A “passive” treatment system operates using gravity and natural processes without the need for chemicals or energy demanding mechanical processes. The system consists of a series of ponds followed by a constructed wetland.
What is a passive water treatment system called?
The passive treatment system consisted of a 0.31-acre vertical flow pond (clay lined/limestone underdrain anaerobic organic substate) to neutralize pH, and a 0.34- acre constructed wetland (clay lined/emergent wetland plants) to remove residual iron and dissolved organic compounds carried over from the vertical flow pond.
What are constructed treatment wetlands?
A “passive” treatment system operates using gravity and natural processes without the need for chemicals or energy demanding mechanical processes. The system consists of a series of ponds followed by a constructed wetland.
What is a passive treatment system for a settling pond?
passive treatment system was constructed here in 2006 to capture the iron contamination before it entered Sewickley Creek. A “passive” treatment system operates using gravity and natural processes without the need for chemicals or energy demanding mechanical processes. The system consists of a series of ponds followed by a construct-ed wetland.
What is an example of a passive treatment method?
liability. In recent years, a variety of passive treatment systems have been developed that do not require continuous chemical inputs and that take advantage of naturally occurring chemical and biological processes to cleanse contaminated mine waters. The primary passive technologies include constructed wetlands, anoxic
What is passive water treatment?
Passive water treatment systems are systems that do not require the ongoing addition of chemical reagents to conduct treatment. As a result these systems: Have low running and maintenance costs. Are long term treatment options.
How does a water treatment system work?
As sewage enters a plant for treatment, it flows through a screen, which removes large floating objects such as rags and sticks that might clog pipes or damage equipment. After sewage has been screened, it passes into a grit chamber, where cinders, sand, and small stones settle to the bottom.
How is acid mine drainage treated?
Some common methods include: Reclamation of contaminated land by (1) adding lime or other alkaline materials to neutralize the acidity, and (2) adding uncontaminated top soil, planting vegetation, and modifying slopes to stabilize the soil and reduce infiltration of surface water into underlying contaminated material.
What are the 4 most common types of household water treatment systems?
Four Common Water Treatment Methods:Reverse Osmosis Water Filtration. Reverse Osmosis is a process where water pressure is employed to force water through a semi-permeable membrane. ... Ultraviolet Water Sterilization and Filtration. ... Filtration. ... Distillation.
What are the 7 stages of water treatment?
These include: (1) Collection ; (2) Screening and Straining ; (3) Chemical Addition ; (4) Coagulation and Flocculation ; (5) Sedimentation and Clarification ; (6) Filtration ; (7) Disinfection ; (8) Storage ; (9) and finally Distribution.
What two acts ensure that mining operations do not contaminate water?
These laws outline the responsibilities of several federal agencies, such as the Environmental Protection Agency (EPA), in regulating mining operations. Other acts, such as the Safe Drinking Water Act, can be relevant to specific mining operations.
What does acid mine drainage look like?
Acid drainage is often marked by “yellow boy,” an orange-yellow substance (visible in the photo on this page) that occurs when the pH of acidic mine-influenced water raises above pH 3 (approaching more neutral conditions), so that the previously dissolved iron precipitates out.
How long will acid mine drainage continue?
At some mines, acidic drainage is detected within 2–5 years after mining begins, whereas at other mines, it is not detected for several decades. In addition, acidic drainage may be generated for decades or centuries after it is first detected.
How do wetland systems retain metals?
Mechanisms of metal retention within wetlands listed in their order of importance include: 1) formation and precipitation of metal hydroxides, 2) formation of metal sulfides , 3) organic complexation reactions , 4) exchange with other cations on negatively-charged sites, and 5) direct uptake by living plants. Other mechanisms include neutralization by carbonates, attachment to substrate materials, adsorption and exchange of metals onto algal mats, and microbial dissimilatory reduction of Fe hydroxides and sulfate. The way in which a wetland is constructed ultimately affects how water treatment occurs. Two construction styles currently predominate: 1) "aerobic" wetlands consisting of Typha and other wetland vegetation planted in shallow (<30 cm), relatively impermeable sediments comprised of soil, clay or mine spoil, and 2) "anaerobic" wetlands consisting of Typha and other wetland vegetation planted into deep (>30 cm), permeable sediments comprised of soil, peat moss, spent mushroom compost, sawdust, straw/manure, hay bales, or a variety of other organic mixtures, which are often underlain or admixed with limestone. In aerobic wetlands, treatment is dominated by processes in the shallow surface layer. In anaerobic wetlands, treatment involves major interactions within the substrate.
