Fate of Escherichia coli and Escherichia coli O157 in soils and drainage water following cattle slurry application at 3 sites in southern Scotland

Abstract. Slurry from farm animals may contaminate water supplies, rivers and bathing waters with faecal coliforms, such as Escherichia coli . Where animals harbour the O157 strain the hazard to human health is particularly high, but both the hazard level, and the low incidence and sporadic nature of the excretion of E. coli O157 make it difficult to study this strain under field conditions. The survival of total E. coli and of E. coli O157 were compared in the laboratory for two soils under controlled temperature and moisture. E. coli O157 die-off rate was the same as or quicker than for total E. coli . This result meant that field experiments studying the fate of total E. coli should give a satisfactory evaluation of the risk of water contamination by the O157 strain. In four field experiments at three sites, slurry containing total E. coli numbers of 2.2 × 10⁴ to 5.7 × 10⁵ colony forming units per mL (c.f.u. mL^–1) was applied to drained field plots. Field die-off was faster than expected from laboratory experiments, especially in one experiment where two weeks dry weather followed application. In all but this experiment, the first drain flow events after slurry application led to very high E. coli concentrations in the drains (10³ to 10⁴ c.f.u. mL^–1). E. coli O157 was present in the slurry used for two of the experiments (33 c.f.u. per 100 mL in each case). However the proportion of E.coli O157 was very low (about 1 in 10⁵) and it was not detected in the drainage water. After the first week E. coli drainage water numbers decreased rapidly but they were 1–10 c.f.u. mL^–1 for much of the sampling period after slurry application (1–3 months).     

Parameterization of the MACRO model to represent leaching of colloidally attached inorganic phosphorus following slurry spreading

Abstract. The dual porosity soil water and contaminant transport model MACRO was tested for its suitability to represent water flows and leaching of phosphorus (P) through field drains following spreading of slurry. These flows are characterized by very high loadings of P, including a high proportion in colloidally attached form, for about one week following winter spreading of slurry, followed by quite a rapid decline to the low background level. Use was made of the option in MACRO for representing colloid facilitated contaminant transport. The model simulates transport through macropores and soil matrix pores (micropores) of contaminant carrying colloids, as well as trapping of colloids by straining and filtration using an adaptation of standard filtration equations. Calibration involved selecting soil hydraulic parameters, colloid filtration coefficients and P sorption characteristics for two soils from measured and literature values. Both P in solution and P attached to colloids were represented in simulated outputs. Reasonable agreement was found between simulated and measured water and leached P flows. Work with the model suggests that macropore flow through the soil to field drains of colloidally transported P is an important component of water pollution associated with slurry spreading     

奶牛养殖废水厌氧出水的吹脱混凝处理试验研究

为探索高效、可行的养殖废水处理方法,以马鞍山蒙牛现代牧场废水处理中的UASB出水为研究对象,进行吹脱和混凝试验处理。通过UASB出水吹脱处理试验,对比不同p H值、吹脱时间、气液比(体积比)、温度等参数对氨氮的去除效果,再对吹脱出水进行混凝处理试验,选择PFS(聚合硫酸铁)、PAC(聚合氯化铝)为混凝剂,分别研究混凝剂投加量、p H值、搅拌速率、搅拌时间、沉淀时间对混凝效果的影响。结果表明:吹脱试验中,当p H值为11、吹脱时间为5 h、气液比为3000、温度为30℃时,氨氮去除效果最好,去除率达85.5%,UASB出水氨氮浓度由468.1 mg·L-1降到67.9 mg·L-1。混凝试验中,确定PFS为较佳混凝剂,当PFS投加量为2.85 g·L-1、搅拌速率为180 r·min-1、搅拌时间为4 min、沉淀时间为20 min时,处理效果最好,处理水CODCr和SS分别由713.4、458.0 mg·L-1降到154.1、123.2 mg·L-1,去除率分别达到78.4%和73.1%。出水氨氮略有降低,降至50.9 mg·L-1,最终出水达到《畜禽养殖业污染物排放标准》(GB 18596—2001)。     

