Potent removal of cyanobacteria with controlled release of toxic secondary metabolites by a titanium xerogel coagulant.
Cyanobacteria blooming is a serious environmental issue throughout the world. Removal of cyanobacterial cells from surface water with controlled release of cyanobacterial organic matter (COM), especially toxic microcystins (MCs), would potentially reduce the processing burden in follow-up water treatment. Coagulation is a key technique in water treatment. Herein, the potential application of a novel titanium xerogel coagulant (TXC) was evaluated for the treatment of cyanobacteria-laden water in terms of cyanobacteria removal efficiency, variation of cell viability, the release and evolution of COM in the floc accumulation and storage process. Under acidic to neutral conditions, TXC showed a higher removal efficiency of approximately 99% for cyanobacteria and a lower residual Ti concentration than the widely-used commercial polyferric sulfate (PFS) and polyaluminum chloride (PAC). Another advantage of TXC was the reduced MCs concentration caused by the released acetylacetone (AcAc) from the hydrolysis of TXC. Under solar irradiation, AcAc degraded the extracellular MCs from an initial concentration of 40 μg/L to a residual concentration of 7 μg/L during a 16-day floc storage process. The low residual Ti concentration (< 0.04 mg/L) and the efficient removal of COM/MCs following TXC coagulation reduced the toxicity to photobacteria. The results demonstrate that TXC is a promising dual-effect coagulant for treatment of cyanobacteria-laden water.
PubMed Abstracts
PubMed Abstracts