What is the second section of Acid Mine Drainage Control and Treatment?
This paper is the second section in “Acid Mine Drainage Control and Treatment,” a chapter in a new book entitled “Reclamation of Drastically Disturbed Lands,” being prepared by the American Society for Agronomy and the American Society for Surface Mining and Reclamation. The anticipated release date for this book is 1998. The author thanks Tiff Hilton, Ben Faulkner, Alan Sexstone, Paul Ziemkiewicz, Robert Darmody, John Sencindiver, Tim Phipps, Jerry Fletcher, Keith Garbutt, Bill Hellier, Art Rose and two anonymous reviewers for helpful comments during the review process. Acid mine drainage research at West Virginia University is supported by grants from the College of Agriculture and Forestry, the National Mine Land Reclamation Center, the USDI Bureau of Mines, the West Virginia Division of Environmental Protection, and from funds appropriated by the Hatch Act.
What is AMD treatment?
Active chemical treatment of AMD to remove metals and acidity is often an expensive, long term liability. In recent years, a variety of passive treatment systems have been developed that do not require continuous chemical inputs and that take advantage of naturally occurring chemical and biological processes to cleanse contaminated mine waters. The primary passive technologies include constructed wetlands, anoxic limestone drains (ALD), successive alkalinity producing systems (SAPS), limestone ponds, and open limestone channels (OLC).
How does bioremediation work?
Bioremediation of soil and water involves the use of microorganisms to convert contaminants to less harmful species in order to remediate contaminated sites (Alexander 1993). Microorganisms can aid or accelerate metal oxidation reactions and cause metal hydroxide precipitation. Other organisms can promote metal reduction and aid in the formation and precipiation of metal sulfides. Reduction processes can raise pH, generate alkalinity, and remove metals from AMD solutions. In most cases, bioremediation of AMD has occurred in designed systems like anaerobic wetlands where oxidation and reduction reactions are augmented by special organic substrates and limestone. In a few cases, substrates have been incorporated into spoils to aid in in-situ treatment of water by the use of indigenous microorganisms.
What is multi-celled wetland remediation?
multi-celled wetland remediation system is used to treat groundwater contaminated by spilled fuel. Several years of operation have shown that the system is successfully removing BTEX and PAHs before discharge into a local stream.
What are the considerations for wetlands?
The design considerations for constructed wetlands systems are varied and site dependent1. Municipal wastewater treatment systems are most concerned with the reduction of suspended solids, organic matter, pathogens, phosphates, and ammonium and organic nitrogen. Other kinds of wastewater treatment wetlands may be concerned with these same contaminants in addition to other organic compounds, residual explosives, or metals. Some system designs anticipate exactly what kinds of contaminants the wetlands will receive, and at what levels, while others face variable and unpredictable wastewater flows. Some wetland systems treat specific substances, such as airplane deicer fluid. Other systems, such as a stormwater runoff system, may receive a mixture of contaminants, with levels of incoming water varying widely with season and year.
What is the effluent water quality monitoring program?
The data from this program will allow for evaluation of the effectiveness of the wetland based on baseline contaminant levels. The object was to develop a facility that would meet a number of needs, and this was accomplished at an estimated $3 million savings to the City of Edmonton. A storm water storage facility was created, providing fill for a highway expansion. Additional benefits of the system include reduced downstream flooding, improved runoff quality, and created habitat for wildlife.
What is the purpose of the wetlands project?
The purpose of the project is to demonstrate how constructed wetlands might be implemented at other DoD sites to treat deicing fluid runoff. Extensive initial sampling is still taking place to establish accurate baseline levels of contaminants in surface water in the area. Goals for the wetland include reduction in biochemical oxygen demand levels, which increase with additions of propylene glycol. Monitoring for BOD5 will allow for evaluation of wetland efficiency at removing propylene glycol. The goal will be to achieve average levels of BOD5 < 30 mg/L. Other goals of this wetland project include implementing a low cost, low maintenance method of deicing fluid runoff treatment that will improve deicing logistics and flight scheduling, without creating odors or increasing bird air strikes.
How much water can a wetland treat?
The wetland system can treat 200 gallons of water per minute . Water has a residence time of about five days in the system. It has proved to be a successful project. Nitrate levels are consistently reduced to less than 10 ppm. The low long-term operations costs, low energy demands, and wildlife habitat creation contribute to the success of this project. The cost savings in implementing the wetland system over other technologies is estimated to be $15 million.
What is constructed wetlands?
