The Cycle of Nutrients at Industrial Plants: Valorization of Energetic-Laden Wastewater Streams Using Microalgae Scenedesmus Obliquus to Produce Bioenergy

Juliana Abraham^1*, Abhishek Roychowdhury¹, Christos Christodoulatos¹, Yanxia Lin¹, Per Arienti², Benjamin Smolinski², and Washington Braida¹

¹Stevens Institute of Technology

²RDCOM-ARDEC, Picatinny Arsenal

Manufacture of energetic compounds generates large quantities of wastewater streams which need to be treated before disposal to avoid contamination and eutrophication of water bodies. A sustainable approach is proposed to recover nutrients from wastewaters and obtain energy in an industrial base munitions facility. Ten different fully characterized wastewater streams with various levels of organic carbon content and N-NO₃^- were assessed for microalgae toxicity using Scenedesmus obliquus ATTC® 11477 as target microorganism. Toxicity experiments were performed per quadruplicates in microplates for 6 days at 25ºC, 120 rpm under a 14:10 hours light:dark photoperiod and 3700 lux of light intensity. The results showed that the majority of the wastewater streams assessed could be used as nutrient media without pretreatment while only two of the streams required chemical treatment due to high growth inhibition. Moreover, significantly higher biomass growth (as compared to controls) was obtained in bioremediation tests, executed with the same microalgae cultures but without nutrient addition, likely due to the degradation of these energetic compounds by the microalgae, as suggested by analytical evidence. Consequently, the culture of S. obliquus using these wastewaters was scaled-up to 100L open pond raceway reactors to assess nutrients uptake in addition to lipid and biomass production. This study suggests the potential feasibility of using explosives-laden industrial untreated wastewater along with CO₂ (atmospheric or flue gases) for microalgae biomass production which can subsequently be transformed into various types of bio-renewable energy such as biodiesel by transesterification or biogas by anaerobic digestion.