Potential of diatom consortium developed by nutrient enrichment for biodiesel production and simultaneous nutrient removal from waste water

Abstract

Because of the decreasing fossil fuel supply and increasing greenhouse gas (GHG) emissions, microalgae have been identified as a viable and sustainable feedstock for biofuel production. The major effect of the release of wastewater rich in organic compounds has led to the eutrophication of freshwater ecosystems. A combined approach of freshwater diatom cultivation with urban sewage water treatment is a promising solution for nutrient removal and biofuel production. In this study, urban wastewater from eutrophic Hussain Sagar Lake was used to cultivate a diatom algae consortium, and the effects of silica and trace metal enrichment on growth, nutrient removal, and lipid production were evaluated. The nano-silica-based micronutrient mixture Nualgi containing Si, Fe, and metal ions was used to optimize diatom growth. Respectively, N and P reductions of 95.1% and 88.9%, COD and BOD reductions of 91% and 51% with a biomass yield of 122.5 mg L day and lipid productivity of 37 mg L day were observed for cultures grown in waste water using Nualgi. Fatty acid profiles revealed 13 different fatty acids with slight differences in their percentage of dry cell weight (DCW) depending on enrichment level. These results demonstrate the potential of diatom algae grown in wastewater to produce feedstock for renewable biodiesel production. Enhanced carbon and excess nutrient utilization makes diatoms ideal candidates for co-processes such as CO sequestration, biodiesel production, and wastewater phycoremediation.

Impact of microalgae layer thickness on the treatment performance of drain water

“…After the microalgae layer, the removal ratio was noticeable and affected by the layer thickness, it varied between (22.1 to 46.9%) with an optimum value at the layer of thickness 10 mm and this agreed with the study that proved the success of microalgae in the removal of 91% of COD from wastewater 29 and in another study by 95% 32 . Also, the COD removal continued inside the channel after the microalgae layer due to the availability of enough DO for oxidation of organic and inorganic matters that increased the removal ratios of COD but with declining rates.…”

“…After the microalgae layer, the removal ratio was affected by the layer thickness varied between (15 to 29%) with an optimum value at the layer of thickness 10 mm, and this agreed with the study that proved the success of microalgae in the removal of 51% of BOD from wastewater 29 , and in another study by ratio 93% 13 (but here we are discussing the effect of thickness of microalgae layer on the removal efficiency of microalgae), also the BOD removal continued inside the channel due to the availability of enough DO for oxidation needs. However, the removal rate decreased over time.…”

Domestic Wastewater Treatment and Lipid Accumulation for Biodiesel Production by an Isolated Heterotrophic Microalgae from an Arid Climate Zone

“…COD and BOD reductions of 91% and 51% respectively, were achieved over a period of 10 days in Nualgienriched samples [20].…”

Investigation of the Phycoremediation Potential of Freshwater Green Algae Golenkinia radiata for Municipal Wastewater

“…Sustainability 2022, 14, x FOR PEER REVIEW 14 of 20 PO4 −3 , HPO4 −2 and H2PO4 − ) is considered to be the most preferred P-form by microalgae [42,63]. Moreover, if the amount of ortho-PO4 in WW is inadequate, microalgae may transform organic-PO4 to ortho-PO4 and use it [33,64].…”