Remoção mecânica de plantas aquáticas: análise econômica e operacional
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Data
2002-01-01
Autores
Antuniassi, U.R. [UNESP]
Velini, Edivaldo Domingues [UNESP]
Martins, D. [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Brasileira da Ciência das Plantas Daninhas
Resumo
A remoção de plantas aquáticas tem sido utilizada como opção ao controle químico e biológico, em razão de restrições ambientais em algumas regiões brasileiras. O objetivo deste trabalho foi desenvolver um modelo para análise econômica e operacional da remoção mecânica de plantas aquáticas, visando realizar estudo econômico comparativo com o controle químico. A operação foi estudada num reservatório de uma usina de bombeamento em Barra do Piraí-RJ. O sistema consiste de retroescavadeiras instaladas em balsas, usadas para cortar as plantas e liberá-las no fluxo de água. Antes da tomada d'água existe uma barreira flutuante que intercepta as plantas, as quais são removidas por um guindaste fixo nas margens. As plantas são armazenadas por algum tempo e depois descartadas. Existe, ainda, um sistema de limpeza das grades da tomada d'água. Dados do volume total de plantas descartadas foram coletados durante 14 meses, assim como foi avaliado o volume de biomassa produzido por área das principais espécies infestantes. A empreiteira que administra o serviço forneceu planilhas de custos e outro parâmetros operacionais. Um modelo foi desenvolvido para calcular custos por hectare de plantas removidas. Os resultados mostraram custo médio mensal de US$ 17.780,28 por hectare. Apesar do alto custo, o sistema de remoção demonstrou capacidade de controlar apenas 4,1% da área infestada no reservatório, na época da coleta dos dados. Simulando dados de uma aplicação de glyphosate, o controle químico custaria apenas 0,23% do custo da remoção. Análises de sensibilidade mostraram que a compactação das plantas para transporte, o volume de plantas produzidas por área e o custo do transporte são os parâmetros principais para a otimização.
Mechanical removal of aquatic weeds has been an option to biological and chemical control because of environmental restrictions in some places in Brazil. The objective of this study was to develop a model for economic and operational analysis of a mechanical removal system for aquatic weeds, aiming a comparative study related to chemical control. The operation was studied in a reservoir linked to a pumping plant in Barra do Piraí-RJ, Brazil. The system consists of some cranes floating on rafts used to cut weeds and release them into the water flow. Before the suction intake there is a floating barrier to trap the weeds, which are removed from the reservoir by another crane, fixed on the embankment. Weeds are stored for some time and then transported to a disposal place. In addition, there is a fence to protect the suction intake from weeds that passed through the barrier and a mechanical system to clean up the fence. Data related to the total volume of weeds transported to the disposal place were collected for 14 months, and the volume produced per square meter of infestation for the major weeds was assessed. The company in charge of the system provided costs and other operational parameters, developing a model based on operational and cost parameters to calculate the total cost per hectare of weeds removed. The results showed an average monthly cost of US$ 17,780.28 per hectare of weeds removed. Despite the high costs, the system was able to control only 4.1% of the infested area in the reservoir at the time data was collected. Using simulated data for glyphosate application, chemical control would cost only 0.23% of the mechanical removal cost. The Sensitivity analyses showed that the compaction of the weeds for transportation, the volume of weeds produced per area and the cost of transportation are major parameters for the optimization of the system.
Mechanical removal of aquatic weeds has been an option to biological and chemical control because of environmental restrictions in some places in Brazil. The objective of this study was to develop a model for economic and operational analysis of a mechanical removal system for aquatic weeds, aiming a comparative study related to chemical control. The operation was studied in a reservoir linked to a pumping plant in Barra do Piraí-RJ, Brazil. The system consists of some cranes floating on rafts used to cut weeds and release them into the water flow. Before the suction intake there is a floating barrier to trap the weeds, which are removed from the reservoir by another crane, fixed on the embankment. Weeds are stored for some time and then transported to a disposal place. In addition, there is a fence to protect the suction intake from weeds that passed through the barrier and a mechanical system to clean up the fence. Data related to the total volume of weeds transported to the disposal place were collected for 14 months, and the volume produced per square meter of infestation for the major weeds was assessed. The company in charge of the system provided costs and other operational parameters, developing a model based on operational and cost parameters to calculate the total cost per hectare of weeds removed. The results showed an average monthly cost of US$ 17,780.28 per hectare of weeds removed. Despite the high costs, the system was able to control only 4.1% of the infested area in the reservoir at the time data was collected. Using simulated data for glyphosate application, chemical control would cost only 0.23% of the mechanical removal cost. The Sensitivity analyses showed that the compaction of the weeds for transportation, the volume of weeds produced per area and the cost of transportation are major parameters for the optimization of the system.
Descrição
Palavras-chave
plantas aquáticas, remoção mecânica, custos, aquatic weeds, mechanical removal, costs
Como citar
Planta Daninha. Sociedade Brasileira da Ciência das Plantas Daninhas , v. 20, n. spe, p. 35-43, 2002.