Water works engineers are now turning to a new generation of pneumatic valve actuators that are capable of executing the instructions of electronic control systems with the necessary precision to accurately control effluent flow. Surprisingly simple but rugged in construction, this new breed of actuators also is meeting the need to reduce downtime, as some of the first ones to debut in 1981 are still in operation without needing a spare (new) part.
Reverse Osmosis - Anion-Filtration Water Plant Run by a Single Automation Platform with Fieldbus Communications
A new 3.0 mgd water treatment plant on North Carolina's Cape Hatteras is believed to be the first in the United States to apply Foundation fieldbus for device-level control communications. The plant, built by the Dare County Water Department near the famous Cape Hatteras Lighthouse, has been operating without a problem since startup more than two years ago. Fieldbus has been widely applied in all process industries including electric power generation, an industry also cautious to adapt new technology.
A study published as part of the EPA's Environmental Technology Verification (ETV) Program verifies the performance of a Fyne Process membrane filtration plant tested on high organic-laden surface water in Barrow, Ark. The plant was able to remove significant levels of organics--precursors to disinfection byproducts such as trihalomethanes (THM) and haloacetic acids (HAA)--producing water that easily met the disinfection byproduct standards set by the EPA's stringent Stage 1 D/DBP Rule.
Occasionally, height is an issue in a filtration system's housing design. A few years ago, Eden Equipment Company of Huntington Beach, Calif., was approached by a client with just this issue. Due to the client's specific requirements for their system, Eden's original ideas and drawings for this horizontal vessel needed to be redesigned. In addition to the height restrictions on their system, they also needed a design that could withstand a Seismic Zone 4 earthquake.
The AQUA 2000 Project is a build-own-operate-transfer (BOOT)
project, delivered and operated by Vivendi Water Australia. It includes the
construction and operation for 25 years of a water treatment scheme for the
Coliban Water Authority in Victoria, located in southeastern Australia.
Products in Action
On average there are 50 to 75 significant desalination projects per year in the United States with an average capacity of approximately 1 million gallons per day. The majority of these projects utilize membrane processes such as nanofiltration (NF) or reverse osmosis (RO).
In the late 1990s, one western Pennsylvania sewage treatment plant (STP) sought to process Class B biosolids on-site, eliminating the expense of hauling liquid off-site and significantly decreasing associated labor costs. At the same time, the plant needed to achieve higher cake solids and provide strict odor control. In addition, the selected equipment also had to be able to greatly enhance process efficiencies at not just the one plant, but its sister facility as well. Fortunately, USFilter offered a fairly simple solution to meet the STP's seemingly complex needs.
Robert W. Mau and Dean Clemons
Ann Arbor, a densely populated university town of 180,000, has been seeing an increase in urban redevelopment pressure in recent years as developable land has become scarce and land values have risen. The city of Ann Arbor has worked closely with the County Drain Commissioner’s office to use this redevelopment as an opportunity to improve the quality of stormwater flowing into the county drains.
Since the passing of the Clean Water Act, the industry has made great strides in improving the quality of point source discharges to the environment. As treatment technologies continue to improve, non-point source pollution becomes a more significant contributor to environmental degradation.
Based on the City of Hollywood’s experience, the use of 316L stainless steel should be evaluated carefully due to the potential for problems in the erection and construction of water treatment facilities that will be in contact with high chloride water and/or other corrosive chemistries. As with many membrane facilities, much of the stainless steel is exposed (not buried), which subjected it to atmospheric as well as water quality problems. Therefore, unless the quality control of the raw and reject water (chemical, physical and microbial) can be assured, 316L stainless steel may not be the appropriate material for engineers to specify.