Leachate

Leachate clogging in the Leachate Collection System (LCS) due to chemical precipitations and biofilms produced by microbial activities is a common phenomenon in any Municipal Solid Waste (MSW) landfill. This study focuses on quantifying the factors that impact the micro-environment of leachate; and microbial activities that help the precipitates to form and attach to the LCS. It also evaluates the performance of operational changes that have been implemented or the potential alternatives and recommends the possible measures to reduce the severity of clogging. A field scale side-by-side pipe network, and several laboratory setups were used in this study. Calcite is identified to be the predominant phase present in the precipitates using XRD/XRF analysis which, concur with the previous studies. Microbial growth and activities enhance the precipitation of CaCO3 in LCS. Clogging in LCS pipes can be controlled if not eliminated by continuous monitoring along with frequent cleaning with physiochemical processes.

Landfilling, by all indications, will continue to be the predominant method of solid waste disposal. Traditional civil engineering drainage medium (i.e. sand or gravel) are being replaced by geosynthetics which are much thinner in an effort to create more usable volume for waste. This study examines the effect of compressive creep of geonets as used in leachate collection and detection systems, and how it affects in-plane drainage. HDPE geonet was subjected to a compressive load of 110 psi. The in plane flow rate of municipal solid waste leachate was measured, as well as the change in thickness, for 120 days. In addition, geonet samples were placed between two pieces of HDPE geomembrane. These samples were subjected to a normal load of 140 psi for 120 days. The samples were then inspected for sign of geonet imprint into the geonet, or for strand layover.

Modem technology has led to a new generation of landfill liner systems that are
highly efficient at intercepting and removing leachate. Many of the modem liner systems
are so effective that little or no leakage occurs through the liner systems. What leakage
may occur is so minimal that, although it can be theoretically predicted, it cannot be
measured, i.e., the resulting groundwater concentrations are well beneath minimum
detection levels of available monitoring well technology. In addition to being highly
effective, some modem liner systems are constructed with two liners separated by a
drainage medium which detects and removes any leakage through the top liner.
These significant improvements in liner system technology have led many landfill
designers, operators, and regulators to question the necessity for current monitoring well
practices. Currently, landfills are required to have a large number of monitoring wells,
and the associated large installation, sampling, and testing costs are inevitably reflected
in higher tipping fees or higher taxes. In either case, the costs are borne by the public.
If the number and frequency of sampling of monitoring wells could be reduced,
significant cost savings could be realized, and the money saved could perhaps be better
spent elsewhere.
This thesis reports the results of research conducted at eleven landfills constructed
with modem landfill liner systems to determine the actual and probable efficacy of the
role o: monitoring wells, and conducts a cost-saving analysis to evaluate whether funds
would have been better spent elsewhere.

Since the United States Environmental Protection Agency (USEPA) began requiring landfills to implement a leachate collection system in 1991, the proper disposal of leachate has become a growing concern. The potential toxicity of landfill leachate will contaminate groundwater and soil if not managed properly. Research has been made in efforts to manage leachate in a cost-effective, single treatment process. Photocatalytic oxidation is an advanced oxidation process (AOP) which has shown ability to reduce toxicity of an array of leachate constituents including organics, inorganics and heavy metals. The purpose of this manuscript is to scale up the batch scale study of TiO2 photocatalytic degradation of leachate utilizing a pilot scale falling film reactor. In this research project, the use of UV/TiO2 for the removal of chemical oxygen demand (COD), ammonia, alkalinity and color will be studied in order to optimize catalyst dosage, determine pH effects and reaction kinetics and develop preliminary cost estimates.