Aboveground Modular, Permeable Reactive Barrier System for Rainfall Runoff Treatment

Abstract

A method for the treatment of liquid runoff, such as rainfall or irrigation runoff, to prevent the transportation of solutes. The method comprises permeable reactive barriers constructed to be permeable to rainfall runoff streams, and to effectively contact the stream with the contained media to facilitate removal of solutes from the runoff stream. Said method of rainfall runoff treatment is easily deployed in a variety of settings and easily maintained over long periods of time.

Description

FIELD OF THE INVENTION

The present invention relates generally to the field of pollution abatement. More particularly, it concerns a system of treating liquid runoff, such as rainfall or irrigation runoff, to prevent the transportation of solutes wherein permeable barrier structures are assembled in the path of runoff streams with single or multiple containers of media that remove the solute(s) from the runoff stream as the stream flows through the structure.

Agricultural, industrial, commercial and public facilities often contain substances on or near the ground surface that may achieve mobility as solutes in accumulated liquid runoff and leave the premises in a runoff stream. Methods to mitigate the transfer of solutes in runoff streams include the construction of catchment basins wherein the runoff stream accumulates until it either evaporates or permeates into the ground, grass filter strips wherein runoff stream's velocity is reduced allowing infiltration, and drainage systems incorporating buried permeable barriers wherein runoff drainage is directed through a buried barrier comprised of media that immobilizes the solutes as the drainage passes through. These present methods are limited in application by installation requirements that are not suitable for many settings. Catchment basins require a large space that may not be available particularly at established facilities. Grass filter strips may also require a large space and may be less effective on steep slopes. Buried permeable barriers may require an additional drainage system to direct the runoff through the barrier.

Performance of grass filtration strips may not be adequate during high rainfall events and the long term performance of buried permeable barriers may be limited by the effective capacity of the media utilized to act on the solute(s) and by decreases in permeability requiring difficult maintenance.

SUMMARY OF THE INVENTION

Accordingly the present invention provides a system for the treatment of liquid runoff, such as rainfall or irrigation runoff, comprising permeable barriers that allow the liquid runoff to effectively contact a media within the permeable barrier to facilitate removal of the solute(s) from the runoff stream. One embodiment of this system comprises single or multiple containers of media. The containers of media are constructed to be permeable to liquid runoff streams, to effectively contact the contained media with the liquid runoff stream to facilitate removal of the solute(s) from the runoff stream, and to easily attach together to collectively form permeable barriers of various shapes and sizes suitable for many settings and runoff flow rates, placed in the path of runoff streams on the ground surface. Said system for liquid runoff treatment is easily deployed in a variety of settings and easily maintained over long periods of time.

Following long-standing patent law convention, the terms “a” and “an” mean “one or more” when used in this application, including the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

FIG. 1 depicts a plot of land containing a substance being first mobilized by liquid (rainfall) runoff and subsequently captured as the runoff stream passes through the permeable barrier.

FIG. 2 depicts an individual media container constructed of pliable netting with holes on reinforced end strips to facilitate anchorage and attachment to other containers.

FIG. 3 depicts multiple media containers anchored to the ground surface and attached to each other forming a permeable barrier structure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a system of treating liquid runoff, such as rainfall or irrigation runoff, to prevent the transportation of solutes. The system comprises the assembly of individual containers of media constructed to be permeable to runoff streams, to effectively contact the runoff stream with the contained media to facilitate removal of solutes from the runoff stream, and to easily attach together to collectively form permeable barrier structures of various shapes and sizes in the path of runoff streams. Advantages of the present system include the ease of deployment and maintenance of the permeable barriers. For example, the individual containers of media can be of a size and weight that can be handled manually for installation and maintenance and the barriers can be constructed on the surface in the path of rainfall runoff.

The system of the invention is useful for capture or immobilization of a variety of contained solutes from rainfall runoff using a variety of sorbent or active media. The media has a surface that takes up and holds solutes, and includes zeolites, cation exchange media, activated carbon, and reactive media for example. A solute is a dissolved substance. In a preferred embodiment, a substantially solid zeolite sorbent material (zeolite) is the media used for removal of ammonia or ammonium (ammonia) in solution in rainfall runoff from agricultural land as the runoff passes through a permeable barrier placed in the path of the runoff stream. The permeable barrier is comprised of individual containers that are constructed to contain the zeolite pieces, allow fluid flow through the containers and across the zeolite pieces, conform in shape to the ground surface, provide means to anchor to the ground, provide means to attach to other similar containers, and resist degradation over long periods of time ranging from months to years.

Ammonia is present on many agricultural lands as a result of commercial fertilizer application to crops, poultry litter and dairy cattle manure application to pastures, and other activities. Ammonia is a beneficial substance on the agricultural land but when mobilized by rainfall runoff and taken off premises into streams and other bodies of water it can be a harmful pollutant. In many settings it is not practical to impound the rainfall runoff or to utilize grass filter strips to mitigate ammonia transport from the premises. In many of these cases the preferred embodiment allows for a barrier to ammonia transport to be placed on the ground surface in the path of the runoff stream that permits drainage and is easy for agricultural landowner/operators to install and maintain. It is the aim of the present invention to inhibit the transportation of solutes in rain water drainage using a barrier without inhibiting the transportation of the rain water along the drainage pathway. It is recognized that other barriers can be constructed with multiple containers for drainage control, for example sand bag barriers that are constructed to inhibit the flow of drainage. One embodiment of the present invention may utilize the characteristic of sand bags in that the shape of the bags or containers conform to the ground surface and other adjacent bags forming a structure that does not require anchorage or attachment of the individual containers.

