Test PB Collection: FTE

Storage reservoir with heavy biological growth. Photo: L. Schwankl Copper-based biocides are very effective at controlling biological contaminants in water, and are most often used to control algae and other organisms in irrigation ponds and reservoirs.

Ozone is formed by passing oxygen through an electric discharge field (corona discharge method) or by exposing oxygen to ultraviolet radiation (UV ozone generation). Ozone (O3), contains three oxygen atoms as compared to the two oxygen atoms in a normal oxygen molecule (O2).

Sand media filters Photo: L. SchwanklSuspended particulate materials in irrigation water may be inorganic (sand, silt, and clay), organic (algae, bacteria, plant debris, fish, insect larvae, etc.) or any other floating or suspended materials.

Drained reservoir used for settling iron from groundwater source. Photo: L. SchwanklBiological clogging problems associated with groundwaters are substantially less common than those associated with surface waters.

Venturi injector. Photo: L. Schwankl Naturally occurring chemicals in groundwater that is used for irrigation can leave chemical precipitates in emitters, such as calcium carbonate (lime), iron and manganese compounds, and iron sulfide.

Screen filter Photo: L SchwanklThe degree of filtration is expressed as mesh size or equivalent mesh size. The mesh size is the number of openings per inch. For example, a 200-mesh filter has 200 openings per inch.

Iron staining on building from high-iron groundwater Photo: L. Schwankl Iron and manganese bacteria in water can form a filamentous growth which can lead to emitter clogging. The source of the iron bacteria is often a well which has been contaminated during the well drilling process.

Groundwater being pumped into a standpipe Photo: L. Schwankl Iron bacteria can be introduced to the well at the time it is drilled and once present is very difficult to eliminate. Most treatments simply keep the iron bacteria problem under control.

Venturi injector plumbed across a valve used as a pressure drop Photo: L. Schwankl Although the source of iron bacteria contamination is usually the well, the iron bacterial contamination can also be present in the microirrigation system. The treatment is to use a biocide to eliminate the bacteria.

Water being pumped into a storage reservoir Photo: L. Schwankl Groundwater that is to be used as a water source for microirrigation should be analyzed to determine whether it poses a clogging hazard.