Assessment of hydraulic conductivity improvement due to vibration application at riverbank

Groundwater abstraction is a process of obtaining subsurface water sources for variety purpose of consumption. However, due to long and continuous pumping, the efficiency might decrease because of soil clogging. This decreased can be quantified and reflected as the change of hydraulic conductivity (K) values at the pumping site. This study aims to assess the variability of soil hydraulic conductivity at groundwater pumping site and also to study the effectiveness of vibration method to improve the hydraulic conductivity by comparing the result of before and after vibration is applied. The study was carried out by measuring the K values using slug test at wells MW01 and MW02 with two durations of vibration which were 45 minutes and 60 minutes. The result shows that values of hydraulic conductivity of the soil were found to have increased for both MW0l and MW02 wells. On first trial, the hydraulic conductivity increases for MW0l and MW02 are 16.7% and 39.3% while on second trial, the percentage increases for MW01 and MW02 are 54.3% and 11.1% respectively. Although the change for MW02 decreased for 60 minutes vibration, it can still be noted as there is a positive impact of vibration to the K value and further extensive data collection will be able to provide better assessment. Thus, it has been proven that the vibration method can be effective in reducing the soil clogging effect and also able to improve the hydraulic conductivity of the soil.

WETLANDS CONSTRUÍDOS COM MEIO SUPORTE DE SOLO NA REMOÇÃO DE COLIFORMES TERMOTOLERANTES DE ESGOTOS DOMÉSTICOS

<p>O trabalho avaliou o desempenho dos <em>wetlands</em> construídos de fluxo vertical (WCFV) com meio suporte de solo misturado com areia na remoção de coliformes termotolerantes (CTer). O experimento era composto por dois sistemas: 1. Monocultura: Latossolo vermelho-amarelo plantado com a cultura do arroz (<em>Oriza sativa</em> L), operado com diferente taxa de aplicação de hidráulica (TAH) de esgoto de 4 cm/d, 8 cm/d e 15 cm/d; 2. Policultura: Latossolo amarelo plantado com as culturas do arroz (<em>Oriza sativa</em> L), do feijão (<em>Phaseolus vulgaris</em> L) e do milho (<em>Zea mays</em>), operado com TAH de 2,4 cm/d e 4,7 cm/d. As eficiências de remoção de CTer variaram, respectivamente, de 87,8% a 100% e 97,8% a 100% nos sistemas 1 e 2. Os fatores que contribuíram para a remoção de CTer foram a baixa umidade, o baixo teor de matéria orgânica e a colmatação. Os dois solos se mostraram eficientes na remoção de CTer. A rotação de culturas proporcionou uma remoção maior e em um período mais longo de tempo de operação, além de ter contribuído para um maior controle a colmatação do solo. Independentemente do tipo de solo e dele estar sendo cultivado com monocultura ou policultura, nos primeiros cinco meses de operação dos sistemas (1º ciclo), as TAH mais baixa favoreceram uma maior remoção de CTer com maior variabilidade nas eficiências de remoção. Com a continuidade da aplicação do esgoto para tratamento (2º ciclo), as eficiências de remoção reduziram e se tornaram aproximadamente constantes, sendo maiores quando se utilizou maior TAH.</p><p><strong>Palavras chaves:</strong> condutividade hidráulica; águas residuárias; microrganismos patogênicos; colmatação, rotatividade de culturas.</p><p> </p><p align="center">WETLANDS CONSTRUCTED WITH SOIL SUPPORT MEDIUM IN REMOVAL OF THERMOTOLERANT COLIFORMS FROM DOMESTIC SEWAGE</p><p><strong>Abstract</strong></p><p>The work evaluated the performance of constructed wetlands vertical flow (WCFV) with soil support medium mixed with sand in the removal of thermotolerant coliforms (ThC). The experiment consisted of two systems: 1. Monoculture: Red-yellow Latosol planted with rice (<em>Oriza sativa</em> L), operated with hydraulic application rates (HAR) of 4 cm/d, 8 cm/d and 15.0 cm/d; 2. Polyculture: Yellow Latosol planted with rice (<em>Oriza sativa</em> L), beans (<em>Phaseolus vulgaris</em> L) and maize (<em>Zea mays</em>), operated with HAR of 2.4 cm/d and 4.7 cm/d. ThC removal efficiencies ranged from 87.8 to 100% and 97.8 to 100%, respectively, in systems 1 and 2. The factors that contributed to the removal of ThC were low humidity, low organic matter and clogging. Both soils proved to be efficient in removing ThC. Crop rotation provided greater removal in a longer period of operation, in addition to controlling soil clogging. Regardless of the type of soil and whether it is being cultivated with monoculture or polyculture, in the first five months of operation of the systems (1st cycle), the lower HAR favored greater removal of ThC with greater variability in removal efficiency. With the continued application of sewage for treatment (2^nd cycle), the removal efficiencies reduced and became approximately constant, being higher for the highest HAR.</p><p><strong>Key words: </strong>hydraulic conductivity; wastewater; pathogenic microorganisms; clogging, crop rotation.</p>