Surfactant removal and biomass production in a microalgal-bacterial process: effect of feeding regime

Abstract

<jats:title>Abstract</jats:title> <jats:p>The influence of the feeding regime on surfactant and nutrient removal and biomass production was evaluated in three high rate algal ponds for primary domestic wastewater treatment. Feeding times of 24, 12 and 0.1 h d−1 were studied in each reactor at a similar hydraulic retention time of 7.0 days and organic load of 2.3 mg m−2 d−1. Semi-continuous feeding at 12 and 0.1 h d−1 showed better microalgal biomass production (0.21–0.23 g L−1) and nutrient removal, including nitrogen (74–76%) and phosphorus (80–86%), when compared to biomass production (0.13 g L−1) and nitrogen (69%) and phosphorus (46%) removals obtained at continuous feeding (24 h d−1). Additionally, the removal efficiency of surfactant in the three reactors ranged between 90 and 97%, where the best result was obtained at 0.1 h d−1, resulting in surfactant concentrations in the treated effluent (0.3 mg L−1) below the maximum freshwater discharge limits.</jats:p>

CO2 Uptake and Domestic Wastewater Treatment by Chlorella vulgaris

“…Nevertheless, these concentration can be reduced to less than 1 mg/L with treatment efficiencies of 97.99% (in 40% DWW) and 98.91% (in 60% DWW). Similar results were found in a study conducted by Serejo et al (2020) [36], where absorption efficiencies reached 90-97%, much higher than those for nitrogen and phosphorus. Several other microalgae species, such as Scenedesmus sp., Chlamydomonas sp., Chlorococcum humicola, and Botryococcus braunii, have also showed performance above 90% in eliminating surfactants when applied to urban wastewater with a retention time of 10 days in a batch system hena [37].…”

“…The 26th Conference of the Parties (COP26), which took place in Glasgow, Scotland in 2021, marked a collective commitment by various countries to limit the global temperature increase to a maximum of 1.5 °C and achieve net zero emissions (NZE) by 2050 [1]. According to Stated Policies Scenario (STEPS) projection, CO2 emissions from energy and industry sector will rise by 2 Gt in the coming decade, going from 34 Gt in 2020 to 36 Gt in 2030 which is expected to have a significant global impact, resulting in a temperature rise of 2.7 °C [2]. Consequently, it will impact thermal comfort of urban areas in the future [3], disrupt agricultural ecosystems [4], lead to changes in the distribution, structure, and function of plants [5,6], a surge in infectious diseases [7], and have economic implications on Gross Domestic Product (GDP) growth [8] that can contribute to "eco-anxiety" about climate change [9].…”

Cultivation of Desmodesmus multivariabilis for the Treatment of Cosmetic Wastewater

“…This may be related to the algae alternating its metabolism. When D. multivariabilis is under environmental stress, it releases organics in large amounts in an attempt to alter the growing conditions [47].…”

Exploration of Microalgae-Activated Sludge Growth Performance in Lab-Scale Photobioreactors under Outdoor Environmental Conditions for Wastewater Biotreatment

“…In particular, the bio-flocculation of microalgae and the subsequent self-settling recovery, among other benefits derived from the synergistic interaction, has attracted serious attention [4,[7][8][9]. In previous studies, the best experimental outcomes regarding removal potential have been reported largely for MAS inoculum ratios of 1:3 [10][11][12], 3:1 [13], 1:5, and 1:2 [14,15], using both high-rate algae pond (HRAP) and photobioreactors (PBRs). The MAS inoculum ratio has been shown to significantly influence pollution removal efficiency in co-culture systems [16].…”