不同碳氮比对干法厌氧消化产沼气特性及细菌群落多样性的影响

为研究不同初始C/N值的混合物料对甘蔗叶干法厌氧消化过程中理化参数以及产沼气特性的影响及产气最佳的C/N值厌氧消化过程中细菌群落结构多样性,研究采用牛粪与甘蔗叶以及啤酒厂滤泥这3种有机固废物混合并加入自行研究设计的发酵罐里进行厌氧消化,并采用Nested-PCR（巢式PCR）技术扩增消化过程中细菌的16S rDNA V3区域,并通过DGGE方法分析初始C/N值为15.02厌氧消化过程细菌群落的多样性。实验结果表明,初始C/N值为15.02的混合物料产甲烷最佳,最高累计产气量为1 748.63 mL·kg-1,甲烷最高含量为59.26%,最高日产甲烷量为13.58 mL·kg-1;通过研究最佳C/N值为15.02的细菌多样性,可知在厌氧消化过程中细菌数量和群落结构丰富多样,样品间的细菌群落结构差异性相对较大,样品间存在与产沼气相关的共有的优势细菌。     

污泥与葡萄糖不同配比联合厌氧消化对污泥中多环芳烃去除效能及细菌群落的影响

为分析污泥与葡萄糖不同配比进行联合厌氧消化对污泥中多环芳烃(PAHs)去除效能及细菌群落的影响,在中温(35±1)℃条件下,以未添加葡萄糖的污泥厌氧消化为对照(CK),研究了活性污泥与葡萄糖按不同有机质含量(挥发性固体(VS)质量比)分别为1∶0.1、1∶0.3和1∶0.5对PAHs去除效能及细菌群落的影响。结果表明,葡萄糖添加量的增加并未进一步提高PAHs的降解能力。P1实验组(VS_(污泥)∶VS_(葡萄糖)=1∶0.1)对消化污泥中∑PAHs的去除能力最强;降解速率可达到(60.56±8.10)%;且高分子质量PAHs(≥4环)的降解速率显著高于低分子质量PAHs(2～3环)(P0.05)。苯并(a)蒽、?、苯并(b)荧蒽和苯并(k)荧蒽的平均降解速率均大于62%;而苯并(a)芘的降解速率达到(59.60±14.05)%。此外,使用16S r RNA技术,检测消化污泥中细菌群落发现,向污泥中添加葡萄糖,可能通过促进Actinobacteria、 Bacteroidetes_vadin HA17、 Spirochaetes、 Planctomycetes和norank_f_Anaerolineaceae菌群的生长,从而提高污泥中PAHs的去除能力。     

共接种瘤胃微生物和厌氧污泥的水稻秸秆中试厌氧消化系统性能评估

针对富含木质纤维素底物利用效率低的问题,通过在中试厌氧消化系统中共接种瘤胃微生物和厌氧污泥来改善水稻秸秆中木质纤维素的水解,采用逐步提升底物有机负荷(OLR)的方式,评估了接种后水稻秸秆的厌氧消化效率。结果表明,在反应体系底物有机负荷达到4.26 g·(L·d)⁻¹(以VS计)时,系统表现出最佳的厌氧消化性能,此时沼气产率为528 mL·g⁻¹ (以VS计),甲烷产率为287 mL·g⁻¹,容积沼气生产强度达到2.20 L·(L·d)⁻¹。在反应器有机负荷从1.05 g·(L·d)⁻¹提升到4.26 g·(L·d)⁻¹的运行过程中,系统的纤维素降解率稳定在(71 ± 2)%,半纤维素降解率稳定在(92 ± 4)%,木质素降解率稳定在(15 ± 3)%。这种稳定性表明反应器的连续运行成功地形成了高效的木质纤维素降解体系,结果可为实际规模化应用提供参考。     

