聚丙烯酰胺降解菌的分离和鉴定

三次采油产生的大量含聚丙烯酰胺(PAM)的污水急需处理,其核心问题是PAM的生物化学降解。文章叙述了从含聚合物油田污水中分离到七株PAM降解菌的过程,并对其营养物体系进行了初步研究及分子生物学鉴定。结果表明,分离到的七株菌可以以PAM为唯一氮源和碳源进行生长,但是生长速度较慢,添加液蜡或酵母膏等可导致微生物菌群的共代谢,能加快PAM的生物降解。七株菌分别归类于放线杆菌纲和α-变形菌纲及芽孢杆菌,与数据库中已知菌的同源性均超过98%。     

HYDROLOGIC RESPONSE OF MASSACHUSETTS WATERSHEDS1

Hydrologic response, defined as the annual direct runoff divided by the annual precipitation, was computed for twenty-one watersheds in or near western Massachusetts, using a total of 232 years of hydrologic records. Variability of the results over the period of analysis was greater than is desirable to inspire confidence in the usefulness of the hydrologic response function; however, the results do suggest that the hydrologic response concept, with appropriate refinements, could be applied successfully to the problem of delineating hydrologic provinces and determination of drainage and storage in unregulated watersheds.     

EVALUATING DIRECT BENEFIT ESTIMATION PROCEDURES FOR IRRIGATION PROJECTS: A SIMPLIFIED APPROACH1

ABSTRACT: An integral part of evaluating the net benefits generated by an existing or proposed irrigation project is the assessment of the associated impacts in commodity markets. Traditionally, these impacts have been measured by either assuming no change in commodity prices and calculating net returns to project farmers, or by allowing commodity prices to fall in accordance with a given elasticity of demand and subtracting commodity production costs from the associated area under the commodity demand curve. In either case, it is implicitly assumed that supply is perfectly inelastic. This article establishes that traditional approaches to measuring direct benefits are biased. Formulae are presented for calculating the maximum absolute and relative error which may result from using these techniques as a function of project size. Direct benefit estimates are then evaluated for three irrigation projects in Nebraska, illustrating how these results can be used to improve project evaluation procedures.     

FePMo12催化电化学反应降解染料废水的研究

采用IR和XRD等方法对自制磷钼酸铁(FePMo12)杂多酸进行表征,表明杂多阴离子具有Keggin结构.将FePMo12负载于修饰后的4分子筛(4A)上制备FePMo12/APTES-4A催化剂填充于电化学反应器中,考察电化学氧化体系对酸性大红3R染料废水的脱色效果.结果表明,FePMo12/APTES-4A催化剂对酸性大红3R模拟废水具有良好的催化效果,当活性组分负载量为3%时,在pH为4,槽电压为22 V,曝气量为0.08 m3·h-1,极板间距为3.0 cm反应条件下,90 min后脱色率达到75.3%,COD和TOC去除率分别达到65.4%和46.0%.加入支持电解质Na2SO4和NaCl后,NaCl对电催化降解染料废水有促进作用,而Na2SO4的加入使得废水的脱色效率降低.采用可见-紫外光谱对反应过程中间产物进行分析,表明染料分子中的共轭体系已基本被破坏.     

A review of environmental characteristics and effects of low-molecular weight organic acids in the surface ecosystem

Low molecular weight organic acids （LMWOAs） are prevalent on the earth＇s surface. They are vital intermediate products during metabolic pathways of organic matter and participate in the tricarboxylic acid cycle during life activities. Photochemical reactions are pivotal for LMWOAs＇ origination and play a large role in determining their diversity and their ultimate fate. Within the long time that organic matter is preserved in sediments, it can be decomposed and converted to release organic and inorganic pollutants as well as C, N, and P nutrients, which are of potential ecological risk in causing secondary pollution to lake water. The sediment pool is a comprehensive and complex compartment closely associated with overlying water by various biochemical processes, during which LMWOAs play critical roles to transport and transform elements. This article elucidates geochemical behaviors of LMWOAs in the surface environment in details, taking natural water, soil, and aerosol as examples, focusing on reviewing research developments on sources and characteristics, migration and mineralization of LMWOAs and relevant environmental effects. Simultaneously, this review article depicts the categories and contents of LMWOAs or their contribution to DOC in environmental media, and evaluates their importance during organic matter early diagenesis. Through concluding and discussing the conversion mechanisms and influencing factors, the next research orientations on LMWOAs in lake ecosystems are determined, mainly concerning relationships with hydrochemical parameters and microorganisms, and interactions with pollutants. This will enrich the knowledge on organic matter degradation and related environmental effects, and help reconstruct a theoretical framework for organic compound succession and influencing factors, providing basic data for lake eutrophication and ecological risk assessment, conducive to better control over water pollution and proper management of water quality.     

Effects of ozonation and coagulation on effluent organic matter characteristics and ultrafiltration membrane fouling

Effluent organic matter （EfOM） is the major cause of fouling in the low pressure membranes process for wastewater reuse. Coagulation and oxidation of biological wastewater treatment effluent have been applied for the fouling control of microfiltration membranes. However, the change in EfOM structure by pre-treatments has not been clearly identified. The changes of EfOM characteristics induced by coagulation and ozonation were investigated through size exclusion chromatography, UV/Vis spectrophotometry, fluorescence spectrophotometry and titrimetric analysis to identify the mechanisms in the reduction of ultrafiltration （UF） membrane fouling. The results indicated that reduction of flux decline by coagulation was due to modified characteristics of dissolved organic carbon （DOC） content. Total concentration of DOC was not reduced by ozonation. However, the mass fraction of the molecules with molecular weight larger than 5 kDa, fluorescence intensity, aromaticity, highly condensed chromophores, average molecular weight and soluble microbial byproducts decreased greatly after ozonation. These results indicated that EfOM was partially oxidized by ozonation to low molecular weight, highly charged compounds with abundant electron- withdrawing functional groups, which are favourable for alleviating UF membrane flux decline.     

