In order to ensure effective cleaning of a drip irrigation system, it is necessary to use different cleaning types and specific products in an established sequence according to the type of clogging.
First of all, the difference between surface and sub-irrigation systems should be well-understood. The cleaning of the former is often overlooked, while the cleaning of the latter is very important and crucial since it is not possible to frequently replace the lines which, among other things, are expected to last for several years.
CLEANING TYPES AND SEQUENCES. SUBSTANCES TO BE TO USED
The first cleaning of the line is aimed at eliminating any organic substances.
In order to remove these substances, the first cleaning must be carried out using oxidizing products such as hydrogen peroxide and bleach (sodium hypochlorite).
Alternatively, a mixture based on metanoic acid, ethenoic acid, hydrogen peroxide and potassium permanganate can be used.
The most available product on the market is certainly sodium hypochlorite.
It is good to choose the bleach with a low chlorine concentration, possibly not higher than 5%, since chlorine is a toxic element for plants.
Despite of the above-mentioned reasons, bleach is a good product to dissolve organic substances inside the irrigation system, as the chlorine is not retained by the soil and it can be easily removed by guaranteeing an abundant water rinse treatment.
Hydrogen peroxide presents fewer risks for crops. To proceed with hydrogen peroxide cleaning, it is necessary to respect the concentration of about 3 or 4 liters of hydrogen peroxide per cubic meter of water. To check the correct passage of the hydrogen peroxide through the system, it is enough to introduce the substance until you see the solution of water and hydrogen peroxide coming out from the farthest dripper.
It is good to let the solution function for about an hour before rinsing the system. It is also advisable to repeat the procedure several times to be sure that you have cleared all system areas, even the most peripheral.
Once the organic substances have been removed and the system has been rinsed, all the occlusions caused by organic substances will have been eliminated; so, the second cleaning procedure with acid can be carried out in order to eliminate mineral substances, deposits, and chemical sediments formed.
Cleaning with acid must be done at the end of each season.
It is essential to precede this cleaning by the one using oxidizing substances. Indeed, if cleaning with acid is carried out first, the organic substances could detach from the surfaces and clog the drippers.
The use of acid substances such as nitric, phosphoric or sulfuric acids, allows to remove the mineral residues.
Acids should be used carefully as they are very corrosive to metals. Therefore, it is fundamental to proceed with the use of the acid solution only in PVC pipes avoiding metal elements that would be damaged.
It is also good to check the acid resistance of your injection pump and use personal protections during usage.
To prevent system damage, it is prudent to never inject pure acid into the irrigation line, but always perform a preventive water dilution. Always remember to inlet water into the system first and only then the acid, and not vice versa.
The amount of acid used to obtain a desired concentration must be adjusted before injecting the solution into the system. For the removal of mineral residues and bacteria, any solution with a pH of about 4.5 is effective. The irrigation lines should be washed with the selected acid solution for about an hour. Afterwards, rinse the lines with water to remove any remaining acid solution.
Rinsing the irrigation line with water is crucial to keep the system healthy. If the lines are still rough because of substances accumulation, the acid solution can be left overnight for further soaking.
This cleaning should deal with all microorganisms and the accumulation of particulates in the system. When working with any acid, be sure to wear appropriate safety equipment to protect your face, hands, and skin. Safety glasses, gloves and full covering clothes must always be used.
It may be helpful to have an approved neutralizer on hand for possible accidents.