水肥管理对热带地区双季稻田CH4和N2O排放的影响

水稻土被广泛认为是甲烷（CH₄）和氧化亚氮（N₂O）主要排放源,深入研究不同水肥管理条件下热带地区双季稻田CH₄和N₂O的排放特征,对补充我国双季稻田温室气体排放研究的不足意义重大.本研究设置8个处理：常规灌溉-施磷钾肥（D-PK）、常规灌溉-施氮磷钾肥（D-NPK）、常规灌溉-施氮磷钾+有机肥（D-NPK+M）、常规灌溉-施有机肥（D-M）、长期淹水-施磷钾肥（F-PK）、长期淹水-施氮磷钾肥（F-NPK）、长期淹水-施氮磷钾+有机肥（F-NPK+M）和长期淹水-施有机肥（F-M）.采用密闭静态箱-气相色谱法测定双季稻田CH₄和N₂O排放量,测定水稻产量和估算全球增温潜势（GWP）及温室气体排放强度（GHGI）.结果表明：①早稻季和晚稻季CH₄累积排放量分别为10.3~78.9 kg·hm^-2和84.6~185.5 kg·hm^-2.与F-PK和F-NPK处理相比,早稻季F-NPK+M和F-M处理显著增加CH₄累积排放量.同一施肥条件下,长期淹水处理CH₄累积排放量高于常规灌溉处理.灌溉和施肥极显著影响早稻季CH₄累积排放量.②早稻季和晚稻季N₂O累积排放量分别为0.18~0.76 kg·hm^-2和0.15~0.58 kg·hm^-2.与F-PK处理相比,早稻季F-NPK处理N₂O累积排放量显著增加;与D-PK相比,D-NPK、D-NPK+M和D-M处理显著增加N₂O累积排放量.与F-PK相比,晚稻季长期淹水其它处理N₂O累积排放量显著增加;与D-PK处理相比,D-NPK和D-M处理N₂O累积排放量显著增加.施肥极显著影响早稻季N₂O排放;灌溉和施肥极显著影响晚稻季N₂O排放.③早稻和晚稻产量分别为7310.7~9402.4 kg·hm^-2和3902.8~7354.6 kg·hm^-2,且F-NPK和F-M处理下早稻产量显著高于F-PK和D-NPK、D-PK和D-NPK处理.与PK处理相比,同一灌溉条件下其余3种施肥处理均显著增加晚稻产量.早稻季GWP和GHGI分别为580.8~2818.5kg·hm^-2和0.08~0.30 kg·kg^-1.与F-PK处理相比,常规灌溉条件下早稻季各施肥处理间GWP无显著性差异;但长期淹水条件下F-NPK+M和F-M处理GWP均显著增加.早稻季F-NPK+M和F-M处理GHGI显著高于其它处理.晚稻季GWP和GHGI分别为3091.6~6334.2 kg·hm^-2和0.50~1.23 kg·kg^-1.灌溉显著影响早稻和晚稻季GWP和GHGI,施肥对晚稻季GWP和GHGI的影响不显著.④土壤NH₄⁺-N含量和5 cm土温均与CH₄排放呈极显著负相关,pH与CH₄排放呈极显著正相关,但与N₂O排放呈显著负相关.土壤NH₄⁺-N和NO₃^--N含量与N₂O排放呈极显著负相关.综合作物产量、GWP和GHGI考虑,D-NPK+M可推荐为当地最优的减排稳产的水肥管理模式.     

