Mike-O-Pedia FAQs for Water Treatment Professionals
The purpose of the “Mike-O-Pedia” is to share knowledge with our peers. We will be posting on a regular basis and look forward to answering questions or discussing comments and applications with our dealer customer base.
Topic: Water Softeners
Which Salt to Do We Use?
- Sodium Chloride
- Solar Salt
- Salt pellets
- Potassium Chloride
- May be used in place of sodium chloride. If user is clinically monitoring sodium intake suggest use of reverse osmosis drinking water system.
- Chemically treated salt specifically designed to clean resin for iron removal softener.
- Softeners prevent scale.
- Softened water will dissolve calcium scale very gradually from existing plumbing.
- Caution – If your customer has experienced severe scale build up in pipes or water heating devices he/she might not see zero soft water results due to the erosion of the calcium.
- Run cold water from high flow tap to ascertain whether the water is soft -> you may experience the same with iron removal.
Removing Iron with a Water Softener
- Ferrous (Fe ++) or clear water iron can be removed by a water softener
- Compensate for hardness & manganese by using this formula:
- Compensated hardness = 2 x iron + 2 x manganese + hardness
- Gallons between regenerations = compensated hardness / capacity of softener
- If the formula yields less than 1,000 gallons between regenerations use a larger softener
- Other considerations when using a softener to remove iron:
- A higher salt dosage is required – 10-15 lbs. per cubic foot.
- Fine mesh cation resin yields better results when iron is greater than 3 ppm.
- Use of a resin cleaning system or salt is recommended.
- Do not use an upper screen. Iron will clog the slots.
- When do I NOT use a water softener for hardness and/or iron removal?
- Cloudy water iron (ferric Fe+++)
- Heavy sedimentation
- Iron bacteria
- Organic iron
- TDS greater than 450 ppm
- pH higher greater than 8.5
Water Hardness & Low pH
- Hardness greater than 10 gpg? Acid neutralizer media will not easily dissolve – place softener before neutralizer. Don’t want to do that? Feed soda ash with chemical feed pump.
- Caution – When sizing a water softener, add 4-6 additional grains of hardness to your water test to compensate for the additional hardness coming from calcium carbonate neutralizing media.
Should I use an upper screen?
- Almost always. If removing iron greater than 2 ppm remove the upper screen. Iron can accumulate on the screen and ruin the efficiency of the softener
What type of resin do I use in a softener?
- Always specify softener resin also known as cation resin must be in the sodium form (Na).
- Caution – Malfunctioning Res-Up feeders may depress pH and convert the resin from the sodium (Na) form to the Hydrogen H+ form and result in very low pH water.
How long does softener resin last?
- For residential service in chlorine & iron free water about 10-15 years.
- Where chlorine or chloramine & iron are present about 2-5 years.
Should I install a water softener to remove lead?
- A softener may be used to reduce lead however, it should always be backed up by reverse osmosis treatment at the kitchen tap.
- Lead will not affect softener operation however, Caution – contract with customer to monitor lead levels at least annually.
Topic: Activated Carbon
GAC Specifications – What do they measure?
How closely in size is the contaminant to a molecule of iodine? The higher the iodine number the better the removal of molecules which closely resemble iodine. Iodine is a small molecule therefore it measures ability to adsorb lower molecular weight smaller substances.
Molasses number Is a measurement of the degree of decolorization of a standard molasses solution. It is a relative guideline for measuring the capacity of the carbon to remove color molecules.
Demonstrates the carbons ability to withstand degradation during handling – before and after it is placed into service. Lower abrasion numbers result in more dust and fines.
Density, Backwashed & Drained (BWD)
This is the number of pounds required to fill a cubic foot of volume capacity. Caution– The density of activated carbon types varies.
TCN – Trace Capacity Number
The Trace Capacity Number measures the number of high energy pores in an activated carbon product. These high energy pores are required to remove difficult to adsorb contaminants, such as MTBE. The theory behind the test is similar to the Iodine number, where the iodine number reports the mg Iodine per gram of carbon in a standard iodine solution. Since iodine is so strongly adsorbed, it is essentially fills all of the adsorption pores (high energy and low energy). The TCN number uses a more difficult to adsorb species and reports the mg loaded per gram of carbon. A higher TCN number on a carbon would indicate a higher number of high energy pores, which would suggest better loading in an application with difficult to remove contaminants.
The ash content of a carbon can be defined as the noncombustible mineral matter that is contained in activated carbon. It is the residue that remains after the combustion of a carbonaceous material and is normally defined on a weight basis. The ash content is dictated by the raw material used to manufacture an activated carbon product and is why a high purity raw material is necessary to produce a high purity activated carbon product. There are also additional post-processing steps, such as acid washing, to reduce the amount of ash content in an activated carbon product.
Water Soluble Ash
Ash measures the level of purity. It is the inorganic residue left after the heating process. It consists of silica, calcium, alumina, iron, magnesium with a potential for arsenic. Carbon may be acid washed or water rinsed to reduce ash content. Water extractable ash has the highest impact on the product quality as it affects the effluent.
Can Activated Carbon be regenerated?
Activated carbon cannot be regenerated like ion exchange resin. Activated carbon can be reactivated by carbon manufacturers. The reactivation process is similar to the original activation process. The resulting product is distributed for waste water applications. Municipalities contract to reactivate segregated lots for re-use.
