Elimination de l'azote et du phosphore dans un lagunage à haut rendement

L'objectif de cette étude est de comprendre le fonctionnement épuratoire de l'écosystème particulier que constitue le lagunage à haut rendement (LHR) afin de déterminer les principaux facteurs responsables de l'élimination de l'azote et du phosphore.Sur un bassin de 48 m2, alimenté eu eaux usées domestiques préalablement traitées pendant une semaine dans un bassin primaire ont été suivies selon un rythme hebdomadaire les formes carbonées, azotées et phosphorées dis-soutes et particulaires, les variables caractéristiques de l'activité photosynthétiques (chlorophylle a, pH et 02) et les données climatiques (rayonnement solaire et température). Une analyse en composantes principales réalisée sur l'ensemble des résultats a montré, d'une part l'opposition des variables climatiques et photosynthétiques aux formes minérales de l'azote et du phosphore (N-NH4 et P-PO4) et d'autre part l'influence de la charge organique sur le fonctionnement du système.L'évolution des formes azotées et phosphorées présente un effet saisonnier marqué. En hiver ou lors de surcharge organique importante, une augmentation du temps de séjour peut améliorer les rendements épuratoires. L'évolution de la matière organique dissoute est indépendante du cycle saisonnier. Au cours des deux années du suivi on observe une adaptation progressive de l'écosystème à la dégradation de la matière organique.Dans le lagunage à haut rendement l'élimination de l'azote et du phosphore est liée principalement à l'activité algale, qui entraîne une assimilation biologique et une élévation du pH, responsables des phénomènes chimiques de volatilisation de l'azote ammoniacal et de précipitation de phosphate de calcium.High rait algal ponds (HRAP) for wastewater treatment have been the locus of a lot of attention since their creation by Professor W.J. OSWALD in the early 1960' s. These aquatic ecosystems are hypereutrophic because of massive nutrient introduction with the wastewater influent. This kind of pond is very different from oxidation ponds because al short residence times (2 to 12 days), shallow depths (0.30 to 0.60 m) and constant mechanical mixing which improves algal growth.This study has been carried out in a small town in the department of Herault (France). The objective is to establish the efficiencies and mechanisms for nitrogen and phosphorus remval from secondary domestic wastewater by treatment by HRAP. A high rate algal pond of 48 m2 surface area and 35 cm depth, constantly mixed with paddle wheels was studied (fig. 1). Residence limes changed from 2 te 12 days with solar radiations and influent loading. The samples were collected once a week from the in- and outflow at 3 p.m. - Dissolved and particulate COD, varions nitrogen and phosphorus compounds, suspended solide, chlorophyll-a, pH, dissolved oxygen, temperature and irradiation were determined.The results of principal component analysis show a negative correlation between (1) the climatic and photosynthetic parameters and (2) inorganic nitrogen and phosphorus compounds, as well as the influence of organic loading on the HRAP efficiency.The chronological clustering analysis was performed on the data taking into account the discontinuities of effluent autrient contents (fig. 4). During the first year, from February to September 1988, good climatic conditions were shown to favour photosynthetic activity and consequently a good ammonia and orthophosphate removal. Front September 1988 to February 1989, the effluent was characterized by high ammonia and orthophosphate levels because of unfavourable climatic conditions and low photosynthetic activity. During the second year, the objective was to improve removal efficiencies ; the residence time was changed with solar radiations and influent loading. The results of the chronological clustering analysis of ammonia and orthophosphate levels showed only one sequence (February 1989-January1990) because the seasonal variations of nutrient removal were attenuated. The optimal residence time was found to be 4 days in summer and 12 days in winter.The evolution of dissolved chemical oxygen demand is independent of seasonal conditions but decreases with the maturity of the system (< 50 mg . l-1).The mass balance of nitrogen and phosphorus compounds has been established (fig. 5). In high rate algal pond influent, the main nitrogen form is ammonia. In the effluent the main nitrogen form is suspended organic nitrogen. The oxidized forms (NO2- et NO3) present very low levels ; nitrification is a minor process in the system. Ammonia is reduced by both assimilation and stripping ; suspended organic nitrogen in the effluent is an indicator of assimilation by algal biomass and loss of nitrogen is an indicator of ammonia stripping. With regard to directive 91/271 EEC concerning domestic wastewater treatment, partial algal separation is necessary in order to achieve 15 mg • l-1 total nitrogen, which is the limit for zones sensitive to eutrophication.The residual phosphate levels are controlled by pH, which is responsible for instantaneous calcium phosphate precipitation. As the dissolved calcium concentrations are high in the calcareous region near the site (Ca = 125 mg • l-1), the pH of the water will be the main contraint on phosphate elimination in the HRAP. Theoretical calculations indicate that the precipitate is probably an amorphous tricalcium phosphate in pseudoequilibrium (fig.6). Phosphate concentrations are much higher titan the values expected for calcium hydroxyapatite in equilibrium (MOUTIN et al., 1992). The limit of 2 mg • l-1 for phosphores can only be attained when pH reaches or exceeds 9.Nitrogen and phosphorus removal is correlated mainly with phytoplanktonic activity, which controls biological nutrients assimilation and pH levels. High pH values are responsable for ammonia stripping and calcium phosphate precipitation