As used herein, the term “zeolite” means a three dimensional, microporous, crystalline solid that includes aluminum, silicon and oxygen in a regular framework. Natural zeolite material exist that may be mined and crushed into various size pieces. In the preferred embodiment the natural zeolite species utilized is clinoptilolite because of a high affinity for ammonia. The preferred size of the zeolite pieces is greater than three-eighths of an inch and less than two inches in diameter. After prolonged use the clinoptilolite media can be maintained within the individual containers, for example, by washing out accumulated silt, eluting accumulated ammonia by washing with ammonia free water, or desorbing accumulated ammonia by rotating the containers to expose to sunlight.

Referring to FIG. 1 a plot of agricultural land 1 is depicted containing ammonia 2 on the surface and a permeable barrier structure 6 comprised of multiple containers of clinoptilolite pieces 8. The individual containers of clinoptilolite media 8 are fastened together to form the permeable barrier structure 6, the bottom most layer of containers 8 is anchored with stakes to the ground surface 1. Accumulated rainfall mobilizes some of the ammonia 2 in rainfall runoff 4. The rainfall runoff 4 flows along the existing drainage paths to the permeable barrier structure 6. The ammonia containing rainfall runoff 4 flows through the permeable barrier structure 6 wherein the clinoptilolite media takes up the ammonia. Rainfall runoff 10 exits the permeable barrier structure containing little or no ammonia.

Referring to FIG. 2, a preferred embodiment of an individual container 16 of clinoptilolite media 12 is comprised of netting 18 forming a bag with two reinforced ends 14. The netting 18 is formed with material that resists photodegradation, has apertures small enough to contain the clinoptilolite media, sufficient mechanical strength to resist rupture during transportation, installation, and maintenance, and is sufficiently pliable to conform to the shape of the ground surface. Reinforced ends 14 are comprised of a material with suitable strength to securely close netting 18 and to accommodate optional anchorage holes 21 and optional attachment holes 20 and is either sewn or welded onto the netting. If added anchoring is desired, anchorage holes 21 and attachment holes 20 may be punched through reinforced end material 14 and may include reinforcing grommets (not shown). In the preferred embodiment containers 16 are sized to hold approximately 50 pounds of clinoptilolite media sized between three-eighths and two inches in diameter.

Referring to FIG. 3, permeable barrier structure 22 is comprised of individual containers 16 attached together with attachment cords 24 through attachment holes 20 and anchored to the ground surface with anchorage stakes 28 inserted through anchorage holes 21 and driven into the ground surface. Permeable barrier structures 22 can be assembled with various widths, lengths, and heights using combinations of multiple containers in order to accommodate site requirements based on the ground surface geometry of the rainfall runoff flow path, the rates of rainfall runoff flow, the concentration of ammonia in the rainfall runoff, or the desired time between required maintenance.

Even though the invention has been described with a certain degree of particularity, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing disclosure. Accordingly, it is intended that all such alternatives, modifications, and variations which fall within the spirit and the scope of the invention be embraced by the defined claims.

Claims

1. (canceled)

2. A system of treating liquid runoff to prevent transportation of solutes dissolved in a liquid runoff stream, comprising: multiple modular containers of media placed in the flow path of a liquid runoff stream to form a permeable barrier that removes solutes from the liquid runoff stream while allowing relatively unimpeded flow of the liquid stream through said permeable barrier, said containers constructed to permit intra-container fluid flow and intra-container contact between the liquid runoff stream and said media.

3. The system of claim 2 wherein said containers are comprised of an outer netting material, said netting material having apertures small enough to contain said media; and said media contained in said netting in such a way that said containers are sufficiently pliable to conform to irregular surfaces, such as a ground surface.

4. The system of claim 2 wherein said containers are comprised of means for securing said containers to other containers or to a fixed surface such as the ground.

5. The system of claim 4 wherein said means for securing said containers comprises holes of sufficient strength to facilitate securing of said containers with devices such as ropes, straps, hooks, or stakes.

6. The system of claim 4 wherein said means for securing said containers comprises straps fixed to the containers.

7. A system according to one of claims 2-6 or 8-10 wherein the media comprises clinoptilolite.

8. A system according to claim 7 wherein the solute comprises ammonia or ammomum.

9. A system according to claim 2 wherein the modular containers are shaped so as to substantially eliminate any gaps, holes or voids between them.

10. A system according to claim 2 wherein the permeable barrier is substantially planar relative to the direction of the flow path of the liquid runoff stream.

11. A system according to claim 2 wherein each of the modular containers forming the permeable barrier has a substantially planar face relative to the direction of the flow path of the liquid runoff stream.