Recovery of ammonia from poultry litter using flat gas permeable membranes

The use of flat gas-permeable membranes was investigated as components of a new process to capture and recover ammonia (NH₃) in poultry houses. This process includes the passage of gaseous NH₃ through a microporous hydrophobic membrane, capture with a circulating dilute acid on the other side of the membrane, and production of a concentrated ammonium (NH₄) salt. Bench- and pilot-scale prototype systems using flat expanded polytetrafluoroethylene (ePTFE) membranes and a sulfuric acid solution consistently reduced headspace NH₃ concentrations from 70% to 97% and recovered 88% to 100% of the NH₃ volatilized from poultry litter. The potential benefits of this technology include cleaner air inside poultry houses, reduced ventilation costs, and a concentrated liquid ammonium salt that can be used as a plant nutrient solution.     

Removal of organic pollutants and nutrients from olive mill wastewater by a sand filter

The aim of this work was to examine the performance of a sand filter in treating modern olive mill (OMW) effluents after dilution with domestic wastewater on a one-to-one basis. The experimental pilot consisted of a column of opaque PVC, and the sand filter was filled with 50 cm of sand and 10 cm of gravel in the top and the bottom of the filter. The alimentation (4 cm/day) was done sequentially following a 1 day wet/3 days dry cycle. The OMW effluent was very acidic with a pH of 4.12, and had high concentrations of phenolic compounds (7.2 g/L) and total chemical oxygen demand (65 g/L). The percolation of the diluted OMW through the sand filters caused an increase in pH from 4.84 to 8.25 and a 90% removal of total suspended solids. The sand filter treatment also led to important reductions in organic matter (90% of total COD, 83% of dissolved COD and 92% of phenolic compounds) and nutrients (91% of Kjeldahl-nitrogen, 97% of ammonia-nitrogen, 99% of nitrate-nitrogen and 99% of phosphates). The flow rate became very low indicating clogging of the sand pores after 10 weeks. HPLC analysis of the diluted OMW before and after passage through the sand filter showed an important reduction in the toxic monomeric compounds after the treatment.     

Application of nutrient loading models to the analysis of trophic conditions in Lake Okeechobee,Florida

Lake Okeechobee (surface area = 1830 km², mean depth = 3.5 m), the largest lake in Florida, is eutrophic and has nitrogen and phosphorus loading rates in excess of nearly all established criteria. The lake is not homogeneous regarding trophic conditions, and spatial and temporal variations occur regarding nutrient limitation. Nonetheless, phosphorus loading rate and trophic state data fit reasonably well to various input-output models developed for temperate lakes. Modification of the models by regression analysis to fit data for Florida lakes resulted in improved predictions for most parameters. Analysis of nutrient management alternatives for the lake indicates that a 75% reduction of phosphorus loading from the largest source (the Taylor Creek-Nubbins Slough watershed) would reduce the average chlorophyll a concentration by less than 20%. Complete elimination of inputs from the largest nitrogen source (the Everglades Agricultural Area) would decrease the average nitrogen concentration in the lake by about 20%. Limitations of nutrient inputoutput models regarding analysis of trophic conditions and management alternatives for the lake are discussed.     

湖泊富营养化相关物理量的定量关系

湖水中总磷、总氮、叶绿素a、透明度、均温层氧亏量是与水体富营养化密切相关的几个物理量。研究结果表明,它们之间有一定的相关关系,可用数学公式定量表示。本文针对这些关系进行了概括和整理。     

ENVIRONMENTAL AUDITING: Exceedance of Critical Loads for Lakes in Finland,Norway, and Sweden: Reduction Requirements for Acidifying Nitrogen and Sulfur Deposition

/ The main objectives of this study were to identify the regions inFennoscandia where the critical loads of sulfur (S) and acidifying nitrogen(N) for lakes are exceeded and to investigate the consequences for depositionreductions, with special emphasis on the possible trade-offs between S and Ndeposition in order to achieve nonexceedance. In the steady-state model forcalculating critical loads and their exceedances, all relevant processesacting assinks for N and S are considered. The critical loads of N and S areinterrelated (defining the so-called critical load function), and therefore asingle critical load for one pollutant cannot be defined without makingassumptions about the other. Comparing the present N and S deposition withthe critical load function for each lake allows determination of thepercentage of lakes in the different regions of Fennoscandia where: (1) Sreductions alone can achieve nonexceedance, (2) N reductions alone aresufficient, and (3) both N and S reductions are required but to a certaindegree interchangeable. Secondly, deposition reduction requirements wereassessed by fixing the N deposition to the present level, in this wayanalyzing the reductions required for S, and by computing the percentage oflakes exceeded in Finland, Norway and Sweden for every possible percentdeposition reduction in S and N, in this way showing the (relative)effectiveness of reducing S and/or N deposition. The results showed clearregional patterns in the S and N reduction requirements. In practically thewhole of Finland and the northern parts of Scandinavia man-made acidificationof surface waters could be avoided by reducing S deposition alone. In thesouthern parts of Sweden some reductions in N deposition are clearly neededin addition to those for S. In southern Norway strong reductions are requiredfor both N and S deposition.KEY WORDS: Acidification; Critical load; Exceedance; Sulfur; Nitrogen;Deposition; Lake     

