MICROCOMPUTER APPLICATIONS
EM INDUSTRIAL WASTEWATER TREATMENT
Eric F. Palmer, Project Manager
Melvin R. Hockenbury, Manager, Industrial Wastes
Engineering-Science, Inc.
Atlanta, Georgia 30329
One of the most significant realiziations in the field of wastewater treatment in recent
years is that our competence in the operation of facilities must be upgraded in order to
achieve the goals of the Clean Water Act. It has become apparent that the performance
capabilities of the treatment processes installed far exceed the capabilities of the operations
personnel to control them; therefore, the full potential of the treatment facilities is not often
attained. Several options are available to alleviate this problem, but we have found one of
the most promising and innovative approaches to be a microcomputer based, near-real time
process control system.
Computers of various types and sizes have been used for some time in wastewater treatment applications generally with rather limited success. We feel there are some fundamental
features of wastewater treatment that have limited and will probably continue to limit the
utilization of computers. These features are the lack of control over the system inputs and
the lack of reliable primary monitoring elements to provide accurate data. The ramification
of these limitations is that on-line computers tied directly into process control equipment
will not generally be successful. However, we have found that recent developments in the
computer hardware field have made avadable very powerful, reliable and inexpensive microcomputers that can be used in an off-line, near-real time system in wastewater treatment
plants.
The general approach is as follows. The normal plant monitoring and laboratory analytical data are collected by the operator and entered into the microcomputer. Once the necessary data are loaded in the system, the operator initiates a set of process control programs
which utilize the stored data and evaluate them using a pre-programmed operations strategy.
Upon completion of the data evaluation, the system prompts the operator with specific
operating instructions to be carried out. This system has the benefit of providing the operator with a powerful calculating tool and fundamentally based operating strategy, but still
maintains the reliability associated with the operator himself actually carrying out key operating functions. This is the essence of the system we have developed and the particulars
and other features are described in detail below.
DEVELOPMENT OF THE SYSTEM
Three major tasks are required to fully develop a microcomputer near-real time control
system (see Figures 1 and 2):
1. develop control strategies;
2. develop microcomputer system; and
3. implement and debug system.
The development of control strategies is accomplished by first describing the wastewater
treatment facility by unit process. Each unit process must be further defined as to pertinent
parameters such as flow, temperature, etc. The limitations of each unit process are also defined, for example, maximum pumping rates or minimum flow rate. Any historical data
available for a unit process are collected and analyzed as to trends and optimal operating
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