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1.
A two-line denitrifying phosphorus removal process (2L-DPR) was established treating low C/N municipal wastewater efficiently in our previous studies, while hydraulic retention time (HRT) is one of the most important factors determining the substrate loading, contact time for biomass, and pollutants and further affect performance of the whole system. Removal and transformation mechanism of organic carbon (C), nitrogen (N), and phosphorus (P) were investigated together with mass balance under various HRTs (6, 9, and 18 h) in the established 2L-DPR process. The results showed that in anaerobic units, the concentration of the main storage products in activated sludge such as poly-hydroxyvalerate (PHV) and poly-hydroxybutyrate (PHB) at HRT of 9 h was higher than that under other HRTs. The highest TN and TP removal efficiency was also achieved under the HRT of 9 h with removal rates of 55.9% and 84.6% respectively. Increasing HRT from 6 to 9 h greatly enhanced TN removal in anoxic and aerobic units; however, HRTs had little influence on COD removal with effluent concentration of 48.6, 49.1, and 48.9 mg/L, respectively. HRT affected phosphorus up-taken in anoxic and aerobic units rather than on the release of phosphorus processes in anaerobic units.  相似文献   

2.
Hydraulic retention time (HRT) influence improving sludge flocculation with adding the polyelectrolytes (non-ionic, anionic, and cationic) was studied on an activated sludge (AS) system fed with synthetic domestic wastewater (SDW), dairy industry wastewater (DIW), and caramel industry wastewater (CIW). The sludge volumetric index, food/microorganism ratio (F/M), and mixed liquor volatile suspended solids at different HRTs (6, 8 and 10 h) were monitored on an experimental model. Results showed that both SDW and IW had the best sludge flocculation conditions at 8 h and 100 mL of non-ionic polyelectrolyte (0.2 mg L?1). In addition, this phenomenon reached the organic matter removal efficiencies of 95.9, 95.7, and 94.2% for SDW, DIW, and CIW, respectively. Therefore, optimum HRT increased the organic matter removal efficiencies by 10%, sludge concentration by 37% (22–55%), and F/M ratio by 70%. Moreover, the polyelectrolytes used in AS improved the sludge flocculation by 2.9 times.  相似文献   

3.
A kinetic analysis of the anaerobic digestion process of wastewater derived from the production of protein isolates from extracted sunflower flour was carried out. The digestion was conducted in a laboratory-scale fluidized bed reactor with saponite (magnesium silicate) as support for the mediating bacteria at psychrophilic temperature (15-19 degrees C). Soluble chemical oxygen demand (COD(s)) removal efficiencies in the range of 95.9-69.0% were achieved in the reactor at organic loading rates (OLR) of between 0.57 and 2.49 g total COD (COD(t))/L d, hydraulic retention times (HRT) of between 20.0 and 4.5 days, and average feed total COD concentration of 11.3 g/L. The yield coefficient of methane production was 0.32 L of methane (at STP) per gram of COD(t) removed. The total volatile fatty acid (TVFA) levels and the TVFA/alkalinity ratio were lower than the suggested limits for digester failure for OLR and HRT up to 2.26 g COD(t)/L d and 5.0 days, respectively. The specific rate of substrate uptake, r (g COD(s)/g VSS d), correlated with the concentration of biodegradable substrate, S (g COD(s)/L), through an equation of the Michaelis-Menten type. The maximum substrate utilization rate, k, and the Michaelis constant, K(s)(), were found to be 0.125 g COD(s)/g VSS d and 124 mg COD(s)/L, respectively. This proposed model predicted the behavior of the reactor very accurately showing deviations lower than 10% between the experimental and theoretical values of substrate uptake rates. A mass (COD(t)) balance around the reactor allowed the COD equivalent of methane volume (W(CH)4) to be obtained, which gave a value of 2.89 g COD(t)/L CH(4), which was virtually coincident with the theoretical value of 2.86 g COD(t)/L CH(4).  相似文献   

