Tratamiento de aguas residuales urbanas mediante lagunas de alta carga: evaluación experimental

[ES] El objetivo del presente estudio es determinar las condiciones de explotación de dos lagunas experimentales que permiten obtener un mayor rendimento de eliminación de la materia orgánica y los nutrientes del agua residual urbana. También se pretende establecer el rendimiento de los decantadores secundarios experimentales utilizados para la separación de la biomasa del fitoplancton que crece en las lagunas. Se han estudiado durante un año dos lagunas de alta carga provistas cada una de un decantador secundario en serie. La eliminación de la materia orgánica y los nutrientes se ha evaluado mediante estrategias operacionales diferenciadas definidas a través del control del tiempo de retención hidraulico. La evolución de la concentración de la biomasa del fitoplancton del líquido de mezcla de las lagunas está controlada por la radiación solar y la temperatura, y no resulta afectada por las diferentes estrategias de explotación adoptadas. El rendimiento anual medio de eliminación de la biomasa del fitoplancton observado en los decantadores secundarios es de 70-80% y no es afectado por las diferentes condiciones operacionales. La concentración media de la materia en suspensión en los efluentes es de 50-60 mg/l. El rendimiento de eliminación de la materia orgánica (DQO) es muy similar en las dos lagunas y no depende de las estrategias operacionales adoptadas. Para que las lagunas de alta carga produzcan un agua equivalente a un efluente secundario es suficiente adoptar un tiempo de retención de 4 dias en primavera y verano, y 8 dias en otoño e invierno. Se puede alcanzar un buen rendimiento de eliminación de nitrógeno aumentando el tiempo de retención durante el otoño y el invierno a 10 dias. Para alcanzar concentraciones de fósforo en el efluente iguales o inferiores a 1 mg/l es necesario dotar al sistema de instalaciones complementarias para su tratamiento.García, J.; Hernández-Mariné, M.; Mujeriego Sahuquillo, R. (1998). Tratamiento de aguas residuales urbanas mediante lagunas de alta carga: evaluación experimental. Ingeniería del Agua. 5(2):35-50. https://doi.org/10.4995/ia.1998.2748SWORD355052Abeliovich, A., (1986) Algae in wastewater oxidation ponas. In: Handbook of Microalgal Mass Culture (Richmond, A. ed.). CRC Press. Boca Ratón, pp. 331-338.APHA-AWWA-WPCF., (1995) Standard Methods for the Examination of Water & Wastewater. 