The use of fluidized-bed bioreactors in waste and drinking water treatment has several advantages, the most significant of which is the specific removal rate, which is an order of magnitude higher than that of equivalent activated sludge processes. In this paper, the usual concept of nitrification-denitrification in separated units is replaced by a new concept in which the two processes are performed together in a single high-performance fluidized-bed. Based on the former nitrifying reactor, new equipment was designed. This reactor contained a fluidized bed with separated aerobic and anoxic sections for nitrification and denitri fication respectively. This was accomplished by the use of different-diameter sand as carrier material and appropriate reactor shape, recirculation, feed and aeration conditions. The reactor (20 L fluidized-bed volume) was operated for 3 months. It was fed with synthetic waste water (50 L/h) containing 25-40 mg NH₄ ⁺-N/L. Propionic acid and ethanol in a 1:4 ratio were used as the carbon source (2.3 g C/L) for deni trification, fed in at different points of the reactor. Ammonium removal reached 50%, while denitrification was 75%. The total nitrogen removal rate was 0.8-1.2 kg N/m ³.d. A new simple hydrostatic pressure method was used to monitor biofilm thickness in the fluidized bed. During the experiments the oxidation-reduc tion potential (ORP) was tested as a tool to monitor reactor performance; its use for the control of the process was found to be limited.

En experimentos realizados en invernadero, algunos autores han mostrado que el sulfato amónico origina mayor acidez y salinidad que otras fuentes de nitrógeno. Los inhibidores de la nitrificación (NI) tienden a acumular amonio en los suelos al retardar la oxidación a nitratos. Este amonio acumulado también tendría un efecto sobre la salinidad del suelo. Consecuentemente, el objetivo de este trabajo fue evaluar la salinización del suelo y agua de drenaje, debido al efecto asociado a la adición de NI, dimetilpirazolfosfato (DMPP) y diciandiamida (DCD), al fertilizante nitro-sulfato amónico (ASN). Este experimento fue realizado en condiciones de campo con un cultivo de maíz irrigado. Se midieron el drenaje y la concentración de Na durante dos periodos de cultivo (2006 y 2007) y también se determinó el sodio lixiviado. Los tratamientos con NI (DCD y DMPP) dieron lugar a mayores concentraciones de Na en la solución del suelo y consecuentemente mayores cantidades de Na lixiviado (en 2007, ASN-DCD 1.292 kg Na/ha, ASN-DMPP 1.019 kg Na/ha). Con el tratamiento de ASN sin inhibidor, también aumentó la concentración en el suelo y el Na lixiviado (en 2007, 928 y 597 kg Na/ha para ASN y el control, respectivamente). El aumento de la concentración de amonio en el suelo, debido a los tratamientos con NI, podría deberse al desplazamiento de los iones Na del complejo de cambio, mediante un proceso que finalmente conduce a un aumento de la salinidad. Los tratamientos que incluyen amonio en la formulación del fertilizante junto a un NI originaron un mayor grado de salinización debido al amonio procedente del fertilizante y al amonio acumulado procedente de la inhibición de la nitrificación. | In experiments carried out in greenhouses, some authors have shown that ammonium sulphate induces greater soil acidity and salinity than other sources of N. Moreover, nitrification inhibitors (NI) tend to cause ammonium to accumulate in soil by retarding its oxidation to nitrate. This accumulated ammonium would also have an effect on soil salinity. Consequently, the aim of this paper was to evaluate the soil and leaching water salinization effects associated with adding NI, dicyandiamide (DCD) and dimethylpyrazole-phosphate (DMPP) to ammonium sulphate nitrate (ASN) fertilizer. This experiment was carried out in the field with an irrigated maize crop. Drainage and Na concentration were measured during both seasons (2006 and 2007) and leached Na was determined. The treatments with NI (DCD and DMPP) were associated with greater Na concentrations in soil solutions and consequently higher rates of Na leaching (in 2007, ASN-DCD 1,292 kg Na/ha, ASN-DMPP 1,019 kg Na/ha). A treatment involving only ASN also increased the Na concentration in soil and the amount of Na leached in relation to the Control (in 2007, ASN 928 kg Na/ha and control 587 kg Na/ha). The increase in the ammonium concentration in the soil due to the NI treatments could have been the result of the displacement of Na ions from the soil exchange complex through a process which finally led to an increase in soil salinity. Treatments including ammonium fertilizer formulated with NI produced a greater degree of soil salinization due to the presence of ammonium from the fertilizer and accumulated ammonium from the nitrification inhibition.