4.
Water Movement Characteristics in a Multi-Soil-Layering System   总被引：2，自引：0，他引：2  
The Multi-Soil-Layering (MSL) system consists of soil units arranged in a brick-like pattern that are surrounded by layers of zeolite or alternating particles with a homogeneous size that allow a high hydraulic loading rate. Characteristics of the changes in the water movement, hydraulic retention time (HRT) and system weight during the wastewater treatment in the MSL system were investigated using a laboratory-scale MSL system (D10 × W50 × H73 cm). As the loading rate increased from 1,000 to 5,500 L m−2 d−1, wastewater preferentially flowed into the permeable layers in the MSL, which decreased the contact of the wastewater with the soil mixture layers. HRT was inversely related to the loading rate. HRT decreased from 20 to 1 h, as the loading rate increased from 250 to 6,000 L m−2 d−1. As an indicator of the system condition, the weight variation of the system was determined during the wastewater treatment. When the weight was stable, input and output of wastewater and decomposition of organic matter appeared to be equilibrated. When the weight increased, the system started to clog. Due to clogging, the efficiency of COD and phosphorus removal decreased, while the efficiency of nitrate removal increased.  相似文献   

5.
Ong  S. L.  Liu  Y.  Lee  L. Y.  Hu  J. Y.  Ng  W. J. 《Water, air, and soil pollution》2004,157(1-4):245-256
A lab-scale novel biofilm reactor system, Ultra-Compact Biofilm Reactor (UCBR), was studied to investigate its performance and operational characteristics for domestic sewage treatment. The reactor was operated at four different hydraulic retention times, namely, 90, 60, 30 and 15 min. The operating ranges of volumetric loading rates in terms of COD, BOD5, NH+ 4-N and TKN were 5.6-62.1 kg COD/m3 d, 2.6-32.5 BOD5/m3 d, 0.6-3.2 kg NH+ 4-N/m3 d and 0.82-6.2 kg TKN/m3 d, respectively. The COD, BOD5 and NH+ 4-N removal efficiencies at 90-min hydraulic retention time (HRT) and 60-min HRT could exceed 80%, 90% and 99%, respectively. The corresponding maximum biomass concentrations were 12.0 g/L and 15.0 g/L at 90-min HRT and 60-min HRT, respectively. At 30-min HRT, the biomass concentration increased to a maximum of 24.0 g/L. However, COD and BOD5 removal efficiencies decreased to 75% and 80%, respectively, while the NH+ 4-N nitrification efficiency decreased to only 25% to 30%. These observations suggested that high biomass concentration alone was not sufficient to provide a high removal capacity in a UCBR. Further reduction in HRT to 15 min led to an excessive biomass decline from 22.5 g/L to 4.0 g/L. On the whole, the UCBR was able to sustain COD removal and NH+ 4-N conversion of up to 5.96-18.70 kg COD/m3 d and 0.73-1.00 kg NH+ 4-N/m3 d, respectively.  相似文献   

6.
Static granular bed reactor (SGBR) and upflow anaerobic sludge blanket (UASB) reactor were demonstrated at mesophilic condition for the treatment of pulp and paper mill wastewater. The hydraulic retention times (HRTs) were varied from 4 to 24 h following 29-day start-up period. The overall chemical oxygen demand (COD) removal efficiency of the SGBR was higher than the UASB during this study. At 4 h HRT, the COD removal was greater than 70 % for the SGBR and 60 % for the UASB. Biomass yield and volatile fatty acids concentration of SGBR were slightly less than UASB at organic loading rates ranging from 1.2 to 5.1 kg/m3/day. The results indicated that the SGBR system can be considered a viable alternative system for anaerobic treatment for pulp and paper wastewater.  相似文献   

