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Abstract
A white sulfur slime produced by certain sulfur bacteria clogged drip irrigation emitters when the water contained H2S. Systems were cleaned by irrigating continuously for 3 weeks after first eliminating O2 leaks. After cleanout, growths of sulfur bacteria were prevented by keeping the lines full of water and free of O2 between irrigations. Intermittent injection of chlorine to yield a free residual level of 0.5 ppm prevented sulfur bacterial growths. Lowering the pH to 6.4 with SO2 or 6.0 with HCl also inhibited sulfur bacterial growths.
Abstract
Some drip irrigation systems installed in central and south Florida citrus groves have ceased to function properly because of filter and emitter clogging. The most serious clogging has been a slime formed by filamentous sulfur bacteria. The most abundant sulfur bacteria was Thiothrix nivea Robenhorst, a common inhabitant of warm mineral springs in Florida. The bacteria oxidize H2S to S and can clog small openings within a brief period of time. Beggiatoa sp., a sulfur bacteria, was also found in the slime although the organism occurred most frequently in emitter orifices.
Another serious clogging factor has been Fe deposits in the form of filamentous, gelatinous ochre. The Fe deposits were associated with iron bacteria. The sticky sludge adhered to filters, grooves, and orifices of emitters. Iron sulfide clogged filter screens and accumulated in the grooves of some emitters.