Proceedings

Food waste (FW) is a problem and an opportunity. This paper will review the alternative
routes for its management. In the UK, the majority of FW is still landfilled. Traditionally, FW
has been fed to pigs but part of the reaction to the 2001 outbreak of foot and mouth disease
in the UK was to ban this “swill feeding” and introduce stringent requirements for treating FW
that later was the basis of EU regulation. There is also an obligation to reduce landfilling of
biodegradable [municipal] waste (domestic FW) to reduce the global warming potential
(GWP) of greenhouse gas emissions. Landfilling FW has a GWP of +743 kgCO2e/tFW.
Taking FW out of the waste stream makes separation of dry recyclables easier. Home
composting is ideal in many ways, though it is difficult to determine its GWP because there is
a range of skill in managing the process. However, many are unable or not inclined to
undertake home composting.

Kerbside collection involves storing FW, which has a number of disadvantages. FW is not
ideal for centralised composting because of its high moisture content and biodegradability, the
route has a GWP of -14 kgCO2e/tFW. In contrast, centralised AD has a GWP of -162 or -215
kgCO2e/tFW depending whether sanitisation is by pasteurisation or thermal hydrolysis (TH).
Retrofitting TH to increase the capacity of existing AD is a good commercial opportunity for
water companies, as well as environmentally virtuous. Local authorities and others are
waking up to the idea that food waste disposers divert FW at source, are convenient, and
welcomed by householders. Field studies have demonstrated they do not adversely affect
sewerage or wastewater treatment infrastructure. Where the sludge is treated by AD and the
biogas used for electricity, the GWP of this route is -199 kgCO2e/tFW.

KEYWORDS
Anaerobic Digestion; Composting; Food Waste Disposer; Incineration; Kerbside Collection;
Landfill; Thermal Hydrolysis