89 resultados para gross nitrification


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Six isonitrogenous (gross protein content 35%) and isoenergetic (gross energy content 17 kJ g(-1)) diets were formulated to investigate the effects of inclusion of plant proteins on the gibel carp (Carassius auratus gibelio L.). The plant proteins tested were: soybean cake (SBC), potato protein concentrate (PPC), peanut cake (PNC), cottonseed cake (CSC) and rapeseed cake (RSC). Fish meal (FM) was used as control. In each diet, 27% of the protein was supplied by fish meal, and the rest supplied by the plant protein tested. Each diet was fed to three groups of gibel carp for 8 weeks in a recirculation system. Specific growth rate (SGR) in fish fed the control diet was significantly higher than those in the other groups, and SGR in fish fed the PPC was significantly lower than in fish fed other plant proteins. There was no significant difference in SGR among the other groups. Feeding rates were ranked in the order: RSC > CSC > FM > PNC > SBC > PPC. Conversion efficiency was highest in groups fed FM, SBC and PNC, followed by groups fed CSC and RSC, and was lowest in the group fed PPC. The fish fed PPC showed lower protein retention than those fed FM and SBC. FM showed highest energy retention while PPC showed lowest, There was no significant relationship between SGR and intake of digestible protein (g g(-1) day(-1)), digestible lysine (g g(-1) day(-1)), digestible methionine (g g(-1) day(-1)) or digestible total essential amino acids (g g(-1) day(-1)), suggesting that the differences in SGR could not alone account for any of these variables.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A growth trial was conducted at 30 degrees C to investigate the effect of body size on growth and energy budget of Nile tilapia. The average initial body weights of the four size groups tested were 9.3, 34.1, 80.3 and 172.4 g, respectively. Fish were fed to satiation twice a day with a diet containing 35.6% crude protein. Food consumption (C-max: kJ/day) increased with body size (W: g) according to the relationship: Ln C-max = 1.45 + 0.42 LnW. The final body contents of dry matter, crude protein and ash per unit body weight increased with increasing body size while contents of fat and energy were independent of body size. Specific growth rates of wet weight, dry weight, protein and energy decreased as the fish increased in size. Feed efficiencies in wet weigh, dry weight and crude protein decreased with increasing body size, while that of energy remained unchanged. The proportions of energy intake allocated to the various components (faecal energy, excretory energy, heat production and recovered energy) of the energy budget were not significantly affected by body size, and the average budget was: 100IE-18.5(+/- 1.33)FE + 5.9 (+/- 3.09)(ZE + UE) + 49.3(+/- 3.77)HE + 26.3(+/- 6.23)RE, where IE, FE, (ZE + UE), HE and RE represent gross energy intake, faecal energy, excretory (non-faecal) energy loss, heat production and recovered energy (growth), respectively. It is suggested that the decrease in growth rate in larger fish is mainly due to the decrease in relative food intake. (C) 1997 Elsevier Science B.V.