Treatment – Dry and Wet Waste

Solid waste is passed through a skid mounted shredder to reduce the volume and cut the solids into pieces, suitable for feeding into the incinerator for burning.  The shredder is explained in a separate chapter below. 

The shredded waste drops by gravity to the dry garbage silos placed under each main shredder.  The waste is conveyed into a vertical steel duct fitted with two hydraulic operated knife gate valves. 

The dewatered food waste (FW) from the screw press is discharged into stainless steel silos.  The silos are fitted with a level sensor, vent line connection and inspection hatch.  The silos are fitted with screw conveyors in the bottom for discharge either into the dryer or for emergency discharge.  For emergency discharge, food waste is pumped overboard through a sea water ejector system. 

Bio waste (BW) comes through the advanced waste water process (AWP).  The treatment of bio waste is explained below.  When both the food waste and the bio waste have been separately dewatered they are stored, either in separate silos or in a combined silo.  These waste streams are then called wet waste. 

The incinerator is designed to burn mixed solid waste (composed of glass, plastic, cans, card-boards, rags, etc.), sludge oil and dewatered food waste (FW), and bio waste (BW) separately or even simultaneously, if so required.  The incinerator is also designed to handle all types of plastic. 

The operation of the incinerator is explained below.

Mechanical pre-treatment for bio sludge

The bio sludge with approx 2% total solids (TS) is pumped to the decanter for dewatering.  A decanter’s normal capacity is around 3.5 m3/h.  The bio waste has to be mixed with polymer to create flocculates, so a flocculation pump station adds diluted polymer into the bio waste.  The bio waste and polymer are mixed in the decanter centrifuge, forming solids and liquids.  The...

Internal dryer

The internal dryer (ID) is a single shaft paddle dryer that operates inside the incinerator.  The paddle shaft rotates in a trough, called a bedstone.  These bedstones are made of a special kind of refractory material which keeps its shape, so the paddle shaft can receive wet waste and dry it in the furnace.  The ID is located within the incinerator’s primary chamber. 

Wet waste with a...

Incinerator system

The incinerator is a furnace designed for burning dry waste, wet waste, sludge oil and most kinds of solid waste.  Combustion takes place in a semi-pyrolytic process with the addition of combustion air in order to achieve smoke-free combustion. 

The shredded burnable waste is fed by gravity into the incinerator feeding chamber.  Hydraulic operated gate valves feed correct amounts of...

Dry waste treatment equipments

The heavy duty shredder is a skid mounted unit with twin shafts, driven by an electric motor with a gearbox. The shredder cuts the dry waste into small pieces to reduce its storage volume and to optimise the size of the waste for feeding into the incinerator.

 The unit is fitted with an anti-blocking system, which reverses the motion of the rotor...

The densifier is designed to densify aluminum cans and steel tins, compacting them in order to reduce their storage volume.  The hydraulically driven densifier is fully automatic, and the control system notifies when the machine must be emptied.  The end product, a block of compacted tin or aluminium, is discharged to a pallet for easy handling, ready for recycling ashore.

 

The glass crusher is used for breaking glass bottles in order to reduce the storage volume required by glass recycling.  This high volume breaker is based on rotating knives, giving it a high capacity.  The stand-alone unit is fast and efficient, crushing bottles and collecting the crushed glass in a container below.

The cardboard press is a large, top-loaded baler for compacting cardboard or other materials, featuring either a single chamber or a multi chamber system.  The compactor is usually supplied as a hydraulically driven, twin chamber compactor for plastic and cardboard, equipped with a control panel and emergency stop.  The press head is easy to slide sideways and position over either chamber....

The sorting table is very useful for separating dry waste, bottles and cans, simplifying the segregation of waste collected from cabins, provision areas or communal areas.  The sorting table is normally located directly in front of the shredder for easy access to the separated waste storage.