Synchronization in Von Bertalanffy’s models

Many data have been useful to describe the growth of marine mammals, invertebrates and reptiles, seabirds, sea turtles and fishes, using the logistic, the Gom-pertz and von Bertalanffy's growth models. A generalized family of von Bertalanffy's maps, which is proportional to the right hand side of von Bertalanffy's growth equation, is studied and its dynamical approach is proposed. The system complexity is measured using Lyapunov exponents, which depend on two biological parameters: von Bertalanffy's growth rate constant and the asymptotic weight. Applications of synchronization in real world is of current interest. The behavior of birds ocks, schools of fish and other animals is an important phenomenon characterized by synchronized motion of individuals. In this work, we consider networks having in each node a von Bertalanffy's model and we study the synchronization interval of these networks, as a function of those two biological parameters. Numerical simulation are also presented to support our approaches

Oftalmopatía tiroidea: determinación de parámetros de actividad clínica de la oftalmopatía tiroidea como factor pronóstico de respuesta al tratamiento inmunosupresor

Objective: To determine the usefulness of the clinical, biochemical and thyroid imaging parameters in patients with thyroid-associated ophthalmopathy, in predicting their response to immunosuppressive treatment. Methods: This retrospective study of 16 patients with thyroid ophthalmopathy considered a number of variables including sex, age, thyroid hormone levels, treatment of the thyroid dysfunction, clinical activity score (CAS), severity (NOSPECS) of the ophthalmopathy, signs in standardized A-mode ultrasonography, in CAT and/or NMR, and previously used treatments and their effectiveness. Results: The average age of the patients was 50.81 (S.D: 11.89) years; there were 5 males (31.3%) and 11 females (68.8%). The ophthalmopathy was classified as active in 10/16 patients (62.5%) and inactive in 6/16 (37.5%); and as moderate in 9/16 (56.25%) and severe in 7/16 (43.75%) according to the severity defined in NOSPECS. Ultrasonography was diagnostic in 100% of the cases. The severity decreased significantly (p ≤ 0.05), however the clinical activity decrease did not reach significance (p=0.38) during immunosuppressive therapy. Better results were obtained during treatment of patients with a higher CAS (p=0.04) and in those with more severe ophthalmopathy (p=0.02). There was a tendency for the patients with higher levels of TSI to respond better to the treatment (p=0.06). Conclusions: The CAS is the best parameter to quantify the activity of the disease and predicting the response to treatment. The higher the CAS and the more severe the ophthalmopathy, the better the response to treatment. No association existed between thyroid function and the activity or severity of the ophthalmopathy; or the effectiveness of treatmen

