Landfill leachate is the liquid formed by the decomposition of waste in the landfill and infiltration of water through that waste. It contains high concentrations of ammonia and organic contaminants (measured in terms of chemical oxygen demand, COD). Biochar, produced from woody residues separated from municipal waste, was used for the reduction of COD of the leachate. The produced biochar was characterized by scanning electron microscopy, Raman spectroscopy, Brunauer–Emmett–Teller surface area analysis and x-ray photoelectron spectroscopy. By following response surface methodology and specifically the Box–Behnken design, the optimum conditions and effects of time, temperature and biochar dosage were determined. It was stated that biochar dosage was the most influential factor, whereas adsorption time and temperature had a lesser effect on the process. The optimum conditions for COD removal from the leachate were the following: treatment time 140 min, temperature 31 °C and biochar dosage of 1.95 g, where a 75.5% COD removal was achieved. At these conditions, the NH₄⁺-N concentration was reduced by 23%. The spent biochar sample was regenerated by successively washing it with HF, ethanol and NaOH, and the regenerated sample achieved COD removal rates of 71%, indicating the potential for multiple uses.

垃圾填埋场渗滤液是由垃圾在垃圾填埋场中分解并通过垃圾渗入水形成的液体。它包含高浓度的氨和有机污染物（根据化学需氧量（COD）测量）。由从城市垃圾中分离出来的木质残渣产生的生物炭可用于减少渗滤液的COD。产生的生物炭的特征在于扫描电子显微镜，拉曼光谱，Brunauer-Emmett-Teller表面积分析和X射线光电子能谱。通过遵循响应面方法，尤其是Box-Behnken设计，确定了最佳条件以及时间，温度和生物炭剂量的影响。据指出，生物炭的用量是影响最大的因素，而吸附时间和温度对工艺的影响较小。从渗滤液中去除COD的最佳条件如下：处理时间140分钟，温度31°C，生物炭剂量为1.95 g，其中COD去除率为75.5％。在这些条件下，NH₄ ⁺ -N浓度降低了23％。通过依次用HF，乙醇和NaOH洗涤将用过的生物炭样品再生，再生后的样品实现了71％的COD去除率，表明有多种用途的潜力。