The tricycle is carrying carton and styrofoam boxes. The stuff was collected for recycling and usually goes to a larger recycling collection center, where it will be transferred to larger trucks, which in turn will haul the carton and boxes to the actual recycle plant.
Transporting carton and styrofoam boxes in this way is officially forbidden in China, but in reality nobody really cares, especially not this late at night. And recycling is for the common good, right?