Nakarmi Kanchan J, Daneshvar Ehsan, Mänttäri Mika, Bhatnagar Amit
Department of Separation Science, LUT School of Engineering Science, LUT University, Sammonkatu 12, FI-50130, Mikkeli, Finland.
Department of Separation Science, LUT School of Engineering Science, LUT University, Sammonkatu 12, FI-50130, Mikkeli, Finland.
J Environ Manage. 2023 Nov 1;345:118922. doi: 10.1016/j.jenvman.2023.118922. Epub 2023 Sep 7.
Treatment of septic tank wastewater (STWW) with high concentrations of ammonium (NH) and total phosphorus (TP), is challenging in decentralized areas. Utilizing microalgae for STWW treatment can simultaneously recover nutrients in the form of high-value microalgal biomass. However, despite the potential benefits, microalgal treatment of STWW is rarely reported. Therefore, this work utilized bench-scale photobioreactors (PBR) to investigate different factors that could affect microalgal cultivation in STWW and treatment efficiency. Accordingly, it was observed that suspended solids present in STWW did not significantly affect the microalgae growth and nutrient removal efficiencies in bubble column PBR. On the other hand, the effect of endemic microorganism could not be verified in this study due to observed fungal contamination and change in nutrient profile of STWW after autoclave. Nevertheless, the highest microalgal growth and nutrient removal efficiencies of NH-N = 79.14% and TP = 41.11% were observed within 14 days of photoautotrophic cultivation in raw STWW. Further, 25 days of upscaled photoautotrophic cultivation in 4-L bubble column PBR was performed to study biomass yield, nutrient removal kinetics, and nutrient removal efficiency. Consequently, 0.75 g‧L dry biomass was produced with improved removal efficiency of NH-N (96.16%), and TP (69.57%). Elemental analysis of biomass revealed that 62.99 ± 1.46 mg‧L TN and 11.41 ± 1.42 mg‧L TP were recovered. Further, 1.02 g carbon dioxide (CO) was bio-fixed with every liter of STWW treated. The findings of this study revealed that microalgae can be successfully utilized for the removal and recovery of nutrients from STWW.
处理含有高浓度铵（NH）和总磷（TP）的化粪池废水（STWW），在分散地区具有挑战性。利用微藻处理STWW可以同时以高价值微藻生物质的形式回收养分。然而，尽管有潜在益处，但微藻处理STWW的报道却很少。因此，本研究利用实验室规模的光生物反应器（PBR）来研究可能影响STWW中微藻培养和处理效率的不同因素。据此观察到，STWW中存在的悬浮固体对鼓泡塔PBR中的微藻生长和养分去除效率没有显著影响。另一方面，由于观察到真菌污染以及高压灭菌后STWW养分特征的变化，本研究无法验证本地微生物的影响。尽管如此，在未经处理的STWW中进行14天的光合自养培养后，观察到微藻生长和养分去除效率最高，NH-N为79.14%，TP为41.11%。此外，在4-L鼓泡塔PBR中进行了25天的放大光合自养培养，以研究生物质产量、养分去除动力学和养分去除效率。结果，产生了0.75 g‧L的干生物质，NH-N（96.16%）和TP（69.57%）的去除效率有所提高。生物质的元素分析表明，回收了62.99±1.46 mg‧L的TN和11.41±1.42 mg‧L的TP。此外，每处理一升STWW可生物固定吸收1.02 g二氧化碳（CO）。本研究结果表明，微藻可成功用于从STWW中去除和回收养分。
