Caustic, Ferric Chloride, HCL – Their Uses in Water Treatment

Enduramaxx Caustic, Ferric Chloride, HCL - Their Uses in Water Treatment

Caustic, Ferric Chloride, HCL – Wastewater Treatment Chemicals

How are these three highly corrosive and dangerous substances used in the treatment of water? Let’s take a brief look at what happens and how to store these toxic items safely.

HCL Hydrochloric Acid to remove scale

Hydrochloric acid is a reactive liquid; it serves to produce water treatment chemicals, batteries and feed phosphates.  During the manufacture of steel, hydrochloric acid (HCL) is used to remove rust in a process called “steel-pickling”. The iron (Fe) in the rust combines with the chlorine (Cl) in the acid to form FeCl3 – ferric chloride.

Ferric Chloride for Coagulation – what happens?

The ferric chloride is used in the coagulation part of the treatment of water, it has a very low pH, and the caustic is added to raise the pH to about level 5, or the optimum level.  Hydrochloric acid may help reduce the odour, and when water is added to ferric chloride, hydrochloric acid is produced.

Coagulation is the agglomeration of particles suspended in the water. There heavier aggregates sink to the bottom of the tank, from which it can be removed. Various chemicals can be used to make this happen – and ferric chloride is a popular and inexpensive choice. It is especially useful in causing the phosphates to precipitate out in the sludge, which can be collected, and the valuable minerals recycled.

Caustic soda, or sodium hydroxide (NaOH) for pH neutralization

Caustic soda or sodium hydroxide (NaOH) is used to increase the pH of the water without adding calcium ions that are needed for calcium carbonate precipitation to occur.  Also known as caustic, is sodium hydroxide is probably the most widely used alkaline neutralizing chemical used in industry today.  Sodium hydroxide is relatively easy to handle, inexpensive, and effective for neutralising strong or weak acids.  NaOH 32% is the most commonly used concentration.

Properties of FeCl3, caustic and HCl

All of these substances are highly corrosive. The very term “caustic” means “able to burn”. They are all dangerous and require special tanks to store them safely and special tanks for when they are used to treat water.

What kind of tanks are needed?

Stainless steel tanks are corroded by these substances and are not suitable. One-piece moulded plastic tanks, without joints and safely containing liquids with specific gravities up to 2 SG are needed.

The type of product to be stored may have specific specifications. The Material Safety Data Sheet (MSDS) outlines these, and the tanks must comply. Bunded tanks or tanks with a double wall give an extra level of safety since any leak from the inside tank is contained within the outer tank.

Enduramaxx tanks for Caustic, Ferric Chloride, HCL

Our plastic tanks are manufactures by a rotational moulding process, which results in a one-piece tank with no seams or joints. The chemical storage tanks can hold acids and chemical with a specific gravity of up to 2 SG. We use the highest grade of material to meet any specification requires, and our tanks are UV stabilised, so they are not degraded by exposure to sunlight.

We have a wide range of sizes from 50 litres to 30,000 litres, and they have lifting lugs, overflow, inlet and outlet point to take up to 150mm fittings. They can be customised with welded flanges, additional bulkheads and more. We can design tanks to your specific requirements taking into account factors such as the particular chemical to be stored; the temperature needed as well as your on-site features.

Our chemical dosing tanks range in size from 50 litres up to 1,500 litres. They each have a screw fitting lid and a flat section on top of the tank for mounting equipment such as chemical dosing pumps, instruments and mixers. Each can be bunded to comply with the HSE requirements.

Hydrochloric Acid Tanks

Hydrochloric acid has a distinct smell and burns. The tanks are made from PE to resist corrosion. HCl can emit fumes, and these too are corrosive, so the tank needs to have scrubbers plus airtight connections to all fittings.

Our Caustic Tanks

Our caustic soda tanks include a bunded cone bottomed tank for safety and ease of cleaning.

Ferric Chloride Storage Tanks

Our selection of ferric tanks includes storage, mixing and the bunded cone-bottomed tanks.

You can see that we have a range of suitable specialist tanks to store and utilise ferric, caustic solutions and hydrochloric acids.  You can choose the shape that suits you. We have flat bottomed tanks and cone bottomed tanks as well as double bunded tanks. You can see our range of bunded chemical tanks here. If you would like to discuss your specific need, please give us a call on 01778 562810 our specialists will be happy to help.

Main image istock

Main Menu