There are multiple reasons why your water is tinted. In surface water there are natural organic matters that produce a yellowish tint or color. By adding disinfectant chemicals, carcinogenic Disinfection By-Products (DBPs) can be formed.
Why is my water tinted yellow or brownish?
In surface water, natural organic matter exists in either non-dissolved or dissolved form. The dissolved forms of matter are known as Dissolved Organic Carbon (DOC), while the sum of dissolved and non-dissolved carbon is known as Total Organic Carbon (TOC).
The DOC in water is what produces the yellowish tint or color, and is measured in Color Units (CU). If this type of discoloration is present in the water, then adding disinfectant chemicals such as chlorine, bromine, or bleach will create Disinfectant By-Products (DBPs), which are carcinogenic.
Since these chemicals are commonly used in disinfecting water supplies, water discoloration presents a significant health risk to drinking water usage.
What are Disinfection By-Products (DBPs) exactly?
Disinfection by-products (DBPs) are a class of chemical by-products known as trihalomethanes (THMs). They are formed when chlorine or bromine interacts with the natural organic materials found in water. DBPs also include other formed products, such as haloacetic acids, haloacetonitriles, haloketones, and chlorophenols. The composition and levels of specific DBPs are determined by water quality, water treatment conditions, and disinfectant type.
Primary sources of DBPs are chlorinated drinking water and recreational water bodies, such as swimming pools. A 2005 article from Environmental Health Perspectives showed that you don’t just have to drink the water, either: hot showers, washing dishes and washing clothes in DBP-filled water directly correlated with higher concentrations of THMs in people’s blood. Additionally, the article showed that THMs are absorbed through the skin as well as by ingestion.
Using flocculation-filtration to remove the discoloration from water
For larger scale projects, such a municipal water production, Seccua recommends the flocculation-filtration method. Seccua has installed hundreds of these types of public water systems world-wide; most of them are in Germany, the United States, and Canada.
Using activated carbon filtration to remove the discoloration from water
Seccua offers its Seccua Biofilter to remove DOC from water. Seccua recommends activated-carbon filtration for residential use, due to the lower volumes of water that have to be processed compared to commercial water consumption. Whoever designs the system must make sure that the contact time between the activated-carbon filter and the water is at least 10 minutes.
The feed-water to the Virex Pro Connect system was taken in from Lake Ely, Minnesota. Feed-water showed Color of 60 CU. Flocculant was added upstream the Virex Pro Connect system (please get back to Seccua for further information on type and concentration of flocculant added).
The Virex Pro filtered at a flow of 2.8 gpm. The Virex Pro Connect system controlled an automated hourly back-wash with filtered water through a back-wash pump. Also the feed-pump was connected to the system, no additional control was required.
As required per U.S. EPA Filtration Guidance manual for membrane filters applied in filtration of surface water or surface influenced water, the Virex Pro Connect performed a daily, fully automated Direct-Membrane-Integrity test.
- The filtrate of the Seccua Virex Pro showed no yellow tint any more, Color was removed by two-thirds to 20 CU (feed: 60 CU).
- The filter membrane of the Virex Pro did not loose any permeability during the test period of one week, so a very sustainable state-of-operation was achieved.
- The removal of 27% of TOC also leads to a significant reduction in Disinfection-by-Products (DBP).
Seccua has many more data available, which will help you to design your color- and DBP-removal process. Please feel free to get in touch with us and we will send you further information.