Significance and Use
This test method is performance oriented for determining if, and to what degree, different liquids create biological activity on geotextile filters thereby reducing their flow capability. The use of the method is primarily oriented toward landfill leachates but can be performed with any liquid coming from a particular site or synthesized from a predetermined mixture of biological microorganisms.
The test can be used to compare the flow capability of different types of geotextiles or soil/geotextile combinations.
This test will usually take considerable time, for example, up to 1000 h, for the biological activity to initiate, grow, and reach an equilibrium condition. The curves resulting from the test are intended to indicate the in situ behavior of a geotextile or soil/geotextile filter.
The test specimen can be incubated under non-saturated drained conditions between readings, or kept saturated at all times. The first case allows for air penetration into the flow column and thus aerobic conditions. The second case can result in the absence of air, thus it may simulate anaerobic conditions.
The flow rate can be determined using either a constant head test procedure or on the basis of a falling head test procedure. In either case the flow column containing the geotextile or soil/geotextile is the same, only the head control devices change.
Note 1—It has been found that once biological clogging initiates, constant head tests often pass inadequate quantities of liquid to accurately measure. It thus becomes necessary to use falling head tests which can be measured on the basis of time of movement of a relatively small quantity of liquid between two designated points on a clear plastic standpipe.
If the establishment of an unacceptably high degree of clogging is seen in the flow rate curves, the device allows for backflushing with water or with water containing a biocide.
The resulting flow rate curves are intended for use in the design of full scale geotextile or soil/geotextile filtration systems and possible remediation schemes in the case of landfill lechate collection and removal systems.
1.1 This test method is used to determine the potential for, and relative degree of, biological growth which can accumulate on geotextile or geotextile/soil filters.
1.2 This test method uses the measurement of flow rates over an extended period of time to determine the amount of clogging.
1.3 This test method can be adapted for nonsaturated as well as saturated conditions.
1.4 This test method can use constant head or falling head measurement techniques.
1.5 This test method can also be used to give an indication as to the possibility of backflushing and/or biocide treatment for remediation purposes if biological clogging does occur.
1.6 The values in SI units are to be regarded as the standard. The values provided in inch-pound units are for information only.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.