A review of plant-based coagulants for turbidity and cyanobacteria blooms removal

Abstract

In recent years, the proliferation of Harmful Cyanobacterial Blooms (CyanoHABs) has increased with water eutrophication and climate change, impairing human health and the environment in relation to water supply. In drinking water treatment plants (DWTPs), the bio-coagulation based on natural coagulants has been studied as an eco-friendly alternative technology to conventional coagulants for both turbidity and CyanoHABs removal. Plant-based coagulants have demonstrated their coagulation efficiency in turbidity removal, as reported in several papers but its ability in cyanobacterial removal is still limited. This paper mainly reviewed the application of plant-based coagulants in DWTPs, with focus on turbidity removal, including cyanobacterial cells. The future potential uses of these green coagulants to reduce noxious effects of cyanobacterial proliferation are presented. Green coagulants advantages and limitations in DWTPs are reviewed and discussed summarizing more than 10 years of knowledge.

Nature‐based coagulants for drinking water treatment: An ecotoxicological overview

“…Limited information on the cost of raw natural coagulants is available (Ang & Mohammad, 2020; El Bouaidi et al, 2022). In some studies, the cost of natural coagulants has been shown to be less than that of chemical coagulants generally requiring intensive pH adjustment of the water to be treated to achieve the desired removal efficiency (Choy et al, 2014).…”

“…These plant species are characterized by the presence of several compounds, namely, proteins, polysaccharides, phenol and flavonoids substances, cellulose, and pectin (Madhu et al, 2020; Ouhaddou et al, 2022; Rostami‐Vartooni et al, 2016), which have been proven in the literature to exhibit a coagulant effect allowing their application to remove algal cells and organic matter (El Bouaidi et al, 2022; Graham et al, 2010; Kebaili et al, 2018).…”

“…Natural coagulants present several advantages. In addition to their relative low cost (El Bouaidi et al, 2022), natural coagulants allow less sludge production, and the produced sludge is bio‐degradable and contains no harmful substances, which allow their further valorization in agronomic application (Hameed et al, 2016; Kansal & Kumari, 2014).…”

“…Water resources devoted to drinking activities are experiencing worldwide serious concerns due to eutrophication and especially toxic cyanobacterial blooms (CyanoHABs) (Paerl et al, 2014). High concentrations of these organisms in raw water may lead to several problems such as the release of toxic secondary metabolites, taste and odor compounds, and disinfection by-product precursors (Clemente et al, 2020;El Bouaidi et al, 2022). The prevalence and distribution of toxic CyanoHABs in freshwater is increasing, making their removal one of the major challenges of drinking water treatment plants (DWTPs) (Anderson et al, 2002;Hudnell, 2008;Lopez et al, 2008).…”

Adsorbents Used for Microcystin Removal from Water Sources: Current Knowledge and Future Prospects

“…Numerous existing approaches have been adopted to remove CyanoHABs and their deleterious MCs from water sources. Indeed, some technologies, like coagulation-flocculation, air floatation, sedimentation, filtration, and disinfection, show high removal efficiencies of cyanobacteria cells [8][9][10][11]. These conventional methods are, however, ineffective for removing soluble MCs released into water during cell aging and/or as a result of cell deterioration caused by external stressors or by the treatment itself [12,13].…”