7.
为了考察曝气生物滤池(biological aerated filter,BAF)处理玉米青贮渗出液的效果及其影响因素,重点考察了水力负荷、气水比、有机负荷和滤床高度。结果表明:水力负荷从0.5m3/(m2.h)升高到3.0m3/(m2.h)过程中,化学需氧量(COD)和NH3-N的去除率先升高后降低,当水力负荷1.5m3/(m2.h)时COD和NH3-N的去除率分别达到最大为83.5%、74.9%;增加气水比使得系统中溶解氧充足,可明显提高COD和NH3-N去除率,当气水比为3.5:1时COD和NH3-N的去除率分别达到最大为87.5%、75.2%;低有机负荷不利于COD和NH3-N的去除,当有机负荷为COD2.4kg/(m3.d)时,COD和NH3-N去除率最低分别仅为49.6%、58.5%,有机负荷为COD4.8kg/(m3.d)时去除率最高分别可达80.9%和75.9%,但过高的有机负荷反而对NH3-N去除不利,当有机负荷为COD7.2kg/(m3.d)时,NH3-N去除率降低为61.7%;滤床高度对硝化反应去除NH3-N影响较大,NH3-N生物硝化反应去除行为主要发生在0.6～1.0m区域。试验表明采用BAF系统处理玉米青贮渗出液是可行的,也为类似性质废水处理和改善农村水环境质量提供有益的参考。  相似文献   

8.
Given the high turnover of fine roots in mountain grasslands, knowledge of their decomposition rates and the capacity of mountain grassland soils to stabilize root-derived C are central to understand the role of these ecosystems as potential C sinks. Here we studied the decomposition of fine roots in mountain grasslands and estimated the rates at which root-C and -N incorporated into protected pools at two soil depths. For this purpose, we incubated standard 13C- and 15N-labelled wheat roots mixed with unlabelled soil at 5 and 20 cm depth in two mountain grassland sites. Particle size fractionation allowed the quantification of the labelled wheat root-C and -N allocated to each size fraction (coarse sand, fine sand and silt plus clay sized) as well as their incorporation rates into the finest fraction. Between 62% and 78% root-C remained in the soil after one year of field incubation, faster decomposition being registered at the warmest site. In the following two years, roots decomposed much more slowly. In contrast to reports in the literature, our results indicate that decay rates during the first year were highest in the deep layer. The incorporation of wheat root-derived organic matter into the silt plus clay size fraction was also much greater during the first year of decomposition than in the following two years and also slightly higher in the deep soil than in topsoil. The incorporation rates of root-13C and root-15N into this fraction also suggest that the wheat-derived organic matter associated with this fraction was N-enriched and less recalcitrant (i.e., less resistant to acid hydrolysis) than that recovered from the coarser fractions. Furthermore, recalcitrant organic matter incorporated much more slowly than labile organic matter did. We conclude that the conditions of the subalpine grassland subsoil are more favourable for root decomposition than the topsoil and that the organic matter that incorporates into the protected pool is characterised by a high N content and low biochemical recalcitrance.  相似文献   

9.
Biochemical modification of plant materials may contribute considerably to the formation and stabilization of soil organic matter, but its significance remains elusive in turfgrass systems. This study aimed to close this knowledge gap by examining the dynamics of soil organic matter in turfgrass systems as well as its stability using δ13C and δ15N records. Two geographic locations, each containing 3 or 4 turfgrass systems of different ages were used as the study sites because site-associated differences, in particular soil pH (alkaline versus acidic) might cause divergence in microbial processing during organic matter decomposition and resynthesis. We observed that soil C storage was ∼12% greater in the alkaline site than the acidic one. In addition, accumulation rates of soil organic C and N were about 3-fold higher in the alkaline site. Soil organic matter was physically fractionated into light and heavy fractions. Heavy fraction from the alkaline site mineralized more slowly than the acidic one, indicating that soil organic matter was more stable in the alkaline site. Furthermore, the stability of soil organic matter based upon δ15N records and C-to-N ratio of organic matter was again found to be more stable in the alkaline site than the acidic one. While both soil δ13C and δ15N increased as turfgrass systems aged, rates were greater in the alkaline site than the acidic one. Temporal shifts in soil δ13C and δ15N were attributed mainly to isotope fractionation associated with microbial processes rather than selective preservation of 13C- or 15N-enriched chemical compounds of plant materials. Our results suggested that microbial decomposition and resynthesis played an important role in organic matter stabilization in turfgrass systems and this microbial processing could be managed via microbial activity-regulating factors, such as soil pH.  相似文献   