水位变化对消落带氨氧化微生物丰度和多样性的影响

南水北调来水进入密云水库将直接引起水库水位上涨,这必将影响消落带土壤中氨氧化微生物的丰度和多样性,从而影响消落带中氮循环过程.采用分子生物学方法,探讨了水位变化对消落带氨氧化细菌(AOB)和古菌(AOA)的生物多样性和丰度的影响.Real-time PCR结果显示,2015年9月消落带岸上/水陆界面土壤和沉积物中AOA和AOB的丰度范围分别为1.00×10~7~3.91×10~7copies·g~(-1)和5.49×10~6~9.77×10~6copies·g~(-1).2015年11月水位比9月上升3 m,淹没区土壤/沉积物中AOA和AOB的丰度范围分别为5.80×106~1.56×10~7copies·g~(-1)和2.14×10~6~4.40×106copies·g~(-1),比被淹没前有所下降,但AOA的丰度始终高于AOB,说明AOA比AOB更适合在低氨氮的消落带环境中生长,并且更能适应低氧环境.水位上升3 m后,水陆交界面土壤中AOA和AOB的多样性均有所增加,而在沉积物中多样性减少.水位上涨之前,AOA大多数OTU属于Nitrososphaera、Nitrosopumilus,而水位上涨之后,大多数OTU归属于土壤簇Nitrososphaera,即在低氧消落带环境中土壤簇Nitrososphaera为优势AOA菌.对于AOB,水陆交界面土壤和沉积物中Nitrosopira和Nitrosomonas分别在氨氧化过程中发挥作用.     

低分子有机酸对三峡库区沉积物吸附Pb2+影响研究

以长江三峡库区万州段消落带区的沉积物为研究对象,通过等温吸附平衡实验研究不同浓度的柠檬酸、草酸对沉积物吸附Pb2+的影响.实验结果表明:消落带沉积物对Pb2+的吸附量随着Pb2+离子平衡浓度的增加而增大,Pb2+平衡浓度在0.08～80 mg/L时,其最大吸附量为8 762.00 mg/Kg.不同浓度的柠檬酸、草酸会在不同程度上抑制沉积物对Pb2+吸附,2 mmol/L柠檬酸对沉积物吸附Pb2+的能力是浓度为4 mmol/L时的1.12倍,草酸条件下为1.02倍.即高浓度的低分子有机酸抑制消落带沉积物对Pb2+的吸附.     

低分子有机酸对硫杆菌活性的抑制作用及对土壤重金属脱除的影响

施用有机肥能够降低污染土壤重金属溶解性和生物可利用性,但在淹水厌氧等环境中,有机肥会分解产生大量低分子有机酸,会抑制嗜酸性硫杆菌的生物活性.通过摇瓶实验研究了低分子有机酸对硫杆菌的毒害抑制效果和不同硫杆菌对各类有机酸的耐受水平.结果表明,纯体系培养下,A.ferrooxidans和A.thiooxidans活性抑制率在72 h内达到90%以上,所需甲、乙、丙、丁酸最低浓度分别为41.2、78.3、43.2、123.4 mg·L~(-1)和81.9、230.4、170.1、123.4 mg·L~(-1).其中,甲酸对A.ferrooxidans和A.thiooxidans的抑制作用最显著,A.thiooxidans相比A.ferrooxidans对4种有机酸具有更高的耐受性.新鲜重金属污染土壤在生物酸化初期(0 h)加入4种有机酸对后续土壤酸化过程影响较小,但12 h后加入有机酸却能使土壤生物酸化基本停止,导致土壤重金属脱除率大幅度下降.这为有机肥改良重金属污染土壤的生物修复可行性提供一定理论依据.     

沸石床多级生物膜焦化废水处理系统的NH+4-N去除稳定性研究

焦化废水处理中预处理蒸氨工艺不稳定容易引起生物处理出水NH⁺₄-N的波动,为了在有机物去除的同时提高生物系统对NH⁺₄-N的去除效果和稳定性,采用对NH⁺₄-N有良好吸附性能的天然斜发沸石为生物填料构建沸石床多级生物膜系统,考察了进水负荷对系统运行稳定性的影响、抗冲击负荷能力以及系统的功能分区和污染物迁移转化规律.结果表明,当系统进水NH⁺₄-N负荷≤0.21 kg/(m³·d)、COD负荷≤1.35　kg/(m³·d)时,出水NH⁺₄-N和COD的平均浓度分别为(2.2±1.2)mg/L和(228±60)mg/L,平均去除率分别达(99.1±0.5)%和(86.0±2.6)%.在低、高两次NH⁺₄-N冲击负荷［0.03　kg/(m³·d)和0.06　kg/(m³·d)］条件下,系统对NH⁺₄-N的平均去除率仍然分别高达99.0%和92.9%,高于对比系统的96.8%和89.3%,表现出良好的抗NH⁺₄-N冲击负荷性能与处理稳定性.系统好氧单元反应器沿程出现脱碳/硝化功能区(C/N区)和硝化功能区(N区),其中N区的NH⁺₄-N 降解速率为C/N区的2～8倍.系统进水中相对分子质量＜1×10³、 1×10³～1×10⁴、 ＞1×10⁴的TOC浓度分别为227.6、104.8和35.0 mg/L,处理出水中的TOC浓度分别为31.2、 22.9和31.5 mg/L,其中相对分子质量＜1×10³和1×10³～1×10⁴这2个范围的有机物降解良好,出水残余物质主要为相对分子质量＞1×10³的有机物.