Integrated Flow-based System Displaying an In-line Mini Soil Column to Monitor Iron Species in Soils Leachates

ABSTRACT

Contamination of ground water as a consequence of soil leaching processes is an issue of major concern. In this context, a simulation of the soil leaching process was designed. A sequential injection (SI) method to monitor the soil leaching of iron complexes with in-line rain simulation for leachate production is described. The developed methodology comprises the SI determination of both iron(III) and 3-hydroxy-4-pyridinones iron(III) complexes, coupled to a mini soil column (mSC) for displaying in-line rain simulations. The described SI method enabled iron(III) determination within the range 2.0–35 µmol L^?1, with a detection limit of 0.42 µmol L^?1, and determination of iron(III) complexes in the range 1.0–45 µmol L^?1. It was successfully applied to leachates from laboratory scale soil columns (LSSC), with good precision for both iron(III) and iron complexes determinations: calculated relative standard deviation (RSD) of 5% and 6%, respectively. A step further in automation and miniaturization was attained with the incorporation of a mini soil column for the in-line leachate production. The system enabled the soil leachate production and assessment in less than 5 min, including determinations in triplicate.     

垃圾渗滤液与城市污水合并处理脱氮

为了解决垃圾渗滤液与城市污水合并处理氮难以稳定达标排放的问题,采用倒置A2/O法合并处理混合污水脱氮.结果表明,水力停留时间是脱氮效果的限制因素,试验条件下水力停留时间至少应保证9 h.好氧池溶解氧浓度增加对总氮去除不利;在60%～100%的范围内提高污泥回流比对有机物去除和反硝化有利;混合液回流比在100%～200%范围内增加对反硝化有一定促进作用.在水温25～30℃、泥龄20 d、MLSS3 000～3 500 mg/L、HRT11h、DO 3 mg/L、R80%、r200%时,有机物和脱氮效果同步达到最优,且出水浓度均可稳定地达到<城镇污水处理厂污染物排放标准>(GB18918-2002)一级A标准.     

序批式活性污泥法处理城市垃圾填埋场渗滤液的试验研究

采用单池ＳＢＲ法对城市垃圾填埋场渗滤液处理进行了试验研究，对亚硝化型硝化的可能性作了探讨。采用ＳＢＲ法的最佳运行模式，对ＣＯＤＣｒ，ＢＯＤ５，ＮＨ３－Ｎ分别为４２０￣４２１６ｍｇ／Ｌ，４０￣９９０ｍｇ／Ｌ，１２０￣４０８ｍｇ／Ｌ的渗滤液进行处理，其去除率分别达到８７．３２￣９６．５６％，９５．２２￣９９．３３％，９０．６９￣９９．３４％，并提出了三池运行模式。     

Ca2+对磷酸铵镁沉淀法处理垃圾渗滤液的影响研究

磷酸铵镁沉淀法因其反应时间短,操作简便和原材料容易获得的优势被广泛利用在垃圾渗滤液的处理中。在生活垃圾产生的渗滤液中出存在着大量的Ca2+,而这些Ca2+会对磷酸铵镁沉淀法处理渗滤液产生一定影响。实验通过设置渗滤液中Ca2+的浓度探索Ca2+对磷酸铵镁沉淀法降低COD和氨氮的影响。在实验中,磷酸铵镁沉淀法对氨氮的去除率从65.12%下降至42.52%,同时COD的去除率也从51.90%下降至37.87%。实验证明,垃圾渗滤液中Ca2+的含量会影响Mg2+与PO43-和氨氮结合,降低氨氮和COD去除率。     

垃圾渗滤液处理的生化冷却系统设计与运行

从冷却系统工艺流程设计、冷却系统设备选型、冷却系统工艺控制设计、冷却系统设计影响因素及冷却系统运行问题与解决这5个方面对垃圾渗滤液处理的生化冷却系统进行阐述,以期为其工程设计和实践提供技术基础。     

分离式两相厌氧发酵渗滤液回流对发酵过程影响

为研究分离式两相厌氧发酵工艺中渗滤液回流对其发酵过程的影响,在试验室对分离式两相工艺流程进行模拟,实现两相间渗滤液相互回流。比较分析渗滤液在喷淋和浸泡两种回流方式下的产气性能,重点分析两种回流方式下渗滤液pH值、挥发性脂肪酸总量及成分的变化以及其与产气量之间的关系,并计算出两种回流方式下的单位物料TS产气量,试验结果表明：分离式两相厌氧发酵工艺中,系统在渗滤液浸泡回流方式下稳定性更好,产气性能更佳,累计产气量是喷淋回流方式的2倍,其物料单位质量TS产气量可达217.88 mL/g。     

Responses of methane oxidation to temperature and water content in cover soil of a boreal landfill

