RESUMEN
Tobacco is the most widespread non-food crop in the world. In Brazil, tobacco cultivation is one of the main commodities of the southern region. However, its production is associated with environmental impacts and risks to human health, which have yet to be quantified. This paper uses midpoint and endpoint life cycle assessment (LCA) to analyze the potential environmental damage and human health risk associated with agricultural production of conventional Virginia (CV), organic Virginia (OV), and Burley (BU) tobacco varieties. Organic tobacco production substitutes synthetic fertilizers and pesticides with organic compounds in the cropping stage. The results show that for one ton of dried tobacco, BU, CV, and OV emit 1,610, 1,426, and 1,091 kg CO2 eq, respectively. For organic production, greater impacts are linked to the land use (LU) impact category. The endpoint results showed that OV production resulted in a higher potential for human and environmental damage than BU and CV. The drying of green OV and CV tobacco requires the burning of firewood, which emits high levels of particulate matter and is associated with human health (HH) damage. Overall, the HH damage category accounts for 68%, 82%, and 78% of the total score points associated with the production of BU, CV, and OV.
Asunto(s)
Fertilizantes , Nicotiana , Agricultura , Brasil , Humanos , VirginiaRESUMEN
RESUMO O sistema integrado com microalgas (MA) e wetland construído de fluxo vertical (wetland construído pós-microalgas - WCPMA) foi aplicado para a realização de ensaios de tratamento de efluentes no campus da Universidade de Santa Cruz do Sul, no Rio Grande do Sul (UNISC-RS). Águas negras e amarelas foram alimentadas para esse sistema em regime de batelada a partir de um tanque equalizador da estação de tratamento de efluentes da universidade, considerando tempo de detenção hidráulica (TDH) de três dias para cada unidade do sistema integrado. O comparativo de desempenho foi feito com unidades também envolvendo a sequência de tanque de armazenamento de efluentes (TAE) + sistema de controle (C), somente com suporte de areia e brita, em triplo estágio, bem como wetlands construídos de fluxo vertical, também em triplo estágio. O abastecimento utilizou fatores de carga em termos de demanda química de oxigênio (DQO) de 2,4±0,9 g m-1dia-1 para o TAE e de 26,7±11,2 g m-1dia-1 para as unidades de wetlands construídos, de MA+WCPMA e de C (sem o cultivo da Hymenachne grumosa). Em relação à unidade TAE+MA+WCPMA, as reduções dos parâmetros de cargas poluentes foram mais significativas em termos de demanda bioquímica de oxigênio (DBO5) (58%), fósforo total (63%) e, principalmente, nitrogênio amoniacal no sistema integrado, com redução de 100%. Em termos de toxicidade aguda com Daphnia magna, a detoxificação foi efetiva, com variações de valores de EC50 de 58 a 100%. O estudo obteve resultados expressivos que indicam que o sistema MA+WCPMA é uma alternativa promissora no tratamento de águas residuárias para unidades geradoras descentralizadas, possibilitando maior redução da ação eutrofizante.
ABSTRACT The application of integrated systems with microalgae (MA) and Vertical Flow Constructed Wetland Post Microalgae (CWPMA) was performed for campus wastewater treatment assays located in Santa Cruz do Sul (UNISC-RS). Black and yellow waters were fed to systems in batch regime from equalizer university wastewater treatment plant tank, considering hydraulic detention time (HDT) of three days for each unity of the integrated system (MA+CWPMA). The comparison of performances was also made with units involving storage tank wastewater (STW)+Control System (C), only supported with sand and gravel in triple stage, as well as CWs, also triple stage. The supply used load factors in terms of COD 2.4±0.9g m-1 day-1 (for STW) and 26.7±11.2 COD m-1day-1 for the units of CWs; MA+CWPMA and Control (without the cultivation of Hymenachne grumosa). Reductions of the parameters of pollution loads were more significant in terms of BOD5 (58%), total phosphorous (63%) and especially in terms of ammonia nitrogen in integrated STW+MA+CWPMA, with a reduction of 100%. In terms of acute toxicity with Daphnia magna, detoxification was effective, with EC50 values ranging from 58 to 100%. The study developed obtained significant results that indicate this is a promising alternative in the treatment of wastewater for decentralized generating units, allowing greater reduction in eutrophic action.
RESUMEN
The microalgae Desmodesmus subspicatus (Chlorophyta) was cultivated in a tubular photobioreactor using effluent from the wastewater treatment plant of the University of Santa Cruz do Sul, Brazil to demonstrate the reactor's operation. The algae's ability to remove nutrients from wastewater and the oleaginous potential of the algae's biomass were also evaluated. Total phosphorus and ammonia nitrogen were measured. The photobioreactor consisted of a system of three acrylic tubes, a reservoir, connections and a CO2 supply. The gas supply was semicontinuous with CO2 added from a cylinder. The culture's growth was estimated from cell numbers counted on a daily basis. Lipid content in the biomass was analysed using gas chromatography. A maximum cell density of 9.11 x 10(6) cellsmL-1 and a dry weight of 234.00 mg L-1 were obtained during cultivation without CO2, and these values rose to 42.48 x 10(6) cells mL-1 and 1277.44 mg L-1, respectively, when CO2 was added to the cultivation. Differences in the quality of the effluent and the presence of CO2 did not result in different lipid profiles. The presence ofpalmitic acid and oleic acid was notable. The average extracted oil content was 18% and 12% for cultivation with and without the input of CO2, respectively.