Constructed wetlands can be designed to emulate the features of natural wetlands, such as acting as a biofilter or removing sediments and pollutants such as heavy metals from the water.
22.
There have been efforts in recent years to ensure the undisturbed retention of the natural wetland areas of the lake which act as both a biofilter and a refuge for wildlife.
23.
A commonly used technique is to measure the odor concentration at the emitting surface, and combine this with the volumetric flow rate of air entering the biofilter to produce an emission rate.
24.
The main influencing factors are the water composition, the biofilter hydraulic loading, the type of media, the feeding strategy ( percolation or submerged media ), the age of the biofilm, temperature, aeration, etc.
25.
Very large airflows may be treated and although a large area ( footprint ) has typically been required a large biofilter ( > 200, 000 acfm ) may occupy as much or more land than a football field this has been one of the principal drawbacks of the technology.
26.
Floating habitat islands were installed with salicornia salt marsh plants at Sydney Olympic Park Authority in 2011 providing nesting sites for local and migratory birds including black swans, black-winged stilts, red-necked avocets, Pacific black ducks and chestnut teals, using the Aqua Biofilter product.
27.
The newest, and largest, biofilter addition to Plum Creek cost $ 9.5 million, yet even though this new technology is expensive, in the long run it will cost less overtime than the alternative exhaust-cleaning incinerators fueled by natural gas ( which are not as environmentally friendly ).
28.
Also, instead of a single, large support system ( typically 10 feet depth of media for chemical scrubbers ), there are multiple stages of media support, that can change the design requirements of the vessel . ( See biofilter for similar technology that is usually performed outside of an FRP vessel .)
29.
Keeping the pH in a suitable range ( 5.0-9.0 for freshwater systems ) is crucial to maintain the health of both the fish and biofilter . pH is typically controlled by the addition of alkalinity in the form of lime ( CaCO 3 ) or sodium hydroxide ( NaOH ).
30.
The world's largest vegetated floating islands 4 acres in size were installed in 2004 using Aqua Biofilter " ! product with Canna ( plant ) at Lake Tai, China using materials including a combination of polyurethane open cell filter foam, closed cell polyethylene floatation foam, bamboo and coconut fibre filter foam mix with wicking ability to supply water to plant roots.
