Microalgae population dynamics in photobioreactors with secondary sewage effluent as culture medium

Abstract

Nitrogen and phosphorus present in sewage can be used for microalgae growth, possibiliting cost reduction in the production of microalgae at the same time that it decreases the eutrophication potential of the effluent. This research aimed at monitoring the native community of microalgae and coliform bacteria in a secondary effluent from anaerobic municipal sewage treatment. Two treatments (aerated and non-aerated) were performed to grow microalgae under semi-controlled conditions in semi-closed photobioreactors in a greenhouse. The results showed no significant pH and coliforms (total and Escherichia coli ) variation between treatments. Nutrient concentrations were reduced supporting microalgae growth up to 10 7 cells.mL −1 independent of aeration. Exponential growth was obtained from the first day for the non-aerated, but a 5 day lag phase of growth was obtained for the aerated. Chlorella vulgaris was the dominant microalgae (99.9%) in both treatments. In the aerated, 5 algae classes were detected (Chlorophyceae, Cyanophyceae, Chrysophyceae, Bacillariophyceae and Euglenophyceae), with 12 taxa, whereas in the non-aerated, 2 classes were identified (Chlorophyceae and Cyanophyceae), with 5 taxa. We concluded that effluent is viable for microalgae growth, especially Chlorella vulgaris, at the same time that the eutrophication potential and coliforms are decreased, contributing for better quality of the final effluent.

Nutrient Removal by Suspended and Biofilm Microalgae for Treating the Wastewater of Agro-Industrial Pig Farm

“…However, for biofilm microalgal system, an average pH in the beginning of cultivation cycle was 7.51, and then the pH was rapidly increased up to an average of 8.92 after the first 2 days of cultivation time, but after that the pH was slowly decreased through the end of cultivation cycle and ended up with an average of 7.03 ( Table 1). These results are in agreement with the study of Marchello et al [38], which also found that pH had a tendency to increase when microalgae were growing due to a reduction of CO 2 in the system. Besides, the decreased pH in biofilm system could be explained by a lower phototrophic activity of microalgae, which possibly caused by the light and/or nutrients limitation.…”

Effect of Different Light Sources on Algal Biomass and Lipid Production in Internal Leds-Illuminated Photobioreactor

“…Nitrogen and phosphorus present can be used for microalgae growth (organic pollutants into cellular constituents in lipid and carbohydrate forms) and possibly lead to cost reductions in the cultivation of microalgae. Chlorella vulgaris (C. vulgaris) was observed as one of the dominant microalgae strain by using sewage as the cultivation medium [3,6] .…”

Microalgae Potential and Multiple Roles—Current Progress and Future Prospects—An Overview

“…Microalgae releases some exudates which inhibit the growth of pathogenic microorganisms. Microalgal treatment is sustainable and efficient in the reduction of coliforms in effluent before being discarded from the sewage treatment plants [77].…”