19th edition. American Public Health Association. Washington D.C.Azov, Y. & Shelef, G., (1982) Operation of high-rate oxidation ponds: theory and experiments. Wat. Res.16: 1153-1160.Cromar, N.J., Martin, N.J., Christofi, N., Read, P.A. & Fallowfield H.J. (1991) Determination of nitrogen and phosphorous partitioning within com-ponents ofthe biomass in a high rate algalpond: significance for the coastal environment ofthe treatedeffluent discharge. Wat. Sci. Tech. 23 (6): 251-258.De Pauw, N. & Salomoni, C. (1990) The use of microalgae in wastewater treatment: achievements and constraints. In: Biológical Approach to Sewage Treatment Process: Current Status and Perspectives (Madoni, P. ed.). Perugia. pp. 329-352.El Halouani, H. (1990) Lagunage a Haut Rendement: Caractérisation Physicochimique de l'Ecosystéme. Etude de son Aptitude à l'Elimination de l'Azote et du Phosphore dans l'Epuration des Eaux Usées. Thése de Doctoral. Université de Montpellier I. 154pp.El Halouani, H., Picot, B., Casellas, C., Pena, G. & Bontoux, J. (1993) Elimination de l'azote et du phosphore dans un lagunage à haut rendement. Revue des Sciences de l'Eau 6: 47-61.Fallowfield, H.J. & Garret, M.K. (1985) The treatment of wastes by algal culture. Journal of Applied Bacteriology. 53rd Symposium Supplement. pp. 187-205.García, J. (1996) Eliminació de Matèria Orgànica i Nutients en Llacunes d'Alt Rendiment. Tesi Doctoral. Universitat de Barcelona. 301 pp.Lavoie, A. & De la Noüe, J. (1987) Harvesting of Scenedesmus obliquus in wastewaters: auto- or bioflocculation? Biotech. Bioeng. 30: 852-859.Lincoln, E.P. & Koopman, B. (1986) Bioflocculation of microalgae in mass cultures. In: Algal Biomass Technologies (Barclay, W.R. & Macintosh, R.P. eds.). Nova Hedwigia Beiheft83. pp. 207-211.Nurdogan, Y. & Oswald, W. (1995) Enhanced nutrient removal in high-rate ponds. Wat. Sci. Tech. 31(12): 33-44.Oswald. W.J. (1986) A Syllabus on Waste Pond Fundamentals (Oswald, W.J. ed.).1401 University of California. Berkeley. 187 pp.Oswald, W.J. (1991) Introduction to advanced integrated wastewater ponding systems. Wat. Sci. Tech. 24: 1-7.Oswald, W.J. (1995) Ponds in the twenty-first century. Wat. Sci. Tech. 31 (12): 1-8.Pearson, H.W. (1996) Expanding the horizons of pond technology and application in an environmentally conscious world. Wat. Sci. Tech. 33 (7): 1-10.Picot, B., El Halouani, H., Casellas, C., Moersidik, S. & Bontoux, J. (1991) Nutrient removal by high rate pond system in a Mediterranean climate. Wat. Sci. Tech. 23: 1535-1541Shelef, G. & Azov, Y. (1987) High-rate oxidation onds: the israeli experience. Wat. Sci. Tech. 19: 249-255.Shelef, G., Moraine, R. & Oron, G. (1980) Algal mass production as an integral part of waste treatment & reclamation system. In: Algae Biomass (Shelef, G. & Soeder, C.J. eds.). Elsevier/North Holland Biomedical Press. Amsterdam. pp. 163-190.Sukenik, A. & Shelef, G. (1984) Algal autoflocculation-verification and proposed Mechanism. Biotech. Bioeng. 16: 142-147.WPCF. (1990) Natural Systems for Wastewater Treatment. Manual of practice FD-16. WPCF. Alexandria. 270 pp.Zadorojny, C, Saxton, S. & Finger, R. (1973) Spectrophotometric determination of ammonia. Journal WPCF 45: 905-912