椰糠生物炭对热区双季稻田N2O和CH4排放的影响

基于稻菜轮作模式,选择海南双季稻田为对象进行氧化亚氮（N₂O）和甲烷（CH₄）排放的原位监测,探究椰糠生物炭对该系统稻田温室气体排放的影响.试验设当地常规施肥对照（CON）、氮肥配施20 t·hm^-2生物炭（B1）、氮肥配施40 t·hm^-2生物炭（B2）及不施氮对照（CK）4个处理,采用静态箱-气相色谱法监测整个水稻种植季稻田N₂O和CH₄排放,并估算增温潜势（GWP）和温室气体排放强度（GHGI）.结果表明,早稻季N₂O排放动态与土壤矿质氮含量密切相关,排放集中在水稻苗期与分蘖期施肥后,各处理早稻季N₂O累积排放量为0.18~0.76 kg·hm^-2,相较于CON处理,生物炭处理减排18%~43%,其中B2处理达显著水平;生物炭可能通过促进N₂O的还原减少早稻苗期N₂O排放;提高土壤硝态氮含量而增加了早稻分蘖期N₂O排放.晚稻季N₂O排放集中在抽穗期和成熟期,累积排放量为0.17~0.34 kg·hm^-2,B1处理减排37%,B2增加3%,差异均不显著.稻田CH₄排放高峰出现在早稻季后期与晚稻季前期.各处理早稻季CH₄累积排放量为3.11~14.87 kg·hm^-2,CK较CON处理增排39%,生物炭处理可能提高土壤通气性限制早稻季产CH₄能力,B1和B2处理分别较CON减排28%和71%;晚稻季CH₄累积排放量为53.1~146.3 kg·hm^-2,排放动态与NH₄⁺-N含量极显著正相关,CK和B1分别较CON处理增加52%和99%,B2处理显著增加176% CH₄排放.早稻季B1和B2处理较CON分别增产12.0%和14.3%,晚稻季分别增产7.6%和0.4%.由于晚稻季甲烷排放的增加,施用生物炭增加了双季稻田总增温潜势（GWP）,其中高量生物炭达显著水平;不同施用量生物炭对双季稻田温室气体排放强度（GHGI）无显著影响.椰糠生物炭在热区稻田温室气体减排方面的应用仍需进一步研究.     

生物炭施用两年后对热带地区稻菜轮作土壤N2O和CH4排放的影响

通过探究生物炭施用两年后对海南典型稻菜轮作模式土壤氧化亚氮（N₂O）和甲烷（CH₄）排放的影响,旨在明确生物炭在该模式下对温室气体排放的长期效应,可为我国热带地区稻菜轮作系统N₂O和CH₄减排提供理论依据.田间试验共设置4个处理,分别为：不施氮肥对照（CK）、施氮磷钾肥（CON）、施氮磷钾肥配施20 t·hm^-2生物炭（B1）和施氮磷钾肥配施40 t·hm^-2生物炭（B2）处理.结果表明：①相较于CON常规施氮处理,B1和B2添加生物炭处理显著减少了早稻季32%和54%的N₂O排放,但在晚稻季B1和B2处理显著增加了31%和81%的N₂O排放,辣椒季N₂O的累积排放量则显著高于早稻和晚稻季,且B1处理显著减少了35%的 N₂O的排放,B2处理相较于CON处理无显著性差异;②B1和B2比CON处理显著减少了早稻季63%和65%的CH₄排放,在晚稻季B2处理显著增加了41%的CH₄排放,B1处理相较于CON处理无显著性差异,辣椒季各处理CH₄的累积排放量无显著性差异;③晚稻季贡献了稻菜轮作系统主要的总增温潜势（GWP）,CH₄的排放量决定了GWP和温室气体排放强度（GHGI）的大小.生物炭施用两年后,B1降低了整个稻菜轮作系统的GHGI,B2增加了GHGI,并达到显著水平,但B1和B2处理在早稻季和辣椒季显著降低了GHGI,仅B2处理在晚稻季增加了GHGI;④B1和B2相较于CON处理显著增加了早稻产量33%和51%,且B1和B2处理显著增加辣椒季产量53%和81%,晚稻季除不施氮肥CK处理外,其它处理产量无显著性差异.研究结果表明,热带地区稻菜轮作系统温室气体排放的大小主要取决于晚稻季的CH₄排放,而生物炭施用两年后仅低量生物炭配施氮肥有显著的减排作用,但高低量生物炭配施氮肥对早稻和辣椒季作物增产具有持续性.     

