System and method for landfill dewatering using a venturi air lift liquid pump
A system and method for enhanced leachate collection from a solid waste landfill site are provided. The landfill site can include, without limitation, one or more landfill waste layers, one or more leachate layers, a landfill liner layer, and a groundwater layer. A landfill gas well extends from the ground surface and passes down through the landfill waste layer and encounters a leachate layer within the waste mass. The well is configured to capture landfill gas and remove leachate from the leachate layer of the landfill site and transport it to the landfill surface. An airlift venturi pump can create venturi effect and generate discharge to deliver leachate to the landfill surface. The leachate can be piped to a gravity drain system, frac tank, collection sump or other onsite holding area, or transported to an approved offsite location for disposal.
1 . An airlift venturi pump for collecting leachate from a solid waste landfill, comprising:
an upstream entry pipe configured to receive the leachate from the landfill, the upstream entry pipe defining a first axis;
an airlift section in fluid communication with the upstream entry pipe and configured to receive leachate from the upstream entry pipe, the airlift section comprising:
an inlet pipe defining a first inside diameter,
an outlet pipe defining a second inside diameter,
a throat disposed between the inlet pipe and the outlet pipe, wherein the throat has a diameter that is narrower than the first inside diameter and the second inside diameter, and wherein the throat is configured to facilitate a venturi effect and transport the leachate therethrough, and
an air conveyance pipe at least partially positioned within the first inside diameter and defining a second axis parallel with respect to the first axis, the air conveyance pipe configured to inject air into the inlet pipe; and
a downstream exit pipe in fluid communication with the airlift section and configured to transport the leachate away from the airlift section.
2 . The airlift venturi pump of claim 1 , further comprising an upstream riser section in fluid communication with the upstream entry pipe and configured to deliver leachate to the upstream entry pipe and a downstream riser section in fluid communication with the downstream exit pipe and configured to deliver leachate away from the downstream exit pipe.
3 . The airlift venturi pump of claim 2 , wherein the airlift venturi pump is located underground at the solid landfill site, and wherein the air conveyance pipe is connected by a flange connection to an air conveyance fitting comprising a pair of 90-degree elbows, and wherein the air conveyance pipe is configured to inject air into the venturi pipe in an upward direction, and wherein the downstream exit pipe is configured to deliver leachate from the underground at the solid waste landfill to a ground surface.
4 . The airlift venturi pump of claim 3 , wherein the airlift venturi pump is configured to be located up to fifty feet underground at the solid landfill site.
5 . The airlift venturi pump of claim 1 , wherein the air conveyance pipe comprises:
an air conveyance riser portion extending at least partially along a landfill waste column;
an air conveyance outlet portion positioned at least partially within the first inside diameter; and
at least one bend configured to redirect flow from the air conveyance riser portion to the air conveyance outlet portion.
6 . The airlift venturi pump of claim 5 , wherein at direction of flow of air along the air conveyance riser portion is opposite a direction of flow of the air along the air conveyance outlet portion.
7 . The airlift venturi pump of claim 6 , wherein the at least one bend comprises a first 90-degree bend and a 90-degree second bend, the first and second 90-degree bends configured to redirect flow from the air conveyance riser portion to the air conveyance outlet portion by 180 degrees.
8 . The airlift venturi pump of claim 1 , wherein the first inside diameter is equal to the second inside diameter.
9 . A system for collecting leachate from a solid waste landfill, comprising:
a landfill gas well that extends from a ground surface and through a landfill waste layer to a leachate layer within the solid waste landfill; and
an airlift venturi pump disposed within the landfill gas well and configured to collect leachate from the leachate layer, the airlift venturi pump comprising:
an upstream entry pipe configured to deliver leachate from the landfill;
an airlift section in fluid communication with the upstream entry pipe and configured to receive leachate from the upstream entry pipe, the airlift section comprising:
an inlet pipe defining a first inside diameter,
an outlet pipe defining a second inside diameter,
a throat disposed between the inlet pipe and the outlet pipe, wherein the throat has a diameter that is narrower than the first inside diameter and the second inside diameter, and
an air conveyance pipe comprising an outlet portion that is positioned at least partially within the first inside diameter and oriented in a direction other than orthogonal with respect to the inlet pipe, the air conveyance pipe configured to inject air into the airlift section; and
a downstream exit pipe configured to deliver leachate away from the airlift section.
10 . The system of claim 9 , further comprising an upstream riser section in fluid communication with the upstream entry pipe and configured to deliver leachate to the upstream entry pipe and a downstream riser section in fluid communication with the upstream entry pipe and configured to deliver leachate to the downstream exit pipe.
11 . The system of claim 10 , wherein the airlift venturi pump is located underground at the solid landfill site, and wherein the air conveyance pipe is connected by a flange connection to an air conveyance fitting comprising a pair of 90-degree elbows, and wherein the air conveyance pipe is configured to inject air into the venturi pipe in an upward direction, and wherein the downstream exit pipe is configured to deliver leachate from the underground at the solid waste landfill to a ground surface.
12 . The system of claim 11 , wherein the airlift venturi pump is configured to be located up to fifty feet underground at the solid landfill site.
13 . A method for collecting leachate from a solid waste landfill, comprising:
passing the leachate through an airlift venturi pump, the airlift venturi pump comprising an upstream entry pipe configured to receive the leachate from the landfill, an airlift section in fluid communication with the upstream entry pipe, the airlift section having an inlet pipe, an outlet pipe, and a throat disposed between the inlet pipe and the outlet pipe, the throat having a diameter that is narrower than both the inlet pipe and the outlet pipe, and a downstream exit pipe in fluid communication with the airlift section and configured to transport the leachate away from the airlift section; and
introducing, by an air conveyance pipe, an air stream into the inlet pipe, wherein the air conveyance pipe is at least partially inside the inlet pipe such that the air conveyance pipe and the upstream entry pipe have parallel axes; and
facilitating a venturi effect in the throat to create a vacuum and pull the leachate therethrough.
14 . The method of claim 13 , wherein the airlift venturi pump further comprises an upstream riser section in fluid communication with the upstream entry pipe and configured to deliver leachate to the upstream entry pipe and a downstream riser section in fluid communication with the upstream entry pipe and configured to deliver leachate to the downstream exit pipe.
15 . The method of claim 14 , wherein the airlift venturi pump is located underground at the solid landfill site, and wherein the air conveyance pipe is connected by a flange connection to an air conveyance fitting comprising a pair of 90-degree elbows, and wherein the air conveyance pipe is configured to inject air into the venturi pipe in an upward direction, and wherein the downstream exit pipe is configured to deliver leachate from the underground at the solid waste landfill to a ground surface.
16 . The method of claim 15 , wherein the airlift venturi pump is configured to be located up to fifty feet underground at the solid landfill site.