Assessment of Industrial Byproducts as Permeable Reactive Barriers for Landfill Leachate Management

Laboratory scale studies were conducted to investigate the feasibility of Industrial by-products as potential alternative medium to conventional gravel in the drainage layer of leachate collection system as permeable reactive barriers (PRBs) for landfill leachate treatment. Industrial by-products were used to treat effectively the landfill leachate, which is an innovative in-situ remediation technology. This study will open a tremendous scope of using industrial byproducts as potential medium for treating leachate and this would reduce the magnitude of the current industrial waste disposal problem and convert one waste into a beneficial material. Industrial waste, such as Steel plant by-product (Waste slag), Tire industry by-product (scrap-tire-shreds) and Rice Sheller by-product (Rice husks) were studied. The availability and the cost are important criteria in selecting a reactive material. These Industrial waste materials are inexpensive and abundant, and are, therefore, ideal for low cost leachate treatment. Leachate treatment efficiency was evaluated on the basis of percentage reduction in concentration of leachate parameters before and after treatment by passing through Test Cells 1 to 11 having different combinations of conventional gravel and various Industrial by-products with total thickness 500 mm of PRBs (multibarrier). Treated leachate samples were collected from Test Cells 1 to 11 at the interval of 30, 60 and 90 days. The percentage reduction in various leachate parameters was maximum with Test Cell-11 having combination of rice husk (125 mm), waste slag (125 mm), scrap-tire-shreds (125 mm) and gravel layer (125 mm) in equal proportion as PRBs (multibarrier). It has been observed that leachate sample after passing through combined beds of Industrial by-products and conventional gravel gave better results in comparison to Test Cell-1 containing conventional gravel bed singly. This performance trend can be attributed due to combined effect of conventional gravel and Industrial by-products bed on adsorption, ion exchange reactions, filtration, precipitation and biological uptake. The percentage reduction in BOD5, COD, Chloride (Cl − ), Nitrate (NO3 − ), Phosphorus (P), Sulphate (SO4 2) value was maximum upto 76.5%, 83.5%, 64.4%, 81.2%, 73.5% respectively. For reliable expectation on the longevity of PRBs (multibarrier), column test has to be performed for longer periods of time and the changes in material reactivity need to be observed.