稻油不同轮作模式对农田甲烷和氧化亚氮排放的影响

以南方稻区不同轮作模式为研究对象,采用静态箱-气相色谱法研究水稻-油菜轮作处理的甲烷（CH₄）和氧化亚氮（N₂O）排放特征,并估算稻田增温潜势（GWP）和温室气体排放强度（GHGI）.结果表明,双季稻田、一季中（晚）稻田、油菜地和休闲地CH₄平均排放量分别为135.25,55.64、5.05和1.89 kg ·hm^-2,稻季CH₄排放占不同轮作周年CH₄排放的91.8%~98.5%,稻田土壤水溶性有机碳与CH₄排放呈显著正相关,常规晚稻稻田CH₄排放比杂交晚稻高18.7%（P<0.05）;双季稻田、一季中（晚）稻田、油菜地和休闲地N₂O平均排放量分别为0.94、0.64、1.38和0.24 kg ·hm^-2,油菜地的N₂O排放占周年排放的57.2%~70.2%,双季稻和一季稻处理的冬闲农田N₂O排放占周年排放的17.8%和30.6%,杂交稻和常规稻稻田N₂O排放无显著性差异;双季稻-冬闲和双季稻-油菜的GWP处理高于稻-油和稻-冬闲处理,稻季排放CH₄的GWP占轮作周年GWP排放的71.2%~90.9%;GHGI以稻-稻-油菜最高,稻-油和稻-冬闲处理较低,综合环境效益和经济效益,建议南方稻区选择杂交晚稻-油菜的种植模式,有利于南方多熟制稻田的温室气体减排.     

地膜覆盖对菜地垄沟CH4和N2O排放的影响

为了探讨地膜覆盖对菜地垄沟温室气体CH₄和N₂O排放的影响,以位于西南大学农业部重庆紫色土生态环境重点野外科学观测试验站内辣椒-萝卜轮作菜地为研究对象,采用静态暗箱/气相色谱法,进行为期1 a的田间原位观测.本试验设置常规和覆膜两种处理方式,研究地膜覆盖对菜地垄沟中CH₄和N₂O排放的影响.结果表明,地膜覆盖能极显著提高土壤全年pH（P<0.01）,显著提高全年的地表温度和地下5 cm温度（P<0.05）,显著提高萝卜季土壤含水率（P<0.05）.不论是辣椒季还是萝卜季,覆膜显著降低了垄的CH₄排放（P<0.05）,辣椒季垄的CH₄平均排放通量常规和覆膜处理分别为0.110 mg·（m²·h）^-1和0.028 mg·（m²·h）^-1,萝卜季分别为0.011 mg·（m²·h）^-1和-0.019 mg·（m²·h）^-1,但覆膜对沟的CH₄排放没有显著影响（P>0.05）,辣椒季常规和覆膜处理分别为0.058 mg·（m²·h）^-1和0.057 mg·（m²·h）^-1,萝卜季分别为0.083 mg·（m²·h）^-1和0.092 mg·（m²·h）^-1,对比垄和沟,除了辣椒季常规处理下垄CH₄排放量显著高于沟,其它均为沟显著高于垄,这与西南地区较高的降雨量下沟内较稳定的缺氧环境有关.覆膜处理对N₂O没有显著影响,辣椒季垄N₂O的平均排放通量常规和覆膜处理下分别为65.41 μg·（m²·h）^-1和68.39 μg·（m²·h）^-1,萝卜季分别为78.43 μg·（m²·h）^-1和66.19 μg·（m²·h）^-1,辣椒季沟N₂O的平均排放通量分别为19.82 μg·（m²·h）^-1和22.85 μg·（m²·h）^-1,萝卜季分别为35.80 μg·（m²·h）^-1和40.00 μg·（m²·h）^-1,均无显著差异（P>0.05）,对比垄和沟,垄N₂O的排放量显著高于沟,N₂O主要由垄向大气排放.CH₄排放通量与地表及地下5 cm温度呈显著正相关,N₂O的排放通量仅与碱解氮和铵态氮含量呈显著正相关.     

