COST EFFECTIVE AND ENERGY EFFICIENT
WASTEWATER TREATMENT
H. David Stensel, Manager
Biological Systems
Eimco Environtech
Salt Lake City, Utah 84110
John D. Wright, Partner
Hazelet and Erdal Engineers
Louisville, Kentucky 40202
INTRODUCTION
The cost of wastewater treatment can be a significant burden on both the taxpayer
and industrial discharger.   The design engineer must endeavor to provide the most cost
effective system for a particular wastewater treatment problem.   A cost effective design
is one that reliably meets effluent standards at minimum costs without any additional
problems.   The major cost considerations in a cost effective design are capital, operation, maintenance and manpower.   About forty percent of a plant's operating cost
may be due to energy requirements [ 1 ].   These costs must be minimal while providing
stable wastewater treatment.   The system should also be simple to understand and
operate to enhance its reliability and availability of qualified operators.   For industrial
wastewater treatment, a major design consideration also is the systems ability to handle
variable or shock loads.
Cost effective wastewater treatment plant designs may be based on two factors:
(a) the wastewater treatment process or system selection, and (b) value analysis of the
components of that wastewater treatment system.   The process selected can have a major impact on the overall capital and operating cost.   The value analysis effort optimizes
the system cost by dividing the total treatment system into its basic treatment functions
and evaluating these functions.   Such functions include pumping raw wastewater, pretreatment, the biological treatment phase, activated sludge return, clarification, chlorina-
tion, etc.
The process selection step will determine the size, number and cost of unit operations as well as operation, maintenance and energy costs.   This is a major step in the
cost-effective analysis.   The design engineer has the task of selecting from a number of
wastewater treatment processes today.   The purpose of this paper is to describe one
such process, the Carrousel Activated Sludge System, which has been introduced in the
United States and has proven to be cost effective in many cases.    Some of the
Carrousel Activated Sludge System application experiences in treating industrial wastewater will also be discussed.   This system was recently bid in its first U.S. municipal-
industrial wastewater treatment application at Campbellsville, Kentucky.   The treatment
requirements, cost considerations, process selection, and value analysis efforts will be
described for the Campbellsville plant.
CARROUSEL ACTIVATED SLUDGE DESCRIPTION
The Carrousel Activated Sludge System was developed by Dwars, Heederik, and
Verhay, Ltd., Consulting Engineers in Holland in the late 1960s [2].   Their goal was to
796