Water quality restoration by harvesting mixed culture microalgae using Moringa oleifera

Abstract

Excessive growth of microalgae due to use of fertilizers, detergents, and discharge of domestic waste results in the eutrophication and degradation of the water quality of lakes and ponds. The present study aimed to improve the quality of pond water by harvesting mixed cultures of microalgae grown in a pond using Moringa oleifera (MO) extract as a coagulant. The study comprises evaluating the effects of coagulant dose, pH, mixing time, mixing rate, settling time, temperature, and algal biomass concentration on nutrient and microalgae cell removal. The pond water quality restoration was assessed by characterization of raw and MO‐treated water. The MO was found to be very effective for mixed culture microalgae harvesting with flocculation efficiency of 92.97% at dose of 15 ml/L of MO extract, pH 8, mixing time 5 min, mixing rate 30 rpm, and 20‐min settling time. The results have shown significant improvement in pond water quality with reduction in turbidity from 388.16 ± 48.23 to 8.39 ± 1.0 NTU, chlorophyll‐a from 635.01 ± 86.20 to 15.03 ± 1.5 mg/m3, total nitrogen (TN) from 20.37 ± 4.64 to 12.10 ± 1.19 mg/L, and total phosphorus (TP) from 2.05 ± 0.10 to 1.61 ± 0.24 mg/L. Practitioner points Production of biomass and water quality improvement of the pond at the same time MO extract shows better removal efficiency at a lower dose with fast kinetics Cost‐effective flocculant saves time and energy during flocculation Common bioflocculant to remove both microalgae and nutrients.

Development of environmental biotechnology and control of emerging biological contaminants: the grand challenge for a sustainable future

“…In this issue of Water Environment Research, we can find valuable works that present original results linked to the previously discussed topics as follows: the restoration of water quality by harvesting mixed culture microalgae (Singh & Patidar, 2020), the removal of phosphate using innovative beads (Malicevic et al, 2020), the evaluation of the bacteriological and chemical quality in a clinical center (Humudat, Al-Naseri, & Al-Fatlawy, 2020), and other interesting studies.…”

Use of Aloe vera as an Organic Coagulant for Improving Drinking Water Quality

“…A significant number of studies have proved that replacing metal salts with natural coagulants may reduce the environmental impact associated with the coagulationflocculation-sedimentation process. In detail, efficient organic coagulants have been obtained from several vegetal materials such as Moringa oleifera [22][23][24][25], Cactus [26], Acorn [12,27], Alyssum seeds [28], Citrus fruit peel [29], Fava bean [30], Cassia obtusifolia seed gum [31], Dolichos lablab [32], and Lens culinaris [33] The mechanism of coagulation induced by organic coagulants differs from that induced by metal-based coagulants. Coagulation is aimed at destabilizing the colloidal suspension by the following two phenomena: (1) adsorption and neutralization of charges, or (2) adsorption and bridging of colloids [34,35].…”

The potential use of natural coagulants for microalgae harvesting: a review

“…The MO is used for hardness, turbidity, and heavy metal removal(Elemile et al 2021;Ojewumi et al 2021). Compared to a chemical-based coagulant, MO is readily available, cost-effective, eco-friendly, biodegradable, has no harmful byproducts, and produces low sludge volume(Singh & Patidar 2020;Ogunmodede et al 2021;Alazaiza et al 2022). MO unique properties include low toxicity, low cost, high coagulation properties, and affordability, making MO a promising alternative for microalgae harvesting from aqueous media (AbdulHamid et al 2016).…”