10.
Zhou  Ping  He  Jiahan  Qian  Yi 《Water, air, and soil pollution》2003,144(1-4):81-100
Domestic wastewater with an influent COD of 160 to 327 mg L-1 was evaluated for treatment by the Biofilm Airlift Suspension-reactor (BAS-reactor). Ceramic materials withdiameters of 0.25–0.5 mm (for reactor (1)) and 0.5–0.71 mm(for reactor (2)) were used as carriers, respectively. Theresults show that reactor (1) with smaller carriers outperformedreactor (2) with larger carriers. At steady state, the BAS-reactors showed high COD removal efficiencies. When the HRT was kept at 0.5 hr, the mean effluent CODs were 33±4 and 58±5 mg L-1 for reactors (1) and (2), respectively, at a confidence interval of 95% (p = 95%). When HRT was extended to 1.0 hr, these values decreased to 24±2 and 30±3 mg L-1 for reactors (1) and (2), respectively (p = 95%). Biomass concentration increased whilebiofilm thickness decreased with an increase in carrierconcentration. Biomass concentrations as high as 6.16±0.12 and 5.50±0.10 g VSS L-1 (p = 0.95) were achieved at carrier concentrations of 100 g L-1 forreactors (1) and (2), respectively. Biofilm thickness had a significanteffect on reactor performance: with an increase in biofilm thickness, biomass concentration increased and the critical gas velocity to maintain carrier fluidization decreased. An oxygenation model for a BAS-reactor was proposed and the effectsof gas velocity and carrier concentration on the oxygen transfercoefficient were examined. It was found that oxygen transfer coefficient increased with gas velocity while the relationship between carrier concentration and oxygen transfer coefficient wascomplicated. During a period of more than three months of steadystate operation, carrier washout with the effluent was negligible.Comparison of the parameters of the conventional activated sludgeprocess to that of the BAS-reactor shows that the BAS-reactor isa promising wastewater treatment process with high efficiency andlow operation cost.  相似文献   

11.
Climate change is predicted to reduce or delay annual wintertime snow pack formation in the forests of the northeastern US. Any delay in snowpack formation could increase soil freezing in winter and, thereby, alter soil characteristics and processes. We examined the hypothesis that delayed snowpack would disrupt soil structure and change organic matter bioavailability in an experimental snow removal study at the Hubbard Brook Experimental Forest (HBEF), NH, USA. Pairs of reference and snow removal treatment plots were studied in four different sites at HBEF. Snow was removed from November–January of two winters, inducing soil freezing throughout both winters. Size class distribution and organic matter concentration and content of aggregates, and carbon and nitrogen mineralization potential of size fractions were quantified for surface mineral soils in the spring of both years immediately after snowmelt. In the first year of sampling, the only significant effect of snow removal was an increase in the smallest (<53 μm) size fraction of mineral soil. In the second year, snow removal increased organic matter concentrations of macroaggregate (250–2,000 μm) and microaggregate (53–250 μm) size fractions. This change corresponded to an increase in net N mineralization potential and the ratio of N to C mineralized in the macroaggregate fraction, but there were no effects of snow removal on C mineralization. We propose that soil freezing increases the movement of organic matter from organic to mineral soil horizons and increases the N content of mineralizable substrates in mineral soil following years with delayed snowpack formation.  相似文献   

