A multifunctional ship for the collection and recycling of ocean debris and the system thereof may include a hull; a detection device provided on the hull to detect ocean debris floating on the sea or deposited on the seabed; a collection device installed on the hull to collect the ocean debris detected by the detection device; a sorting device installed on the hull to sort the ocean debris collected by the collection device; a compressing device installed on the hull to compress the sorted ocean debris to compress and remove moisture and reduce the volume; a waste plastic recycling device installed on the hull to produce recycled oil by thermally decomposing the waste plastic compressed in the compressing device; a storage tank installed at the bottom of the hull to store the recycled oil produced; and a purifier for purifying wastewater generated in the process of producing recycled oil.

A plant for the treatment of waste water on board of vessels having a collection tank of black water and grey water, a primary treatment unit including a band filter, a secondary treatment unit including a micro-filtration or ultra-filtration module and a tertiary treatment unit including an ozone treatment module is provided.