This research analyzed three green microalgae (Scenedesmus sp., Chlamydomonas sp., and Chlorella sp.) and two cyanobacteria (Synechocystis sp. as unicellular strain and Nostoc sp. as filamentous strain) native from Costa Rica to remove high concentrations of ammonium and phosphate. Cultures were exposed for 120 h to initial concentrations of 70 mgL-1 ammonium and 9 mgL-1 phosphate, under constant light intensity of 60 µmol m-2s-1. Chlorella sp. showed the highest growth rate, followed by Chlamydomonas sp. and the cyanobacteria Nostoc sp. In contrast, Scenedesmus sp. and Synechocystis sp. cultures grew less than the other ones. The highest percentage of ammonium removal was achieved with Chlorella sp. followed by Chlamydomonas sp. and Synechocystis sp., then Scenedesmus sp. and Nostoc sp. Microalgae removed totally the initial phosphate concentration within 72 h, while cyanobacteria Synechocystis sp. and Nostoc sp. removed phosphate partially. These microorganisms are promising for wastewater reclamation. | La presente investigación utilizó las microalgas Scenedesmus sp,. Chlamydomonas sp. y Chlorella sp. y las cianobacterias Synechocystis sp. y Nostoc sp. nativas de Costa Rica, con el propósito de analizar la capacidad de remoción de amonio y fosfato. Las cepas se colocaron en medio de cultivo sintético, con concentraciones iniciales de amonio de 70 mgL-1 y fosfato de 9 mgL-1. El cultivo se realizó durante 120 h, con luz constante a una intensidad de 60 µmol m-2s-1. Se cuantificaron las siguientes variables cada 24 h en todos los cultivos: a) la tasa de crecimiento (µ), b) productividad (mgL-1h-1), c) concentración de amonio y fosfato. La microalga Chlorella sp. presentó la mayor tasa de crecimiento, luego Chlamydomonas sp. y la cianobacteria Nostoc sp. Los cultivos Scenedesmus sp. y Synechocystis sp. presentaron un menor crecimiento. La mayor remoción de nitrógeno se presentò en Chlorella sp., seguida por Chlamydomonas sp. y Synechosystis sp., Scenedesmus sp. y Nostoc sp. El fosfato se removió en forma total por las microalgas antes de las 72 h, mientras que en Synechocystis sp. y Nostoc sp. fue removido parcialmente. El estudio indica potenciales aplicaciones especialmente de la microalga Chlorella sp. en la remoción de amonio y fosfato en aguas residuales urbanas.

Mandalay is a major city in central Myanmar with a high urban population and which lacks a central wastewater management system, a solid waste disposal process, and access to treated drinking water. The purpose of this study is to investigate the groundwater quality of local dug wells and tube wells, determine quantitative data on characteristics of the Amarapura Aquifer, and compare seasonal variations in groundwater flow and quality. Water samples were collected during the dry and wet seasons, then analyzed for major ion chemistry using ion chromatography to identify indicators of wastewater contamination transport to the shallow aquifer and to compare seasonal variations in groundwater chemistry. An open-source analytic element model, GFLOW, was used to describe the physical hydrogeology and to determine groundwater flow characteristics in the aquifer. Hydrogeochemistry data and numerical groundwater flow models provide evidence that the Amarapura Aquifer is susceptible to contamination from anthropogenic sources. The dominant water types in most dug wells and tube wells is Na-Cl, but there is no known geologic source of NaCl near Mandalay. Many of these wells also contain water with high electrical conductivity, chloride, nitrate, ammonium, and E. coli. Physical measurements and GFLOW characterize groundwater flow directions predominantly towards the Irrawaddy River and with average linear velocities ranging from 1.76 × 10⁻² m/day (2.04 × 10⁻⁷ m/s) to 9.25 m/day (1.07 × 10⁻⁴ m/s). This is the first hydrogeological characterization conducted in Myanmar.