12.
曝气对垂直流湿地处理水产养殖废水脱氮的影响   总被引：1，自引：3，他引：1  
人工湿地作为一种有效的污水处理技术,现已被逐渐拓展到水产养殖业中。鉴于其与养殖竞争有限土地资源的弊端,如何构建节地高效型湿地成为未来研究的重点。曝气增氧是强化潜流湿地净化效能的重要措施之一,但是关于曝气强度以及净化效率与影响因素的关系仍缺乏深入系统的研究。为此,该文设计构建了7组不同要素组合的垂直流湿地小试系统,同步或分阶段探讨了曝气强化对垂直流湿地脱氮的影响。研究结果表明,无论曝气与否,构建的7组湿地系统于试验运行工况下都存在明显的硝化过程,且空气复氧和植物根系泌氧足以弥补硝化作用耗氧量。曝气增氧进一步强化了湿地内部的矿化和硝化过程;鉴于养殖废水不缺乏碳源(该研究各组湿地进水碳氮比在28.4~30.6之间),湿地内部的反硝化几率增大,导致曝气后总氮的去除效率提高。但是曝气条件下过高的溶解氧又会进一步抑制反硝化过程,从而也会导致系统总氮去除速率的下降。因此,对垂直流湿地而言,曝气强度不是愈高愈好。为了获得更高的脱氮效率,建议可以通过延长水力停留时间或者在垂直流湿地尾部增设水平潜流湿地来补充反硝化过程,进而提高系统对总氮的去除效果。  相似文献   

13.
Water resources are threatened globally and declining water quality is primarily due to stormwater, agricultural, urban, and mining runoffs. Steamboat Creek in Nevada is the largest non point source (NPS) of pollution to the Truckee River. Treatment wetlands are a cost-effective and reliable technique to control NPS pollution, therefore, a large-scale wetland along Steamboat Creek has been proposed as a component of a regional watershed restoration plan. This study used ten parallel pilot-scale wetland mesocosms, and tested the effects of drying and rewetting, hydraulic retention time (HRT), and high nitrogen loading on the efficiency of nutrient and total suspended solids (TSS) removal. Drying and rewetting produced noticeable effects on nutrient retention, but the effect was short-lived. During longer HRT period nutrient removal in manipulated mesocosms with an 8 h HRT were higher than controls with a 4 h HRT. Reducing the HRT from 4 h to 30 min further decreased nutrient interception. During increased influent nitrogen loading (9.5?±?2.4 mg l?1), manipulated mesocosms functioned as sinks for total nitrogen (TN) with removal efficiency increasing from 45?±?13% to 87?±?9%. The average change in TN concentration was 9.1?±?2.2 mg l?1. Drying/rewetting and varying HRT influenced total phosphorus (TP) and TSS similarly, and TP removal was associated with TSS removal. Results can help make decisions regarding wetland construction, management, and operation more effective in order to reduce nutrient loads to the Truckee River.  相似文献   

14.
In forest soils where a large fraction of total phosphorus (P) is in organic forms, soil micro-organisms play a major role in the P cycle and plant availability since they mediate organic P transformations. However, the correct assessment of organic P mineralization is usually a challenging task because mineralized P is rapidly sorbed and most mineralization fluxes are very weak. The objectives of the present work were to quantify in five forest Spodosols at soil depths of 0-15 cm net mineralization of total organic P and the resulting increase in plant available inorganic P and to verify whether net or gross P mineralization could be estimated using the C or N mineralization rates. Net mineralization of total organic P was derived from the net changes in microbial P and gross mineralization of P in dead soil organic matter. We studied very low P-sorbing soils enabling us to use lower extractants to assess the change in total inorganic P as a result of gross mineralization of P in dead soil organic matter. In addition, to enable detection of gross mineralization of P in dead soil organic matter, a long-term incubation (517 days) experiment was carried out. At the beginning of the experiment, total P contents of the soils were very low (19-51 μg g−1) and were essentially present as organic P (17-44 μg g−1, 85-91%) or microbial P (6-14 μg g−1; 24-39%). Conversely, the initial contents of inorganic P were low (2-7 μg g−1; 9-15%). The net changes in the pool size of microbial P during the 517 days of incubation (4-8 μg g−1) and the amounts of P resulting from gross mineralization of dead soil organic matter (0.001-0.018 μg g−1 day−1; 0.4-9.5 μg g−1 for the entire incubation period) were considerable compared to the initial amounts of organic P and also when compared to the initial diffusive iP fraction (<0.3 μg g−1). Diffusive iP corresponds to the phosphate ions that can be transferred from the solid constituents to the soil solution under a gradient of concentration. Net mineralization of organic P induced an important increase in iP in soil solution (0.6-10 μg g−1; 600-5000% increase) and lower increases in diffusive iP fractions (0.3-5 μg g−1; 300-2000% increase), soil solid constituents having an extremely low reactivity relative to iP. Therefore, soil micro-organisms and organic P transformations play a major role in the bioavailability of P in these forest soils. In our study, the dead soil organic matter was defined as a recalcitrant organic fraction. Probably because gross mineralization of P from this recalcitrant organic fraction was mainly driven by the micro-organisms’ needs for energy, the rates of gross mineralization of C, N and P in the recalcitrant organic fraction were similar. Indirect estimation of gross mineralization of P in dead soil organic matter using the gross C mineralization rate seems thus an alternative method for the studied soils. However, additional studies are needed to verify this alternative method in other soils. No relationships were found between microbial P release and microbial C and N releases.  相似文献   