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Nile tilapia weighing 8.29-11.02 g were fed a practical diet at seven ration levels (starvation, 0.5, 1, 2, 3, 4% body weight per day and satiation) twice a day at 30 degrees C. Feed consumption, apparent digestibility, nitrogenous excretion and growth were determined directly, and heat production was calculated by difference of energy budget. The relationship between specific growth rate in wet weight (SGR(w), percentage per day) and ration size (RL, percentage per day) was a decelerating curve described as SGR(w) = 2.98 (1 - e(-0.61(RL-0.43))). The apparent digestibility coefficients for dry matter and protein showed a decreasing pattern with increasing ration while the apparent digestibility coefficient of energy was not significantly affected by ration size. The proportion of gross energy intake lost in nitrogenous excretion tended to decrease with increasing ration. Feed efficiency was highest, and the proportion of gross energy intake channelled to heat production was lowest, at an intermediate ration level (2% per day). The energy budget at the satiation level was: 100IE = 16.9FE + 1.2(ZE + UE) + 62.3HE + 19.6RE, where IE, FE, (ZE + UE), HE and RE represent gross energy intake, faecal energy, excretory (non-faecal) energy loss, heat production and recovered energy (growth), respectively. (C) 1997 Elsevier Science B.V.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this work a practical scheme is developed for the first-principles study of time-dependent quantum transport. The basic idea is to combine the transport master equation with the well-known time-dependent density functional theory. The key ingredients of this paper include (i) the partitioning-free initial condition and the consideration of the time-dependent bias voltages which base our treatment on the Runge-Gross existence theorem; (ii) the non-Markovian master equation for the reduced (many-body) central system (i.e., the device); and (iii) the construction of Kohn-Sham master equations for the reduced single-particle density matrix, where a number of auxiliary functions are introduced and their equations of motion (EOMs) are established based on the technique of spectral decomposition. As a result, starting with a well-defined initial state, the time-dependent transport current can be calculated simultaneously along with the propagation of the Kohn-Sham master equation and the EOMs of the auxiliary functions.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Solid acid 40SiO(2)/TiO2-SO42- and solid base 30K(2)CO(3)/Al2O3-NaOH were prepared and compared with catalytic esterification activity according to the model reaction. Upgrading bio-oil by solid acid and solid base catalysts in the conditioned experiment was investigated, in which dynamic viscosities of bio-oil was lowered markedly, although 8 months of aging did not show much viscosity to improve its fluidity and enhance its stability positively. Even the dehydration by 3A molecular sieve still kept the fluidity well. The density of upgraded bio-oil was reduced from 1.24 to 0.96 kg/m(3), and the gross calorific value increased by 50.7 and 51.8%, respectively. The acidity of upgraded bio-oil was alleviated by the solid base catalyst but intensified by the solid acid catalyst for its strong acidification. The results of gas chromatography-mass spectrometry analysis showed that the ester reaction in the bio-oil was promoted by both solid acid and solid base catalysts and that the solid acid catalyst converted volatile and nonvolatile organic acids into esters and raised their amount by 20-fold. Besides the catalytic esterification, the solid acid catalyst carried out the carbonyl addition of alcohol to acetals. Some components of bio-oil undertook the isomerization over the solid base catalyst.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

