Mainstream Deammonification: Preliminary Experience Employing Granular AOB-Enriched Biomass at Low DO Values

The deammonification process represents one of the most convenient pathways for nitrogen removal from wastewater. A great deal of scientific articles dwells on the treatment of sidestream fluxes, whereas applications to mainstream waters represent a novel field. Among the general challenges of deammonification, one of the most important is the effective selection of ammonia oxidizers (AOB) over nitrite oxidizers (NOB), but also the typical slow start-up periods. In addition to such issues, mainstream deammonification has to face water temperatures and alkalinity reserves lower than those of sidestream fluxes and higher content of organic matter. An attempt was made to tackle such challenges by employing a lab-scale plant; low dissolved oxygen (DO) values (average 0.78 mg/L) and granular AOB-enriched biomass were used in order to address exclusion of nitrite oxidizers. The granules also allowed better biomass retention. The hydraulic retention time (HRT) was established initially at 24 h and later decreased to 12 h, as to possibly enhance the performance of the reactor. After 52 days of operation, Anammox biomass was also inoculated to the reactor. The results showed a maximum nitrogen removal efficiency of 54%. Moreover, little quantities of nitrates were observed throughout the experiment (<5 mg N/L twice, under the limit of quantification the rest of the sampling days), meaning that NOB out-selection techniques worked properly. Retention of biomass was also positively addressed and yielded a final SRT value of 15.6 days. Therefore, the proposed solution for mainstream deammonification was demonstrated to be promising and more research would be necessary to optimize it.     

Evaluation of Deammonification Process by Response Surface Models

The influence of the operational variables on the Anammox process has been generally researched considering each variable separately. However, the optimization of the process also requires the identification of the more significant variables and their possible interactions. Response surface models were successfully applied to evaluate the performance of the Anammox process in a deammonification system (i.e., one-stage biofilm Anammox process) taking into account the combined effects caused by two sets of three variables. Specific Anammox activity was measured by a manometric method and used as the response variable. The obtained models pointed out that the significant variables were the temperature, the value of pH, and the ratio between the unionized species of the substrates (free ammonia and free nitrous acid (FA/FNA)). There were interactions among them caused by chemical equilibriums. Total nitrogen concentration and ammonium concentration were found to be not significant in the tested range. According to the models, the optimum values of temperature, pH, and free ammonia to free nitrous acid ratio within the test ranges were, respectively, 30°C, 7.0, and 0.3. Further research at higher temperatures and lower values of pH and FA/FNA ratios would be necessary in order to find the absolute optimum conditions for the process. The obtained model can be also useful in order to develop control strategies that take into account the significant variables and their optimum ranges. A strategy to control deammonification reactors has been proposed, according to the results of the modeling.     

IMPACT OF SALT STRESS ON MICRONUTRIENTS IN CORDYLINE FRUTICOSA VAR. ‘RED EDGE'

This trial was carried out to study the influence of the nutrient solution on the microelements concentration and distribution in C. fruticosa var. ‘Red Edge' plants. Four treatments were tested: T₁ [control, 1.5 dS m^?1, 14.3 mmol L^?1 sodium chloride (NaCl)], T₂ (2.5 dS m^?1, 22.2 mmol L^?1 NaCl), T₃ (3.5 dS m^?1, 32.7 mmol L^?1 NaCl) and T₄ (4.5 dS m^?1, 38.2 mmol L^?1 NaCl). In roots and stems, iron (Fe) concentrations were lower in the no saline treatment. Stems accumulated more Fe with treatments T₃ and T₄. Copper concentration and extraction were not affected by salinity. The highest manganese (Mn) concentration in roots was observed in T₂, while in petioles was higher in T₃ and T₄. Manganese extraction reached higher levels in the saline treatments in roots and stems, while in petioles it was lower in T₁, T₂ and T₃. In roots, zinc (Zn) concentration was lower with the extreme treatments. Micronutrients concentration in leaves was unaffected by salinity, because an exclusion mechanism that consists on accumulation in roots and stems was developed.     

