Calcium nitrate is a water-soluble inorganic compound that is used in agriculture, wastewater treatment, concrete, and more. This article will discuss calcium nitrate’s properties, benefits, setbacks, and uses, particularly in wastewater treatment.
Calcium Nitrate Definition
Calcium nitrate, otherwise known as Norgessalpeter (Norwegian salpeter), is an inorganic nitrate salt and calcium salt with the formula Ca(NO3)2x.
The chemical compound is produced by using nitric acid to treat limestone, then neutralizing the solution with ammonia. Calcium nitrate can also be obtained by using milk of lime to absorb nitrogen oxide.
Calcium Nitrate for Wastewater Odor Removal
Calcium nitrate is used in wastewater management to remove unwanted odors during treatment. This compound restricts the metabolism of components that are known to create odors, like hydrogen sulfide, by creating an anoxic biology.
Sewer networks and municipal wastewater facilities both use calcium nitrate to remove odors in public water supplies. Adding calcium nitrate causes sulfide to biologically dissolve in septic wastewater. Additionally, calcium nitrate restricts odor-producing compounds from being produced in anaerobic conditions by facilitating oxidation reduction.
Calcium nitrate can either be used to prevent the formation of hydrogen sulfide odor or used to eliminate odors in applications where hydrogen sulfide is already present.
Calcium Nitrate For Enhanced BOD Removal
Calcium nitrate is also used to prevent oxygen deficiency in wastewater treatment plants.
Oxygen deficiency has a variety of causes, including an excess of sulfur-containing chemical compounds, failing aerators, and a power outage. If the oxygen supply doesn’t meet the oxygen demand, there is a risk that the treatment plant’s biochemical oxygen demand (BOD) permit limits may be violated. Using nitrate salt in liquid form, such as calcium nitrate, is an effective long-term solution to prevent a deficiency in oxygen.
Calcium Nitrate Properties and Dosing
Calcium nitrate can be purchased in liquid or granular form.
Liquid calcium nitrate, which is most commonly used, is available in bulk, typically between 2,000 and 4,000 gallons. It can cost around $2,000 to $2,500 per gallon. Granular calcium nitrate can be purchased in bags from 100 pounds to 2,000 pounds in weight. As an alternative to calcium nitrate, sodium nitrate salts are also available.
Benefits of Calcium Nitrate for Water Treatment
The key benefits of using calcium nitrate for water treatment are is affordability, storage safety, chemical properties and formation prevention of hydrogen sulfide.
Affordable
Calcium nitrate is low-cost to buy in bulk, making it an affordable long-term solution for large-scale wastewater treatment applications.
Safe to Store
While long-term exposure to calcium nitrate can be hazardous to humans, it is not hazardous to most storage materials nor is it flammable, so it’s safe to store on-site in fiberglass or plastic tanks.
Favorable Chemical Properties
Because calcium nitrate is highly soluble in water and is non-volatile, it will linger in wastewater until it is used by the water’s bacteria content.
Prevents Formation of Hydrogen Sulfide
Without the presence of oxygen or calcium nitrate in wastewater, bacteria may form hydrogen sulfide as a byproduct of reacting with sulfide. Adding calcium nitrate to the water prevents the formation of hydrogen sulfide as bacteria will use calcium nitrate over sulfide.
Setbacks of Calcium Nitrate for Water Treatment
Some of the setbacks of calcium nitrate for water treatment include it's delay in effectiveness from the time of dosing treatment and the impact it has on increasing nitrate content in the water that has been treated with it.
Not an Immediate Solution
It takes two-to-three hours for calcium nitrate to have the desired effect in removing odors, so this compound cannot be used to provide an immediate water treatment solution.
Increases Water’s Nitrate Content
Adding calcium nitrate to water increases the water’s nitrate content. Nitrate is a drinking water contaminant with health effects, and has been known to cause rapid heart rate, dizziness, weakness, and fatigue. Further steps may be required to remove nitrate from water to make it suitable for drinking.
Other Uses of Calcium Nitrate
Aside from treating wastewater, calcium nitrate is also used in other applications, such as concrete, cold packs and fertilizer.
Concrete
Calcium nitrate accelerates concrete and mortar setting, and forms iron hydroxide, which protects the concrete from corrosion.
Cold Packs
When calcium nitrate dissipates, it has a cooling effect, which makes it a useful ingredient in regenerable cold packs.
Fertilizer
Perhaps the most popular use of calcium nitrate is in certain fertilizers. The nitrate in calcium nitrate is used by plants to make proteins for healthy growth, and calcium is used to hold together plants’ cell walls and extend their shelf life. Calcium nitrate is used in both large-scale agricultural products and commercial gardening products.
Additionally, calcium nitrate may be used as a coagulant in latex production and an ingredient in molten salt mixtures.
Takeaway
Calcium nitrate is a water-soluble chemical compound that has numerous uses in water treatment, fertilizers, concrete, and cold packs.
In wastewater treatment, calcium nitrate has two key purposes: to remove odors caused by hydrogen sulfide and to prevent oxygen deficiency. Calcium nitrate is affordable to buy in bulk and safe to store, but increases water’s nitrate content and takes several hours to have the desired effect.