能量流动、物质循环和信息传递共同构成了生态系统三大功能。能量是维持生态系统功能与过程的动力,Jordan(1971)认为能量比干物质更能反映出群落对自然资源(特别是太阳能)的利用情况。Long(1934)率先用热值来表示植物所含能量的多少,此后关于植物热值的研究工作逐渐展开。我国的植物热值研究始于20世纪80年代(杨福囤等,1983;祖元刚等,1986),主要集中在海南(林益明等,2000)、福建(林益明等,2004)、广东(任海等,1999)和浙江(郝朝运等,2006)等热带亚热带植物群落以及内蒙古羊草草原(鲍雅静等,2003),但有关黄土高原地区的植被热值研究尚未见报道。子午岭林区是黄土高原主要的天然次生林区,其植被主要是在弃耕地基础上逐渐恢复起来的(邹厚远等,2002)。由于自然因素与人为因素的影响,子午岭的植被在恢复时间上存在较大差异,形成了处于不同演替阶段的各种植被群落类型。本研究选取的6个代表性植被群落分别是沙棘(Hippophae rhamnoides)群落、山杨(Populus davidiana)群落、白桦(Betula platyphylla)群落、油松(Pinus tabulaeform...

Relevância:

10.00% 10.00%

Publicador:

Resumo:

目前全球缺水、水污染、洪涝灾害以及水土流失仍然非常严重,尤其在我国北方地区。流域水文模型可用来进行不同需水管理的情景分析,为解决我国水问题提供科学依据。分布式水文模型是流域水文模型的发展方向,具有显著特点:1)应用前景广泛,不仅可以模拟流域水文过程,还可以协助模拟泥沙或污染物的运移过程,为水利工程设计、水土保持、环境保护等领域提供技术支持;2)能够预测流域土地利用或气候变化下的流域水文响应过程变化,为管理部门提供决策支持;3)模型所需要的参数全部具有物理意义,可通过实际测量确定,适合模拟实测系列较短或是无观测流域的水文过程;4)对于目前国际水文界的前沿问题—水文尺度转换提供了一种有效的解决途径。 然而分布式水文模型还不完善,如1)真实性问题。对一些水文过程和边界条件还不确定。2)尺度转换问题。目前很少考虑尺度对参数有效性的影响。3)检验问题。还无法判断对有些难以测量的水文状态变量的模拟正确与否。4)计算时间和数据存储的问题。有些分布式水文模型虽然具有很强的水文物理基础和完善的模型结构,但是计算时间过长和(或)数据存储过大,难以应用。上述问题的核心就是对分布式水文模型的核心—单元水文模型的研究不够,需要为进一步完善单元水文模型进行研究。 本文采用饱和入渗理论、Saint-Venant方程、Richards方程、Penman-Monteith方程等等构建了以有限差分法求解的适用于森林流域的单元水文模型,并通过实验室模拟试验和坡地径流场资料进行了验证,主要结论为: 通过不同坡度和不同雨强下的室内坡面产汇流实验模拟,表明:该模型模拟的坡面流和壤中流过程与实测过程基本一致,峰现时间、径流历时、峰值流量、出流总量模拟值与实测值的相对误差均较小,基本小于10%。模型的模拟精度较高,实用性较强,为深入研究壤中流机制和改进流域降雨-径流模型提供了理论依据。 通过坡地径流观测场实测资料的验证,表明:该模型模拟的坡面流过程精度较高,累计流量的精度更高于小时过程的精度,离差系数、效率系数、确定系数均较理想,具有应用价值,有助于改善分布式水文模型在森林流域的模拟效果。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

试验采用室内模拟培养的方法,在不同用量脲酶/硝化抑制剂组合条件下,对辽宁省2种主要土壤—棕壤和褐土尿素氮转化的动态变化进行了研究。 结果表明,脲酶抑制剂N-丁基硫代磷酰三胺(NBPT)和苯基磷酰二胺(PPD)在施用量为尿素N量的0.05%时便有很好的脲酶活性抑制效果,且抑制效果随着脲酶抑制剂用量的增加而增强。NBPT和PPD在棕壤中的有效抑制时间为14天,在褐土中有效抑制时间为7天。两供试脲酶抑制剂相比,棕壤中PPD抑制效果好于NBPT,而在褐土中NBPT抑制效果好于PPD。 抑制剂组合各处理延缓了尿素的水解。土壤NH4+-N含量在前期较低,高峰值的出现延迟了2-6天;在培养中后期各抑制剂组合处理土壤NH4+-N含量显著提高。 抑制剂组合各处理土壤NO3--N含量在整个培养期均显著的降低。且在整个培养期间均显著降低了土壤NH4+的表观硝化率。在培养中后期,各处理能够增加棕壤有效氮含量;褐土中在第21天有效氮含量显著降低,而在第35天则有所回升。 试验表明,DMPP和DCD用量分别在施氮量的0.2%和0.25%时便可以达到很好的硝化抑制效果,且在棕壤中DCD的抑制效果好于DMPP,而在褐土中DMPP的抑制效果显著好于DCD。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

