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.     

Even low to medium nitrogen deposition impacts vegetation of dry, coastal dunes around the Baltic Sea

Coastal dunes around the Baltic Sea have received small amounts of atmospheric nitrogen and are rather pristine ecosystems in this respect. In 19 investigated dune sites the atmospheric wet nitrogen deposition is 3-8 kg N ha⁻¹ yr⁻¹. The nitrogen content of Cladonia portentosa appeared to be a suitable biomonitor of these low to medium deposition levels. Comparison with EMEP-deposition data showed that Cladonia reflects the deposition history of the last 3-6 years. With increasing nitrogen load, we observed a shift from lichen-rich short grass vegetation towards species-poor vegetation dominated by the tall graminoid Carex arenaria. Plant species richness per field site, however, does not decrease directly with these low to medium N deposition loads, but with change in vegetation composition. Critical loads for acidic, dry coastal dunes might be lower than previously thought, in the range of 4-6 kg N ha⁻¹ yr⁻¹ wet deposition.     

Real-life efficiency of urine source separation

Urine source separation (NoMix technology) is a promising innovation in wastewater management. To improve and further develop NoMix technology, it has been implemented in four Swiss households and at our research institute (Eawag). We conducted measurements during one year on frequency of toilet usage (in households 5.2/person/day for weekdays, and 6.3/person/day for weekends), flushing behavior (30–85% small flushes), and recovered urine. We calculate the amount of urine effectively recovered per voiding in NoMix toilets (138 ml/flush in households; 309 ml/flush in women's toilets at Eawag), and waterfree urinals (225 ml/usage). We estimate urine recovery in the households to be maximally 70–75% of the expected quantity, leaving room for technical and behavioral improvements. Based on sampling of N and P concentrations, we suspect nitrogen losses in the extended urine piping system. For households and workplaces, the daily and weekly flushing pattern is recorded. Our results are in accordance with literature data from a shorter period but with more people. These results represent a good dimensioning basis for future urine source separation applications. An example of extrapolation to an entire watershed is presented. The flushing pattern corresponds well with the typical nitrogen loading of a treatment plant.     

Recent Land Cover History and Nutrient Retention in Riparian Wetlands

Wetland ecosystems are profoundly affected by altered nutrient and sediment loads received from anthropogenic activity in their surrounding watersheds. Our objective was to compare a gradient of agricultural and urban land cover history during the period from 1949 to 1997, with plant and soil nutrient concentrations in, and sediment deposition to, riparian wetlands in a rapidly urbanizing landscape. We observed that recent agricultural land cover was associated with increases in Nitrogen (N) and Phosphorus (P) concentrations in a native wetland plant species. Conversely, recent urban land cover appeared to alter receiving wetland environmental conditions by increasing the relative availability of P versus N, as reflected in an invasive, but not a native, plant species. In addition, increases in surface soil Fe content suggests recent inputs of terrestrial sediments associated specifically with increasing urban land cover. The observed correlation between urban land cover and riparian wetland plant tissue and surface soil nutrient concentrations and sediment deposition, suggest that urbanization specifically enhances the suitability of riparian wetland habitats for the invasive species Japanese stiltgrass [Microstegium vimenium (Trinius) A. Camus].     

Changes in Soil Aggregate,Carbon, and Nitrogen Storages Following the Conversion of Cropland to Alfalfa Forage Land in the Marginal Oasis of Northwest China

Maintenance of soil organic carbon (SOC) is important for sustainable use of soil resources due to the multiple effects of SOC on soil nutrient status and soil structural stability. The objective of this study was to identify the changes in soil aggregate distribution and stability, SOC, and nitrogen (N) concentrations after cropland was converted to perennial alfalfa (Medicago sativa L. Algonguin) grassland for 6 years in the marginal oasis of the middle of Hexi Corridor region, northwest China. Significant changes in the size distribution of dry-sieving aggregates and water-stable aggregates, SOC, and N concentrations occurred after the conversion from crop to alfalfa. SOC and N stocks increased by 20.2% and 18.5%, respectively, and the estimated C and N sequestration rates were 0.4 Mg C ha⁻¹ year⁻¹ and 0.04 Mg N ha⁻¹ year⁻¹ following the conversion. The large aggregate (>5 mm) was the most abundant dry aggregate size fraction in both crop and alfalfa soils, and significant difference in the distribution of dry aggregates between the two land use types occurred only in the >5 mm aggregate fraction. The percentage of water-stable macroaggregates (>2, 2–0.25 mm) and aggregate stability (mean weight diameter of water-stable aggregates, WMWD) were significantly higher in alfalfa soils than in crop soils. There was a significant linear relationship between total SOC concentration and aggregate parameters (mean weight diameter) for alfalfa soils, indicating that aggregate stability was closely associated with increased SOC concentration following the conversion of crops to alfalfa. The SOC and N concentrations and the C/N ratio were greatest in the >2 mm water-stable aggregates and the smallest in the 0.25–0.05 mm aggregates in crop and alfalfa soils. For the same aggregate, SOC and N concentrations in aggregate fractions increased with increasing total SOC and N concentrations. The result showed that the conversion of annual crops to alfalfa in the marginal land with coarse-texture soils can significantly increase SOC and N stocks, and improve soil structure.     