Nanoparticles in the management of brown eye spot in coffee

European Journal of Plant Pathology - Brown eye spot (Cercospora coffeicola) is one of the main diseases of coffee (Coffea arabica L.) and represents a serious phytosanitary problem for the crop....     

The use of sodium carbonate to improve curing treatments against green and blue moulds on citrus fruits

The effectiveness of curing oranges and lemons at 33 degrees C for 65h followed by storage under ambient and cold-storage conditions was investigated. This treatment effectively reduced the incidence of Penicillium digitatum (Pers) Sacc and P italicum Wehmer decay on inoculated and naturally infected oranges and lemons stored at 20 degrees C for 7 days. However, it failed to control green and blue mould infections on fruits placed in long-term cold storage, except green mould on oranges, which was effectively controlled. Dipping fruits in a sodium carbonate solution (20 g litre(-1)) for 2.5 min following a curing treatment at 33 degrees C for 65 h satisfactorily reduced green and blue mould incidence during subsequent long-term storage at 4 degrees C on oranges and at 10 degrees C on lemons. The efficacy was greater on injured fruits inoculated after the combination of treatments was applied, achieving a 60-80% reduction in decay in comparison with the curing treatment alone in all cases. A significant reduction of blue mould was also observed on fruits inoculated both before the treatments and on those re-inoculated after the treatments, demonstrating both protectant and eradicant activity. Thus, combining curing at 33 degrees C for 65 h with sodium carbonate treatment effectively controlled these post-harvest diseases on artificially inoculated citrus fruits and protected against re-infection. With naturally inoculated lemons, curing followed by sodium carbonate significantly reduced both green and blue mould incidence, but was not superior to curing alone. With naturally infected oranges, curing significantly reduced blue mould, but decay was not reduced further when followed by sodium carbonate treatment.     

Effect of Overnight Staining on the Quality of Flow Cytometric Sorted Stallion Sperm: Comparison with Tradtitional Protocols

Flow cytometry is considered the only reliable method for the separation of X and Y chromosome bearing spermatozoa in equines. The MoFlo SX DP sorter is highly efficient, allowing the production of foals of the desired sex. However, to achieve acceptable pregnancy rates the currently used protocol requires working with fresh semen obtained close to, or at, the sorting facility. An alternative protocol was tested during two consecutive breeding seasons. Fresh stallion semen was cooled for 20 h, during which staining with Hoechst 33342 took place. On the following day, this sample was flow sorted and compared with spermatozoa from the same ejaculate that had been sexed on the previous day. All sperm parameters evaluated remained unchanged when fresh sorted and refrigerated sorted semen were compared. Pre‐sorting storage at 5°C did not alter sperm velocities nor kinetics, viability or membrane permeability, production of reactive oxygen species, mitochondrial membrane potential or DNA fragmentation index of the sorted sample. The findings open for the possibility of using semen from stallions housed far from the sorting facilities. Processed and stained sperm could be shipped refrigerated on the previous day, sorted and inseminated on the next day.     

Olive pomace amendment in Mediterranean conditions: effect on soil and humic acid properties and wheat (Triticum turgidum L.) yield

The effects of the addition of either crude or exhausted olive pomace at two rates (10 and 20 t ha(-)(1)) on soil and soil humic acid (HA) properties and durum wheat (Triticum turgidum L.) yield were investigated in open-field Mediterranean conditions. Soil amendment with olive pomaces produced a significant increase of total organic, total extractable, humified and nonhumified C forms, and available K contents. With respect to control soil HA, humic-like acids isolated from crude and exhausted olive pomaces were characterized by larger phenolic OH group contents, smaller carboxyl group contents, a prevalent aliphatic character, extended molecular heterogeneity, and smaller aromatic polycondensation and humification degrees. In general, application of olive pomaces to soil produced a number of modifications in soil HAs, including the increase of O and acidic functional group contents, C/N ratio, and aliphaticity and the decrease of C/H ratio and N and C contents. Wheat grain yield increased significantly as an effect of olive pomace amendment. In particular, the increases were related to kernel weight, kernel number per square meter, and soil organic matter content. Possibly, the enhanced amount of soil organic matter in olive-pomace-amended soils relieved wheat of drought stress from anthesis to maturity by promoting a good soil structure, thereby reducing water loss by evaporation.     

