The City of Tyler has released the results of an independent review of its water treatment process conducted by Enprotec/Hibbs & Todd, Inc. The study looked at the causes and possible remedies for high levels of haloacetic acids in the water. Haloacetic acids are a disinfection byproducts (DBP) which are regulated by the US EPA. They are formed when organic compounds in raw water react with chlorine to form chlorinated organic compounds such as haloacetic acids and trihalomethanes. In October of 2015 the city had received notification of high haloacetic acid levels in its drinking water.
The study recommended some operational changes to reduce the haloacetic acid levels, but some of the issues are due to the age of the water plant where the acid levels are the highest. The facility was constructed in 1950s before the onset of increased regulations on water quality. A newer facility uses ozone as a pre-treatment. The study recommends utilizing the ozone at the older water treatment plant, thereby reducing the amount of byproducts created by chlorine.
Ozone has been used extensively in the US and Europe to reduce the formation of chlorine based DBP’s.
Big Bend Water District (BBWD) is the supplier of potable water to the community of Laughlin, the sole source of which is the Colorado River. “The BBWD has over 15,000 acre feet per year as an allotment, but historically Laughlin rarely uses more than 5,000 acre feet of that allotment. BBWD can treat a maximum of 15 million gallons per day. Over a 12-month period, the average per-day flow through the treatment plant is three to four million gallons a day. Intake for the BBWD is located in the Colorado River just north of the Laughlin Bridge; most of the water in the river is a result of snow melt in the Rocky Mountains.
The job of the treatment plant is to remove impurities from the water and make it safe for drinking. The BBWD uses ozone as a disinfectant at the facility. Ozone is generated on-site and prevents the formation TTHMs, which the EPA limits in water.
Trihalomethane – or TTHM – is a by-product of chlorine, when it is used to disinfect drinking water. Ozone can remove some of the precursor compounds that form TTHM and reduces the total amount of chlorine that can form them. While more expensive to generate than other oxidants the tradeoff is a lot less taste and odor issues and much lower TTHMs. BBWD treats with chlorine, the EPA requires the district to maintain a disinfectant residual in the system because it is a surface water system.
New Jersey American Water has built a new water treatment plant in Short Hills, NJ to meet the standards of the Safe Drinking Water Act including the control of disinfection by-products. The new plant was built alongside two older plants, one that was built in 1929 and the second built in 1958. The 1958 plant remained online during construction.
The new facility cost $78 million to build, which was funded by a grant from the New Jersey Environmental Infrastructure Trust, and created 200 jobs. It can produce 14 million gallons of water a day that meets or exceeds state and federal standards.
The new plant has ozone water treatment and allows New Jersey American Water to comply with the by-products disinfection rule and improves taste and odor for the facility’s customers. Raw water is pumped from the reservoir and ozone gas is added to the raw water as needed. A coagulant is added to the water to remove natural organic matter suspended in the water. After that, the water is mixed is rapid mixed with paddle mixers to form floc and then goes on to the Dissolved Air Flotation basins. Tiny bubbles float the floc to the surface and form a sludge blanket which is removed by using a mechanical scrapper. Once it leaves the DAF basin it enters filters which remove any remaining suspended solids from the water. A disinfectant and corrosion inhibitor are then added before the water leaves the plant to the distribution system.
International Ozone Association meeting will be held in Toronto September 18-21. This meeting offers an informative technical program covering ozone and UV application with regard to the following subjects: disinfection and disinfection byproducts, UV validation and monitoring, advanced oxidation processes, ozone in drinking water, ozone in wastewater, and applications of ozone in food processing. Tours of the Horgan and Halton water treatment plants will also be available. There will be an exhibition of ozone and UV related equipment and instruments.
You can register for the event at www.io3a.org. Spartan Environmental Technologies hopes to see you there.
A three-year $106-million project that will replace the chlorine-treatment process with a new advanced 100 MGD plant is underway at the Lakeview Water Treatment plant in Mississauga, Ontario. The process will use a combination of ozonation, ultrafiltration (UF) and ultraviolet (UV) technology. Kenaidan Contracting is the general contractor and CH2M Hill is the consultant on the project which is the largest component of the plant’s overall $209 million Phase Two expansion.
The new process provides faster treatment time and requires less physical space. The footprint of the new plant will be only about 25 per cent of the space a conventional treatment plant would require.
By 2020, Lakeview will be a 100 per cent ozone, UF and UV treatment facility as additional phases of the project come on line. Many WTP’s are moving away from the use of chlorine towards alternatives such as ozone and UV as they try to simultaneously improve disinfection while minimizing disinfection by products.
The Diemer Water Treatment Plant in Yorba Linda shut down for a week to prepare for new equipment. The shutdown will allow crews to upgrade the plant so that it can use ozone as the water’s primary disinfectant, rather than chlorine compounds. Substituting ozone for chlorine compounds as the primary disinfectant reduces the potential for the formation of disinfection byproducts such as trihalomethanes and haloacetic acids that are considered unsafe for human consumption by the US EPA. The work is expected to be completed next year.
The Diemer plant supplies nearly half of Orange County’s water. The plant can treat up to 520 million gallons of drinking water per day, enough for 3 million residents of Orange and Los Angeles counties. The plant generally pulls water from Northern California or the Colorado River.
According to a recent study by the Freedonia Group, worldwide demand for water disinfection products is projected to grow more than 7% annually through 2014. UV and ozone are expected to grow the fastest. Regulations developed in the US and elsewhere to reduce the threats posed by disinfection byproducts have created opportunities for newer technologies such as chloramines, UV and ozone.
Non chemical technologies are expected to register faster growth, in part because many of these technologies offer a more sustainable option relative to products such as chlorine gas or bleach. Ozone offers the favorable attributes of degrading into safe compounds. It is also very effective for taste, odor and color removal.
McCarthy Building Companies has started work on a project for North Texas Municipal Water District, constructing new ozone facilities for the existing water treatment plant in Wylie, Texas. The $112-million project will include the installation of ozone generation equipment and construction of two buildings to house this equipment. McCarthy will also install liquid oxygen storage and feed equipment, which will supply oxygen for ozone generation.
The ozone water treatment process reduces disinfection byproducts as well as taste and odor compounds. As part of the project, McCarthy will construct 11 ozone contactors and install side stream injection systems, ozone-quenching and filter backwash chemical feed systems.
The current water treatment facility has a capacity to treat 770-million gallons of water per day and serves more than 1.6 million residents in North Texas. The engineer on the project is Black and Veatch of Dallas. The project is scheduled for completion in January 2014.