Imidacloprid: Impact on Africanized Apis mellifera L. (Hymenoptera: Apidae) workers and honey contamination

Apis mellifera L. (Hymenoptera: Apidae) is fundamental in the production chain, ensuring food diversity through the ecosystem service of pollination. The aim of this work was to evaluate the impact of imidacloprid, orally, topically, and by contact, on A. mellifera workers and to verify the presence of this active ingredient in honey. Toxicity levels were verified by bioassays. In bioassay 1, the levels correspond to the percentages of 100, 10, 1, 0.1, and 0.01% of the recommended concentration for field application of the commercial product Nortox® (active ingredient imidacloprid), with which we obtained the mean lethal concentration (LC50) in 48 h for A. mellifera, determining the concentration ranges to be used in the subsequent bioassays. Bioassays 2 and 3 followed the guidelines of the Organization for Economic Cooperation and Development, which specify the LC50 (48 h). In bioassay 4, the LC50 (48 h) and the survival rate of bees for a period of 120 h were determined by contact with a surface contaminated with imidacloprid, and in bioassay 5, the interference of the insecticide with the flight behavior of bees was evaluated. Honey samples were collected in agroecological and conventional georeferenced apiaries and traces of the imidacloprid were detected by means of high-performance liquid chromatography (HPLC-UV) with extraction by SPE C18. Bee survival was directly affected by the concentration and exposure time, as well behavioral performance, demonstrating the residual effect of imidacloprid on A. mellifera workers. Honey samples from a conventional apiary showed detection above the maximum residue limits (MRL) allowed by the European Union (0.05 μg mL-1), but samples from other apiaries showed no traces of this insecticide. Imidacloprid affects the survival rate and behavior of Africanized A. mellifera and honey quality.

Briquette production from a mixture of biomass: poultry slaughterhouse sludge and sawdust

This study refers to the development of hybrid briquettes using centrifuged sludge from the wastewater treatment of poultry and sawdust from furniture industry. The aim was to evaluate the performance of briquettes as a source of thermal energy, mitigating the risks of the current elimination and reducing the operational costs of their destination. To know the oxidizing characteristics of the briquettes and their mechanical resistance, superior calorific power, ash content, volatile materials, fixed carbon, and resistance to axial compression were evaluated. Thermogravimetric and differential exploratory calorimetry analyses were performed. Statistical treatments were carried out to verify the most significant factors to produce briquettes, the best proportions of the raw materials, and to evaluate whether there is interference from moisture and glue flour used as a binder. The best condition of the sludge-sawdust mixture was 15% and 85%, respectively, with 6.0% moisture. The best-case treatment had 23.82-MPa mechanical resistance, a calorific value of 17.20 MJ kg^-1, and a density of 1374.15 kg m^-3.

Optimization of the nitrification process of wastewater resulting from cassava starch production

The present study has the objective of optimizing operational conditions of an aerated reactor applied to the removal of ammoniacal nitrogen from wastewater resulting from the production of cassava starch. An aerated reactor with a usable volume of 4 L and aeration control by rotameter was used. The airflow and cycle time parameters were controlled and their effects on the removal of ammoniacal nitrogen and the conversion to nitrate were evaluated. The highest ammoniacal nitrogen removal, of 96.62%, occurred under conditions of 24 h and 0.15 L min^-1 L_reactor^-1. The highest nitrate conversion, of 24.81%, occurred under conditions of 40.92 h and 0.15 L min^-1 L_reactor^-1. The remaining value of ammoniacal nitrogen was converted primarily into nitrite, energy, hydrogen and water. The optimal operational values of the aerated reactor are 29.25 h and 0.22 L min^-1 L_reactor^-1. The mathematical models representative of the process satisfactorily describe ammoniacal nitrogen removal efficiency and nitrate conversion, presenting errors of 2.87% and 3.70%, respectively.

Optimization of the pretreatment of wastewater from a slaughterhouse and packing plant through electrocoagulation in a batch reactor

The purpose of this study is to evaluate the removal of chemical oxygen demand (COD), turbidity and color of wastewater from a pig slaughterhouse and packing plant through the electrochemical technique and to optimize the ΔV (electric potential difference) and HRT (hydraulic retention time) variables in an electrocoagulation batch reactor using aluminum electrodes. The experimental design used was rotatable central composite design. For turbidity, the values for removal efficiency obtained varied from 92.85% to 99.28%; for color, they varied from 81.34% to 98.93% and for COD, they varied from 58.61% to 81.01%. The best optimized conditions of treatment were at 25 min for the HRT and 25 V for the ΔV, which correspond to electrical current of 1.08 A and a current density of 21.6 mA cm^-2. The aluminum residue varied from 15.254 to 54.291 mg L^-1 and the cost of the treatment was US$4.288 m^-3. The novelty of the work was the simultaneous optimization of three response variables using the desirability function applied to the treatment of wastewater from slaughterhouses.

ANÁLISE COMPARATIVA DE MÉTODOS PARA DETERMINAÇÃO DA CURVA DE RETENÇÃO DE ÁGUA EM SOLOS

ANÁLISE COMPARATIVA DE MÉTODOS PARA DETERMINAÇÃO DA CURVA DE RETENÇÃO DE ÁGUA EM SOLOS   Maria Hermínia Ferreira Tavares1; José Jeremias da Silva Feliciano1; Carlos Manoel Pedro Vaz21Centro de Ciências Exatas e Tecnológicas, Universidade Estadual do Oeste do Paraná, Cascavel, PR, mhstavar@certto.com.br 2Empresa Brasileira de Pesquisa Agropecuária, Embrapa Instrumentação Agropecuária, São Carlos, SP.  1 RESUMO             O tradicional método de obtenção da curva de retenção de água no solo através da Câmara de Pressão de Richards é trabalhoso e demorado. Assim, este trabalho teve como objetivo avaliar o emprego de dois diferentes equipamentos TDR, conjugados a tensiômetros, para obter os valores de umidade volumétrica e respectivos valores de tensão, comparando-os aos resultados fornecidos pelo método tradicional. Para as medidas através dos equipamentos TDR, o solo, classificado como Latossolo Vermelho distroférrico (LVdf), foi seco ao ar e passado através de uma peneira2 mm. Os dados de curva de retenção foram ajustados utilizando-se o programa Origin 6.0 Professional através do modelo sugerido por Van Genuchten. A análise dos dados obtidos, realizada através do índice de desempenho c, mostrou que os 2 equipamentos TDR apresentaram performances similares. UNITERMOS: Câmara de Richards, técnica TDR, tensiometria.  TAVARES, M. H. F.; FELICIANO, J. J. S.; VAZ, C. M. P. COMPARATIVE ANALYSIS OF METHODS TO DETERMINE THE SOIL WATER RETENTION CURVE  2 ABSTRACT The traditional method to obtain the soil water retention curve using Richard’s pressure plate apparatus is laborious and time consuming. Thus, the objective of this work was to evaluate the use of two different TDR equipments, coupled to tensiometers, to obtain soil volumetric water content and respective tension values compared to those from traditional methods. For TDR measurements, a Rhodic Hapludox soil was air-dried and passed through a2 mm mesh sieve. Data of water retention curve were adjusted using the Origin 6.0 Professional software and the Van Genuchten model. The analysis of data based on the performance index revealed that the two TDR equipments had similar performances. KEY WORDS: Richard’s pressure plate apparatus, TDR technique, tensiometry.