Constructed wetlands are an innovative and inexpensive treatment approach that have the potential to treat organic and inorganic compounds in wastewater from a range of sources. EPAs Technology Innovation Office (TIO) provided a grant through the National Network for Environmental Management Studies (NNEMS) to prepare a technology assessment report on the use of constructed wetlands for applications other than municipal wastewater. This report was prepared by a first year graduate student from Washington State University during the summer of 2001. It has been reproduced to help provide federal agencies, states, consulting engineering firms, private industries, and technology developers with information on the current status of this technology.
Why are wetlands important?
As they are depleted and affected by development, the importance of natural wetlands in watershed systems becomes increasingly apparent. Efforts to restore and maintain wetlands have been crucial to water quality in many areas. A better understanding of the benefits that wetlands provide has led to the use of constructed wetlands to mimic the filtration processes that take place in the fragile ecosystem of a natural wetland. Constructed wetlands have great potential as a clean-up technology for a variety of wastewaters.
What is the difference between acid neutralizing capacity and alkalinity?
The difference between ANC and alkalinity is that ANC measures the net condition of the water. For example, an ANC below 0 means the water is acidic and has no buffering capacity. If the ANC is above 0, the water has some buffering ability.
What are the two categories of acid water treatment?
The division is based on differences in treatment objectives. Category I methods aim to increase pH and alkalinity; Category II methods attempt to increase pH and alkalinity and remove metals.
How to treat acidic water?
One aim of treatment for acid-impacted water is to increase alkalinity by dissolving substances with calcium carbonate (CaCO 3 ), such as limestone, into the water . While many different substances can add alkalinity, calcium carbonate is most often the major contributor in natural waters.
How does limestone sand affect the water column?
Limestone sand is placed directly into the streambed of high-gradient headwater streams. The sand dissolves into the water column as it spreads downstream during high stream flow periods (see Figure 2). Dissolved limestone sand adds CaCO 3, which in turn results in higher pH and ANC and lowered aluminum concentrations.
How many miles of Pennsylvania streams are acidic?
Over 2,400 miles of Pennsylvania streams do not meet water quality standards due to acid mine drainage (AMD), and the Common-wealth has 135 miles of chronically acidified streams due to acid rain. However, many more miles of streams are degraded to some extent by acid runoff episodes. Acid runoff episodes degrade stream water quality ...
What metals are most toxic in acid rain?
If the ANC is above 0, the water has some buffering ability. Metals —Iron (Fe), manganese (Mn), and aluminum (Al) are common in acid mine drainage. Aluminum (Al) is the most common toxic metal in streams affected by acid rain.
What pH is needed for AMD?
In AMD treatment, iron and manganese precipitate at different pHs. Manganese requires a higher pH—generally around 8.0—compared to the 6.5 needed for iron to precipitate. Often, many passive treatments are unsuccessful at removing manganese due to this high pH requirement.
What is a wetlands?
Constructed wetlands are treatment systems that use natural processes involving wetland vegetation, soils, and their associated microbial assemblages to improve water quality.
Who developed the guidelines for the construction of wetlands?
Answers to common questions. The Guiding Principles were developed by the Interagency Workgroup on Constructed Wetlands (U.S. Environmental Protection Agency, Army Corps of Engineers, Fish and Wildlife Service, Natural Resources Conservation Services, National Marine Fisheries Service and Bureau of Reclamation).
Overview
Types of passive treatment systems
There are many types of water treatment systems available for removing metals from acid mine drainage. Passive treatment systems are a relatively recent technology that involves using sulfate-reducing bacteria or limestone or both to neutralize acidity and precipitate metals. These systems are sometimes called “wetlands” or “bioreactors.” Passive treatment systems differ from active syste…
Advantages
Passive treatment systems are a valuable option for treating acid mine drainage at remote locations. The advantages of passive treatment systems are that they do not require electrical power; do not require any mechanical equipment, hazardous chemicals, or buildings; do not require daily operation and maintenance; are more natural and aesthetic in their appearance and may support plants and wildlife; and, are less expensive than active alternatives.
Disadvantages
There are disadvantages with any water treatment system. The disadvantages of passive treatment systems are that they may require complex discharge permits unless taking a Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) action; may not meet stringent water-quality-based effluent standards; may fail because of poor design or severe winter conditions; and, are a relatively new technology and an area of active research. Fo…
Maintenance
All of the passive treatment systems described will accumulate metal precipitates and will eventually have to be replaced. Research indicates that these systems can be expected to perform for 20 years. The precipitate is not normally a hazardous waste. Nonetheless, regular monitoring, inspection, and maintenance are required, although to a much lesser extent than with active water treatment systems.
See also
• Constructed wetland