Recently the city of Lake Oswego’s water-treatment plant began treating drinking water for taste and odor problems after customers complained about earthy and musty-tasting water flowing from their taps. City officials said the odors and tastes are not dangerous, explaining that a harmless algae bloom in the Clackamas River is responsible.
Algal blooms periodically create periods of taste and odor problems for water treatment plants using lake, reservoir or river water. The typical method of handling the problem is to add ozone or powdered activated carbon. Ozone requires an upfront capital investment, but provides the benefit of added disinfection which might reduce the need for chlorine additions.
Lake Oswego will begin year-round ozone use to treat for taste and odor problems in 2016.
Water from a clay mine near Dean, PA is flowing into Clearfield Creek. The mine, which closed 60 years ago, has polluted about 15 miles of the creek. The U.S. Army Corps of Engineers is exploring various ways to clean up the creek. They are evaluating a water cleanup process that uses ozone to remove solids from polluted streams.
The process involves: a self-cleaning filter, an ozone contact tank and reverse osmosis. Ozone oxidizes metals, lower overall acid levels and enhances settling of the sludge. It uses less chemical than other processes. Demonstrations of the process conducted so far have proved successful in removing metals like aluminum, calcium, iron, manganese and barium from the water and in raising pH levels.
Ozone is a strong oxidant for metals removal and enhances solids removal via micro flocculation, i.e. a process that causes particles to cling together and settle more quickly. Both properties are useful in wastewater treatment applications.
The city of Napa dedicated a drinking water treatment plant that received more than $40 million worth of improvements and expansion over the past three years. With the improvements, the plant can now treat enough water daily to meet the city’s needs into the early months of the summer and, has increased the treatment capabilities from eight million gallons per day to 20 million gallons per day.
Improvements include a new sedimentation basin, two new filters and four refurbished ones, a new chemical containment system, chemical storage tanks and a new data acquisition system that allows the water division to manage the water supply from a central location. The facility now uses ozone to treat its water, this will ensure the plant meets new treatment regulations and those in the pipeline.
Napa obtains water from two local reservoirs: Lake Hennessey and Lake Milliken. With the increased treatment capacity, Napa can now take full advantage of its water entitlement from the state, while saving its reservoir water for the increased demand of summer or for dry years.
The city of Madison, SD is seeking matching grant money to construct a new 1-million-gallon reservoir, install ozone equipment and make other improvements with a total value of 4.6 million dollars.
Engineers have studied Madison’s water system in 2009 and the city’s underground reservoir in 2010 and made recommendations on improvements including addition of ozone equipment to remove two volatile organic compounds called PCE and TCE with a cost of $1.22 million. PCE and TCE are suspected carcinogens. Ozone breaks down organic compounds by oxidation.
If funded, the project is estimated to be completed in 2013.
Oklahoma City’s Lake Hefner Water Treatment Plant is in the midst of a $48.5 million expansion project. The plant will be able to pump out 100 million gallons of tap water each day after the renovation, up from the current 75 million gallons. the growth of the city and surrounding areas has significantly increased demand for water requiring the expansion.
The project started this year and will be finished in 2013. The new facility will use ozone as a pretreatment prior to coagulation and flocculation. Ozone is being increasingly used in drinking water treatment for both disinfection as well as removal of contaminants from the water, e.g. taste and odor compounds, without creating undesirable byproducts.