通过室内培养、模拟和田间试验相结合的方法,对吡唑类化合物的硝化抑制效应与其结构的关系进行了详细研究。结果表明,多数吡唑类化合物都能有效抑制土壤中的硝化作用,其中以3-甲基吡唑(MP)、3,4-二甲基吡唑和4-氯-3-甲基吡唑(ClMP)及其衍生物效果最佳。4-位被氯原子取代能够提高吡唑类化合物硝化抑制效果。但因水解作用的发生,1-位的取代反应、中和反应和络合反应均不能改变其硝化抑制效果。三种效果较好的吡唑类硝化抑制剂,3,4-二甲基吡唑磷酸盐(DMPP)、1-甲胺酰基-3-甲基吡唑(CMP)和ClMP在土壤中的最适用量分别为纯N用量的1.0%、1.0%和0.5%。吡唑类化合物的硝化抑制效果随土壤温度和有机质含量的升高而降低;在培养前期(0~14d)随土壤含水量和pH的升高而升高,在培养后期(>14d)随土壤含水量和pH的升高而降低。 吡唑类化合物随水在土层中垂直迁移与水平扩散速率与其分子的亲疏水性有关,垂直和水平迁移速率均为MP>DMPP> ClMP。土壤有机质含量是影响吡唑类化合物在土壤中吸附量的主要因素,有机质含量越高土壤对吡唑类化合物的吸附性越强。随pH的升高,土壤对吡唑类化合物的吸附能力降低,但在土壤通常所能达到的pH范围(4.5~8.5),pH对吡唑类化合物在土壤中的吸附作用影响不显著。土壤类型、抑制剂种类、温度与是否重复使用都影响吡唑类硝化抑制剂在土壤中的降解速率,一般褐土>棕壤,DMPP>MPC,低温>高温,未重复施用>重复施用。 以玉米为供试作物进行了吡唑类硝化抑制剂效果的田间试验,结果表明,吡唑类硝化抑制剂和尿素同时施用能显著提高玉米生育前期土壤中NH4+-N含量,降低土壤中NO3--N含量;并能提高玉米产量和氮肥表观利用率;且能使NO3-向土壤下层淋移趋势明显减缓。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

土壤类型、温度等条件是影响硝化抑制剂效果的重要因素,为了探讨几种国外报道的高效硝化抑制剂在我国棕壤和红壤上的适应情况,以及温度等条件对于施肥土壤中NO3--N的积累和硝化抑制剂效果的影响,进行了本研究。采用室内培养的方式,研究了ATC、DMPP和CMP(每种抑制剂在两种土壤上分别设两个浓度处理)在我国棕壤和红壤上的效果,与目前应用较多的DCD(0.5%、1.0%两个浓度处理)进行效果对比;研究了温度条件、添加C源及培养条件对土壤中NO3--N积累及CMP硝化抑制效果的影响。结果表明,土壤条件是影响NO3--N积累和所用四种硝化抑制剂(DMPP、CMP、ATC、DCD)抑制效果的一个显著因素,棕壤中氮素转化较快,硝化抑制剂表现出效果较早,在红壤中起效时间较晚,在两种土壤条件下,所用抑制剂都表现出了良好的效果,在60天内ATC、CMP和DMPP的效果与10倍用量的DCD效果类似,甚至好于DCD,在棕壤中同种抑制剂的两个浓度处理之间存在显著差异,但是在红壤几个处理之间没有表现出显著差异;温度条件也是影响NO3--N积累的一个显著因素,从计算硝化抑制率看出,在25℃和30℃下CMP表现出了高效,37℃下抑制率下降,效果变差;添加两个浓度的葡萄糖对于对照中NO3--N的积累以及硝化抑制剂的硝化抑制效果没有表现出显著作用;增加的一步预培养恢复了土壤中微生物的活性在短期内体现了出来,但是长期看对于NO3--N积累量、变化趋势以及硝化抑制率都没有表现出显著作用。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

采用室内培养和田间小区实验相结合的方法,研究了硫脲(TU,0.1%,0.3%,0.5%,1.0%,5.0%)不同浓度以及TU和硝化抑制剂双氰胺(DCD)、脲酶抑制剂苯基磷酞二胺(PPD)组合对土壤脲酶活性、土壤尿素氮转化和玉米产量的影响。室内培养试验表明,硫脲既是一种弱脲酶抑制剂又是一种硝化抑制剂。硫脉对脲酶活性和尿素水解均有显著的抑制作用,但是作用时间较短;硫脉用量为0.1%时,就起到了抑制作用,用量0.3%-1.0%之间差异不显著,用量1.0%-5.0%之间抑制效果随用量增加而加强。硫脉不同用量对土壤NH_4~+-N释放和向NO_3~--N的进一步转化有明显的抑制作用,作用强度随抑制剂用量增加而增强。硫脲不仅仅延缓了土壤NH_4~+-N的释放高峰期一周,而且降低了土壤中NO_3-N的富集,使NO_3~--N的释放高峰期向后推迟了10天。本试验条件下,土壤中的NH_4~+-N向NO3--N转化的时间大约为7~10天;土壤中有效氮的含量主要取决于土壤NH4+-N的含量,受NO3-N含量的影响次之。田间模拟培养表明,硫脲及其抑制剂组合对土壤脲酶活性有显著的抑制作用,抑制时间为2周,其中抑制剂组合TU_1+PPD对脲酶活性的抑制作用持续了65天。TU、TUI+DCD和TUI+PPD,对土壤NH_4~--N的释放有显著的抑制作用,对NH_4~+-N向NO_3~--N的进一步转化有显著的抑制作用,进而影响土壤有效氮的总量。总的来看,硫脲及抑制剂组合的抑制效果,依次是TU_1+P PD>TUI+DCD>TU_2>TU_1。硫服及抑制剂组合对玉米株高、百粒重和产量的影响基本是一致的,TU和抑制剂组合Tul十PPD、TU1+DCD的作用效果显著优于单施尿素,处理之间差异不显著。施用抑制剂显著增加了玉米产量,增产幅度为9.14%~11.49%。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