Characterisation of activated sludge by automated image analysis : validation on full-scale plants

Automated methods based on the analysis of macro- and meso-scale images has been developed to characterise activated sludge in terms of size and shape (fractal dimension) of flocs and abundance of filamentous bacteria. After tests on pilot-scale reactors, the method has been validated on full-scale samples from twelve different wastewater treatment plants in France and Portugal

Crystallographic evidence of theoretically novel anion- interactions

Metals in Catalysis, Biomimetics & Inorganic Material

ODTN: Open Disaggregated Transport Network. Discovery and Control of a Disaggregated Optical Network through Open Source Software and Open APIs

ONOS discovers and manages a topology made of Transponders and a dedicated OLS, using standard protocols (NETCONF/RESTCONF) and models (OpenConfig/TAPI). The demo is a joint collaboration, towards production deployment, between 3 operators and 2 equipment vendors

The effects of thiopurine therapy on health-related quality of life in Inflammatory Bowel Disease patients

<p>Abstract</p> <p>Background</p> <p>The effect of thiopurine immunomodulators on health-related quality of life (HRQoL) in patients with inflammatory bowel disease (IBD) has been controversial. The aims were to evaluate the HRQoL in patients with IBD treated with thiopurines and assess the short- and long-term impacts of the treatment on HRQoL.</p> <p>Methods</p> <p>Ninety-two consecutive patients who started treatment with thiopurines were prospectively included. Evaluation of HRQoL was performed at months 0, 6, and 12 using two questionnaires, the Short-Form Health Survey (SF-36) and the Inflammatory Bowel Disease Questionnaire (IBDQ).</p> <p>Results</p> <p>Baseline score of IBDQ was 4,6, range (2,31-6,84), with an impairment of the five dimensions of HRQoL compared with inactive patients. Results obtained in 8 dimensions of SF-36 showed worse HRQoL than Spanish general population. At 6 months patients had a significant improvement in overall IBDQ score -5,8 (1,58 -6,97)- and also in all IBDQ dimensions. All the 8 dimensions of SF-36 obtained a significant improvement. At twelve months score of IBDQ was 6,1, range (2,7-6,98), with improvement in all dimensions compared with baseline and 6 months. SF-36 showed a similar significant improvement in all subscales.</p> <p>Conclusions</p> <p>Thiopurine immunomodulators alone or with other treatments have a positive and long lasting impact on HRQoL of IBD patients.</p

Conditional KCa3.1-transgene induction in murine skin produces pruritic eczematous dermatitis with severe epidermal hyperplasia and hyperkeratosis

Ion channels have recently attracted attention as potential mediators of skin disease. Here, we explored the consequences of genetically encoded induction of the cell volume-regulating Ca2+-activated KCa3.1 channel (Kcnn4) for murine epidermal homeostasis. Doxycycline-treated mice harboring the KCa3.1+-transgene under the control of the reverse tetracycline-sensitive transactivator (rtTA) showed 800-fold channel overexpression above basal levels in the skin and solid KCa3.1-currents in keratinocytes. This overexpression resulted in epidermal spongiosis, progressive epidermal hyperplasia and hyperkeratosis, itch and ulcers. The condition was accompanied by production of the pro-proliferative and pro-inflammatory cytokines, IL-ß1 (60-fold), IL-6 (33-fold), and TNFa (26-fold) in the skin. Treatment of mice with the KCa3.1-selective blocker, Senicapoc, significantly suppressed spongiosis and hyperplasia, as well as induction of IL-ß1 (-88%) and IL-6 (-90%). In conclusion, KCa3.1-induction in the epidermis caused expression of pro-proliferative cytokines leading to spongiosis, hyperplasia and hyperkeratosis. This skin condition resembles pathological features of eczematous dermatitis and identifies KCa3.1 as a regulator of epidermal homeostasis and spongiosis, and as a potential therapeutic target