Depuração de efluente suinícola por Lemna minor e valorização energética da biomassa por co-digestão anaeróbia

Mestrado em Engenharia do Ambiente - Instituto Superior de AgronomiaOver the last decades, phytodepuration has been considered an efficient technology to treat agricultural wastewaters. Swine wastewater is rich in nutrients that can be used to grow biomass, producing a treated wastewater that can be used for irrigation and a biomass that may be useful for potential energy production by anaerobic digestion (AD). In this study a comparative polishing treatment assays were developed, at a bench scale, through Lemna minor growth in swine wastewater (4%) with similar concentration at a real scale last lagoon and Lemna minor growth in synthetic medium. The highest observed growth rate obtained in swine wastewater was 28.7 ± 2.3 g m-2 day-1 or 3.1 ± 0.3 gDM m-2 day-1. The highest nitrogen and phosphorus uptake rates in swine wastewater system were 140 mg m-2 day-1 and 3.47 mg m- 2 day-1, respectively. The COD removal efficiency was 60.0 ± 1.0%. Furthermore, an integrated approach was investigated assessing possible valorisation of biomass by anaerobic co-digestion of swine wastewater with Lemna minor. Results showed a clear improvement in gas production rate and methane specific production in 40% and 44%, respectively, when compared to mono-substrate digestio