DO在厌氧序批式生物膜反应器中对厌氧氨氧化反应启动的影响

考察了DO在厌氧序批式生物膜反应器(ASBBR)中对厌氧氨氧化反应启动过程的影响.结果表明,当进水采用高纯氮气进行除DO处理后进入ASBBR时,ASBBR很快以厌氧氨氧化反应为主,运行13 d后,NO-3-N生成量、NO-2-N去除量、NH+4-N去除量比开始围绕0.25∶1.30∶1.00上下小幅波动,运行100 d后的总氮容积去除负荷为1.560 kg/(m3·d);当进水不除DO处理进入ASBBR时,从运行的第57天开始,ASBBR内才表现出明显的厌氧氨氧化反应特性,运行到第73天时,NO-3-N生成量、NO-2-N去除量、NH+4-N去除量比开始围绕0.21∶1.20∶1.00上下小幅波动,运行的93～100 d,总氮容积去除负荷稳定在较高水平,最高可达1.090 kg/(m3·d);进水不除DO处理时,会使厌氧氨氧化反应启动迟缓;无纺布作为生物载体,具有较强的抗水力负荷和基质(NH+4-N、NO-2-N)负荷能力.     

厌氧系统中碱处理对污泥减量的影响

碱解预处理污泥和原污泥按一定比例进行混合后,投入厌氧反应器中进行消化,研究其对污泥减量化的影响。结果表明,该处理既可以提高污泥减量率,又能改善污泥厌氧消化性能,提高污泥产气量。当碱处理污泥和原污泥混合比为1∶3时,在混合初期由于稀释作用和水解中和作用,溶液的pH能迅速恢复到中性。SS减少48%,较对照组提高了10%;SCOD减少约80%,较对照组提高20%,而空白对照组因未发生溶胞作用,各参数值均处于较低水平,降解率也维持在较低水平。     

厌氧颗粒污泥藻酸盐对铜离子的吸附研究

从厌氧颗粒污泥中成功提取出细菌藻酸盐并制备成藻酸钙吸附剂,研究其对水中Cu~(2+)的吸附性能。实验结果表明,接触时间、Cu~(2+)初始浓度和溶液初始pH是影响Cu~(2+)吸附性能的重要因素。吸附等温线研究表明,Langmuir模型比Freundlich模型能更好地描述吸附过程。Cu~(2+)在藻酸钙上的吸附动力学过程可以很好地用Pseudo二级动力学方程来描述。以100 mmol/L HCI为解吸剂,可有效洗脱藻酸钙上95%的Cu~(2+),实现Cu~(2+)的回收。     

碳氮比对鸭粪中温厌氧消化的影响

在中温(35±1)℃、6%的料液浓度、pH为中性条件下,采用10 L玻璃瓶作为反应器对碳氮比(C/N)分别为15、20、25和35的4组鸭粪溶液进行厌氧消化实验,系统运行30 d,分析了厌氧消化过程中的COD(化学需氧量)、pH、VFA(挥发性脂肪酸)和产气量的变化。结果表明,碳氮比是影响鸭粪厌氧消化过程的重要因素,调节鸭粪碳氮比至25,可以使其厌氧消化获得最佳的产气效果,COD去除率为24.06%,原料干物质产气率为0.178 m3/kg,产气中甲烷含量为71.5%,产甲烷率为0.127 m3/kg。     

亚硫酸盐、硫化物对厌氧消化的影响

通过人工模拟试验和用两相厌氧工艺处理造纸废水试验,探讨不同浓度SO_3~(2-)和S~(2-)对厌氧消化的影响.结果表明,当[S0_3~(2-)]<0.254g/L时对厌氧消化无明显影响,当[SO_3~(2-)]>0.508g/L时出现抑制现象.而硫化物在不超过0.0656g/L时对厌氧消化无影响,超过0.164g/L时出现明显的抑制现象,一般可通过污泥驯化提高微生物对硫化物的耐毒性.     

