A/O工艺处理猪场厌氧发酵液研究（摘要）

[目的]提供一种快速、稳定、高效的猪场废水处理技术。[方法]通过厌氧/好氧（A/O）反应器处理猪场厌氧发酵液试验,研究了A/O处理猪场厌氧发酵液的启动过程。启动分两个阶段：第一阶段,厌氧（A）、好氧（O）段各自独立培养优势菌群。A/O反应器采用分别启动的方式在各自阶段性反应器中培养优势污泥,即O段好氧反应器先进水,O段运行方式为：曝气6 h,静沉1 h,闲置1 h,DO为0.15 mg/L左右。温度控制在（32±2）℃。出水再补充一定量葡萄糖后加入A段缺氧反应器。A段运行方式为：搅拌2 h,静沉1 h,闲置1 h,DO为3.00 mg/L左右;进水采用稀释15倍后的发酵液,当COD去除率达到80%并稳定运行14 d后,反应器中加入稀释倍数减少1倍的发酵液,直到COD和NH_4~＋-N的去除率稳定在80%时认为此阶段完成。第二阶段,A、O联合启动,逐步提高进水负荷,继续对微生物培养与驯化。当进水的COD和NH_4~＋-N去除率保持在80%以上时,将两个阶段性反应器并二沉池连接起来,设定内循环回流比和污泥回流比为2：1,停留时间为12 h,曝气量为0.50 m~3/h。溶解氧浓度为3～4 mg/L。将发酵液按一定比例稀释后加入反应器,直到全部进水为发酵液,此阶段历时32 d结束。试验过程中需要分析的项目及方法：COD,快速密闭催化消解法;NH_4~＋-N浓度,纳氏试剂分光光度法;NO_3~--N浓度,紫外分光光度法;总氮（TN）,过硫酸钾氧化紫外分光光度法;DO,DO测定仪测量;pH值,便携式pH计测量;温度,水银温度计测量。[结果]当温度为（32±2）℃,回流混合液比和回流污泥比分别为2和1,O段曝气量为0.5 m~3/h时,通过50 d的实际运行,COD、NH_4~＋-N的去除率分别达到89.87%和89.31%,表明反应器启动过程完成。[结论]可为猪场厌氧发酵液无害化技术提供一定的科学依据和借鉴。     

Transformations of mineral nitrogen applied to peat soil during sequential oxic/anoxic cycling

Shifts in oxic and anoxic conditions in soil are most frequently caused by water table fluctuations, heavy rain, snowmelt or flooding, with potentially significant impacts on microbial processes and the ability of soils to convert mineral nitrogen to nitrogen gases efficiently. The impact of oxic/anoxic cycles on nitrogen transformation rates was therefore explored in the upper layer (0-30 cm) of partially degraded peat soil. We hypothesized that high denitrification potential would be conserved due to the high organic matter content of this soil. Mineral nitrogen was applied to approximately 1-cm deep layers of homogenized soil in microcosms, with no external source of readily degradable carbon. Microcosms were subjected to three cycles, each consisting of an oxic phase of 8-11 days and an anoxic phase of 21-28 days. Approximately 2% of the ammonium load was lost through ammonia volatilization during oxic phases and the remainder was nitrified. The accumulated nitrate decreased soil pH from 8.0 to 6.8 before its transformation through denitrification. Nitrification and denitrification rates during the three oxic/anoxic cycles (approximately three months) were 2.9-3.2 kg N ha⁻¹ d⁻¹ and 1.0-2.3 kg N ha⁻¹ d⁻¹, respectively. Extrapolation of these values to 30-cm deep soil layers gave rates that were sufficient for complete transformation of at least 1700 kg N ha⁻¹ of ammonium to nitrogen gases, which is ten-fold greater than the annual nitrogen application of 170 kg N ha⁻¹ permitted by the European directive. Denitrification rates decreased linearly during the three cycles (from 36 ± 2 to 16 ± 1 μg N g⁻¹ d⁻¹ dry soil), projecting cessation of denitrification activity and CO₂ production during the fifth cycle. Storage of peat soil at 4 °C most probably allowed slow degradation of organic matter that was completely oxidized to CO₂ after the soil was exposed to higher temperature (28 °C). Storage of soil for one year did not affect nitrification rate, but reduced denitrification rate, unless soil was amended with a readily degradable carbon source. The data suggest that, despite the high carbon content of this soil, it cannot sustain transformations of high N loads to nitrogen gases for prolonged periods without amendment with readily available carbon.     

