Stabilized landfill leachate treatment by combined physicochemical-nanofiltration processes

Landfill leachate is a complex wastewater which the composition and concent ration of contaminants are influenced by the type of waste deposited and th e age of landfill. In the last years, several processes or process combinat ions were developed and tested to reach requirements for the discharge of l eachate. Among the new processes, membrane processes are considered as prom ising: reverse osmosis is one of the most widely used treatment in the Nort hwestern European countries and nanofiltration is gained in popularity duri ng the last 5 years. Successful application of membrane technology for the treatment of landfill leachates, requires efficient control of membrane fou ling. Two organic membranes of nanofiltration were used for pilot-scale tes ting. Leachates were subject to several pretreatments (pH modification, pre filtration and coagulation with FeCl3) to remove potential foulants includi ng dissolved organic and inorganic substances, colloidal and suspended part icles. These pretreatments do not enhance the performances (retention and p ermeation flux) of membranes because the pH range and the presence of Fe3ions contribute greatly to change the characteristics of organic matter and the surface charges of membranes. However, the results show that nanofiltr ation is sufficient to eliminate refractory GOD. the permeates have a COD l ower than the requirements for discharge. (C) 2001 Elsevier Science Ltd. Al l rights reserved.