水稻秸秆炭及组合改良剂对石漠化地区土壤-玉米系统中重金属迁移特征影响

化学固定是重金属污染土壤修复及改良技术之一。通过盆栽实验,研究了水稻秸秆炭及其与石灰、磷酸盐组合改良剂对石漠化土壤-玉米体系中As、Zn和Pb 3种重金属迁移的影响,分析了玉米及土壤重金属含量、形态变化。结果表明,几种改良剂均显著促进了玉米生长,地上部分生物量：水稻秸秆炭 > 石灰+水稻秸秆炭 > 石灰 > 秸秆 > 磷酸盐+水稻秸秆炭 > 磷酸盐 > 对照。水稻秸秆炭、石灰及其组合均能够提高土壤pH值,抑制重金属向玉米地上部分迁移。添加改良剂后土壤中As的弱酸提取态和可还原态含量显著降低,均小于3 mg·kg-1。水稻秸秆炭、秸秆与石灰及其组合均能够降低土壤中重金属提取态和还原态量,能够降低玉米籽粒中重金属的含量,但玉米籽实中Pb依然超标。     

污泥加热预处理对中温厌氧消化的影响

对污泥加热预处理给中温厌氧混合消化和污泥单独消化带来的影响进行了研究.研究结果表明,污泥加热预处理有利于提高混合消化对 COD 的去除率,尤其是 SCOD 的去除率由 77%增长到 93%,但不利于 TS 和 VS 的去除;而对污泥单独消化,预处理则不利于有机物的去除.采用加热预处理后的污泥进样,混合消化和污泥单独消化的甲烷产气量均有所提高.     

Mass balance and long-term fate of PCDD/Fs in a lagoon sediment and paddy soil, Niigata, Japan

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in a sediment core and in samples of surface sediment and paddy soil collected from the Toyano lagoon and Kameda basin in Niigata, Japan, were analyzed to elucidate the temporal trends of their concentrations in the lagoon sediment and the relationship between the sediment and the paddy soil. The mass balance of these pollutants was also estimated to determine their long-term fate in surface waters. An analysis by chemical mass balance identified the agrochemicals pentachlorophenol and 2,4,6-trichlorophenyl 4-nitrophenyl ether as the major sources of PCDD/Fs. On the basis of the findings regarding the mass balance in the Kameda basin over the last 40 years, we estimate that more than half the input of PCDD/Fs to the Kameda basin has disappeared. We suggest that the PCDD/Fs that flowed out from the paddy fields have been transferred to the lower basin.     

珠江三角洲潮土和水稻土酸缓冲特性试验研究

珠江三角洲潮土和水稻土对不同种类的酸具有一定的缓冲性,不同种类的酸对不同类型土壤的酸化趋势不同。大旺水稻土对酸的敏感性强于龙山潮土,龙山潮土属于稍易受害的稍敏感土壤,大旺水稻土属于易受害的敏感土壤;同一土壤对酸的缓冲能力比对碱的缓冲能力强;不同种类的酸对土壤的敏感性不同,土壤对硝酸的敏感性强于对硫酸的敏感性;土壤加酸后酸缓冲曲线和土壤中铝释放曲线的交点可以作为衡量土壤对酸敏感性的指标,交点越低,敏感性越强;加酸后土壤中铝的释放可以用模型y=nx+k来预测。     