Long term outdoor operation of a tubular airlift pilot photobioreactor and a high rate algal pond as tertiary treatment of urban wastewater.

530 L high rate alga pond (HRAP) and 380 L airlift tubular photobioreactor (TPBR) were operated and compared in a urban wastewater treatment plant (WWTP), with the main purpose of removing nitrogen and phosphorous from the effluent of the WWTP while generating a valuable biomass. The photosynthetic activity in TPBR was during entire experiment higher than HRAP. The maximum areal productivity reached was 8.26 ± 1.43 and 21.76 ± 0.3 g SS m−2 d−1 for HRAP and TPBR respectively. Total nitrogen (TN) removal averaged 89.68 ± 3.12 and 65.12 ± 2.87% for TPBR and HRAP respectively, while for total phosphorus (TP) TPBR and HRAP averaged 86.71 ± 0.61 and 58.78 ± 1.17% respectively. The lipid content showed no significant differences (p < 0.05) between HRAP and TPBR averaging 20.80 ± 0.22 wt%. The main operating disadvantage of TPBR versus HRAP was the sever biofouling which forced to stop the experiment. Under the same conditions of operation TPBR was more limited at low temperatures than HRAP, and HRAP was more light limited than TPBR

Biogas Production from Algae Biomass Harvested at Wastewater Treatment Ponds

Waste-grown microalgae are a potentially important biomass for biofuel production. However, most of the 7,000 wastewater treatment ponds systems in the US do not use algae harvesting. Those that do, typically return the biomass to the ponds, where it decomposes on the pond floor, releasing methane to the atmosphere and degrading water quality. Instead, the algae biomass could be processed in anaerobic digesters. Algae typically yield less methane than wastewater sludge (~0.3 vs. 0.40 L CH4/g volatile solids introduced). Ammonia toxicity and recalcitrant cell walls are commonly cited causes of the lower yields. Ammonia toxicity might be counteracted by co-digesting algae with high-carbon organic wastes. This paper describes the state of the current literature on algae digestion and presents new data on co-digestion with organic wastes. The focus of the project is to identify the essential information required for full-scale implementation of algae co-digestion at wastewater treatment plants, including the optimal conditions to maximize the methane yield, the volumetric methane productivity, and net energy production

Oxalic acid assisted synthesis of ZnS nanoparticles and their optical properties

ZnS nanoparticles and Oxalic acid (OA) assisted Zinc sulfide nanoparticles were synthesized by an easy and low-cost aqueous method using double distilled water as a solvent. A phase change has been observed while increasing the concentration of OA. Morphological studies by Transmission Electron Microscopy (TEM), Optical studies from Ultra Violet Spectroscopy (UV) and Photoluminescence (PL) and structural studies from X-ray diffraction (XRD) have been done to characterize the samples. UV absorption spectrum confirmed the blue shift and formation of nanostructures. From the PL spectrum, it is observed that both ZnS nanoparticles and OA assisted ZnS nanoparticles excited about 370 nm exhibit a blue-green emission between 420 and 470 nm. It may be recognized to the recombination of the imperfection of ZnS nanoparticles. The spherical morphology of ZnS nanoparticles and OA assisted ZnS nanoparticles has been shown in TEM micrographs and the size of the particles was measured as 8–20 nm and it is in good agreement with XRD studies

Effect of an Information Video before Thyroid Biopsy on Patients' Anxiety

Aim To investigate the effects of video-based information on the anxiety of patients who underwent ultrasound-guided thyroid fine-needle aspiration biopsy. Methods Fifty consecutive patients who underwent thyroid fine needle aspiration biopsy were included in the study prospectively. Patients were divided into two groups before the biopsy. 25 patients in Group 1 received only written information about thyroid biopsy. In Group 2, 25 patients received video-based information along with written information. Baseline anxiety of all the patients was evaluated prior to procedure using STAI-S and STAI-T questionnaires. After the written information was provided to the patients in group 1, the STAI-S questionnaire was repeated. In the same way, group 2 patients were asked to repeat the STAI-S questionnaire after written and video-based information were provided. All patients were asked to evaluate pain during biopsy using visual analog scale (VAS). Results There was no significant difference between the groups in terms of age and gender. Although the VAS score was lower in group 2, there was no statistically significant difference between the two groups. When the groups were compared in terms of basal anxiety scores, STAI-T was similar in both groups (p = 0.708). Although STAI-S values were similar in pre and post-information patients in Group 1, the STAI-S values in group 2 were statistically significantly decreased. Conclusion The video based information provided prior to thyroid biopsy draws the attention as an effective and easy to apply method to decrease the anxiety of the patients

Broadband luminescence of Cu nanoparticles fabricated in SiO2 by ion implantation

WOS: 000382594900019PubMed ID: 27344525In this study, we investigate optical properties of metal nanoparticle crystals fabricated by implanting copper (Cu) ions into single silica (SiO2) crystals with 400 key at various ion doses. The Cu implanted SiO2 (SiO2:Cu) crystal produces a broadband luminescence emission, ranging from blue to yellow, and having a blue luminescence peak at 546 nm. Such anomalous luminescence emission bands suggest that the ion implantation may give rise to aggregation of Cu nanoparticles in the host matrix. The boundary element method-based modelling of a given Cu nanoparticle aggregation was employed to justify the broadband luminescence emission. Formation of Cu nanoparticles in SiO2 is predicted through their optical absorption data. The experimental results are compared with results of Mie calculations and we observe that the higher ion dose produces the larger particle size. (C) 2016 Elsevier Ltd. All rights reserved