A MANAGEMENT PROGRAM FOR THE LAND APPLICATION
OF SLUDGES FROM INDUSTRIAL WASTEWATER
TREATMENT FACILITIES
Robert J. Morehouse, Associate Project Engineer
Amir A. Metry, Project Manager
Roy F. Weston, Inc.
West Chester, Pennsylvania 19380
INTRODUCTION
The recognition in recent years of the resource value of some wastewater treatment
plant sludges has led to the land application of these sludges.   The purpose of the land
application of sludge is two-fold:   (a)  to provide nutrients to increase crop yields; and
(b) to act as a disposal method.   Most investigations into the suitability of sludge for land
application have focused on the use of sewage sludge.   This is principally because of the
large volume of sewage sludge generated.   The variability of industrial wastewater treatment plant sludges, particularly the toxic levels of heavy metals, has limited the land
application of these sludges.   Under certain conditions, however, land application of
industrial wastewater treatment plant sludges can be a cost-effective and an environmentally sound disposal method.
Land disposal of industrial wastewater treatment plant sludge can be achieved by either
using a landfill or by applying it to land.   Sludges can be disposed of in landfills as cake
or slurry.   However, several state regulatory agencies discourage disposal of sludge cake and
ban disposal of slurries in landfills.   For application of sludges, one can spread dewatered
sludge cake or sludge slurries over the land.
Landfill disposal generally has the following advantages over disposal by land application:
1. Less land required.   Landfill would involve less land area for the disposal operation
(approximately one order of magnitude less) for the same quantity of sludge.   However, note that the landfill area will be rendered unsuitable for major construction
for plant expansion in the future.
2. Control of odor, vectors, and wildlife nuisances   This should not be a key factor,
the sludges are thoroughly digested before land disposal.
3. Ease of leachate collection and lor treatment.   Because leachate collection and control
can be designed into the landfill, positive control of ground water contamination is
assured.   For land spreading, contaminated runoff can be collected, but some absorption
into the ground water table is inevitable.
Disposal of sludges through land application has the  following advantages over land-
filling:
1. It does not interfere with future utilization, with continued farming, or with any future
construction, despite the fact that spreading needs more land for disposal than land-
filling (an order of magnitude more).  Also, the land can be used over and over for
sludge spreading.
2. The cost for land spreading of sludges is expected to be less, in most cases, than for
disposal in a landfill.
3. Spreading equipment is less expensive and easier to operate than landfilling equipment.
Regular farm equipment (eg., manure spreaders) could be used for sludge spreading.
4. The site designated for spreading can accept wet sludges as well as dewatered sludges.
Such flexibility is not possible when using the landfilling method.
5. The value and the general conditions of the field could easily be maintained (or
perhaps improved) when disposing of sludges by spreading.   No problems of subsidence
or differential setdement are expected in the fields where disposal of sludges is by
spreading
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