复配钝化剂对稻田重金属有效性及其水稻吸收的影响

针对红壤稻米中重金属Cd超标的问题,通过筛选钝化剂并将其复配用于大田实验,以研究复配钝化剂对土壤有效态重金属(Cd、Pb和Cu)及水稻吸收重金属的影响及其作用机理。室内筛选实验表明,在11种无机和有机钝化剂中,海泡石、生石灰和聚丙烯酰胺对土壤重金属钝化效果较好,使有效态Cd、Pb和Cu分别降低了32.4% ~ 89.2%、19.5% ~ 99.1%和49.4% ~ 92.4%,并将它们确定为复配钝化剂的成分。大田实验结果表明,生石灰、聚丙烯酰胺和海泡石复配对土壤中重金属钝化效果最佳,使有效态Cd、Pb和Cu分别降低了28.6%、20.2%和23.5%(p<0.05),其钝化机制为离子交换和络合作用。而且,该复配钝化剂对土壤化学性质影响最小。复配钝化剂使稻米中Cd的质量分数降低了21.7% ~ 93.1%(p<0.05)。另外,复配钝化剂对土壤微生物丰度和多样性没有显著影响。考虑到土壤的安全性和稳定性,推荐将生石灰、聚丙烯酰胺和海泡石复配钝化剂用于降低红壤稻米对Cd的吸收以确保粮食安全生产。本研究结果可为重金属污染红壤稻田的安全利用提供参考。     

Phosphine in paddy fields and the effects of environmental factors

Ambient levels of phosphine (PH₃) in the air, phosphine emission fluxes from paddy fields and rice plants, and the distribution of matrix-bound phosphine (MBP) in paddy soils were investigated throughout the growing stages of rice. The relationships between MBP and environmental factors were analyzed to identify the principal factors determining the distribution of MBP. The phosphine ambient levels ranged from 2.368 ± 0.6060 ng m⁻³ to 24.83 ± 6.529 ng m⁻³ and averaged 14.25 ± 4.547 ng m⁻³. The highest phosphine emission flux was 22.54 ± 3.897 ng (m² h)⁻¹, the lowest flux was 7.64 ± 4.83 ng (m² h)⁻¹, and the average flux was 14.17 ± 4.977 ng (m² h)⁻¹. Rice plants transport a significant portion of the phosphine emitted from the paddy fields. The highest contribution rate of rice plants to the phosphine emission fluxes reached 73.73% and the average contribution was 43.00%. The average MBP content of 111.6 ng kg⁻¹fluctuated significantly in different stages of rice growth and initially increased then decreased with increasing depth. The peak MBP content in each growth stage occurred approximately 10 cm under the surface of paddy soils. Pearson correlation analyses and stepwise multiple regression analysis showed that soil temperature (Ts), acid phosphatase (ACP) and total phosphorus (TP) were the principal environmental factors, with correlative rankings of Ts > ACP > TP.     

人工纳米颗粒输入对稻田土壤Cd形态转化及生物有效性的影响

进入农田土壤的人工纳米颗粒对土壤中重金属迁移转化及毒性的影响仍不明确。通过模拟稻田淹水-落干过程,研究了二氧化钛（TiO2-NPs）、氧化锌（ZnO-NPs）和多壁碳纳米管（MWCNTs）3种典型人工纳米颗粒对水稻土中重金属Cd赋存形态及生物有效性的影响。结果表明,3种纳米颗粒的添加均引起了土壤pH的增加;TiO2-NPs和ZnO-NPs添加能够显著降低土壤中酸可提取态Cd含量;ZnO-NPs的添加对土壤中铁锰氧化物结合态和有机结合态Cd的含量也有明显降低,但不同浓度处理间Cd含量并无显著差异;MWCNTs对土壤Cd形态转化无显著影响。与对照处理相比,添加TiO2-NPs的处理土壤中,CaCl2和DTPA提取态Cd含量分别降低了13.9%~17.5%和5.4%~8.9%,降幅均与TiO2-NPs添加浓度成正比。添加ZnO-NPs的土壤中,DTPA提取态Cd的含量降幅在8.4%~18.7%之间,降低幅度与ZnO-NPs添加浓度成反比。     

Temporal trends and sources of PCDD/Fs, pentachlorophenol and chlornitrofen in paddy field soils along the Yoneshiro River basin, Japan

In order to understand the long-term behaviors of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), pentachlorophenol (PCP), and 2,4,6-trichlorophenyl-4′-nitrophenyl ether (chlornitrofen, CNP) in paddy soil, we measured their concentrations in paddy soil samples collected in 1982 and 1984 (1980s) and in 2000 and 2002 (2000s) from the Yoneshiro River basin, Japan. The concentrations of PCP and CNP decreased from the 1980s to the 2000s, whereas the concentrations of PCDD/Fs and their toxic equivalency (WHO2006-TEQ) remained. The major sources of PCDD/Fs in the paddy soil samples were attributed to impurities in PCP and CNP as a result of comparisons of homologue and congener profiles and principal component analysis. Based on the results of comparison of total input and remaining amount, it is estimated that more than 99% of PCP and CNP applied to the paddy fields had disappeared, whereas most of the applied PCDD/Fs and TEQ remained.     

