28 June 2011
Posted in Center Information
There are several motivations for on-site treatment of collected landfill leachates in FL: insufficient biological activity to sustain recirculative treatment in young landfills, a desire to incorporate leachate in municipal water reclamation regimes, or the need for an on-site source of reuse water for dust control, etc. Laboratory simulation of anaerobic MBR treatment of ‘young’ landfill leachate was used to assess the practicality of and need for further advanced treatments commonly used for water reclamation. The relative strength of ultra-filtration and microfiltration membrane permeates precluded the use of germicidal-UV for disinfection or advanced oxidation. However, it was of interest to explore whether alternative methods for introducing advanced oxidants to leachate could condition leachate for enhanced biological treatment. As O3 has a relatively high redox potential in treated waters and is not limited by the attenuation of light in the water matrix like UV, low-ppm doses of O3 were introduced to sampled leachates prior to anaerobic incubation. For comparison purposes, some leachates were spiked with H2O2 prior to ozonation to induce the rapid formation of the powerful free radical, ·OH. At pre-oxidant doses up to 8 mg/L, O3 was observed to convert significant fractions of refractory leachate organics to DOC that was consumable by aerobic municipal wastewater mixed-liquor. An increase in leachate TOC mineralization was also seen in ozonated leachates that were introduced to anaerobic activated sludge. An additional advantage to ozone pre-treatment of the sampled landfill leachate (Leon County, FL) was identified by observing the advanced oxidation of
emerging anthropogenic organic contaminants. Up to 50% removal of the suspected endocrinedisrupting
compound, bisphenol-a, was measured in leachate at low-ppm doses of O3. An on-site ozone generator could be used to deliver ozone upstream of advanced biological treatment (likely a mix of aerobic, anoxic, and anaerobic for biological nutrient removal) for preconditioning, and simultaneously to the effluent of MBR for disinfection and polishing.