类似但成土因素不同的土壤：巴西始成土的趋同演变

Soils result from the interaction of five independent formation factors.If one factor varies,while the others remain constant,different soils can be produced.Herein,we demonstrated an opposing trend,wherein two soils were similar,despite considerable differences in all factors of soil formation.We sampled two Inceptisols (Oxic Dystrudepts) formed on different parent materials (gneiss vs.mica schist),climate (tropical altimontane vs.warmer,drier plateau),topography (1 650 m,45％ slope vs.1000 m,8％ slope),time (rejuvenated vs.old,stable surface),and vegetation (rainforest vs.Cerrado savanna).The two soils had similar chemical properties,whereas the soil on mica schist had finer particle size distribution,lower porosity,and lower saturated hydraulic conductivity.These properties were related to a coarser blocky microstructure compared to the soil on gneiss.Both soils presented active mineral weathering and pronounced pedoplasmation,demonstrated by clay contents ＞ 300 g kg-1,although only the Dystrudept on gneiss possessed coarse rock fragments.The C horizons of both soils presented fragmented clay coatings suggestive of argilluviation,likely relict,because they were not observed in the B horizons.The similarities in many properties of the two Dystrudepts,despite contrasting factors of soil formation,suggest converging evolution and that soil classification at the subgroup level was efficient in grouping similar formative processes in tropical conditions.Moreover,this work revealed that similar pedogenic processes acting on different factors of soil formation can result in similar soil properties,at least for Inceptisols where further soil development is hindered by topographic limitations.     

Bacterial populations assimilating carbon from C-labeled plant residue in soil: Analysis by a DNA-SIP approach

In this study, ¹³C-labeled rice callus was prepared as a model material for rice straw and was subjected to a DNA-SIP (stable isotope probing) experiment in which the bacterial population was monitored in a soil sample containing decomposing dried callus. Rice callus (¹³C = 78%) contained the more water-soluble organic carbon and less cellulose and lignin carbon than rice straw. The callus in the soil was 37% decomposed after 56 d of incubation in upland moisture conditions. PCR-DGGE analysis demonstrated that the bacterial community in the soil with the callus changed over time, showing a distinct difference between the first (up to 7 d) and second (14 d and later) stages. After isopycnic centrifugation, DNA in the fractions with a buoyant density between 1.759 and 1.734 g ml⁻¹ was subjected to population analysis (¹³C-assimilating populations). Diverse groups of bacterial sequences were retrieved from the ¹³C-labeled DNA fractions: Actinobacteria, Bacilli, γ-Proteobacteria, Chloroflexi, Sphingobacteria, Flavobacteria, Clostridia, Acidobacteria, Cyanobacteria and Candidate Division. Bacilli were detected mainly in the first stage, and Actinobacteria were detected throughout the incubation period. Several DGGE bands in the light fractions became more prominent in the soil with callus, which suggested that the addition of callus promoted the growth of bacteria that fed on soil organic matter, including α-Proteobacteria, γ-Proteobacteria, Bacilli, Actinobacteria, Nitrospira and Gemmatimonadetes.     

A／O工艺处理猪场厌氧发酵液研究

［目的］提供一种快速、稳定、高效的猪场废水处理技术。［方法］通过厌氧/好氧（A/O）反应器处理猪场厌氧发酵液试验,研究了A/O处理猪场厌氧发酵液的启动过程。启动分2个阶段：第一阶段,厌氧（A）、好氧（O）段各自独立培养优势菌群;第二阶段,A、O联合启动,逐步提高进水负荷,继续对微生物培养与驯化,最终完成启动过程。［结果］当温度为32±2 ℃,回流混合液比和回流污泥比分别为2和1,O段曝气量为0.5 m3/h时,通过50 d的实际运行,COD、NH4＋ N的去除率分别达到89.87%和89.31%,表明反应器启动过程完成。［结论］可为猪场厌氧发酵液无害化技术提供一定的科学依据和借鉴。