菜籽饼施加对镉-铜污染土壤中重金属形态转化及其植物有效性的影响

选择菜籽饼作为有机物料,模拟水田条件,研究菜籽饼施用后重金属污染土壤中镉-铜的赋存形态的变化及其有效性的影响。结果表明,菜籽饼施加后,土壤pH波动在0.5内,变化较小。但在一定程度促进土壤中镉、铜由弱酸提取态向可还原态转化,残渣态占比变化均较小。经培养一定时间,植物有效态DTPA-Cd由1.26±0.03下降至0.69±0.03,下降幅度约为45.2%,DTPA-Cu由82.9±0.09下降至48.7±0.09,最大下降幅度约为41.3%,下降较为明显。同时,土壤溶液中可溶性碳（DOC）和可溶性氮（DON）的含量显著增加,分别增加约4.14倍和6.48倍,因此,菜籽饼应用于重金属污染水稻土改良,可以间接降低水稻中重金属的含量。     

上海郊区稻田氮素流失研究

通过测坑和大田小区试验，研究了上海郊区稻田氮素排水流失和渗漏流失的特征、相关因素和流失负荷。结果表明，稻田综合排水TN为6.55mg／L，流失负荷为16．68kg／hm^2，以铵态氮为主，稻田氮素的排水流失负荷为16．68kg／hm^2。稻田渗漏水氮浓度与前茬作物有关，草莓和蔬菜高，麦茬低，TN为5．73mg／L，渗漏负荷为22．92kg／hm^2，其中硝态氮占50％左右。稻田氮素总流失负荷占稻季化肥用量的13．23％。测坑和大田试验都证明，施用有机肥可较多地减少稻田氮素流失量。     

Effects of butachlor on microbial populations and enzyme activities in paddy soil

This paper reports the influences of the herbicide butachlor (n-butoxymethlchloro -2', 6'-diethylacetnilide) on microbial populations, respiration, nitrogen fixation and nitrification, and on the activities of dehydrogenase and hydrogen peroxidase in paddy soil. The results showed that the number of actinomycetes declined significantly after the application of butachlor at different concentrations ranging from 5.5 microg g(-1) to 22.0 microg g(-1) dried soil, while that of bacteria and fungi increased. Fungi were easily affected by butachlor compared to the bacteria. The growth of fungi was retarded by butachlor at higher concentrations. Butachlor however, stimulated the growth of anaerobic hydrolytic fermentative bacteria, sulfate-reducing bacteria (SRB) and denitrifying bacteria. The increased concentration of butachlor applied resulted in the higher number of SRB. Butachlor inhibited the growth of hydrogen-producing acetogenic bacteria. The effect of butachlor varied on methane-producing bacteria (MPB) at different concentrations. Butachlor at the concentration of 1.0 microg g(-1) dried soil or less than this concentration accelerated the growth of MPB, while at 22.0 microg g(-1) dried soil showed an inhibition. Butachlor enhanced the activity of dehydrogenase at increasing concentrations. The soil dehydrogenase showed the highest activity on the 16th day after application of 22.0 microg g(-1) dried soil of butachlor. The hydrogen peroxidase could be stimulated by butachlor. The soil respiration was depressed during the period from several days to more than 20 days, depending on concentrations of butachlor applied. Both the nitrogen fixation and nitrification were stimulated in the beginning but reduced greatly afterwards in paddy soil.