INVESTIGATIONS INTO THE USE OF STRAW TO CONTROL BLUE-GREEN ALGAL GROWTH
Report No FR0285

H A James

March 1992

SUMMARY

I OBJECTIVES

1. To determine the susceptibility of a toxin-producing strain of the blue-green alga Microcystis aeruginosa to the anti-algal agent(s) ('Factor X')-produced during the microbial decomposition of straw in water.
2. To determine the optimal and practically feasible conditions for the effective production of 'Factor X', and to establish a pilot study of production in apparatus suitable for bankside operation.

II REASONS

It has been demonstrated that decomposing barley straw inhibited the growth of a number of green algal species. However, there was no comparable evidence of a similar effect for blue-green algae. If such an effect could be shown, an appropriate means of dosing water bodies with the inhibitory factor would be desirable.

III CONCLUSIONS

Decomposing barley straw can be used to control the growth of blue-green algae.

VI RECOMMENDATIONS

Work on the utility of a bankside digester system to produce the anti-algal agent(s) from barley straw, and to develop a suitable dosing system to treat large water bodies should continue, to allow the feasibility of this approach to be evaluated.

V RESUME OF CONTENTS

From laboratory experiments conducted with a toxin-producing strain of Microcystis aeruginosa, up to 95% inhibition of algal growth was achieved with as little as 2.7 g/m3 straw. Preliminary experiments with other strains of Microcystis aeruginosa produced similar results. Investigations with a prototype bankside digester for the remote production of the anti-algal factor(s) from barley straw, to determine the feasibility of controlling blue-green algal growth in large water bodies, have commenced.

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