Enhanced removal of intracellular organic matters (IOM) from Microcystic aeruginosa by aluminum coagulation

Abstract

a b s t r a c tAlgal organic matter (AOM), especially intracellular organic matter (IOM), increases the levels of color and taste & odor, and promotes the formation of disinfection by-products (DBPs). This study isolated the IOM from Microcystis aeruginosa into the fractions with different molecular weight (MW), i.e., >100 kDa, 30-100 kDa, 10-30 kDa, and 3-10 kDa, and characterized them by techniques of dissolved organic carbon (DOC), UV absorbance and Excitation-emission matrix (EEM) fluorescence spectroscopy. After that, the removal efficiency of these IOM fractions by aluminum sulfate (Al 2 (SO 4 ) 3 , alum) at different Al doses and pH were compared. The removal efficiency of IOM, as indicated by DOC, UV 254 , and OD 680 , increased consistently with higher Al doses, and the maximum removal was determined to be 99.7% for OD 680 , 51.4% for UV 254 , and 38.7% for DOC by alum at 5 mg/L. pH also showed effects, and the maximum removal was achieved at pH 6.5 with the maximum removal of 42.3% for DOC and 61.5% for UV 254 . The higher UV 254 removal as compared to that of DOC indicated the superiority of alum to remove the aromatic IOM species. EEM spectra indicated the higher protein content within these IOM fractions, and the formation of complexes between Al and proteins involved in their removal. IOM with higher MW showed more significant removal of both DOC and UV 254 than that with lower MW, and the sweep flocculation mechanism played an important role. Alum coagulation is effective and available for IOM removal in case of algae bloom and minimize its adverse effects on water safety thereafter.

Comparison of Different Anode Materials to Remove Microcystis aeruginosa Cells Using Electro-Coagulation–Flotation Process at Low Current Inputs

“…In case of Al anode, we obtained only a 40% DOC removal efficiency. Guo et al [40] reported a 38.7% DOC removal efficiency from the IOM of M. aeruginosa at 5 mg/L alum dosage. The charge neutralization process involves the elimination of AOM during coagulation owing to the occurrence of extremely negative charges on AOM [6].…”

Complexation of Copper Algicide and Cellular Organic Matter: Implications for Its Fate in Algae-Laden Surface Waters

“…The binding sequence of functional groups in the CHPI fraction under Cu­(II) perturbation was as follows: amide II υ C–N → aryl υ C–H → polysaccharide ν C–O , aliphatic ν O–H → phenolic υ C–O, δ O–H , aliphatic δ C–H → aryl υ CC → ketone, amide, and carboxyl ν CO . Carboxyl groups usually show the fastest response to heavy metal ions and are concentrated in the CHPI fraction via the anion-exchange process. , However, amide groups in CHPI are the most sensitive moiety to Cu­(II) binding. The binding sequence of functional groups in the NHPI fractions was as follows: polysaccharide ν C–O , aliphatic ν O–H → ketone, and carboxyl ν CO → aryl υ CC → amide II υ C–N → phenolic υ C–O, δ O–H , and aliphatic δ C–H .…”

Impact of algal organic matter on the performance, cyanotoxin removal, and biofilms of biologically-active filtration systems

“…AOM from Microcystis sp. contains a mixture of compounds such as amino acids, peptides, polysaccharides, and proteins (Guo et al, 2017). Cyanobacterial cells were separated from the collected water samples by membrane filtration using a 0.45 μm (pore size) filter.…”

“…Microcystin-LR (MC-LR), one of the most toxic and frequently detected among microcystin congeners, is a hepatotoxin that can be lethal (Gutiérrez-Praena et al, 2012). In addition, cyanobacterial cells release algal organic matter (AOM) containing a wide spectrum of components such as amino acids, peptides, proteins, and polysaccharides (Guo et al, 2017). These are known to serve as precursors for disinfection byproducts (DBPs) (Hong et al, 2009).…”