Patent ID: 8759073

Claim:
A method for effectively controlling harmful organisms in the large-scale culture of microalgae, comprising: a. determining the harmful organism species causing contamination to the microalgae in culture, and the acid and alkali tolerance levels of said harmful organism species; b. adjusting the pH value of the microalgae culture system according to the different acid and alkali tolerance levels of the harmful organisms, and adjusting the pH value back to be suitable for the normal growth of the microalgae when the harmful organisms are determined to be killed or inhibited effectively, wherein when the harmful organism species is identified as alkali tolerant contamination, CO 2 is aerated into the microalgae culture system, and the pH value is adjusted back to be suitable for the normal growth of the microalgae by sufficiently aerating air or with alkalis when the harmful organisms are determined to be killed or inhibited effectively; when the harmful organism species is identified as acid tolerant contamination, the pH value of the microalgae culture system is raised up with alkalis to maintain a higher pH condition for the culture system, and adjusted back to be suitable for the growth of the microalgae when the harmful organisms are determined to be killed or inhibited effectively; when the harmful organism species is identified as mixed contamination, the procedure below is followed depending on the species, harming rate and degree, as well as acid/alkali tolerance levels of the harmful organisms: (1) in the case that alkali tolerant contamination is severer, the sample is first treated at a low pH for a while; after a relatively greater inhibiting and killing impact of this treatment is determined on the targeted harmful organisms, the harmful organisms with the opposite tolerance are treated at a high pH; the pH value is adjusted back to be suitable for the growth of the microalgae when the harmful organisms are determined to be killed or inhibited effectively; or (2) in the case that acid tolerant contamination is severer, the sample is first treated at a high pH for a while; after a relatively greater inhibiting and killing impact of this treatment is determined on the targeted harmful organisms, the harmful organisms with the opposite tolerance are treated at a low pH; the pH value is adjusted back to be suitable for the growth of the microalgae when the harmful organisms are determined to be killed or inhibited effectively.