REAGENTS USED IN WASTE WATER TREATMENT
It is very important for the operator to become familiar with the material safety data sheets for all the reagents being used. Most of them are strong and hazardous. Knowing what to do for accidental contact and acting quickly will minimize possible serious damage and injury.
A moment longer to be safe may prevent a lifetime of costly regret. Be sure to use protective clothing and face shields when working with strong chemicals. Chemicals are corrosive to equipment. Chemical spills should be cleaned up and the area of the spill flushed with water immediately.
Experience further shows us that purchasing departments often buy reagent materials in packages or grades that cost more than necessary. Our reagent outline discusses standard packages and purities necessary for waste water treatment. A brief review of many of the reagents used in waste water treatment. Not all of the reagents listed below are necessary for your system (refer to startup list of chemicals).
Acid, Sulfuric 66 degrees Baume'
Sulfuric acid is a very heavy, oily liquid which is corrosive to all parts of the body. It is usually available in 15 gallon carboys, 55 gallon drums, and bulk size. Sulfuric acid is available in several commercial purities. Waste water treatment only requires a technical grade. Sulfuric acid is used to lower pH in waste treatment applications.
Alum (Aluminum Sulfate)
Alum is an inorganic chemical, highly soluble in water. It is available in several grades or qualities, as well as in several forms. It is usually available in 50 pound and 100 pound bags as well as tank wagons of liquid alum. Wastewater treatment can use a commercial crushed grade. Alum is often used as a coagulant.
Bleach Liquid (Sodium Hypochlorite)
Commercial liquid bleach is usually available as a 15% (trade percent) solution of equivalent chlorine. Larger quantities (tank wagons) are sold on the basis of actual trade percent analysis. Liquid bleach may also have a different strength (from 12-18%). A weaker bleach should cost proportionately less.
Liquid bleach has a reputation for decomposing or becoming weaker on standing. A good quality product has a very slow rate of decomposition and is pale yellow green in color. It would be acceptable to expect at least 30 days of storage without serious loss in strength. NaOcl or more commonly known as bleach is used as an oxidizing agent for some types of cyanide treatment.
If your bleach has an amber or brown color or if it is bubbling (like soda) it is not good bleach. Contact your supplier.
Calcium chloride is a white flaked or granular product usually available in 100 pound bags. Calcium chloride is used when precipitation of fluorides or phosphates is required.
All grades are usually inexpensive, however, since waste water treatment only requires a low grade of CaCl2 your purchase should be at the lowest price.
Open containers of dry calcium chloride will soon pick up moisture from the air and will harden or ultimately will liquefy. Keep open containers re-sealed or use them up as soon as possible.
Caustic Soda (Sodium Hydroxide)
Caustic soda is a very strong alkali which is very corrosive to all parts of the body. It is usually available in 400 pound or 500 pound drums as beads or flakes or as 50% liquid.
The dry form is easy to handle as beads or flakes. Several grades or purities are available. Waste water treatment again only requires a technical commercial grade.
Larger users of caustic soda frequently buy a liquid form called 50% liquid. The dense liquid contains about 6.4 pounds in each gallon. (A 55 gallon drum weighs 700 pounds and contains about 350 pounds of caustic). Liquid caustic freezes at 62 degrees Fahrenheit.
A form of hydrated silica, also called fossil silica and infusorial earth. Used in waste treatment as a precoat or body feed for the filter press.
Ferric Chloride 42 degrees Baume'
Ferric Chloride is a very corrosive acidic material which is sold in the liquid form. Care should be taken to clean up spills and flush them with water. Waste water only requires a commercial or technical grade. The standard strength usually available is 42° which contains approximately 4.6 lbs. of ferric chloride in a gallon. Other strengths are available with less Ferric Chloride in a gallon (39 degrees = 4.0 lbs; 26 degrees = 2.4 pounds). It is used as a treatment chemical.
Ferric Chloride - Calcium Chloride Reagent
Ferric Chloride - Calcium Chloride mixture is often used as a precipitation aid commonly known as Chem-1 or Chem-2.
Ferrous Sulfate is a dry inorganic chemical usually available in 100 pound bags. It is available in various grades. Waste water treatment requires only a commercial or technical grade.
Ferrous Sulfate - Aluminum Sulfate Reagent
Ferrous Sulfate - Aluminum Sulfate mixture is often used as a precipitation aid commonly known as Chem-1 or Chem-2.
Hydrochloric Acid (Muriatic Acid)
This is a very corrosive fuming liquid, strong irritant to eyes and skin, use protective clothing, face shield and mask when handling acids.
Hydrogen peroxide is a very strong oxidizing agent. It is available in varying commercial strengths. Concentrated solutions are very strong irritants and must be handled carefully. Use protective clothing and face mask when handling solutions.
Magnesium Hydroxide is an alkali that has been used for many years to neutralize acids. It is available as an aqueous white slurry of agglomerated particles composed of 55 to 60 percent Mg (OH)2.
Polymer (Polyelectrolyte Coagulant)
Polymer is an organic chemical necessary in waste treatment. There are many grades and types of polymer. It is available in both the liquid form and the powder form. The liquid is easy to use. The powder requires extra equipment and special skills for its use.
Not all flocculants work in waste water treatment. One of the best is a product available from DMP called DMP 73-111.
Sodium Bisulfite (Sodium Metabisulfite)
Sodium Bisulfite is a dry inorganic chemical usually available in 100 pound bags. A strong reducing agent, sodium bisulfite is often used as a chrome reducer. It is available in a variety of grades. Waste water treatment requires commercial or technical grade.
Sodium Hydrosulfite (Dithionite)
Sodium Hydrosulfite in a dry powdered product usually available in 100 and 200 pound metal drums. Sodium hydrosulfite is used primarily for the reduction of hexavalent chromium is situations where the process must be conducted at a neutral or raised pH. It is a flammable product and care should be taken in handling opened containers. Sodium hydrosulfite should be kept covered and special care should be taken to keep the product free of contaminates.