Environmental Engineering Reference
In-Depth Information
Table 10.3 Comparison between food waste and wastewater solids anaerobically digested according to
a comparative study at the East Bay Municipal Utility District Plant in Oakland, California.
Parameter
Food waste pulp
Wastewater solids
Volatile Solids in Feed (%)
85-90
70-80
Volatile Solids Loading (kg/m 3 /day)
10+
3.4 max
COD Loading (kg/m 3 /day)
21+
1-5
Total Solid Fed (%)
10+
4
Volatile Solids Reduction (%)
80
56
Hydraulic Detention Time (days)
10
15
Methane Gas Produced (m 3 /ton)
404
132
Gas Produced (liters/liter of digested volume)
58
17
Biosolids Produced (kg/kg fed)
0.28
0.55
From “East Bay Municipal District's study on anaerobically digested food waste,” n.d.
Picture 10.1 A landfill with gas vent pipes without a collection system for methane gas.
Courtesy US Environmental Protection Agency.
unit of organic waste decreases significantly. Certainly, the return on the investment is an
important factor when considering the installation of anaerobic systems; however, it should
not be the only factor. The environmental benefit achievable with an anaerobic system
should be given a fair weight when making the decision, especially when sustainability is a
main concern.
Landfilling/Incineration Food solid waste should not end up in landfills or incinerators.
There are plenty of options, as have been discussed, to use the residuals without having to
resort to quick and dirty disposal. Landfilling or incineration should be reserved only as
the last resort for cases in which the waste have some chemical or biological contamination
that renders it unsuitable for any of the previous steps of the Food Waste Recovery
Hierarchy.
 
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