花椒(Zanthoxylum bungeanum Maxim.)是川西地区重要的经济植物,化感作用是花椒连作障碍的原因之一,而花椒凋落物和根系分泌物对土壤质量的影响是花椒化感作用的一个重要方面。系统研究花椒如何影响土壤有助于深入理解和解决花椒连作障碍。本文主要以大红袍(10a生)花椒叶和种植过花椒的土壤的浸提液浇灌花椒幼苗进行试验,分析叶浸提液与土壤浸提液对非花椒生长土壤中土壤微生物、土壤酶及土壤化学性质的影响。主要结果如下: 1.花椒叶浸提液和土壤浸提液减少了土壤中微生物的种类、组成和数量。本试验中未施加浸提液的土样中根际微生物明显高于非根际区,在经过花椒叶浸提液处理后,根际细菌、真菌和放线菌数量以及微生物总数都有所减少,这样将会导致土壤中的有效养分的供给减少,进而可能影响植物的生长。 2.施加花椒叶浸提液和土壤浸提液,以及花椒幼苗的栽种,对不同土样中的土壤酶各有促进和抑制作用。在浸提液处理下,水解酶之间及氧化还原酶之间各存在相互促进作用。 3.施加花椒叶浸提液和土壤浸提液均抑制了根际土中全氮和有机质含量,叶浸提液还抑制了无苗土中全磷含量,土壤浸提液还抑制了无苗土中全氮含量与根际土全磷、有机质含量。但两种浸提液均促进了根际土中有效磷和水解性氮含量、根外土中全磷含量,叶浸提液促进了根际土中全磷含量,土壤浸提液促进了根外土中有效磷含量。全氮和有机质含量的下降可能对植物生长发育不利。 4.土壤化学性质与土壤酶活性在不同土样中有不同的相关性。全氮含量在施加叶浸提液的土样中与蛋白酶活性呈正相关。水解性氮含量在施加叶浸提液的土样中与蛋白酶活性、蔗糖酶活性呈正相关。全磷含量在施加叶浸提液的土样中与多酚氧化酶活性呈正相关;在施加土壤浸提液的土样中与蛋白酶活性、蔗糖酶活性呈正相关,与多酚氧化酶活性呈负相关。有效磷含量在施加叶浸提液的土样中与多酚氧化酶活性呈正相关,与蛋白酶活性呈负相关;在施加土壤浸提液的土样中与蛋白酶活性、过氧化氢酶活性呈正相关。有机质含量在施加叶浸提液的土样中与蛋白酶活性、蔗糖酶活性呈正相关。 Zanthoxylum bungeanum is one of the most important cash crops in Eastern Tibetan Plateau. Allelopathic effects could be one of reasons for Z. bungeanum’s continuous cropping impediment. The effects of secretion of leaf and root of Z. bungeanum on soil quality is a important way of Z. bungeanum’s allelopathic effects. However, allelopathic effect of Z.bungeanum on soil microbes, enzyme activities and chemical property were seldom studied. In this study, leaf and soil extracts of Da Hongpao(DHP), the most common varieties of Z.bungeanum in this area, were used to assess allelopathic effect of Z. bungeanum on soil biology and biochemistry by pot experiments . The main results showed that: 1. The irrigation of two kinds of extracts reduced the species, component and quantity of soil microbes. In rhizosphere soil which irrigated by distilled water, the quantity of soil microbes is significantly different from exoroot soil. In rhizosphere soil which irrigated by leaf extracts, the quantity of bacterial, fungi, actionmycete and gross of microbes were decreased, it may resulted in reduce of Available nutrient in soil, and influenced the growth of plants. 2.The irrigation of two kind of extracts reduced or enhanced the enzyme activities in different soils. Interaction between hydrolytic ferments and redoxases were promoted each other. 3. The irrigation of two kinds of extracts reduced the total N and organic matter in rhizosphere soil. Leaf extracts also reduced the total P in soil without seedling. Soil extracts reduced total N in soil without seedling and total P, organic matter in rhizosphere soil. But both extracts also enhanced available P and hydrolysable N in rhizosphere soil, total P in exoroot soil. Leaf extracts enhanced total P in rhizosphere soil. Soil extracts enhanced available P in exoroot soil. The reduction of total N and organic matter may influence growth of plants. 4.Positive correlations between total N and prolease, hydrolysable N and prolease, hydrolysable N and saccharase, total P and polyphenol oxidase, available P and polyphenoloxidase, organic matter and prolease, organic matter and saccharase, were studied in soil irrigated by leaf extracts. In soil irrigated by soil extracts, there are positive correlations between total P and prolease, total P and saccharase, available P and prolease, available P and catalase, while negative correlation between total P and polyphenoloxidase, available P and prolease, available P and catalase was found.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