15.
为了为抑氨菌选择良好的固定化载体,并研究固态抑氨菌剂对降低鸡舍内氨质量浓度的效果,该文将7种有机载体混合成63种组合载体后,选择较佳的组合载体,并以此制成固态抑氨菌剂。于饲喂1000只商品蛋鸡的笼养蛋鸡舍中,将固态抑氨菌剂均匀撒放于鸡粪表面,研究其在鸡舍现场的抑氨效果。菌剂的撒放按照菌剂与鸡粪质量之比进行,试验1期为0.5%,试验2期为1%,试验3期为1.5%,对照1期、2期和3期均不撒放,每天4次测定鸡舍内6个点的温度、相对湿度、氨质量浓度和CO2体积分数,试验共进行36d。结果表明,麦糠、稻壳和玉米芯粉等量混合并以200%吸水率吸附抑氨菌液后制成的固态抑氨菌剂的效果较佳;试验1期鸡舍内氨质量浓度未发生显著变化(P>0.05),试验2期氨质量浓度降低15%(P<0.01),试验3期氨质量浓度降低59.3%(P<0.01);但3期试验均未对舍内CO2体积分数产生显著影响(P>0.05)。结果显示,以有机混合载体吸附抑氨菌液制成的固态抑氨菌剂有明显降低笼养蛋鸡舍内氨质量浓度的作用。该研究结果为生产过程中有效控制蛋鸡舍内的氨质量浓度提供理论参考。  相似文献   

16.
The effect of variations in organic matter removal during harvesting on microbial biomass nitrogen was determined in four Pinus radiata plantations between 9 and 17 years after harvesting. Variation in microbial biomass nitrogen with season and the response of net nitrogen mineralization to organic matter removal after 9 and 17 years were also determined at two of the sites. The microbial biomass nitrogen in the fermentation-humus (FH) layer was correlated with litter fall characteristics and did not vary with organic matter removal, but the total mass of microbial biomass nitrogen in the FH layer was significantly reduced by increased organic matter removal. The microbial biomass nitrogen in the mineral soil was decreased by increased organic matter removal and was strongly correlated with moisture content and total nitrogen concentration. The FH layer microbial biomass nitrogen did not vary with season, but mineral soil microbial biomass nitrogen varied with season at one site, probably due to increased moisture availability. Net nitrogen mineralization in the mineral soil, determined by an anaerobic incubation, was decreased by increased organic matter removal and was strongly correlated with microbial biomass nitrogen. The persistence of the significant differences in microbial biomass nitrogen and net nitrogen mineralization indicated that variations in organic matter removal during harvesting have long-term effects on soil microbial properties and activity during the life of the subsequent rotation. This has implications for the selection of harvesting techniques to promote the maintenance of site productivity and to minimise disruption to the soil biota.  相似文献   

