Industrial and Municipal Sludge Dewatering
The Boeing "Best" System
R. K. AMES, Project Engineer
H.H. PETERS, Research Engineer
R.L. OLSON, Manager
Environmental Protection Systems
Boeing Aerospace Company
Seattle, Washington 98124
INTRODUCTION
Municipal and industrial efforts to comply with stringent water and air pollution
control requirements have resulted in increased sludge handling problems. The quantity of
sludge has significantly increased due to the requirement to remove heavy metals,
phosphates, BODs and suspended solids found in liquid discharges. More importantly, the
variety of sludge has also increased, adding new, difficult to handle materials such as lime
precipitated biological organic mixtures. The concentration of suspended solids and
dewatering of resultant sludges for solids disposal has become a major economic concern
lor both municipalities and industry. The size of the problem ranges from a nuisance to a
task of gigantic proportions: from a few tons per day of biological or oily wastes to
hundreds of tons per day as in the case of power plant stack gas lime scrubbing sludge. This
paper introduces a new proprietary process, the Boeing Extractive Sludge Treatment
(BEST), that will materially reduce sludge handling problems and provide significant
economic advantages.
The Boeing Company has conducted an extensive laboratory and pilot plant scale
program in developing the BEST process. This paper will outline the system concept and
present examples of data obtained during the recently completed laboratory and pilot
testing phase. Emphasis here will be placed on industrial sludge. Currently, a small scale
feasibility test system, Mini-BEST, is being constructed to develop optimum operational
parameters and provide more definitive data to prove the economics of the total system.
Mini-BEST system tests will begin this summer.
BEST utilizes the unique properties of a solvent to dewater organic and inorganic
sludges that are then discharged as a bone dry solid and a clear water effluent. During the
process the sludge is sterilized and any associated oil is recovered. The reclaimed oil is
available for use as an energy source or commercial byproduct. The system is totally
enclosed to avoid the pollution problems normally associated with large volume air
discharge drying and incineration systems.
Of special interest is the low energy requirements of the BEST system when compared
to conventional sludge drying systems. Theoretical savings of 80 to 90 percent in energy can
be realized when the BEST system is used in place of the brute force drying systems
available that require 970 BTU's per pound of water removed.
It is believed that BEST will provide a most attractive solution for sludge dewatering
problems because of its many advantages including economic operation, lack of
environmental impact, and sterile liquid and solid discharge.
SOLVENT
The system is based on a unique application of a family of aliphatic amine solvents
having unusual properties. These properties make possible the processing of even normally
difficult to handle sludges, and they allow the BEST system to remove water and oil without
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