磷素缺乏对好氧污泥颗粒化系统的胁迫影响

为了考查磷素回收方法出水中的磷素残留量对后续生物脱氮系统的影响,选用序批式反应器(SBR),以畜禽养殖沼液为处理对象,探究水质磷素缺乏情况下对好氧颗粒污泥系统运行效果及稳定性的响应情况。结果表明,对于稳态的好氧颗粒污泥系统,在进水磷素缺乏和充足两种情况下MLVSS/MLSS比值分别为94%±4%和92%±2%,表明两个系统均具有较好的生物活性。但是磷缺乏会导致颗粒污泥的微生物聚集稳定性降低,在磷充足情况下Zeta电位为(-7.37±1.23)m V,在磷缺乏情况下Zeta电位为(-10.5±1.27)m V。此外,在进水磷素缺乏和充足两种情况下,系统的氨氮和化学需氧量(COD)的比降解速率分别为(110.03±0.48)、(132.23±0.31)mg NH+4-N·g~(-1)VSS·c~(-1)和(117.64±0.08)、(150.43±0.13)mg COD·g~(-1)VSS·c~(-1),即在磷充足的情况下颗粒化系统具有较好的有机污染物与氮素去除效果。由此可见,好氧颗粒污泥在处理畜禽养殖沼液时,化学除磷方法优化设定应考虑其出水磷素含量对后续生物法稳定性的作用影响,才可保证处理过程中集成工艺对有机质与氮素的处理效率及系统的稳定性。     

Influence of exchangeable potassium on soil erodibility

Abstract. Regular application of slurry manure in large quantities is thought to degrade soil structure and increase erodibility. One hypothesis links this to the large input of potassium which increases the exchangeable potassium percentage (EPP) and, thereby, dispersion. The effect of EPP on erodibility was quantified in three experiments. In the laboratory, eleven rainfall experiments were conducted using a silty topsoil from a typic Hapludalf which was fertilized to EPPs of 4 to 18%. Field rainfall experiments on 22 Inceptisols and Alfisols were used to examine whether the long-term application of monovalent cations (Na⁺, K⁺ and NH₄⁺) with slurry manure had changed soil properties, especially erodibility. In addition, erodibilities of 32 soils determined with natural and simulated rains were taken from literature. The experiments on these 65 soils together covered a wide range of soils, slopes and rainfalls. Dispersion by a large percentage of highly hydrated ions (K⁺, Na⁺) reduced the infiltration rate faster, caused runoff up to 5 min earlier, and increased sediment concentrations by 15g/l compared to low EPP soils. These changes increased soil erodibility of the Universal Soil Loss Equation (USLE) by 0.021 t × h/N × ha (where N = Newtons) for each 1% increase in EPP + ESP (exchangeable sodium percentage). The ESP contributed little to this increase as ESP was less than 1/10 of EPP in the experiments.
Fields with long-term manure application had similar chemical, physical and microbiological soil properties as fields without slurry manure except for slightly greater pH (+ 0.6) and P (+ 17 mg/kg) values. We conclude that, as long as the potassium input and output are balanced, the long-term use of slurry manure does not increase erodibility.     

Beneficial Microorganisms and Metabolites Derived from Agriculture Wastes in Improving Plant Health and Protection

Summary

There is growing interest in the presence of certain naturally-occurring, beneficial microorganisms in agricultural wastes (e.g., processing wastes, composts and anaerobic slurries) that have considerable potential to enhance the growth, health and protection of crops. The numbers of these organisms can be increased through incubation procedures and they can be applied as mixed or pure culture inoculants to soils and plants in waste materials or as sprays and suspensions. The various mechanisms of disease control and plant protection imparted by these beneficial microorganisms may be related to (a) microbe-microbe interactions, (b) plant-microbe interactions, (c) metabolites produced and /or, (d) induced systemic-acquired resistance. Research is needed to elucidate their exact mechanisms or modes-of-action to determine the optimum time, rate and frequency of application for improving plant health and protection.     

