Análise da sustentabilidade ambiental na agroindústria canavieira utilizando a pegada hídrica.

Abstract

Water footprint (WF) is a concept that represents the direct and indirect consumption of water in a given process, product, or area. Currently, the agricultural sector is the main consumer of water worldwide; therefore, studies are necessary the WF of this industry. The objective of the present study is to evaluate WF as an indicator of the environmental sustainability of the sugarcane agroindustry in the municipality of Camutanga, Pernambuco, located in the sub-basin of the Capibaribe Mirim river. The WF assessment was performed according to the WF methodology manual and ISO 14046:2014 with the following steps goal, setting and scope, WF calculation, sustainability assessment, and WF reduction measures. The WF analysis was based on data regarding sugarcane cultivation and the production of ethanol and sugar, from the first crop (2016/2017) and second crop (2017/2018) from the Usina Olho D'Água. For this analysis, the green, blue, and gray WF of the sugarcane agroindustry was evaluated. In the sustainability analysis of the green WF, the normalized difference vegetation index (NDVI) was used for mapping land use and occupation. In studying the environmental sustainability of WF with respect to the examined crops and a historical series from 2000 to 2017, dry, rainy, monthly, and harvest seasons were considered. The indicators used to assess the environmental sustainability of WF consisted of green water scarcity (WSgreen), blue water scarcity (WSblue), and the water pollution level (WPL). In addition, the proposed measures for reducing WF were prioritized for unsustainable footprints. Finally, using the WPL and the classification of human and environmental toxicity, the pollutants used in the two harvests were analyzed to identify the ones least harmful to humans and the environment. The results revealed a total WF of sugarcane amounting to 2364.87 m³/t and 1043.92 m³/t for the first and second crops, respectively, with the largest contribution generated by the gray component at levels of 86% and 75%, respectively. In the product manufacturing process, ethanol obtained a higher WF of approximately 10 m³/t, while sugar obtained a WF of 4.7 m³/t on average for the two harvests. In the hydrographic sub-basin of the Capibaribe Mirim river in which the Usina Olho D'Água is located, the use of agricultural areas prevailed at 41.28%, while the water mirror with 0.52% of the total area of sub-basin. These values for land use and occupation indicate that WSgreen was sustainable for the studied periods. Unsustainable points regarding WSblue were identified only in the dry and monthly periods of the two harvests. The WPL of the sugarcane agroindustry was unsustainable for the majority of periods, with values of 1221.93% and 798.28% for the first and second crops, respectively, represented by the pesticides Diurom 800 and Imazapique. Concluded that the use of the WF to analyze the environmental sustainability of the sugarcane agroindustry succeeded in providing an understanding of the relationship between the industry and water resources in the Capibaribe Mirim sub-basin, aiding in the water management of the region. This study was the first to examine the effects of pesticides as critical pollutants in analyzing the environmental sustainability of the WF of sugarcane cultivation.