Effects of pre-oxidation on the removal of Raphidiopsis raciborskii by coagulation with polyaluminum chloride
Toxic and harmful cyanobacteria blooms with Raphidiopsis raciborskii as the dominant species have erupted frequently in lakes and reservoirs in Southern China,seriously affecting local ecological health and water safety.In this investigation,hydrogen peroxide(H2O2)and sodium hypochlorite(NaClO)were used to study the treatment effect of preoxidation coagulation technology on the disposal of algal water of Raphidiopsis raciborskii.By measuring the length,surface potential,activity and dissolved organic matter of algal filament,the reason why preoxidation promotes coagulation effect is analyzed.The results showed that an escalation in the dosage of oxidants or coagulants correspondingly heightens the removal efficiency of Raphidiopsis raciborskii.Specifically,doses of 0.6 mg·L-1 H2O2 or 1.2 mg·L-1 NaClO reduced the polyaluminum chloride(PACl)dosage from 25 mg·L-1 to 15 mg·L-1,achieving a removal efficiency surpassing 80％.Post oxidation treatment,Fv/Fm of algal cells plummeted from 0.39 to below 0.07,and esterase activity was not observed by fluorescence microscopy,indicating that algal cells were deactivated and membrane permeability increased.H2O2 elevated the Zeta potential of algal water from-14 mV to-10 mV,facilitating the electrostatic neutralization of PAC1 on algal cells,while NaClO exhibited negligible impact on the Zeta potential.Both H2O2 and NaClO augmented the dissolved organic matter(DOM)concentration in algal water from 5.95 mg·L-1 to 7.01 mg·L-1 and 6.68 mg·L-1,respectively.However,the content of strongly negatively charged protein and humic substance components exhibited a notable decrease with H2O2 or NaClO treatment,resulting in a 13.7％or 7.1％enhancement in algal cell removal efficiency.This implies that preoxidation treatment can enhance coagulation effectiveness by influencing DOM characteristics.The outcomes of this study furnish data support and a theoretical foundation for the effectiveness and safety of oxidation coagulation in the treatment of Raphidiopsis raciborskii,underscoring its potential utility in the in-situ emergency disposal of Raphidiopsis raciborskii blooms.
国家科技期刊平台
NSTL
万方数据
