The Kowloon Bay Pilot Composting Plantprocesses about 500 tonnes of food waste annually

This is how it works

A project by Alexandra Hoegberg,

When food waste is delivered to theComposting Plant, it is alreadysource separated. Compostableitems such as eggshells, vegetables,bread, meat and bones, rice,noodles and fruit have beenseparated from non-compostableitems, like different kinds of foodpackaging – including papercartons.

After it has arrived to the Plant, the food waste is first sortedmanually in the Plant’s sorting facility, and is drained of any waste-water.

Source separated waste arrives

photo epd.gov.hk

The second part of the pre-treatment, after the sorting, ismixing the food waste withbulking agents, such as saw dustor wood chips. This is done toensure that the food waste’s masswill get the right porosity andmoisture for optimumcomposting in the next step.

In the Mixing Facilitybulking agents areadded

photo epd.gov.hk

The actual composting beginswhen the mixed waste is fed intothe composting drum units, wherebiological bacteria decomposes thewaste for 10 days. Heat is releasedduring this process, and thetemperature inside the drum iskept between 55oC and 70oC; thistemperature range is ideal forcomposting, and it kills off anyunhealthy pathogens that mightotherwise thrive in such anenvironment.

2 tonnes of food waste isfed into the In-VesselComposting Unit everyday!

photo epd.gov.hk

After 10 days in the compostingdrums, the food waste has turnedinto premature compost. It is nowpiled up in the curing pads, whereit will undergo a curing period ofabout 30 days before it iscompletely decomposed. Duringthe curing, the compost iscultivated and sprayed with waterregularly, to maintain optimumcomposting conditions.

The premature compost ispiled in the Curing Pads tofinalize the compostingprocess

photo epd.gov.hk

When the compost is mature, itis sieved through a so-calledproduct screen, which vibratesand thus removes any rubbish,as well as the bulking agentsthat were added during the pre-treatment. The wood chips thatare removed here are later re-used as bulking agents.In the Product Screen,

items that shouldn’t bea part of the finishedcompost is sifted out

photo epd.gov.hk

The final product is ready to be packed and delivered to the users

photo: normanack