Membrane bioreactor technology: a novel approach to the treatment of compost leachate

Compost leachate forms during the composting process of organic material. It is rich in oxidizable organics, ammonia and metals, which pose a risk to the environment if released without proper treatment. An innovative method based on the membrane bioreactor (MBR) technology was developed to treat compost leachate over 39days. Water quality parameters, such as pH, dissolved oxygen, ammonia, nitrate, nitrite and chemical oxygen demand (COD) were measured daily. Concentrations of caffeine and metals were measured over the course of the experiment using gas chromatography - mass spectrometry (GC/MS) and inductively coupled plasma - mass spectrometry (ICP-MS) respectively. A decrease of more than 99% was achieved for a COD of 116g/L in the initial leachate. Ammonia was decreased from 2720mg/L to 0.046mg/L, while the nitrate concentration in the effluent rose to 710mg/L. The bacteria in the MBR system adjusted to the presence of the leachate, and increased 4 orders of magnitude. Heavy metals were removed by at least 82.7% except copper. These successful results demonstrated the membrane bioreactor technology is feasible, efficient method for the treatment of compost leachate.