生物炭对土CH4、N2O排放的影响

为了探讨生物炭对土CH₄、N₂O排放的影响,采用田间小区试验,测定了生物炭不同添加量（0、20、40、60、80 t·hm^-2）下冬小麦田CH₄、N₂O的吸收/排放通量、小麦产量、土壤有机碳、土壤含水率及不同土层土壤温度.结果表明,CH₄、N₂O的吸收/排放通量随生育期不同变化明显.添加生物炭后,CH₄累积吸收量增加了12.88%~71.61%,当添加量≥ 40 t·hm^-2时,增"汇"作用达到显著水平,且添加量为40 t·hm^-2时CH₄累积吸收量最高;N₂O累积排放量和全球增温潜势与对照相比没有显著差异;温室气体强度降低了13.24%~22.14%.添加生物炭提高了冬小麦产量,增产幅度为1.72%~32.19%,当添加量 ≥ 40 t·hm^-2时,麦田增产效果达到显著水平,40 t·hm^-2生物炭为麦田增产的最适添加量.同时,添加生物炭显著提高了土壤有机碳和土壤含水率,与对照相比,分别增加了1.42~2.69倍、7.08%~11.96%.综合来看,试验土表现为CH₄汇和N₂O源的功能,40 t·hm^-2是其适宜的生物炭添加量.     

对比研究生物炭和秸秆对麦玉轮作系统N2O排放的影响

基于华北集约化农田麦玉轮作系统,对比研究了添加生物炭和秸秆还田对整个轮作周期土壤N₂O排放的影响,为农田土壤N₂O减排和秸秆的资源化利用提供理论依据.试验共设4个处理：①对照（CK）;②生物炭9.0 t·（hm²·a）^-1（C）;③秸秆全量还田（SR）;④在全量秸秆还田的基础上添加生物炭9.0 t·（hm²·a）^-1（C+SR）.结果表明,小麦季,C处理土壤N₂O排放略有降低但差异不显著,SR和C+SR处理促进了土壤N₂O的排放（47.4%和71.8%）;玉米季,C处理降低了土壤N₂O的排放（29.8%）,SR和C+SR处理促进了土壤N₂O的排放（13.4%和35.8%）;小麦季,土壤含水量、NH₄⁺-N和MBN含量是影响土壤N₂O排放的主要环境因子;玉米季,NO₃^--N、NH₄⁺-N和MBC含量是影响土壤N₂O排放的主要环境因子.因此,生物炭对农田N₂O具有巨大的减排潜力,而秸秆直接还田不利于减少N₂O排放,并且在秸秆还田基础上添加生物炭并不能改善这种影响,今后应加强对秸秆腐熟还田技术的研究.     

耕作制度对川中丘陵区冬灌田CH4和N2O排放的影响

采用静态暗箱/气相色谱法连续2 a田间原位测定,研究川中丘陵区冬灌田CH₄和N₂O的排放特征和不同耕作制度对冬灌田CH₄和N₂O排放的影响.结果表明,1a只种1季中稻冬季灌水休闲的冬灌田(PF),在水稻生长期,CH₄平均排放通量为(21.44±1.77)mg·(m²·h)^-1,非水稻生长期为(3.77±0.99)mg·(m²·h)^-1,分别大大低于以前文献报道的在西南其它地方观测值;全年CH₄排放量以水稻生长期CH₄排放量为主,非水稻生长期CH₄排放量仅占全年总排放量的23.2%.冬灌田N₂O排放通量年均值为(0.051±0.008)mg·(m²·h)^-1,且主要集中在水稻生长季,非水稻生长期N₂O排放量仅占全年总排放量的8.1%.在采用水旱轮作制后,冬灌田CH₄排放量大大降低,稻-麦轮作(RW)和稻-油菜轮作(RR)全年CH₄排放量分别为PF的43.8%和40.6%.但冬灌田改为水旱轮作制后,N₂O排放量显著增大,RW和RR的N₂O年排放量分别是PF的3.7倍和4.5倍.综合考虑冬灌田在采用不同耕作制度后排放CH₄和N₂O的全球增温潜势(GWP),无论是短时间尺度还是长时间尺度,采用3种耕作制度全年所排放的CH₄和N₂O所产生的综合GWP都为:PF RW≈RR.在20a、100a和500a时间尺度上,PF分别约是RW和RR的2.6、2.1和1.7倍.冬灌田改为水旱轮作制度后能大大减少CH₄和N₂O所产生的综合GWP.     

