Enhanced nutrient removal from municipal wastewater assisted by mixotrophic microalgal cultivation using glycerol

Abstract

In a present study, nutrient removal from municipal wastewater by Chlorella vulgaris and Nannochloropsis oculata was investigated by using mixotrophic cultivation with glycerol (0 to 5 g/L). Performance parameters were assessed by estimating the removal of total nitrogen, total phosphorus, chemical oxygen demand (COD), biomass growth, chlorophyll content, lipid yield, and fatty acids. With the addition of 2 g/L glycerol, a maximum biomass productivity of 56 mg/L/day was achieved in the mixotrophic culture of C. vulgaris within 12 days. The mixotrophic culture showed a 30-fold increase in biomass productivity compared to the wastewater without any glycerol. However, the highest total nitrogen removal (80.62 %), total phosphate removal (60.72 %), and COD removal (96.3 %) was observed in the N. oculata culture supplemented with 3, 5, and 1 g/L glycerol, respectively. These results suggest that mixotrophic cultivation using glycerol offers great potential in the production of renewable biomass, waste water treatment, and consequent production of high-value microalgal oil. Graphical Abstract Simultaneous biomass production and nutrient removal using microalgae cultivated in wastewater supplemented with glycerol.

Nutrient removal and carbohydrate production potential of indigenous Scenedesmus sp. grown in anaerobically digested brewery wastewater

“…The differences in phosphorus removal among various studies might be due to the uptake of phosphorus by microalgae is affected by algal physiology, initial phosphate concentration, and chemical form of available phosphate, light intensity, pH, and temperature (Gupta et al 2016). Choi and Lee (2014) also shown that removal of TN depends on the N/P ratio, which affects biomass growth and, N and P nutrients removal in wastewater.…”

Opportunities and Challenges of Microalgal Cultivation on Wastewater, with Special Focus on Palm Oil Mill Effluent and the Production of High Value Compounds

“…Perez-Garcia 115 found the highest growth rate and ammonium uptake of C. vulgaris growing on sterilized municipal wastewater when adding sodium acetate under heterotrophic conditions, while the absence of external carbon supplementation resulted in reduced growth. Gupta et al [49] reported that the addition of glycerol enhanced biomass productivity and nutrient uptake of C. vulgaris and Nannochloropsis oculata, when cultivated on municipal wastewater. Similar results were reported by Ma et al [87] who reported that nutrient uptake and lipid yield was increased when synthetic wastewater was supplemented with waste glycerol.…”

“…To optimize wastewater utilization, pretreatment processes of the raw source need to be employed. Several researchers reported that a high turbidity from the wastewater may induce heterotrophic or mixotrophic growth that benefits biomass production, lipid accumulation, and nutrient uptake [5,49]. Furthermore, to provide CO 2 for mixotrophic cultivation, and lowering COD and BOD content in POME, the wastewater could be processed in an anaerobic fermentor, resulting in methane that could be used directly as an energy source.…”

Microalgal cultivation with waste streams and metabolic constraints to triacylglycerides accumulation for biofuel production

“…Crude glycerol can be used as a feedstock for the cultivation of lipid producing microalgae and the lipid produced can then be reused for biodiesel production. Growth and lipid production studies using glycerol as an organic C‐source have been conducted using C. protothecoides, C. vulgaris , S. limacinum, N. oculata , B. braunii , Haematococcus sp ., Nannochloris sp ., and Scenedesmus sp . to demonstrate the potential for recycling crude glycerol generated during biodiesel production in the cultivation process.…”