In drip irrigation systems the more important scaling agents are organic compounds, organo-minerals from eutrophicated water bodies and iron from groundwater. To mitigate the clogging there are maintenance programs for irrigation systems, consisting of regular washings in the field with acid and hypochlorite, bench or test line’s dosing of acids or detergents. In addition there are other treatments such as oxygenation of the water and precipitation of iron, acidification of nutrient solutions, and for the specific case of organo-mineral compounds, sodium hypochlorite or calcium at a maximum concentration of 1 ppm in all the emitters controlled daily.
The use of chlorine generates compounds such as chloramines and trihalomethanes that may affect beneficial populations of microorganisms for the soil and contaminate surface waters. They are strong oxidizing agents that should be treated with protection systems for the staff to avoid accidents during the process. There are other products that may be an alternative to hypochlorite and have advantages because they are organic and biodegradable with lower handling risks. . Non-active biocatalysts, such as OrTec, can be an alternative to using hypochlorite.
Below is the report of a recent trial using OrTec in a drip irrigation system
OBJECTIVES OF THE TRIAL:
1.1 GENERAL: To evaluate the continued use of a Non-Active Biocatalyst as a protective and anti-clogging agentin the drip lines instead of sodium hypochlorite, under conditions of hydroponic water recirculation.
1.2 SPECIFICS: Compare the coefficient of variation of water flow in drip lines’ emitters after 20 weeks of daily use dosed as recommended.
2. MATERIALS:
- Non-Active Biocatalyst
- Sodium hypochlorite 13% / density 1.21gr/cc.
- Drip irrigation automated system divided into two irrigation heads, one with an injection system of Chlorine and the other with the Non-Active Biocatalyst, before the filtering system
- Automated self-cleaning filtering rings systems of 120 microns
- Brand new drip lines HidroPc ND self-compensated, anti-drain very susceptible to partial or total plugging.
- Place: Flower Nursery
3. METHODOLOGY:
3.1. DESCRIPTION OF THE TREATMENTS:
TO: Standard management of the farm: injection of sodium hypochlorite (12 ppm) to secure 0.5 ppm of free chlorine HOCl, Cl0–) at the end of the dripping line on a continuous basis in the irrigation water. Located in Head 1.
T1: Using the Non-Active Biocatalyst as anti-clogging agent at a concentration of 20 ppm injected continuously into the irrigation water. Located in Head 2.
3.2 VARIABLES TO EVALUATE:
Increase in the coefficient of variation of the flow drip of each line.
We measured 8 irrigation lines, 18 emitters per line for a total of 144 measurements per treatment.
CVi = standard flow deviation / average flow per line. Before starting treatment.
CVf = standard flow deviation / average flow per line. 20 weeks later.
CVi and CVf = coefficient of variation initial and final respectively.
The increase in the coefficient of variation ICV calculation is as follows: ICV = CVi-CVf for each treatment.
We evaluate the change in flow because it is not possible to find on commercial terms and conditions drip lines with the same coefficient of variation.
3.3 EXPERIMENTAL DESIGN:
We selected the lines for the evaluation completely at random.
Analysis of variance of the increase in the coefficient of variation over 20 weeks for each treatment.
3.4 PROTOCOL:
3.4.1 DATA COLLECTION (Variable evaluation)
| VARIABLE | Measurement(How?) | Sample to evaluate (How many?) | Frequency(How often?) |
| Coefficient of variation. | Initial measurement before starting treatment, and 20 weeks later. We consider the increases in the coefficient of variation in the same lines and emitters for each treatment. | 8 lines per sector, 18 emitters per line, marked with paint. | At the begining and end of the trial. |
3.5 START DATE:
June 13, 2007
3.6 COMPLETION DATE:
November 1, 2007
4. RESULTS:
The table shows the initial coefficient of variation (week 0), the final after 20 weeks and the increase in the different lines controlled in each treatment (see full data below).
Table 1. Coefficient of variation measured in eight drip lines (18 emitters per line) in each treatment.
|
|
Hypochlorite |
Non-Active Biocatalyst |
||||
|
Lectures |
Week 0 |
Week 20 |
Diff. |
Week 0 |
Week 20 |
Diff. |
|
1 |
4.6 |
5.7 |
1.1 |
5.6 |
8.3 |
2.8 |
|
2 |
4.7 |
7.7 |
3.0 |
5.5 |
8.3 |
2.7 |
|
3 |
6.7 |
9.8 |
3.1 |
5.3 |
6.8 |
1.5 |
|
4 |
5.1 |
9.3 |
4.3 |
4.7 |
8.7 |
3.9 |
|
5 |
5.6 |
7.1 |
1.4 |
5.9 |
8.0 |
2.1 |
|
6 |
4.3 |
7.3 |
3.0 |
6.3 |
5.2 |
-1.0 |
|
7 |
5.1 |
8.8 |
3.7 |
6.3 |
6.6 |
0.4 |
|
8 |
8.7 |
8.7 |
-0.1 |
6.5 |
6.4 |
-0.1 |
|
Average |
5.7 |
8.2 |
2.4 |
6.1 |
7.3 |
1.3 |
|
|
|
|
|
|
|
|
After 20 weeks of treatment with sodium hypochlorite the drip lines increased its coefficient of variation average from 5.7% to 8.2% (2.4% increase), showing that during that time the uniformity of application was reduced from 94.3% to 91.8%, although it remained within the normal standard ranges of the ASAE (uniformity greater then 90%), nevertheless due to the short trial it may indicate that if the trend is maintained the problem may become serious.
For its part lines treated with the Non-active Biocatalyst increased the flow coefficient of variation from 6.1% (week 0) to 7.3% (20 weeks) an increase of 1.3%, showing that during that time the uniformity of application was reduced from 93.9% to 92.7%, keeping the uniformity higher than with hypochlorite.
5. CONCLUSIONS: The Non-Active Biocatalyst could perfectly replace the use of sodium hypochlorite in preventing clogging in drip systems. The Non-Active Biocatalyst can be used for preventive maintenance of irrigation systems. It should be assessed as corrective or curative agent in systems that have a high rate of clogging.
6. RECOMMENDATIONS: If the cost analysis is favorable, it is recommended to use this type of product to replace hypochlorite due to the advantages of environmental and industrial safety that provides.