恶臭假单胞菌;异养硝化-好氧反硝化;自养硝化;生活污水脱氮;Pseudomonas putida;heterotrophic nitrification-aerobic denitrification;autotrophic nitrification;nitrogen removal for domestic wastewater treatment

Relevância:

10.00% 10.00%

Publicador:

Resumo:

畜禽废水是农村水环境污染的主要来源之一,其处理的难点在于脱氮。传统生物脱氮法具有能耗高、需大量外加碳源等缺点,开发低成本、高效率的新型生物脱氮技术具有重要意义。 本研究将短程硝化反硝化和厌氧氨氧化两种脱氮新技术结合,让前者为后者创造去除可降解COD、降低总氮负荷、调整pH、调整氨氮和亚硝酸盐氮浓度比例等进水条件,而后者可在无需外加碳源的条件下进一步脱氮,二者结合可成为高氨氮、低C/N废水脱氮的新途径。 试验以低碳氮比猪场废水为研究对象,首先进行了短程硝化反硝化预处理研究,同时启动并运行调控厌氧氨氧化反应器,最后以经过短程硝化反硝化预处理的猪场废水为进水,进行厌氧氨氧化脱氮考察。实验表明:(1)短程硝化反硝化作为厌氧氨氧化的预处理工序是可行的。猪场废水通过短程硝化反硝化,可以达到基本去除可生化COD、部分脱氮、控制出水氨氮和亚硝酸盐氮浓度之比在1︰1左右、pH在7.5~8.0的目的, COD和总氮平均去除率分别为64.3%、49.1%,出水可达到厌氧氨氧化反应的进水要求。(2)采用模拟废水启动厌氧氨氧化反应器,经过5个月左右的运行调控,反应器启动成功并稳定运行,最高总氮去除率为87.1%,总氮容积去除率最高达到0.14kg/m3.d;整个稳定阶段,氨氮、亚硝酸盐氮、硝酸盐氮的变化量之比为1︰1.21︰0.33。(3)经过短程硝化反硝化预处理的猪场废水厌氧氨氧化脱氮效果稳定,氨氮、亚硝酸盐氮、总氮、COD的平均去除率分别为93.0%、99.4%、84.6%、18.1%,处理效果与模拟废水处理系统相比无明显变化。(4)经过短程硝化反硝化预处理后,猪场废水中残留有机物成分在厌氧氨氧化反应过程中无显著变化,主要为酯类和烷烃类物质;残留有机物对厌氧氨氧化效果无明显影响。(5)采用PCR技术进行特殊功能菌种检测,结果表明模拟废水处理系统和猪场废水处理系统的菌群中均含有厌氧氨氧化菌和好氧硝化菌;通过blast比对,厌氧氨氧化菌扩增序列与未培养的Planctomycetales菌和Candidatus Brocadia fulgida菌16S rRNA部分序列相似性分别为95%、90%。(6)MPN法菌种计数结果显示,模拟废水处理系统和猪场废水处理系统的菌群中均含有硝化细菌、亚硝化细菌和少量反硝化菌,实验条件下的微生物系统是一个厌氧氨氧化菌与好氧硝化菌、反硝化菌共存的系统。 Poultry wastewater is one of the main source of water pollution in rural areas,and nitrogen removal is the most difficult part in treating poultry wastewater. There are some disadvantages in traditional nitrogen removal, such as high energy consumption and more additional organic carbon. It is important to develop ecolomical and efficient technologyies. Shortcut nitricfication/denitrification, as a pretreatment process, was combined with Anammox in this research, so that part of total nitrogen and most degradable COD could be removed by the former, and further nitrogen removal could be implemented by the latter. The combination of the two technologies was a new approach to treat wastewater with high ammonium and low C/N. Piggery wastewater with low C/N was treated in lab-scale experiment. Firstly, shortcut nitrification/denitrification was investigated, and Anammox reactor was started up successfully at the same time. Then piggery wastewater after pretreatment was treated by Anammox. The results showed :(1) It was feasible to take nitrification/denitrification as the pretreatment process of Anammox. By using this process, part of total nitrogen and COD were removed, the ratio of ammonium and nitrite reached around 1︰1 and the pH was about 7.8, which were favorable for Anammox. The average removal percentage of COD and total nitrogen were about 64.3% and 49.1%, respectively. (2) Simulated wastewater was used to start up Anammox reactor. The reactor was started up successfully within 5 months and stable performance was achieved. The highest nitrogen removal reached 87.1% and the biggest volumetric total nitrogen removal rate reached 0.14kg/m3.d. The average ratio of ammonium, nitrite and nitrate was 1:1.21:0.33. (3)Taking the effluent of shortcut nitrification/denitrification as the influent, the nitrogen removal efficiency of Anammox was stable, and the the average removal percentage of ammonium, nitrite, total nitrogen and COD were 93.0%, 99.4% , 84.6% and 18.1%, respectively, which had little difference with that by using simulated wastewater..(4) After pretreatment, the residual organic carbon in piggery wastewater showed no obvious change during the Anammox process, and the main organic compounds were saturated hydrocarbon and ester, which had no obvious negative effect on Anammox process.(5) By PCR technology, the existence of Anammox bacteria was confirmed and the aerobic nitrifying bacteria was found to coexist as well. The result of blast showed that the identities of Anammox bacterium to part of 16S rRNA sequence of uncultured Planctomycetales bacterium and Candidatus Brocadia fulgida bacterium were 95% and 90%, respectively.(6)By MPN method, nitrite oxidizer, ammonium oxidizer and denitrification bacteria were detected in both simulated and piggery wastewater treatment system of Anammox, and the microorganism system was composed of Anammox bacteria,aerobic bacteria and denitrification bacteria together.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

