Land fill leachates are the result of water percolating through solid waste buried at the site. Land fill make provisions to capture this water for treatment. The waste can be a significant challenge to treat because of high content of organic matter, ammonia, salts and metals. Leachates vary due to a variety of factors including landfill age. New landfills produces leachates that are more biodegradable which are easier to treat. As the land fill ages biodegradability of the organic matter decreases. This means that treatment processes must include non biological treatment steps such as physical, and chemical process for older land fills.
At the recent International Ozone Association meeting a paper was presented on the use of ozone in combination with biological treatment (Ozone-Enhanced Biological Treatment of Landfill Leachates, Claudio Di Iaconi(1) , Antonio Lopez(1) and Achim Ried(2), 1 Water Research Institute, CNR, Bari, Italy; 2 ITT W&WW Herford, Germany). Normally to treat COD the ozone dose is typically between 2-3 mg Ozone per mg of COD. This can make the treatment process expensive. Ozone tends to make refractory organic compounds more biodegradable. Therefore, by pretreating the wastewater with ozone, the biological treatment process can assume a larger portion of the treatment burden. In addition, because ozone adds oxygen to the wastewater, the biological process is more efficient. the paper indicates that in some configurations the ozone demand is lowered to less than 0.7 mg Ozone per mg of COD.