₂ concentrations in layers of different depths in semi-aerobic and anaerobic landfills was analyzed over a period of 5 years. The results showed that most of the municipal solid waste became basically stable after 5 years of landfill disposal. In the upper and middle layer, the concentration of CH₄ in the semi-aerobic landfill was significantly lower than that in the anaerobic landfill in different landfill periods, while in the lower layer, there was little difference in the CH₄ concentration between the semi-aerobic and anaerobic landfills. The average concentration of CH₄ and CO₂ in the anaerobic landfill was always higher than that in the semi-aerobic landfill, while the O₂ concentration showed an opposite variation in different landfill periods. This was related to the aerobic reaction of landfill waste around the perforated pipe in the semi-aerobic landfill, which inhibited effective landfill gas generation.     

微氧水解强化复合型人工湿地中试反应器的性能研究

考察两组微氧水解强化复合型人工湿地(MA-HCW)组合的中试反应器,对城市黑臭水体的净化处理效果。两组反应器分别种植风车草和菖蒲两种植物,运行的水力负荷为0.2 m~3/(m~2·d)。结果表明,种植风车草的人工湿地系统(A系统)的总体净化效果略优于种植菖蒲的人工湿地系统(C系统)。A系统的COD、BOD5、TN、NH_4~+-N、TP、TSS平均去除率分别为69.65%、75.2%、58.33%、38.46%、59.8%、82.1%。研究表明,微氧水解功能段有效降低了进水中TSS的浓度,起到预防湿地系统堵塞的作用。数据分析显示COD、NH _4~+-N和TN的去除率与溶解氧和温度有相关性。     

基于环保投资特征的广西环境保护问题研究

以2004年-2014年中国环境统计年鉴和广西年鉴数据为基础,分析了广西环保投资水平、规模、结构、增长速度等特征,并剖析广西环保投资存在的问题.结果表明,2004年-2014年广西环保投资规模呈增加趋势,占GDP的比例低于全国平均水平,存在环保投资不足、增速与GDP速度不匹配、投资结构不合理等问题.建议应完善环保投资机制,调整环保投资核算体系,优化环保投资结构以及建立多元机制提高环保投资效率,确保环保投资与社会经济发展水平相适应.     

舰载飞机腐蚀控制与防护技术

分析了舰载飞机高温、高湿、高盐雾的服役环境特点,并阐述了舰载飞机易发生的腐蚀问题,提出了舰载飞机腐蚀防护与控制的研究思路,并对舰载飞机先进腐蚀控制与防护技术进行了总结,包括结构防护设计、选用综合性能优良的耐蚀材料、防护技术、舰上腐蚀控制维护/维修技术等。总结了舰载飞机全面腐蚀控制研究重点发展方向及建议。     

珠三角空气质量数值预报系统的检验与订正研究

通过对珠三角空气质量预报模式的模拟结果进行检验,发现模式预报值整体偏小,特别是峰值,但变化趋势与实测一致,峰值都能较好模拟出.模式对PM10的预报准确率要高于PM2.5,从等级预报来看PM10和PM2.5的二级预报准确率要高于一级,利用MOS方法对模式预报结果进行订正,订正后颗粒物平均偏差都有一定程度的下降,颗粒物等级预报准确率PM10由64.7%提高到77.6%,PM2.5由59.9%提高至74.5%,准确率的提高明显.     

页岩气开采对水环境的影响及其治理技术研究

页岩气是一种清洁、低碳、高储量的非常规天然气能源,已成为全国油气资源勘探开发的新亮点,其快速发展影响着世界能源格局.然而,页岩气开采带来了巨大的环境风险,如水污染、大气污染、固体废弃物污染和土壤污染等.文章主要分析了页岩气钻井过程、压裂过程及采气过程可能出现的水环境问题,如水资源消耗、地表水污染及地下水污染等;总结了针对不同类型废水的处置措施及处理技术,以期为处理页岩气开采过程中产生的不同类型的废水提供理论依据.     

汽车4S店表面涂装有机废气监测的研究

汽车4S店表面涂装有机废气排放现已成为城市重要的污染排放源之一,中国目前暂未针对该行业废气排放制定相关标准.对汽车4S店有机废气的监测情况及国外、国内地方相关标准做了简单的介绍,对表面涂装工艺和污染治理提出一些对策.对多家汽车4S店的监测情况进行了概述,建议加强汽车4S店表面涂装大气污染物排放控制和管理,改善区域大气环境质量,促进表面涂装工艺和污染治理技术的进步,尽快规范相应管理措施,才能有效控制汽车表面涂装大气污染物的排放.