人工湿地构筑根孔作用下土壤物质分布状况

嘉兴市石臼漾湿地应用人工构筑根孔技术,以玉米秸秆和油菜秸秆按比例混合埋植于土壤亚表层,作为湿地的基质/填料。在湿地运行一年半后,按照正交设计表,以埋植秸秆的种类(S)、填埋的土壤层次(L)、距离秸秆外环的远近(D)和秸秆周围土壤的表观颜色(C)作为实验因素,对秸秆周围养分物质浓度、土壤酶活性以及铁含量进行采样分析。实验结果显示:玉米秸秆和油菜秸秆腐烂较充分,分别形成较发达的粗根孔和细根孔;根孔周围土壤呈中度还原状态;粗根孔具有较强的优先流效应,其周围土壤具有较高的养分物质含量和较低的Fe2+/Fe3+比。粗根孔周围土壤具有较高的磷酸酶活性,而细根孔周围具有较高的β-葡糖苷酶活性和脲酶活性。综合比较,人工湿地构建初期,径级较大秸秆腐烂后形成的粗根孔发挥着更高的水分传导效率和更强的物质截留效应。     

Biomass and nutrient concentration of sweet corn roots and shoots under organic amendments application

Two field experiments were conducted at the Waimanalo research station on the island of O'ahu, Hawaii to study the effect of chicken (CM) and dairy (DM) manures on biomass and nutrient concentration in sweet corn roots and shoots. Sweet corn (super sweet 10, Zea Mays L. subsp. mays) was grown for two consecutive growing seasons under four rates of application (0, 168, 337, and 672 kg ha^{? 1} total N equivalent) and one time (OTA) or two time (TTA) applications of organic manure types and rates. There were significant effects of types, rates, and number of manure applications on dry biomass and macro- and micro-nutrient concentration in roots and shoots tissues. Results of root tissue indicated a significant accumulation of N and C under CM and DM treatments compared with the control treatment. Manure application rates significantly increased the accumulation of N and C in root tissue. Dry weight of roots and shoots and both macro- and micro-nutrient contents in the plant tissues significantly increased under TTA treatment compared with OTA treatment. There was a significant correlation (r² = 0.46 to 0.81) between root biomass, macro-, and micro-nutrient contents during both growing seasons. The results of the study indicates that amending soils with CM at the highest application rate provided the best crop performance in terms of root and shoot biomass, crop N, C, and other macro- and micro-nutrients.     

Microwave enhanced advanced oxidation process for treating dairy manure at low pH

This study investigated the treatment of dairy manure using the microwave enhanced advanced oxidation process (MW-AOP) at pH 2. An experimental design was developed based on a statistical program using response surface methodology to explore the effects of temperature, hydrogen peroxide dosage and heating time on sugar production, nutrient release and solids destruction. Temperature, hydrogen peroxide dosage and acid concentration were key factors affecting reducing sugar production. The highest reducing sugar yield of 7.4% was obtained at 160°C, 0 mL, 15 min heating time, and no H₂O₂ addition. Temperature was a dominant factor for an increase of soluble chemical oxygen demand (SCOD) in the treated dairy manure. The important factors for volatile fatty acids (VFA) production were microwave temperature and hydrogen peroxide dosage. Temperature was the most important parameter, and heating time, to a lesser extent affecting orthophosphate release. Heating time, hydrogen peroxide dosage and temperature were significant factors for ammonia release. There was a maximum of 96% and 196% increase in orthophosphate and ammonia concentration, respectively at 160°C, 0.5 mL H₂O₂ and 15 min heating time. The MW-AOP is an effective method in dairy manure treatment for sugar production, nutrient solubilisation, and solids disintegration.     

Nanofiltration of concentrated and salted tuna cooking juices

Tuna cooking juice from a Tunisian tuna-processing unit has a high level of polluting load: chemical oxygen demand (COD) is comprised between 4 and 20 g L⁻¹, nitrogen kjedahl (NK) between 0.6 and 3 g L⁻¹ and dry matter between 120 and 160 g L⁻¹. The juice has thus to be treated before being rejected into the environment. This paper considers the nanofiltration (NF) of these concentrated organic/inorganic mixtures using an AFC 30 (NF) membrane. The work focusses on the effect of organic and inorganic matters on the permeate flux and rejections of these matters. For this purpose, mixtures of salt and organic pollution (COD), used as model solutions, were prepared by the dilution of a typical industrial tuna cooking juice. The permeate flux was found to decrease when salt and organic matter concentrations increase. The recovery rate in organic matter decreases with increasing salt or organic matter content and the recovery rate of salt decreases when the COD concentration increases.     

