Arsenic is among the most well-known, most feared drinking-water contaminants, and for a good reason. If consumed, it can cause several severe symptoms and, in extreme cases, even death. But before we get into a detailed conversation about the adverse effects it can have on the human body, let's discuss how it reaches our source water in the first place.
Since chlorine technology was first used in the US to disinfect drinking water in Jersey City, NJ, in 1908, most waterborne diseases have been eliminated in the U.S. Chlorine is still the most common disinfectant for drinking water and wastewater. Chlorine is also used for disinfection and as a biocide in numerous industries.
The scientific journal Ozone Science and Engineering published an article entitled: Efficacy of Ozone to Reduce Chlorinated Disinfection By-Products in Quebec (Canada) Drinking Water Facilities, authored by Ladji Meite; Macellin Fotsing and Benoit Barbeau. The following post is a summary of that article.
The impact of ozonation on the reduction of chlorinated disinfection by-products (DBPs) formation was investigated in 15 full-scale Quebec’s WTPs using ozonation as part of their treatment.
The most common locations for the ozonation process were respectively post-ozonation (9), intermediate ozonation (3), and pre-ozonation (3).
Sampling campaigns were replicated for each WTP in warm waters (June–August) as well as cold waters (November–April). Samples were collected before and after full-scale ozonation and were chlorinated in the laboratory to perform DBPs measurements under uniform formation conditions (UFC) tests. A lab-scale ozonation was also performed on each sample to standardize ozonation conditions of all investigated waters. As part of the research, total trihalomethanes (TTHM) and the sum of six haloacetic acids (HAA6) were measured after chlorination
In full-scale ozonation conditions, TTHM-UFC and HAA6-UFC reductions averaged respectively 27 and 32%.
Biodiesel is created through a transesterification reaction, a process in which vegetable oil is reacted in excess of methyl alcohol in the presence of an alkaline catalyst.
Utilities face new challenges every day. Where treatment facilities were once expected to simply disinfect water, they must now avoid creating disinfection byproducts during the process. New and more stringent regulations require the removal of additional micro-pollutants and emerging contaminants. But finding the best technology to accomplish these goals can be difficult.
Ozone is commonly used in the treatment of drinking water, but not everyone understands what it is, how it’s used, or the benefits and risks associated with it. We created this blog post to provide a brief introduction to Ozone.
How is Ozone Used for Water Treatment?
Ozone is among the most powerful oxidizing agents known to exist. For this reason, it is often used to compliment chlorine disinfection of drinking water. By using ozone, utilities can limit or avoid the use of chlorine if there’s a concern about dangerous byproduct formation. Once introduced to the treatment process, ozone can safely eliminate a wide range of organic compounds and microorganisms.
Stand-alone ozone effectively treats non-biodegradable contaminants, including micropollutants which are substantially untreated through the conventional activated sludge process. Ozone also treats groundwater that has been polluted by metals, like iron and manganese and inorganics, such as hydrogen sulfide (H2S), that are easily oxidated by O3. Ozone can also be used to remove unwanted colors, smells, and flavors from the water.
What is Ozone?
Ozone is an allotrope of oxygen (different structural modifications of the same element). There
are two main allotropes of oxygen: a diatomic molecule that is made up of two oxygen atoms,
oxygen or dioxygen (O2), and a triatomic molecule made up of three atoms of oxygen, ozone
Triatomic oxygen (ozone, O3), is an inorganic molecule. As a gas it is pale blue in color with a distinctively pungent smell. This very reactive allotrope is destructive to materials like rubber and fabrics and is also damaging to lung tissue. Traces of it can be detected as a sharp, chlorine-like smell, coming from electric motors, laser printers and photocopiers. It is also the strange odor a person would smell after a thunderstorm.
The Lariana Depur wastewater treatment plant in Fino Mornasco, Italy, treats wastewater from multiple textile manufacturers in the Como region, known as the heart of the textile industry. Since 1994, ozone has been used to remove the dark blue-purple color — the result of the dyes used in the textile dyeing and printing process — from the water.
Investing in drinking water and wastewater systems is an essential step in protecting both public health and the environment. Yet, given the recent economic climate, making the decision to move forward on any capital project is one that involves a great deal of planning and consideration. Two key factors that should always be considered are cost and reliability.