M. A. Martinez

Influência de um polímero hidroabsorvente sobre a retenção de água no solo

Com este trabalho, objetivou-se avaliar a influencia da concentracao de um polimero hidroabsorvente nas caracteristicas de retencao de agua de dois solos classificados como Latossolo Vermelho-Amarelo, de textura franco-argilo-arenosa, e Argissolo Câmbico Vermelho-Amarelo, de textura argilosa. Os estudos consistiram na obtencao das curvas caracteristicas de retencao de agua desses solos misturados com o polimero hidroabsorvente Terracottem®, nas concentracoes 0,01, 0,05, 0,10, 0,15 e 0,20 dag kg-1. A avaliacao de alteracao das caracteristicas de retencao de agua foi feita com base nos valores de disponibilidade total de agua (DTA) no solo e nas umidades correspondentes a capacidade de campo e ao ponto de murchamento permanente. Verificou-se que, para potenciais matriciais superiores a -1,0 MPa, a retencao de agua foi maior a medida que se aumentou a concentracao do polimero na mistura, para os dois solos estudados. No entanto, para potenciais matriciais inferiores, a retencao de agua nao foi influenciada pela concentracao do produto. O polimero, usado na concentracao de 0,2 dag kg-1, aumentou a umidade no potencial matricial de -0,03 MPa em cerca de 41% para o solo franco-argilo-arenoso e em 37% para o solo argiloso, em relacao as respectivas testemunhas, com aumento da DTA correspondente a 123 e 135%, respectivamente.

Treatment of swine wastewater using organic filters

The primary treatment of swine wastewater can be done by filtration. To this end, the study of alternative materials as a filter media is necessary. With this objective, rice husk, coffee straw, sugarcane trash, triturated corncob, wood sawdust and fine vegetable coal were used as media, conditioned in PVC tubes of 100 mm in diameter and 500 mm in height. The filtering system was maintained under saturated flow conditions. Little or no change was detected in the concentration of N-total, Ca, Mg and Zn in the effluent of the filter, although the concentration of P-total and K increased in the effluents of the filters of rice husk, coffee straw, triturate corncob, reaching a maximum removal efficiency of 43.6%. Removal efficiencies of sedimentable solids higher than 90.0% were obtained in all materials employed as a filtration media, although total solids removal efficiency was less than 33.0%.

Influência da granulometria da serragem de madeira como material filtrante no tratamento de águas residuárias

The objective of this work was to evaluate the influence of the particle size of sawdust as filtering material on the efficiency of swine wastewater treatment. The three ranges of particles size used were 0.84 to 1.19; 1.19 to 2.00 and 2.00 to 2.83 mm. The values of biochemical oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS), total-N, total-P, total-K, total-Na, total-Cu and total-Zn were determined in the affluents as well as in the effluents. Curves of the relative concentrations of these parameters and the filtered layer were obtained. The range of particle size corresponding to the largest diameter of the material was more suitable for reducing the BOD and COD (40 and 80%, respectively). The large particle size also allowed to remove about 70% of the TS. On the other hand, the smallest particle size removed about 50% of the nitrogen. The range of particle size did not affect the removal of phosphorus, although removal up to 65% were obtained. Sodium and potassium were not removed by the sawdust filters. Copper and zinc removal were above 95%, the smallest particle size showing highest copper removal.

INFLUÊNCIA DO TIPO DE AMOSTRAGEM NA CONSTANTE DIELÉTRICA DO SOLO E NA CALIBRAÇÃO DE SONDAS DE TDR

The technique of TDR (time-domain reflectometry) is an important tool for the study of soil water content. For a correct use of this technique, models that relate the volumetric water content in soil with the soil dielectric constant must be calibrated, considering the characteristics of each soil. The purpose of this study was to evaluate the influence of soil type and sampling form (disturbed and undisturbed samples) on the dielectric constant (Ka) of the soil and the performance of models to estimate the volumetric water content in soil (θ) by TDR. The soils were a Haplic Cambisol, an Oxisol and a Typic Quartzipsamment, with different textures. Disturbed and undisturbed Haplic Cambisol and Oxisol samples were collected, but only disturbed Typic Quartzipsamment samples, due to its low aggregation. Calibration was performed with probes consisting of three rods (effective length 0.10 m and resin length 0.05 m), spaced 0.017 apart and without resistor on the center rod, connected to a TDR 100 (Campbell Scientific) equipment. The Ka values, for a same e value, were affected by variation of the soil type, but not influenced by the type of soil sampling (disturbed or undisturbed). For the models tested to estimate e as a function of Ka, the cubic polynomial model fit the θ data determined by gravimetry best for the Typic Quartzipsamment and Haplic Cambisol, whereas for the Oxisol a linear model fit better.