17.
Conversion of natural forest to intensive cultivation makes to soil susceptible to flooding, declining fertility and loss of organic matter (OM) and reduced water movement into and within the soil. We studied infiltration rates and related soil penetrating indicators of forested and cultivated soils in humid tropical coastal plain sands in Southern Nigeria. Results showed that mean-weight diameter (MWD) and water stability of aggregates were higher in forested than cultivated soils. Stable aggregates > 1.00 mm were 16.5% and 31.1% respectively, for cultivated and forested soils at 0–15 cm depth, indicating formation of more macro-aggregates in forested soil. Soil disturbance through cultivation decreased hydraulic conductivity and increased bulk density of the soil. Infiltration rate attained after 2 hours was higher in forested soil. Temporary infiltration rate of 178 mm hr?1 at initial time in cultivated soil was followed by very low infiltration rate of 7 mm hr?1 after 2 hours. Soil organic matter (SOM), saturated hydraulic conductivity, MWD and total sand correlated positively with infiltration rates are r = 0.76, 0.61, 0.57 and 0.51 respectively. Changes in these parameters are dependent on surface soil disturbance by cultivation. Cultivation of forest decreased infiltration rates and water transmission properties of the soil.  相似文献   

18.
针对猪场沼液有机质含量高,其他处理工艺周期长、成本高、难去除的问题。采用包含氧化钙水溶液和AlCl3的二元共沉淀体系去除沼液有机污染物。探究了沉淀剂配比、投加量、反应时间、沼液初始pH等因素对有机物去除效果的影响。结果表明:当共沉淀剂体积比为1∶2.5、投加量为1∶1(体积比)、反应时间60 min、pH为9时有机质最大去除率达到93%。通过对反应前后沉淀物XRD、FITR和SEM分析,表明共沉淀剂可与沼液中带负电有机质通过电荷吸引以及与正价金属离子的络合作用絮凝沉淀有机物。沉淀反应迅速且去除有机质较为彻底,在养殖场废水处理中具有良好的工业应用前景。  相似文献   

19.
土壤侵蚀对紫色土坡耕地耕层障碍因素的影响   总被引：2，自引：0，他引：2  
紫色土坡耕地是长江上游重要的耕地资源,明确不同侵蚀程度下紫色土坡耕地耕层土壤的主要障碍因素及障碍因素变化特征,对紫色土坡耕地耕层土壤质量调控和持续利用具有重要价值.以紫色土坡耕地耕层土壤为研究对象,设置5个侵蚀程度(0、5、10、15、20 cm)的原位控制试验.从土壤属性角度出发,选取容重、总孔隙度、饱和导水率、土壤...  相似文献   

20.
The small organic matter content of mineral soils makes it difficult to obtain 13C and 15N nuclear magnetic resonance (NMR) spectra with acceptable signal-to-noise ratios. Subjecting such samples to hydrofluoric acid removes mineral matter and leads to a relative increase in organic material. The effect of treatment with 10% hydrofluoric acid on bulk chemical composition and resolution of solid-state 13C NMR spectra was investigated with six soils, some associated particle size fractions, plant litter and compost. The treatment enhanced the signal-to-noise ratio of the solid-state 13C NMR spectra. The improvement in spectrum quality was greatest in the clay fraction of soil contaminated with coal ash. The removal of paramagnetic compounds associated with the ash may be the main reason for the improvement. Based on total C, total N, C/N ratio and intensity distribution of the solid-state 13C NMR spectra, no changes in organic matter composition could be detected, except for a possible loss of carbohydrates. After treatment with HF, solid-state 15N NMR spectra of particle size fractions were obtained and indicated that the observable nitrogen is present mostly as peptides and free amino groups. Extraction with hydrofluoric acid is recommended as a routine treatment prior to solid-state 13C and 15N NMR on soil containing little C or N and soil samples containing paramagnetic compounds from natural or anthropogenic sources.  相似文献   

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