Soil fulvic acid properties as a means to assess the use of pig slurry amendment

Soil amendment with animal manures is a common practice for either increasing soil organic matter (SOM) and nutrient content or disposing of wastes from intensive animal industries. However, the application of organic amendments that are not sufficiently mature and stable may adversely affect soil properties, especially the content and quality of SOM pools. In this work, the effect of the consecutive annual additions of pig slurry (PS) at rates of 0 (control), 90 and 150 m³ ha⁻¹ per year over a 4-year period on the soil fulvic acid (FA) fraction of SOM was investigated in a field plot experiment conducted under semiarid conditions on a Calcic Luvisol in Toledo province, Spain. The FAs isolated from PS and control and amended soils were characterized for chemical, compositional, structural and functional properties by use of elemental and functional group analysis, and ultraviolet/visible, Fourier transform infrared (FT IR), fluorescence and electron spin resonance (ESR) spectroscopies. PS-FA was characterized by a prevalent aliphatic character, large contents of acidic functional groups, S- and N-containing groups and polysaccharide components, extended molecular heterogeneity, small organic free radical (OFR) contents and small degrees of aromatic ring polycondensation, polymerization and humification. With respect to the control soil FA, the PS-amended soil FAs were characterized by a smaller extraction yield, O and OFR contents and ratios of absorbances at 465 and 665 nm, and larger C, N, S, COOH and phenolic OH contents, C/N ratios and aliphaticity. Statistical analysis of experimental data showed that, with some exceptions, these effects generally increased with increasing cumulative amount of PS applied to soil over time. In conclusion, cumulative PS application to soil over time modifies the content and properties of the FA fraction of SOM. Thus, this material should not be considered as a mature organic amendment and should be treated appropriately before it is applied to soil, so as to increase the degree of humification and enhance its potential as a soil organic fertilizer.     

Tracing trophic pathways through the marine ecosystem of Rapa Nui (Easter Island)

1. The structure of food webs provides important insight into biodiversity, organic matter (OM) pathways, and ecosystem functioning.
2. Stable isotope analysis (δ¹³C and δ¹⁵N) was used to characterize the trophic structure and the main OM pathways supporting food webs in the Rapa Nui coastal marine ecosystem.
3. The trophic position of consumers and isotopic niche metrics were estimated for different assemblages (i.e. mesozooplankton, emergent zooplankton, reef invertebrates, reef fishes, pelagic fishes, and seabirds). Furthermore, the relative importance of different OM sources (i.e. macroalgae, zooxanthellate corals, and particulate OM [POM]) was assessed for heterotrophic consumers using Bayesian mixing model (MixSIAR).
4. Results show a clear pattern of ¹³C and ¹⁵N enrichment from small-sized pelagic and benthic invertebrates, to reef and pelagic fishes, and seabirds. Most invertebrates were classified as primary consumers, reef fishes as secondary consumers and pelagic predators and seabirds as tertiary and quaternary consumers.
5. Isotopic niche metrics indicate a low trophic diversity for pelagic assemblages (mesozooplankton and pelagic fishes), in contrast to reef fauna (invertebrates and fishes), whose higher trophic diversity suggest the exploitation of a wider range of trophic resources. Overlapping of standard ellipses areas between reef invertebrates and reef fishes indicates that both assemblages could be sharing trophic resources.
6. Mixing models results indicate that POM is the main trophic pathway for mesozooplankton, macroalgae (Rhodophyta) for emergent zooplankton, and a mix of coral-derived OM and Rhodophyta for coral reef assemblages such as macrobenthos and reef invertebrates. In contrast, POM contribution was notably more important for some pelagic fishes and seabirds from upper trophic levels.
7. This study provides key elements for conservation efforts on coral reefs, management planning and full-implementation of the recently created Rapa Nui Multiple Use Marine Protected Area.