It is possible to reactivate activated carbon with steam. Beverage manufacturers have large carbon filters which have steam injection. The heat from the steam will push off the more weakly held contaminants freeing up pores for continued use. The steam also sanitizes the carbon bed. Steam reactivation will restore the life of the carbon bed but eventually the cost outweighs the benefit and a new carbon bed must be installed.
Which type of carbon do I use?
- Hydrogen Sulfide (H2SO4)
- Use Catalytic Carbon only in a single tank with peroxide – download article here Applying Peroxide
- In presence of sulfur reducing bacteria (black slime) treat with chlorine and KDF cubes.
- Use any carbon for chlorine removal. It is a chemical reaction is on the surface of the carbon similar to ion exchange.
- Backwashing extends the life by removing sediment from the carbon bed.
- Rebed or change out the activated carbon when black particles or gray water is seen in standing water – such as toilet bowls; or when there is increased pressure drop across the carbon bed.
- Except to polish after primary treatment activated carbon is not recommended for tannin removal.
- VOC (Volatile Organic Contaminants)
- Caution – there are too many variables contact the Urbans Aqua for help.
- POS POA PFOA
- Only coal based carbon should be used.
- Dual tank operation – worker / guard with sample port between and after.
- Strongly recommend use of a totalizing meter after guard tank.
- Download paper here
- Taste and Odor
- Any carbon will work.
- Pre-treatment to RO
- Coconut base carbon is physically harder and produces very little fines.
- High Purity Applications
- Acid Washed Carbon removes dissolved, naturally occurring metals.
What is Enhanced Coconut Carbon?
- According to Calgon Carbon enhanced coconut is basically a standard coconut product that undergoes additional processing (chemical fluxing agents and thermal conditions) to transform a coconut’s pore structure to be more like a reagglomerated bituminous coal-based product. Coconut based activated carbons traditionally have a very tight pore structure (microporous) while reagglomerated bituminous coal based products have a broad range of pore structures (micro, meso, and macroporous).
Topic: Arsenic Removal
Arsenic is a grey, semi-metal element. Arsenic enters ground water from both natural sources and human activity. Contamination can sometimes be traced to deep-water brines produced from gas and oil well drilling. It is also be found in wood preservatives and may be a byproduct of herbicide production.
Arsenic has a primary drinking standard because it is known to have health effects when present in drinking water. Skin lesions, circulatory problems and nervous disorders can occur. Prolonged exposure may result in skin, bladder, lung and prostate cancer. For this reason, the EPA has set the MCL to 0.01 mg/L (micrograms per liter). Arsenic removal from wells
Arsenic Reduction/Removal from Water
Arsenic is one of the hardest ions to remove from water. It usually occurs in water as either arsenate (AsV) or arsenite (AsIII). Test results report the total arsenic concentration including arsenic as arsenate and arsenic as arsenite. Aresenite is a greater health concern and more difficult to remove. For this reason, most treatment solutions start by adding an oxidant to the water to convert all arsenic to the arsenate form. Oxidation can be accomplished through the addition of chlorine, ozone or greensand. Note: Chloraminated water utilizing only monochloramine (NH2Cl) will not completely oxidize AsIII to AsV).
Heating or boiling water will not remove arsenic from water, it may increase the concentration as the water is evaporated off.
To determine the best removal treatment the water must first be tested by a certified lab.
Removal methods include Activated Alumina, Manganese Greensand Filtration, Distillation, and Reverse Osmosis. Urbans Aqua offers specialty products – Purolite’s FerrIX™ A33E and Graver’s Metsorb®. All products used for arsenic removal should be NSF or WQA Gold Seal Certified.
Before embarking on a treatment regiment, a full water analysis is necessary. Since Arsenic is anionic, you must test for competing anions. Both Purolite and Graver have a water profile work sheet that must be filled out, so they can better estimate bed life. Contact Urbans Aqua for equipment system design.
|Activated Alumina||Potential for non-hazardous disposal as solid waste.
|Highly selective for AsV; AsIII must be oxidized
pH < 6.5 or lower if silica is present
|Distillation||Reduces to < 2 ppb||Only practical for small quantities of water treatment|
|Ion Exchange Anion SBA I & II||Effective for AsV
Optimum pH >7
|AsIII must be oxidized and removed prior to resin bed.
Nitrate, fluoride, selenium & sulfate will compete with AsV for exchange sites resulting in earlier exhaustion.
|Manganese Greensand||Effective for AsV||AsIII must be oxidized and removed prior to greensand filter. Iron must be present in raw water equal to or greater than the arsenic.
|Reverse Osmosis (RO)||Effective for AsV||AsIII must be oxidized and removed prior to RO. Care must be taken to prevent damage to membrane.
|FeriX™A33E||Selective removal of arsenic.
pH for treatment 7
Operates similarly to ion exchange resin.
EBCT 2.5-5 Minutes (typically 3 minutes).
Low pressure differential
|Potential for nitrate dumping.
Offsite regeneration available for large installations.
|Metsorb®||Removes AsV & AsIII.
EBCT 1.5-3 Minutes.
Also removes lead, cadmium, copper, zinc, chromium+6 & selenium.
Potential for non-hazardous deposal as solid waste.
|Potential for high pressure differential.