垃圾卫生填埋是国内外城市垃圾的主要处置方法。垃圾渗滤液是渗入填埋场垃圾的降水混合垃圾降解过程中产生的物质而形成的混合物,是垃圾填埋场向环境排放的主要污染物。渗滤液由于其所含高浓度有机和无机污染物,且其中很多物质有生物毒性或难生物降解,难于治理。特别是到填埋晚期,渗滤液中高浓度的氨氮更是增加了治理的难度。渗滤液场外硝化-原位反硝化是填埋场氮管理的新途径。本文利用从环境中筛选出优势硝化功能菌对渗滤液中的高浓度氨氮进行生物硝化,经硝化后的渗滤液回灌至以垃圾柱模拟的生物反应器填埋场,在填埋场内实现原位反硝化。 上述目标通过以下两部分来实现: 第一部分:渗滤液场外硝化。首先从污水厂的硝化污泥中富集并筛选出硝化功能菌,在模拟氨氮废水中优化。将驯化的硝化功能菌接种于连续式完全混合反应器(CSTR)进行高氨氮渗滤液硝化研究。在200余天的连续运行中,反应器硝化和有机物去除效果良好。在最大氨氮负荷和有机物负荷分别为0.65 g N l-1 d-1 和3.84 g COD l-1 d-1时,氨氮和COD去除率分别高于99%和57%。实验过程中发现,游离氨(FA)和溶解氧(DO)浓度对反应器中亚硝酸盐的积累影响很大。 第二部分:渗滤液原位反硝化。本文利用一个垃圾填充柱模拟生物反应器填埋场,研究了硝化渗滤液回灌对垃圾降解的影响,和回灌的硝化渗滤液中TON(总氧化态氮)对填埋场生物反应器产甲烷作用的影响。最后利用变性梯度凝胶电泳(DGGE)分析了硝化渗滤液回灌对垃圾填埋场菌群结构的影响。结果表明:回灌的TON被完全还原,反硝化为主要反应,最大TON负荷为28.6 mg N kg-1 TS d-1。当垃圾柱TON负荷大于11.4 mg N kg-1 TS d-1时,出现了产甲烷抑制,抑制作用随TON负荷的增加而加强。在此过程中,反硝化逐渐代替产甲烷作用成为填埋场内垃圾降解的主要反应,且更多产生的是清洁的氮气,而非温室气体甲烷。直到实验结束时,回灌硝化渗滤液的垃圾柱的甲烷产量仅相当于对照的2.5%,并且回灌的硝化渗滤液还加速了填埋场垃圾的降解与稳定。通过DGGE进行菌群结构分析发现,由于TON对填埋场的长期作用,反硝化菌增多而产甲烷菌减少。 Landfill still remains the chief method for MSW management around the world. Leachate is a mixture of rainfall permeating through landfill and organic and inorganic matters generated during decomposition of the wastes in the landfills, characterized as highly complicated and refractory wastewater. Ex-situ nitrification and sequential in-situ denitrification represents a novel approach to nitrogen management at landfills. In the present paper, nitrification was carried out in a continuous stirred tank reactor (CSTR) inoculated with nitrifying bacteria which were isolated from municipal WWTP of Chengdu city. The nitrified leachate from CSTR was recirculated to a lab-scale municipal solid waste (MSW) column where in-situ denitrification took place. The above object was achived through two parts as following: First, ex-situ nitification of leachate. After acclimated in simulated wastewater for 3 month, nitrifying bacteria isolated from WWTP nitrifying sludge were added to the CSTR for nitrification. The results over 200 days showed that the maximum nitrogen loading rate (NLR) and the maximum organic loading rate (OLR) was 0.65 g N l-1 d-1 and 3.84 g COD l-1 d-1, respectively. The ammonia and COD removal was over 99% and 57%, respectively. Moreover, the effects of free ammonia (FA) and dissolved oxygen (DO) on nitrification were investigated. Second, in-situ denitrification was studied in a municipal solid waste (MSW) column. Variation of nitrified leachate and its effects on the decomposition of municipal solid waste (MSW) were studied in a lab-scale MSW column to which nitrified leachate was recirculated. Additionally, DGGE was employed to investigate the microbial community of both MSW columns. The results suggested: complete reduction of total oxidized nitrogen (TON) was obtained with maximum TON load of 28.6 mg N kg-1 TS d-1 and denitrification was the main reaction responsible. Methanogenesis inhibition was observed while TON load was over 11.4 mg N kg-1 TS d-1 and the inhibition was enhanced with the increase of TON load. Denitrification gradually took over methanogenesis to become the main reaction responsible for decomposition of MSW while nitrogen gas, a clean byproduct, was generated instead. Till the end of the experiment, the average weekly methane production in the denitrification column was as low as 2.5% of that of the control, and the rate of decompition and stability of MSW was accelerated by the recirculation of the nitrified leachate.Owing to long term exposure of nitrified leachate to landfill, denitrifying bacteria increased and methanogen decreased.