Counseling Brazilian Farmers on Their Management Activities

The study identified some reasons that explain the limited use of scientific management tools by Brazilian farmers. A matrix of management activities was built to classify these reasons. Primary data used in the study were collected during two phases. During the first, 8 focus group manned by cash crop farmers, beef cattle farmers, and extension agents and counselors, were used to produce qualitative information. During the second phase, quantitative informations were collected via a survey with 494individual questionnaires applied to the same public covered by phase one. For the statistical tests performed 95% of significance was required. Some conclusions of the study are: (1) farmers differ significantly from extension agents or counselors on farm management subjects; (2) farmers do not alter their strategic production plans in response to price changes or other signals perceived as short or mid term movements due to costs of changes in their production processes; (3) in organizing their human resources structure farms tend to concentrate into their hands amounts of responsibilities larger than they can handle; (4) in organizing their financial flows there is a large gap between the desired level of details and their abilities to collect the data; and (5) the major difficulties faced in the function of controlling are linked with problems of collecting data. This is due to low levels of formal education that characterize the farm-hired labor.Brazilian farm management, counseling farmers, matrix of management activities., Farm Management, Teaching/Communication/Extension/Profession,

Monitoring denitrification by means of pH and ORP in continuous-flow conventional activated sludge processes

Indirect signal analysis (pH, ORP and DO) are often used in monitoring and control of SBRs (Sequencing Batch Reactors), where operating conditions can be clearly identified during the various cyclic phases. Only few studies applied this methodology to control continuous flow plants, as it is much more difficult to identify operating conditions because of continually variable inflow characteristics. This work applied indirect signal analysis to control pre-denitrification in continuous-flow activated sludge processes: (i) a laboratory-scale plant, fed with synthetic wastewater, simulating real municipal wastewater and (ii) a pilot-scale plant, fed with real sewage. Three different ranges of ORP values identify three operational conditions of the denitrification process. (1) ORP > 0 mV means that nitrates and/or nitrites are present, possibly due to a low C/N ratio. (2) –50 < ORP < –200 mV is typical of normal operating conditions, that is with a balanced C/N ratio. (3) ORP < –350 mV means that oxidized nitrogen load is too low or that C/N exceeds the stoichiometric ratio. The trend of pH, instead, points out if and how the process is evolving from one to another operating condition. The correlation between pH and ORP signals (as well as their derivatives) allows to restore normal operating conditions by acting on the internal recycle flow-rate. Improved denitrification process ensures lower effluent nitrate concentration, and reduce external carbon dosage to achieve stricter nitrogen limits

Performance of electro-osmotic dewatering on different types of sewage sludge

The feasibility of pressure-driven electro-dewatering (EDW) on sludge samples taken after different biological processes, stabilisation methods or mechanical dewatering techniques was assessed. First, the influence of potential values on EDW of anaerobically and aerobically stabilised, mechanically dewatered, sludge samples was investigated. Preliminary tests carried out by applying a constant potential (10, 15 and 20 V) in a lab-scale device confirmed the possibility to reach a dry solid (DS) content of up to 42.9%, which corresponds to an increase of 15% of the dry content in dewatered sludge without the application of the electrical field. Dewatering increased with the applied potential but at the expense of a higher energy consumption. A potential equal to 15 V was chosen as the best compromise for EDW performance, in terms of DS content and energy consumption. Then, the influence of the mechanical dewatering was studied on aerobically stabilised sludge samples with a lower initial DS content: the higher initial water content led to a lower final DS content but with a considerable reduction of energy consumption. Finally, the biological process, studied by comparing sludge samples from conventional activated sludge and membrane bioreactor processes, didn’t evidence any influence on EDW. Experimental results shown that DS obtained after mechanical dewatering, volatile solids and conductivity are the main factors influencing EDW. Anaerobically digested sludge reached the highest DS content, thanks to lower organic fraction

Complete autotrophic process for nitrogen removal from inkjet printing wastewater

Lab-scale results on the treatability of ammonium-rich wastewater from textile digital printing highlight the feasibility of an innovative biological process, based on purely autotrophic bacterial populations: ammonium oxidising bacteria (AOB) and anaerobic ammonium oxidisers (AAO). Activity of AOB has been measured through pH/DO-stat titration and that of AAO has been assessed through manometric tests, on raw mixed wastewater coming from textile-print factories (0.5 to 0-6 gN/L as ammonium nitrogen). AOB activity showed a reduction of 20-40% if compared with maximum activity on a synthetic medium. AAO activity tests showed a residual specific maximum anammox activity (SAA) of 0.1-0.4 gN2-N/gVSS/d, 40-60% of the control values obtained with synthetic wastewater. Activity tests confirmed treatability of the textile wastewater by AAO. Tests have been performed also on concentrated wastewater (2 to 3 gN/L as ammonium nitrogen) from the first rinsing bath. In this case, strong inhibition (between 80 and 100%) of anammox activity was observed. Careful operation of a continuous-flow completely mixed bioreactor can overcome this drawback, as pH and effluent ammonium concentration in the reactor are controlled

Editorial: Ecotechnologies for Wastewater Treatment - Impacting the environment with innovation in wastewater treatment

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Nuevos enfoques para calcular la evaporación y la transpiración

En este trabajo se presenta un modelo matemático desarrollado por F. I. Morton, en Canadá, para calcular la evaporación en grandes áreas, obviando las conocidas dificultades que se encuentran en este tipo de cálculos. El modelo se basa en algunas suposiciones simplificativas con respecto a la disponibilidad de agua en el suelo, así cano soslaya para ciertas condiciones del entorno, las complejas interrelaciones entre el suelo, la vegetación y la atmósfera. La técnica utilizada permite la aplicación de un modelo simple para calcular la evapotranspiración real cano función de la temperatura del aire y la humedad, tal coro se miden en un abrigo meteorológico. Se presenta, también, un ensayo de aplicación de este modelo a diferentes regiones climáticas de la Argentina.This paper present a mathematical model developed by F. I. Marton, in Canada, to calculate the evaporation on large areas obviating the known difficulties found in this type of conputations. The model is based on sane simplifying assumptions regarding the soil water availability as well as on the bypassing, under certain environmental conditions, of the complex interrel at ions between the ground, the vegetation cover and the atmosphere. The technique used enables the application of a simple model to compute the real evapotranspiration as a function of the air temperature and humidity as measured in a normal meteorological shelter. An essay of the application of this model to various different climatic regions of Argentina is also presented.Asociación Argentina de Geofísicos y Geodesta