Water Quality Functions of Riparian Forest Buffers in Chesapeake Bay Watersheds

/ Maryland, Virginia, and Pennsylvania, USA, have agreed to reduce nutrient loadings to Chesapeake Bay by 40% by the year 2000. This requires control of nonpoint sources of nutrients, much of which comes from agriculture. Riparian forest buffer systems (RFBS) provide effective control of nonpoint source (NPS) pollution in some types of agricultural watersheds. Control of NPS pollution is dependent on the type of pollutant and the hydrologic connection between pollution sources, the RFBS, and the stream. Water quality improvements are most likely in areas of where most of the excess precipitation moves across, in, or near the root zone of the RFBS. In areas such as the Inner Coastal Plain and Piedmont watersheds with thin soils, RFBS should retain 50%-90% of the total loading of nitrate in shallow groundwater, sediment in surface runoff, and total N in both surface runoff and groundwater. Retention of phosphorus is generally much less. In regions with deeper soils and/or greater regional groundwater recharge (such as parts of the Piedmont and the Valley and Ridge), RFBS water quality improvements are probably much less. The expected levels of pollutant control by RFBS are identified for each of nine physiographic provinces of the Chesapeake Bay Watershed. Issues related to of establishment, sustainability, and management are also discussed.KEY WORDS: Riparian forest buffers; Chesapeake Bay; Nonpoint source pollution; Nitrogen; Phosphorus; Sediment     

Impact evaluation of agrotechnologies in watersheds

The special project RAISA (Advanced Researches for Innovation in Agricultural Systems) of the National Research Council of Italy concerns the development of new methodologies for the study and evaluation of the impact of agrotechnologies on the environment. In the project, several trans-disciplinary Units have worked together since 1990. The aim of the project is to define systems, using tools such as remote sensing and Geographical Information Systems, for decision making support in land planning and land use management, with particular attention to groudwater table pollution. The fundamental steps for evaluation of the impact of agrotechnologies on the Po river watershed, 75,000 km² in northern Italy, and Tevere (Tiber) river watershed, 17.169 km² in Central Italy are described here. The study concerns particular areas located in the western part of the Po River plain, where flooded rice is the main crop, and in the central plain of the Tevere basin where the risk of water pollution is considerable, due to small and medium sized swine breeding farms. The aspects considered were water pollution due to mineral nitrogen used to fertilize the rice crop and the nitrogen contained in the waste water from pig farms. For the Po river basin the methodology developed was based on the integration of satellite remote sensing images, and the available cartography, such as topographic and thematic maps, together with the hydrological and the toxicological data of the chemical fertilizers employed, summarized in maps of the groundwater table pollution hazard. A simpler evaluation was obtained in the Tevere river basin: the thematic layers were crossed in bi-directional matrices and the result merged with the map of the territorial distributionof the swine. In both cases the selected information was integrated and processed in Integrated sub-basin scale. The GISs led to the development of a user-friendly system for formalizing our knowledge of the degree of pollution hazard in simple and readable maps.Research supported by National Research Council of Italy, Special Project RAISA, sub-project N. 1 Paper N.     

水磨河氮含量分布及时空变化初探

根据2005年水质监测结果,对水磨河无机氮的特征分布及相互之间的相关性进行了初步分析探讨,结果显示,水磨河无机氮中硝酸盐氮含量最高,亚硝酸盐氮含量最低,亚硝酸盐氮与氨氮之间有非常显著的线性关系.通过对1991-2005年的监测资料分析,表明水磨河各断面无机氮含量呈下降趋势,但水磨河自上而下无机营养盐N总体浓度升高,说明氮污染还在延续,形势不容乐观.     

氮氧化物生态环境中的转化及危害

在对氮氧化物污染引起奶牛亚硝酸中毒事件的调查基础上，通过室内模拟实验研究氮氧化物的转化过程及测定方法，探讨氮氧化物的生态环境中的转化规律，分析其危害途径和机理，研究表明氮氧化物中的二氧化氮遇水迅速反应生成硝酸和亚硝酸，而对生态环境和人畜产生危害。     

Selective catalytic reduction of nitrogen oxides over a modified silicoaluminophosphate commercial zeolite

Nitrogen oxides(NO_x:NO,NO_2)are a concern due to their adverse health effects.Diesel engine transport sector is the major emitter of NO_x.The regulations have been strengthened and to comply with them,one of the two methods commonly used is the selective catalytic reduction of NO_xby NH_3(NH_3-SCR),NH_3being supplied by the in-situ hydrolysis of urea.Efficiency and durability of the catalyst for this process are highly required.Durability is evaluated by hydrothermal treatment of the catalysts at temperature above 800°C.In this study,very active catalysts for the NH_3-SCR of NO_xwere prepared by using a silicoaluminophosphate commercial zeolite as copper host structure.Characterizations by X-ray diffraction(XRD),scanning electron microscopy(SEM)and temperature programmed desorption of ammonia(NH_3-TPD)showed that this commercial zeolite was hydrothermally stable up to 850°C and,was able to retain some structural properties up to950°C.After hydrothermal treatment at 850°C,the NO_xreduction efficiency into NH_3-SCR depends on the copper content.The catalyst with a copper content of 1.25 wt.%was the most active.The difference in activity was much more important when using NO than the fast NO/NO_2reaction mixture.