Theoretical and Experimental Analysis on the Pressure Filtration Technology in Slurries Treatment

Treatment of waste drilling slurries has become one of the important problems encountered in urban construction. The application of pressure filtration technology brings significant advantages in slurries treatment. In order to give a better insight into the mechanism of pressure filtration, a model was introduced to analyze the relationship between filtration pressure, time and treatment results. The proposed model was validated using existing data. The parametric studies of the model show that the increase of the filtration pressure can reduce the filtration time and the permeability coefficient of the filter cake, While filtration time decreases very slowly beyond a certain extent. In addition, the relationship among filtration pressure, time and treatment results is further validated by test results.     

基于摄入养分含量预测猪新鲜粪便肥料成分含量的试验研究

试验旨在建立基于摄入养分含量的数学模型，用来预测猪粪便肥料成分含量。通过饲养试验得到摄入养分含量和猪粪便中肥料成分含量的实测数据，对其进行统计分析。由方差分析得出：不同的日粮水平对粪中、尿中和粪尿混合物中总氮含量影响显著，对尿中和粪尿混合物中钾含量影响显著，对磷和铵态氮的含量影响均不显著；不同日粮水平对粪中磷的百分含量的影响显著。由回归分析得到：利用摄入粗蛋白的量可预测粪、尿和粪尿混合物中总氮的含量；利用摄入钾的量可预测尿中和粪尿混合物中钾的含量；利用摄入磷的量可预测粪中磷的百分含量。     

猪粪尿中添加不同底物对挥发性脂肪酸和本土菌群的影响研究

猪炎尿中含有一些未经消化的有机物质,如蛋白质、淀粉,在厌氧或兼性厌氧条件下,粪尿中的微生物能利用这些有机质作为代谢底物,产生挥发性脂肪酸、醇类、胺类、芳香类等恶臭化合物,然而很少有研究比较不同底物在粪尿恶臭产生过程中的作用.本研究采用室内培养方法,将收集的新鲜猪粪、尿和去离子水按10:7:3的比例(重量比)进行混合摇匀配成猪排泄物样本,旨在探讨蛋白质、淀粉等不同底物在类尿挥发性脂肪酸等恶臭化合物产生过程中的作用及其对粪尿本土菌群的影响.结果表明,玉米淀粉、酪蛋白的添加均促进了猪粪尿中总挥发性脂肪酸的产生量,5周后未添加的对照组、添加玉米淀粉、酪蛋白组总挥发性脂肪酸浓度分别南培养初期的60 mmol·L-1增加至5周后的133、183、172 mmol·L-1.就炎尿中总挥发性脂肪酸的具体组分而言,酪蛋白的添加增加了异丁酸、戊酸、异戊酸等长链或分支的挥发性脂肪酸存猪粪尿总挥发性脂肪酸中的比例,5周内异丁酸、戊酸、异戊酸占总挥发性脂肪酸比例分别由培养前的1.4%、7.4%、5.6%增加至5周后的13.9%、10%、14%.本土菌群中,玉米淀粉、酪蛋白的添加促进了猪粪尿中乳酸菌、优杆菌的增殖.玉米淀粉、酪蛋白的添加对链球菌、梭菌作用效果并不相同,玉米淀粉更易于链球菌的生长,而酪蛋白更易于梭菌的生长.     

畜禽粪便固液分离研究

畜禽粪便的固液分离是处理和利用畜禽粪便的重要环节之一。为此,论述了固液分离在畜禽粪便处理中的作用,介绍了几种主要的分离方法及其基本原理;综合分析了国内外各种分离设备的特点、结构形式、适用范围及不足之处;并就开发新的分离设备提出建议。此研究有助于在畜禽粪便的处理中合理选择固液分离设备,对提高固液分离的技术水平提供参考。