Nutrient mitigation capacity in Mississippi Delta, USA drainage ditches

Eutrophication and hypoxia within aquatic systems are a serious international concern. Various management practices have been proposed to help alleviate nutrient loads transported to the Gulf of Mexico and other high-profile aquatic systems. The current study examined the nutrient mitigation capacity of a vegetated (V) and non-vegetated (NV) agricultural drainage ditch of similar size and landform in the Mississippi Delta. While no statistically significant differences in ammonium, nitrate, or dissolved inorganic phosphorus mitigation between the two ditches existed, there were significant differences in total inorganic phosphorus percent load reductions (V: 36% ± 4; NV: 71% ± 4). However, both agricultural drainage ditches were able to mitigate nutrients, thus reducing the load reaching downstream aquatic receiving systems. Further studies examining ecosystem dynamics within drainage ditches such as sediment and plant nutrient partitioning, as well as microbial processes involved, are needed to provide a better understanding of natural nutrient variability, seasonality and flux.     

Direct and indirect effects of ammonia, ammonium and nitrate on phosphatase activity and carbon fluxes from decomposing litter in peatland

Here we investigate the response of soils and litter to 5 years of experimental additions of ammonium (NH₄), nitrate (NO₃), and ammonia (NH₃) to an ombrotrophic peatland. We test the importance of direct (via soil) and indirect (via litter) effects on phosphatase activity and efflux of CO₂. We also determined how species representing different functional types responded to the nitrogen treatments. Our results demonstrate that additions of NO₃, NH₄ and NH₃ all stimulated phosphatase activity but the effects were dependent on species of litter and mechanism (direct or indirect). Deposition of NH₃ had no effect on efflux of CO₂ from Calluna vulgaris litter, despite it showing signs of stress in the field, whereas both NO₃ and NH₄ reduced CO₂ fluxes. Our results show that the collective impacts on peatlands of the three principal forms of nitrogen in atmospheric deposition are a result of differential effects and mechanisms on individual components.     

盐度、C：N对SBR工艺处理海水产品养殖场废水的影响

海水产品养殖场废水中碳、氮的浓度很高,通过序批式反应器（SBR）处理,能有效的降低碳、氮的浓度。在常温（20℃-25℃）条件下,我们检测了不同盐度、C：N下的处理效果,以期实现SBR工艺运行参数的最优化。实验结果表明：盐度为2．5％～3．5％,C：N为10：1的条件下,除碳和生物脱氮的效果最佳。实验验证了SBR工艺在海水产品养殖场废水处理中可以作为一个非常有效的处理手段而应用。     

Simulation of Nitrogen Dynamics in Soil Using Infocrop Model

Nitrogen is the most widely used fertilizer nutrient, and it is a universally deficient nutrient too, which often severely restricts the growth and yield of crops. To improve N fertilizer management, soil–plant system models can be applied to simulate adequate N supply for both, optimal crop growth and minimal N losses. The likely impact of climate change on the cereal production is of paramount importance in the planning strategies to meet the future growing needs on sustainable grounds. In this scenario models are the effective tools to foresee the probable impacts and for choosing appropriate land use options. The study reported in this thesis, employs field experiments and use of simulation tools to understand the dynamics of soil N balance and relate growth and yield of rice under varying nitrogen inputs. The InfoCrop model was used in this study, which was calibrated with the historic data sets, and subsequently validated with the field experiment conducted at IARI Farm, New Delhi. Simulated results matched well with the observed values in terms of growth and yield of rice and seasonal nitrogen uptake. The components of soil nitrogen balance differed among varying nitrogen level treatments, which was also captured by use of InfoCrop. The model was then taken to climate change impact analysis. The results clearly revealed that when temperature increased, the soil N losses, like denitrification, volatilization, N2O emission increased, whereas grain and biomass yields decreased. The further scope of the study is to validate the study in contrasting agroenvironments.