小麦－玉米轮作期土壤排放N2O通量及总量估算

对小麦-玉米轮作期周年的N₂O通量进行了测定和总量估算,分析了N₂O通量与土壤温度、地温、气温、降水和施氮量的关系。由实验获知,华北平原栾城农业生态系统实验站的农田N₂O通量(N)为10.6-24.2μg/(m²·h),相应的全年排放总量(N)为0.93-2.11kg(hm²·a)。施用尿素的农田排放N₂O量约占化肥施用量的0.54%,施用有机肥和化肥的农田排放N₂O量占总施氮量的0.70%。     

不同种类有机肥施用对稻田CH4和N2O排放的综合影响

以麦茬稻田为对象,研究基肥施用不同有机肥对稻田CH₄和N₂O排放的综合影响.结果表明:有机肥施用对稻田CH₄和N₂O排放的季节变化模式无明显影响,但影响其排放量.与施用化肥(化肥处理)相比,施用菜饼+化肥(菜饼处理)促进CH₄和N₂O的排放,其季节排放总量分别增加了252%和22%;施用小麦秸秆+化肥(秸秆处理)和牛厩肥+化肥(牛厩肥处理)明显增加CH₄排放,增加量分别为250%和45%,同时却减少N₂O排放,分别减少18%和21%;施用猪厩肥+化肥(猪厩肥处理)降低CH₄和N₂O的排放,分别降低4%和18%.对CH4和N₂O排放的综合温室效应分析表明,菜饼和秸秆处理的全球增温潜势(GWP)约为化肥处理的2.5倍,牛厩肥和化肥处理基本持平,但施用猪厩肥可减少10%～15%.各处理的GWP从高到低依次为菜饼、秸秆、牛厩肥、化肥和猪厩肥.单位产量的GWP以秸秆处理最高,菜饼次之,牛厩肥比化肥处理略高,猪厩肥处理最低.从本生长季来看,猪厩肥的施用对于实现环境效益与生产效益的协调发展具有一定作用.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.     

Simultaneous removal of ammonium and phosphate by zeolite synthesized from coal fly ash as influenced by acid treatment

Zeolite synthesized from fly ash （ZFA） without modification is not efficient for the purification of NH4＋ and phosphate at low concentrations that occur in real effluents, despite the high potential removal capacity. To develop an effective technique to enhance the removal efficiency of ammonium and phosphate at low concentrations, ZFA was modified with acid treatment and the simultaneous removal of ammonium and phosphate in a wide range of concentration was investigated. It was seen that when compared with untreated ZFA, only the treatment by 0.01 mol/L of H2SO4 significantly improved the removal efficiency of ammonium at low initial concentrations. The behavior was well explained by the pH effect. Treatment by more concentrated H2SO4 led to the deterioration of the ZFA structure and a decrease in the cation exchange capacity. Treatment by 0.01 mol/L H2SO4 improved the removal efficiency of phosphate by ZFA at all initial P concentrations, while the treatment by concentrated H2SO4 （≥0.9 mol/L） resulted in a limited maximum phosphate immobilization capacity （PIC）. It was concluded that through a previous mild acid treatment （e.g. 0.01 mol/L of H2SO4）, ZFA can be used in the simultaneous removal of NH4＋ and P at low concentrations simulating real effluent.