En este proyecto se presenta el diseño, construcción y operación de un dispositivo portátil para la remoción simultánea de sólidos y nitrógeno amoniacal de aguas del humedal Córdoba, y que posibilita el incremento del oxígeno disuelto mediante aireación por gravedad. El dispositivo está diseñado a escala teniendo en cuenta las condiciones para su puesta en marcha in situ en el espejo de agua del humedal Córdoba. Para ello, hace uso de energía fotovoltaica e incorpora un sistema de control de colmatación de filtros y obstrucción de manguera, con la finalidad de que presente un funcionamiento autónomo. Se consideraron pérdidas de energía, dimensiones de los materiales filtrantes, espesor de lechos filtrantes, consumo eléctrico, peso, y parámetros críticos para un sistema de tratamiento de aguas controlado electrónicamente. | Bioingeniero | Pregrado | This project presents the design, construction and operation of a portable device for the simultaneous removal of solids and ammoniacal nitrogen from the wetlands of the Córdoba wetland, which allows the increase of dissolved oxygen by means of gravity aeration. The device is designed to scale taking into account the conditions for its implementation in situ in the water mirror of the wetland Córdoba. To do this, it uses photovoltaic energy and incorporates a control system for filter clogging and hose clogging, in order to present an autonomous operation. Energy losses, dimensions of filter materials, filter bed thickness, electrical consumption, weight, and critical parameters for an electronically controlled water treatment system were considered

The groundwater abstracted at a well field near the Yamuna River in Central Delhi, India, has elevated ammonium (NH₄ ⁺) concentrations up to 35 mg/L and arsenic (As) concentrations up to 0.146 mg/L, constituting a problem with the provision of safe drinking and irrigation water. Infiltrating sewage-contaminated river water is the primary source of the NH₄ ⁺ contamination in the aquifer, leading to reducing conditions which probably trigger the release of geogenic As. These conclusions are based on the evaluation of six 8–27-m deep drillings, and 13 surface-water and 69 groundwater samples collected during seven field campaigns (2012–2013). Results indicate that losing stream conditions prevail and the river water infiltrates into the shallow floodplain aquifer (up to 16 m thickness), which consists of a 1–2-m thick layer of calcareous nodules (locally known as kankar) overlain by medium sand. Because of its higher hydraulic conductivity (3.7 × 10⁻³ m/s, as opposed to 3.5 × 10⁻⁴ m/s in the sand), the kankar layer serves as the main pathway for the infiltrating water. However, the NH₄ ⁺ plume front advances more rapidly in the sand layer because of its significantly lower cation exchange capacity. Elevated As concentrations were only observed within the NH₄ ⁺ plume indicating a causal connection with the infiltrating reducing river water.

Urban groundwater has often been over-exploited for industrial uses. Now, this usage tends to be reduced or the resource abandoned due to pollution and/or changes in land use. The use and the subsequent disuse of groundwater has resulted in rising water tables that damage underground structures (e.g., building basements and underground car parks and tunnels), leading to the need for additional pumping in urban areas. In the case of the underground parking lot of Sant Adrià del Besòs (Barcelona, NE Spain), large amounts of urban groundwater are pumped to avoid seepage problems. Can this pumped groundwater be used for other purposes (e.g., drinking water and urban irrigation) instead of wasting this valuable resource? To answer this question, it was necessary to quantify the groundwater recharge and to assess the evolution of groundwater quality. The limiting factor at this study site is the groundwater quality because ammonium and some metals (iron and manganese) are present at high concentrations. Hence, further treatment would be needed to meet drinking water requirements. The pumped groundwater could also be used for supplementing river flow for ecological benefit and/or for mitigating seawater intrusion problems. Currently, only a small amount of this urban groundwater is used for cleaning public areas and watering public gardens. This situation highlighted the urgent need to manage this resource in a responsible and more efficient manner, especially in moments of high water demand such as drought periods.