How to improve irrigation water quality with acids

Feb. 15, 2023
Adding acid is a proven way to improve irrigation water quality. Learn some practical suggestions for getting the best results and avoiding mistakes here.

Irrigation water quality can tremendously impact outcomes such as crop growth. Poor quality can slow plant development, cause adverse aesthetic effects and even lead to crop death. Additionally, the excessive content of soluble salts in the water can lead to root injuries, interfering with nutrient uptake.  However, the strategic use of acids allows people to positively influence water quality. Here are some actionable tips to consider when applying this technique.  

Interpret Water Quality Reports Correctly 

Conducting a water-quality assessment is the first step to understanding whether the fluid used for irrigation needs acid-based treatments. Experts recommend performing these evaluations before designating land for crop growth. Otherwise, productive agricultural activity on the property could prove futile.

For example, water with high chloride or sodium content may necessitate using land located elsewhere for crop-growing plans. An alternative is to reduce the chloride and sodium levels with rainwater dilution. Some farmers also explore getting similar outcomes with reverse osmosis filters. However, that option is often prohibitively costly, especially for smaller-scale operations.  

However, water quality reports give people actionable data about their current situations. The pH level, which measures the water’s relative acidity or hydrogen ion concentration, is a good starting point. A pH level of about 7.0 is the optimal range. 

A water quality report will also mention alkalinity, expressed as milligrams per liter. This includes a breakdown of total alkalinity as calcium carbonate, bicarbonate alkalinity and carbonate alkalinity. Calcium carbonate alkalinity below 30 or above 100 milligrams per liter is cause for concern but within the normal range otherwise. 

How Does Alkalinity Relate to Acid Usage? 

Alkalinity is a measure of water’s capacity to neutralize acid. Injecting the liquid with acid can reduce pH levels, but the alkalinity determines the amount of acid needed to cause desired changes. Consider a case of high pH coupled with low alkalinity. Less acid would be required to lower the pH level. The water’s low buffering capacity creates conditions where a smaller amount of acid will do the job. 

People must also be mindful of alkalinity when working with water samples with identical pH levels. Otherwise, they’re more likely to use inappropriate amounts of acid when treating the irrigation water.  

Understanding a water report’s values and whether they represent abnormal levels is critical for informing someone whether it’s time to use acidification to correct identified problems. Accurate pH and alkalinity data are also important because they can affect pesticide usage.  

People should always read the label to get specifics. Generally, when the pH is higher than the pesticide requires, they must add acidifying agents to achieve a balance. However, too much can have a phytotoxic effect.  

Know When Acid Reduction Is Necessary 

A 2020 report warned of a per-person freshwater resource reduction of more than 20% over the last two decades. Sustainable irrigation was mentioned in the document to tackle this pressing issue. A thorough understanding of irrigation water quality will help people get the desired outcomes without wasting water or pursuing improper treatment methods.  

Sometimes, the effective use of acid requires taking measurements and steps to reduce it when necessary. Overly acidic water can corrode pipes. Additionally, certain heavy metals in minerals can harm living things.  

Carbon dioxide is the most likely cause of highly acidic water in industrial settings. Thus, many people control it with carbon dioxide stripping systems. They neutralize the water plus have a protective effect on associated pipes by discouraging corrosion.  

Alternatively, a calcite filter is another option to reduce acidic water problems. It is ideal if the liquid has a pH balance of 5.5 or above. This approach dissolves the mineral in the water, making it less acidic. People also use magnesium oxide to treat acidic water by adding it to filters.  

Using filtration as a neutralization method is straightforward. However, it can raise the water’s hardness, so people must be aware before choosing this option. 

Consider Using Connected Sensors to Manage Irrigation Water Quality  

 A water quality report is critical for establishing baseline readings and informing people if it is time to add acid to address specific problems. However, one downside is that it only captures the conditions associated with a single moment in time. That makes it challenging to determine if and how things change over time.  

Thus, many water quality professionals have begun getting up-to-the-minute and accurate data using Internet of Things (IoT) sensors. Some experts already use the technology for other reasons, including to prevent waste in drought conditions. California recently banned people from irrigating decorative or nonfunctional grass with potable water. This change will reportedly save the equivalent of water used in 780,000 homes, representing a notable reduction.  

However, smart sensor usage can go beyond water conservation. It can also prevent unnecessarily treating water with acids. A sensor network could measure acidity, salinity and turbidity, then periodically update the responsible parties.  

Many systems allow people to set parameters and get immediate alerts if metrics fall outside the expected range. They can then be proactive and add acids to irrigation systems at the proper times and in the appropriate amounts. Otherwise, people risk relying too much on guesswork.  

IoT systems also collect historical data, making it easy to run reports and verify that companies have met or are moving closer to water quality goals. If they aren’t, the gathered information often contains clues about why 

Remove or Improve Process Steps When Possible

Succeeding with irrigation water quality means seeking continuous improvement opportunities. Sometimes, doing things differently results in substantial process changes. For example, options for productive water reuse are under ongoing investigation. People look for new filtration systems and other technologies to help them meet minimum standards.  

Examining new ways of getting the same results may involve eliminating steps while maintaining quality. For example, many manufacturers use sensors for predictive maintenance and only replace parts just before an impending failure. Following the more standardized timelines suggested in equipment user manuals may mean changing components too early or late, wasting time and money. 

Opportunities also exist to streamline steps when treating water with acids. That most commonly happens with injection systems. They require corrosion-resistant chemical feed pumps to add soda ash or sodium hydroxide solution to water with an abnormal pH level. Additionally, people can disinfect the water as they neutralize it by adding sodium hypochlorite along with the neutralizing acid.  

People can also raise productivity and eliminate process steps using digital alkalinity calculators when determining how much acid to add to water. It is easy to find those online in seconds. The other option is manual mathematical calculations, which can be time-consuming and error-prone. 

A rule of thumb is that 1 milliequivalent of acid neutralizes 1 milliequivalent of base. However, the amount of acid to use depends on its strength and the bases in the water. The goal should generally be to neutralize 80%-90% of the water’s bases with the acid.  

Use Acid Wisely to Support Better Water Quality 

These suggestions will help people focus on the proper use of acids to improve irrigation water quality. The method works well and has many possible approaches. However, those considering using it should also remember how water can become too acidic. Thus, knowing when or if it’s necessary to use acid and how much to add is critical. 

Emily Newton is an industrial journalist. She regularly covers stories for the utilities and energy sectors. Emily is also Editor-in-Chief of Revolutionized. 

About the Author

Emily Newton

Emily Newton is the editor in chief of Revolutionized, a popular science publication that dives into the latest innovations in science, technology and industry. 

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