Methane oxidation in a cover soil of a landfill located in a boreal climate was studied at temperatures ranging from 1-19 °C and with water content of 7-34% of dry weight (dw), corresponding to 17-81% of water-holding capacity (WHC) in order to better understand the factors regulating CH₄ oxidation at low temperatures. CH₄ consumption was detected at all the temperatures studied (1-19 °C) and an increase in CH₄ consumption rate in consecutive incubations was obtained even at 1 °C, indicating activation or increase in enzymes and/or microorganisms responsible for CH₄ oxidation. CH₄ consumption was reduced with low water content (17%WHC) at all temperatures. The response of CH₄ consumption to temperature was high with Q₁₀ values from 6.5 to 8.4 and dependent on water content: at 33%WHC or more an increase in water content was accompanied by a decrease in Q₁₀ values. The responses of CH₄ consumption to water content varied at different temperatures so that at 1-6 °C, CH₄ consumption increased along with water content (33-67%WHC) while at 12-19 °C the response was curvilinear, peaking at 50%WHC. CH₄ consumption was less tolerant (higher Q₁₀ values; 6.5-8.4) of low temperatures compared to basal respiration (Q₁₀ values for CO₂ production and O₂ consumption 3.2-4.0). Overall, the present results demonstrate the presence of CH₄-oxidizing microorganisms, which are able to consume CH₄ and to be activated or grow at low temperatures, suggesting that CH₄ oxidation can reduce atmospheric CH₄ emissions from methanogenic environments even in cold climates.     

Control of hydraulic conductivity and chromium mobility in soil-drilling fluid mixtures by polyacrylamide

Land disposal of water-based oil and gas well drilling fluid is an cause of environmental concern due to the high salt concentration and potential chromium (Cr) contamination of groundwater. Safe land disposal of waste drilling fluid and remediation of drilling fluidaffected soils require an adequate hydraulic conductivity for the leaching of excessive salt accumulation and immobilization of Cr to prevent groundwater contamination. Anahuac and Crowley sandy loam surface soils sampled near the southern Louisiana-Texas state line were treated by a batch method with the drilling fluid and two cationic polyacrylamides (PAMs). The PAMs were used as amendments to increase the hydraulic conductivity and the adsorption capacity of the drilling fluid-affected soils for the Cr organic complex. Hydraulic conductivity of the soil-drilling fluid mixtures and light transmittance of the leachates increased, while the Cr mobility decreased by the PAM treatment. The larger PAM molecules were more effective in improving the hydraulic conductivity of the soil-drilling fluid mixtures than the smaller molecules. The Anahuac soil-drilling fluid mixtures showed a higher hydraulic conductivity and lower Cr mobility than the Crowley soil-drilling fluid mixtures apparently because of the higher organic matter content and lower sodium adsorption ratio (SAR) of the former. The hydraulic conductivity, light transmittance, and Cr mobility data indicated that the PAM treatment and soil organic matter enhanced the flocculation and aggregate stability of the soil-drilling fluid mixtures and contributed to the immobilization of the Cr added as lignosulfonate to the soils.     

微电解-Fenton氧化预处理垃圾渗滤液的应用研究

采用微电解-Fenton氧化组合应用的方式预处理垃圾渗滤液,研究了其可行性及不同工艺条件对COD去除率的影响。结果表明:最佳微电解进水pH值控制在2.5,反应时间为40min,出水中H2O2的投加量为8mL/L,反应时间为60min,在此条件下,最高去除率可达到77.4%。     

Dissolved phosphorus composition of grassland leachates following application of dairy‐slurry size fractions

Appropriate management of P from slurry can increase crop production and decrease nutrient loss to water bodies. The present study examined how the application of different size fractions of dairy slurry influenced the quantity and composition of P leached from grassland in a temperate climate. Soil blocks were amended (day 0 = start of the experiment) with either whole slurry (WS), the > 425 μm fraction (coarse slurry fraction, CSF), the < 45 μm slurry fraction (fine liquid slurry fraction, FLF), or not amended, i.e., the control soil (CON). Deionized water was added to the soil blocks to simulate six sequential rainfall events, equivalent to 250 mm (day 0.2, 1.2, 4.2, 11.2) or 500 mm of rainfall (day 18.2 and 25.2), with leachates collected the following day. The results showed that total dissolved P (TDP), dissolved reactive P (DRP), dissolved unreactive P (DUP), orthophosphate, phosphomonoester, and pyrophosphate concentrations generally decreased with the increasing number of simulated rain events. Total dissolved P was leached in the following order WS > FLF ≈ CSF > CON. Dissolved organic C was correlated with TDP, DRP, and DUP in leachates of all treatments. The highest concentrations of dissolved phosphomonoesters and pyrophosphate (147 μg P L^–1 and 57 μg P L^–1, respectively) were detected using solution ³¹P‐NMR spectroscopy in the WS leachates. Overall, there were significant differences observed between slurry treatments (e.g., relative contributions of inorganic P vs. organic P of dissolved P in leachates). Differences were independent from the rate at which slurry P was applied, because the highest dissolved P losses per unit of slurry P applied were measured in the FLF, i.e., the treatment that received the smallest amount of P. We conclude that the specific particle‐size composition of applied slurry influences dissolved P losses from grassland systems. This information should be taken in account in farm‐management approaches which aim to minimizing dissolved slurry P losses from grassland systems.