Caustic Soda in water treatment
PH is an indicator of the acid or alkaline condition of the water. The PH scale ranges from 0-14; 7 indicates the neutral point. The normal pH range of drinking water is 6 – 8.5. The PH is mostly a result of natural geological conditions at the site and the type of minerals found in the local rock. The PH can also be affected by acid rain. Water with a PH value less than 7 is acidic and tends to be corrosive.
Acidic water (low PH) can leach metals from plumbing systems, which can cause pipes to leak. Metals that leach from the pipes (lead from lead pipes or copper from copper pipes) may also cause health problems. Water with a value greater than 7 indicates alkalinity and tends to affect the taste of the water. Alkaline drinking water may take on a “soda” taste. Corrosion problems also can occur in plumbing. The three types of PH adjustment devices are discussed below.
A neutralizing filter is used in drinking water that is acidic (low PH). It is a simple treatment device that raises the PH of water by add-in neutralizing material. However, it should be noted that the neutralization process may increase water hardness.
Neutralizing filters are point-of-entry devices that raise water PH to neutral levels (around 7) which reduces or eliminates plumbing corrosion problems. Calcium carbonate treats water with a PH greater than 6 and synthetic magnesium oxide will treat water with a PH below 6 Untreated water flows through the filter, which is filled with calcium carbonate (limestone) or a synthetic magnesium oxide medium. This material dissolves in the water and raises its PH level.
The biggest drawback to neutralizing filters is that they may increase or cause water hardness if calcium and magnesium are used in the filter. If hard water becomes a nuisance, the neutralizing filter should be followed by a water softener. If water hardness is treated with sodium, it may be unsuitable for people on a low-sodium diet.
In addition to water hardness, neutralizing filters may also cause water pressure loss due to the fact that the water needs to flow through finely ground neutralizing material.
Neutralizing filters are typically installed after the pressure tank, so neither the pressure tank nor the good pump will be protected from corrosion. If the flow rate is high, a liquid injection system may be better than a neutralizing filter, as it is installed before the pressure tank and thus provides corrosion protection to the tank and the plumbing system.
Caustic Soda in Water treatment
This treatment method is used if the water is acidic (low PH). Soda ash (sodium carbonate) and sodium hydroxide raise the pH of the water to near neutral when injected into a water system. Unlike neutralizing filters, they do not cause hardness problems in treated water.
Injection systems are a point-of-entry system. A corrosion-resistant chemical feed pump injects soda ash or sodium hydroxide solution into the water to raise the ph. The solution should be fed directly into the well to protect the good casing and pump from corrosion.
If the water needs to be disinfected as well as neutralized, dual treatment is possible within the injection system by adding a chlorine solution (sodium hypochlorite) along with the neutralizing chemical. Injection systems can treat water with a pH as low as 4.
As with all chemical feed systems, the chemical feed pump must be maintained and the chemical storage tanks refilled. Soda ash, the preferred chemical, is safer to handle than sodium hydroxide. Screens and filters should be periodically checked and cleaned.
Use caution if using sodium hydroxide. If adding it manually, maintain good ventilation to avoid breathing vapors. Add the chemical slowly to the water and ensure complete mixing. Be sure to wear protective gloves, goggles, and clothing to avoid skin and eye contact with the chemical. Store sodium hydroxide in a cool, dry place away from flammable materials.
Individuals on a low sodium diet should consult a doctor before installing an injection system. Use manufacturer specifications to compare sodium levels in the treated water to levels consumed from other sources in the diet. Potassium hydroxide may be used as a substitute for sodium hydroxide but may cost more.