Selective separation of plastic LED lamp components using electrodynamic fragmentation for material recovery.

The recycling of light-emitting diode (LED) lamps and tubes is becoming increasingly important due to their growing market share as energy-efficient lighting technology. Here we report on the use of high voltage electric-pulse fragmentation to recover elementary components such as LED chips and printed circuit boards (drivers). E27 LED lamps with plastic bulbs, which represent 48% of deposits collected by a French company, are used as a case study. More than 150 lamps were tested on a laboratory reactor for electrodynamic fragmentation. The technological process in which highly energetic electrical pulses were applied to materials immersed in water was studied in order to separate the components of the LED lamps using a minimal specific energy. The estimated energy necessary to achieve total separation assessed at 64%, without grinding pretreatment, was 5.2 ± 0.6 kWh per ton, representing a mass recycling rate of 74%. Based on the disassembled material, the commercial value of the recovered materials was thus estimated. Gold, as the most representative material, was found to represent 0.03% of the mass fraction for 83.6% of the total commercial value. The process disassembling capacity is a key issue to increase the recycling rate of current LED lamps and tubes.

Water and acrylamide monomer transfer rates from a settling basin to groundwaters.

The aim of this paper was to estimate the potential leakage of acrylamide monomer, used for flocculation in a settling basin, towards the groundwaters. Surface-groundwater interactions were conceptualized with a groundwater transport model, using a transfer rate to describe the clogged properties of the interface. The change in the transfer rate as a function of the spreading of the clogged layer in the settling basin was characterized with respect to time. It is shown that the water and the Acrylamide transfer rate are not controlled by the spreading of the clogged layer until this layer fully covers the interface. When the clogged layer spreads out, the transfer rate remains in the same order of magnitude until the area covered reaches 80 %. The main flux takes place through bank seepage. In these early stage conditions of a working settling basin, the acrylamide flux towards groundwaters remains constant, at close to 10 g/year (±5).