Influência da competição catiônica nos valores de fator de retardamento e coeficiente de dispersão-difusão de zinco e cobre no solo

The effects of the cationic competition on the retarding factor (fr) and the dispersion-diffusion coefficient (D) were evaluated with conducting metal mobility trials in leaching columns submitted to a saturated and steady flow. Solutions of zinc (700 mg L-1), copper (200 mg L-1) and zinc plus copper in the same concentrations, were used to obtain elution curves. Soil materials from the A, B and C horizons of Oxisol (LVa) and of Ultisol (PVc), collected in Vicosa, MG, were used. In all soil materials used, copper presented higher retarding factor values than zinc, which indicates a higher copper-soil interaction. The low velocities of the solutions resulted in low dispersion-diffusion coefficient values. Cationic competition decreased the soil retention capacity for the cations.

Relação da velocidade de escoamento da solução e do comprimento da coluna de solo com os parâmetros de transporte de potássio em um latossolo e um neossolo

Due to the importance of studying solute displacement in soil columns to evaluate soil and groundwater pollution risks, and the lack of standardization in the soil column length (L) and also the pore-water velocity () used, this study evaluated the relation of L and with the dispersive-diffusive coefficient (D), the dispersivity (λ) and retardation factor (R) of the potassium ion (K+) in an Oxisol and in a Dystric Quartzarenic Neosol. Five column lengths were tested (0.10, 0.20, 0.30, 0.40, and 0.50 m) and four pore-water velocities (0.62, 0.69, 0.75, and 0.81 m h-1 for the Oxisol and 0.37, 0.40, 0.44, and 0.48 m h-1 for the Neosol). A displacement solution of 130 mg L-1 of K+ was applied to the disturbed soil columns saturated with a 5 mmol L-1 CaCl2 solution. The transport parameters R and D were obtained using the computer program Disp; λ was obtained by the equation D = Do + λ, in which Do is equal to 7.13 10-6 m2 h-1 for KCl. The column length and pore-water velocity were related with parameters of the K+ transport in both soils. In the Oxisol, the retardation factor increased with increasing pore-water velocity. In both soils, the retardation factor decreased with increasing column length, the dispersive-diffusive coefficient increased with increasing pore-water velocity and increasing soil column length and dispersivity also increased with increasing column length.

Perda de carga contínua em tubulações conduzindo água residuária da suinocultura

This research was performed to evaluate and introduce mathematical models to estimate head losses in zinc steel, galvanized iron and PVC tubes and diameters ranging from 2 to 6 inches. The total solid concentration of swine liquid manure was: 0.98, 2.08, 4.73, 7.69 and 8.56%. The methods based on the Universal equation using the Generalized Reynolds Number showed an adjustment worse than the ones obtained through the empirical equations proposed in this work. Those equations were established from Duff & Titchener and Modified Hazen-Williams methodologies and showed a better adjustment with coefficients of determinations above 0.98 and thus may be recommended for pumping projects.

Influence of swine wastewater application on the infiltration capacity of a red-yellow podzolic soil.

This work was carried out at the Experimental Area of Hydraulics, Irrigation and Drainage of the Agricultural Engineering Department, at the Federal University of Vicosa, Vicosa, Minas Gerais, Brazil. The aim was to evaluate the influence of successive applications of swine wastewater, with different concentrations of total solids, on the infiltration capacity of a Yellow Red Podzol. The experiment was conducted in a completely randomized design with five treatments and three replications. The treatments consisted of applying water and swine wastewater with 2.4, 7.0, 16.3 and 26.9 g L-1 of total solid concentrations. Fifteen ring infiltrometers were installed in an area of 60 m2, which was divided in plots of 2 x 2 m dimensions. Four infiltration tests were performed at 15 day intervals in each plot. It was concluded that increasing the total solid concentration of swine wastewater caused a reduction of the soil infiltration capacity. In addition, it was observed that successive applications intensified this effect. The total solid concentration of wastewater was more important to reduce the soil infiltration capacity than the levels of sodium absorption ratio and salinity.