Octanol–air partition coefficients of polybrominated biphenyls

The octanol–air partition coefficients (K_OA) for PBB15, PBB26, PBB31, PBB49, PBB103 and PBB153 were determined as a function of temperature using a gas chromatographic retention time technique with 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (p,p′-DDT) as a reference substance. The internal energies of phase change from octanol to air (Δ_OAU) were calculated for the six compounds and were in the range from 74 to 116 kJ mol⁻¹. Simple regression equations of log K_OA versus relative retention times (RRTs) on gas chromatography (GC), and log K_OA versus molecular connectivity indexes (MCI) were obtained, for which the correlation coefficients (r²) were greater than 0.985 at 283.15 K and 298.15 K. Thus the K_OA values of the remaining PBBs can be predicted by using their RRTs and MCI according to these relationships.     

添加不同量的腐殖酸对猪粪堆肥中主要养分变化的影响

腐殖酸是一种可以控制堆肥氮素损失的天然固定剂,通过研究腐殖酸对猪粪堆肥过程中主要养分含量变化的影响,确定了腐殖酸的最佳加入量.结果表明,加入5%含量(占鲜猪粪重)的腐殖酸最有利于发酵反应的进行,能够促进有机质的分解,有效控制氮素损失,可使速效钾含量增加,但对有效磷的转化能力影响不大;与其他处理相比,加入5%含量的腐殖酸...     

河流型硅藻水华研究进展

通过对硅藻水华发生机制相关文献的研究分析,对硅藻水华发生机制做了一般性探讨,并重点关注了河流型水华的发生机制的独特点。河流水华种类主要为中心硅藻纲,静水生态系统水华种类除中心硅藻纲还包括部分羽纹硅藻纲种类。河流水华硅藻种类对营养盐浓度、温度和光照等环境因子具有一定的适应范围。与静水生态系统相比,河流硅藻水华受气象和水文等物理指标的影响更为明显。河流硅藻水华中常具有时滞现象,其中由气象和水文因素引起的时滞现象最为明显。目前河流硅藻水华的防治仍然以上游水库下泄稀释为主,但是这种方法会造成一定的水资源浪费。河流水华硅藻的生理属性、硅藻水华对生态系统的影响、节水与抑制水华的统筹以及其他控制水华的方法都是未来河流硅藻水华研究的重点。     

不同营养水平下悬浮细菌数量对生物粘泥性质的影响

循环水系统中的微生物有悬浮态和附着态,悬浮细菌的存在对附着态生物粘泥的生长及特性有明显影响。通过向模拟循环冷却水系统中投加不同数量初始悬浮细菌,考察在营养水平不同的情况下,悬浮细菌数量对生物粘泥化学组成和脱氢酶活性的影响。结果表明,营养水平不同,初始悬浮细菌数量对生物粘泥的化学组成和脱氢酶活性的影响程度不同;在不同营养水平下,应分别控制初始悬浮细菌数量。贫营养下,初始悬浮细菌数量应控制在6×105个/mL左右;中营养下,初始悬浮细菌数量应控制在1×105～2.6×105个/mL之间;富营养下,初始悬浮细菌数量应控制在0.11×105～2.6×105个/mL之间最不利于生物粘泥的生长。     

厌氧折流板式微生物燃料电池堆影响因素研究

微生物燃料电池(MFC)中输出电压/电流的提升,以及反应器体积的扩展放大是其工程化应用的关键。本文构建了一个总体积为6.4 L的新型厌氧折流板式微生物燃料电池堆(ABSMFC)。以葡萄糖作为底物,探讨了阳极材料、液面高程差和水力停留时间(HRT)等因素对ABSMFC性能的影响。结果表明,碳纤维毡作为阳极时,电池单体外电路平均分压(R_(ex)=1 000Ω)为210 mV,填充石墨颗粒后增加到319.8 mV。格室间存在液面高程差时,电池单体、串联和并联的功率密度分别为207.1、181.1和215.7 mW/m~2,当无液面高程差(即水力相连)时为205.8、69.5和151.5 mW/m~2。4个电池单体串联和并联连接时,HRT对ABSMFC的产电稳定性无影响,溶解性COD的去除率和库仑效率均随HRT的增加而升高,且并联效果优于串联。     

SRT对MBR污泥性质的影响

以浸没式膜-生物反应器(SMBR)处理模拟赖氨酸废水为研究体系,考察SRT在10、20和40 d条件下,SMBR中的胞外聚合物(EPS)组分和含量、污泥沉降性能和污泥相对疏水性等污泥性质的变化及其对膜污染的影响。结果表明,随着SRT的延长,混合液中EPS总量呈递减趋势,TBEPS中蛋白质与多糖的比值呈上升趋势,污泥的沉降性能变差,相对疏水性增强;膜通量下降速率变大,膜污染加重。污泥性质与膜污染的相关性表明,膜污染与蛋白质和多糖的比值、污泥沉降性能和相对疏水性呈正相关关系,而与EPS呈负相关关系。