How to Size an Oil Water Separator

If you are looking for a gravity oil water separator, here is a rule of thumb to determine the size. Multiply your estimated flow rate times 10 and that will be the minimum tank size. For example, if your flow rate is around 30 gallons per minute (gpm) you will want an oil water separator with a separation tank that is at least 300 gallons. This will give the oily water a 10 minute retention time in the separation tank. 10 minutes is usually enough time for gravity separation. If you want to be sure, collect a sample of your ... » Read More

Separating Emulsified Oils in Water

Separating Emulsified Oils in Water Oil can become emulsified in water by mechanical agitation and by chemical emulsification or both. Mechanical Emulsification of Oil in Water Centrifugal pumps often will cause mechanical emulsification. Also, any influent piping that is elevated above the surface of the oily water that is splashing into the tank will also cause emulsification and possible foaming. Oil that is mechanically emulsified will usually separate given enough time. Oil coalescing grids will also assist in separating the emulsified oils. Chemical Emulsification of Oil in Water Degreasers and soaps can chemically emulsify oil in water. Most degreasers and ... » Read More

What Do Oil Removal Claims Really Mean?

When you see a manufacturer claim that his oil water separator will remove oil and grease to below 200 mg/l or some other number, keep in mind what he really saying. They are usually basing their claim using pure water, at 65 to 70 degrees,  with some amount of clean SAE 30 weight motor oil straight from the can. Ask the vendor exactly what they are basing their oil removal claims on. Ask what percent oil was added, ask for exact SAE weight or viscosity and ask the temperature. Bench scale testing of your oily water is usually a good ... » Read More

Clean Water

What Does Clean Water Really Mean?

The words clean water mean different things to different people. Is clean water, water that has absolutely no contaminants at all? Or is clean water, water that may have some contaminants but not at levels you can taste or that are harmful to human health? What Lawyers Will Say About Clean Water Environmental Lawyers will tell you that clean water may have the presence of contaminants, as long as they are below the contaminant levels as set forth in the EPA Drinking Water Standards.   Environmental Lawyers prefer to call water with contaminants, impacted water. And they insist that as long ... » Read More

Water Reuse in Food Processing

Water Reuse in the Food Processing Industry

Water Reuse in Food Processing? Never. Using recycled water — no matter how well it is treated — in contact with the food product being processed is unheard of. The food processing industry has very high standards for food processing.  Even the thought of using recycled waste water for the processing of food is avoided. Even though the treated water may be fine, the perception of using recycled water in contact with food is poorly received. What Does Clean Really Mean? This raises the question of just what is clean. And what does clean really mean? We will attempt to ... » Read More

My Wastewater Stinks Like Rotten Eggs

We received a call last week from a company complaining that the wastewater in the collection pit of their wash bay stunk so bad the workers were not wanting to work. They complained that the wash water in the collection pit smelled like rotten eggs. Hydrogen Sulfide Stinks That rotten egg smell is Hydrogen Sulfide gas (H2S).  This gas is produced by what are called anaerobic (no oxygen) bacteria. Anaerobic bacteria can live in the sludge that settles to the bottom of your collection pit. You can often see small bubbles of this gas coming to the top of the ... » Read More

Ozone in Wastewater Treatment

Some History Ozone has been used in wastewater treatment for over 100 years.  Historically, its main use has been drinking water disinfection.   In Europe ozone treatment of drinking water is common.   In more recent years ozone has been used to treat wastewater for odor control and corrosion control. Ozone Oxidation Ozone is a naturally occurring form of atmospheric oxygen.   The oxygen we breath in has two atoms, Ozone has three.   The third atom of oxygen makes the ozone molecule highly unstable and highly reactive with a very high oxidation potential. Other oxidants such as hydrogen peroxide, sodium hypochlorite (bleach) and ... » Read More

Lowering BOD

Lowering BOD

What is BOD? BOD is Biochemical Oxygen Demand. It is a common yardstick used to determine the strength of wastewater.   It is a test conducted over 5 days and measures the oxygen uptake in mg/l. Your City municipal sewage treatment plant does not want high BOD wastewater as it increases the treatment time and the cost of treating.   Typical BOD from the average household is around 350 mg/l, industrial wastewater can go into the thousands of mg/l BOD. Lowering BOD to Avoid Fees Most municipalities will charge a fee for high BOD.   Take a look at your water and sewer ... » Read More

Granular Activated Carbon GAC

Which Chemicals Will Granular Activated Carbon (GAC) Adsorb?  A Quick Reference Guide.

I get asked all the time about specific chemicals and the probability of being adsorbed by Granular Activated Carbon.   Below is a quick reference guide.   Always ask your carbon supplier for the GAC Adsorption  isotherm for the chemical you want to remove.  The GAC Isotherm will show you the mg of chemical adsorbed per mg of GAC at constant temperature.   Also, bench scale testing is important as certain adsorption rates are affected by pH, soaps and by the presence of Chelating Compounds such as EDTA. Group 1: Chemicals readily adsorbed by Granular Activated Carbon (GAC) GAC commonly used to remove ... » Read More

Waste Water Treatability Testing with Clay Based Flocculants

A printing company in the Dallas area had a wastewater problem. The city of Dallas does not allow dye or inks that discolor the waste water and issued a Notice of Violation stating that the waste water must be pre-treated before discharge to the sewer or to stop the discharge. The company stopped the discharge and began to have waste water hauled off site for disposal. At the same time an internet search for treating options was conducted. Wilson Environmental was contacted and we offered to do a free treatability test. Our treatability test is simply a yes or no ... » Read More