Impact of copper sulfate and hydrogen peroxide on biodegration of microcystin-LR (MC-LR) in surface waters

  • 康 敏詩

Student thesis: Doctoral Thesis

Abstract

Harmful cyanobacteria blooms may deteriorate freshwater environments leading to bad water quality that can adversely affect the health of humans and animals Many cyanobacteria can produce toxic metabolites with microcystin-LR (MC-LR) being the most commonly detected cyanotoxin in fresh water bodies A MC-LR degrading bacteria with 93% similarity with Bacillus sp strain was isolated from a lake (HLPL) in Taiwan and tested for its degradability of the cyanotoxin The results showed that the degradation of microcystin-LR by the isolated Bacillus sp was temperature-dependent and may be simulated by first order model Biomolecular monitoring was also applied to detect three types of genes involved in the degradation The results show that mlrA and CAAX genes were present in the indigenous bacteria in HLPL water samples although GST genes were also investigated for their xenobiotic importance in MC-LR degradation However for the isolated Bacillus sp strain only CAAX genes were detected The results of this first part of the study may serve as a basis to quantify the degradation of MC-LR in natural water environment and to better understand the possible pathways involved in the degradation In addition to the biomolecular aspect of MC-LR biodegradation the impacts of copper sulfate and H2O2 on the degradation of MC-LR and the growth of M aeruginosa and Bacillus sp were carried out in laboratory experiments The results showed that H2O2 could remove M aeruginosa even at low dose of 3 mg?L-1 In addition 1 mg?L-1 copper sulfate and 5 mg?L-1 H2O2 were enough to decimate Bacillus sp population suppressing the biodegradation of MC-LR via Bacillus sp Nevertheless H2O2 showed a better MC-LR removal even at very low light conditions of 2 3 W?m-2 if compared with copper sulfate H2O2 is competitive in terms of cost and sustainability with a capability of degrading organic compounds when it is assisted with UV light Henceforth it may be considered as an alternative algaecide to copper sulfate in reservoirs for algae growth control and management
Date of Award2017 Jun 19
Original languageEnglish
SupervisorTsair-Fuh Lin (Supervisor)

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