United States
Environmental Protection
Agency
Municipal Environmental Reseaj
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S8-82-028 Jan. 1983
4>EPA Project Summary
Engineering Design
Manual for Solid Waste Size
Reduction Equipment
G. M. Savage, D. J. Lafrenz, D. B. Jones, J. C. Glaub, I. Melnyk, and C. C. Wiles
A manual was developed to supply
the solid waste industry with a state-
of-the-art reference to size reduction
information and methods. Emphasis is
on design considerations for size reduc-
tion equipment, but information is also
included on hardware specifications,
selection, and testing; maintenance
and safety; and economics. The manual
is aimed at a diverse group, including
public works and sanitation officials,
equipment manufacturers, system design-
ers, plant operators, and researchers.
Fundamental concepts are thus included
along with empirical data on solid
waste size reduction.
This Project Summary was devel-
oped by EPA's Municipal Environ-
mental Research Laboratory, Cincinnati,
OH, to announce key findings of the
research project that is fufly documen-
ted in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
Size reduction is the most used unit
process in refuse processing—and it is
among the most expensive. Thus its
characterization and control are of signif-
icant interest to the solid waste indus-
try. Over the past 15 years, size reduction
equipment has developed from its role
in simple shred-and-landfill operations
to its position of dominance in full-scale
resource recovery systems. The latter
often i ncl udes a myriad of size reduction
units intended for processing raw solid
waste, air-classified light fractions, re-
covered ferrous scrap, oversized bulky
wastes, and recovered glass fractions.
Thissummary briefly describesa manual
developed for those involved in the size
reduction of municipal solid waste. The
purpose of the manual is to supply the
solid waste industry with a state-of-the-
art reference to size reduction informa-
tion and methods. Although the empha-
sis is on design considerations for size
reduction equipment, the manual also
includes sections on: (1) the specifica-
tion, selection, and testing of size reduc-
tion hardware, (2) aspects of maintenance
and safety applicable to refuse size reduc-
tion, and (3) the economics associated
with refuse shredding. Guidance is also
provided for the proper placement of the
shredder and the material to be processed
in a resource recovery operation.
The project described here is one of
several research projects conducted by
the Municipal EnvironmentalResearch
Laboratory (MERL) to investigate the
size reduction of municipal solid waste
(MSW). The design manual was devel-
oped using much of the information
generated from these following projects:
1. Currently available reports:
Significance of Size Reduction in
Solid Waste Management, Volume
I, EPA-600/2-77-131 (PB
272096);
Significance of Size Reduction in
Solid Waste Management, Volume
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~*i
II, EPA-600/2-80-115 (PB 81-
107096);
Processing Equipment for Resource
Recovery Systems, Volume III—
Field Test Evaluation of Shredders,
EPA-600/2-80-007C (PB 81-
151557).
2. Report in preparation:
Significance of Size Reduction in
Solid Waste Management, Volume
III—Effects of Machine Param-
eters on Shredder Performance.
Use of Manual
The design manual is aimed at individ-
uals with varied connections to refuse
processing and resource recovery, including
public works and sanitation officials,
equipment manufacturers, system design-
ers, plant operators, and researchers.
To meet the needs of such a diverse
group, the scope of the manual is broad
and extends from fundamental concepts
to empirical data on solid waste size
reduction.
The manual primarily emphasizes the
various aspects of design—that is, the
theoretical and empirical knowledge needed
to design a size reduction system. Design
requires far broader information than
that required solely for shredder selec-
tion, but because the industry is rela-
tively new, it lacks design theories suppor-
ted by many years of confirmation in the
field. Compared with the coal and min-
eral processing industries, for which
design theories have been developed
and confirmed for more than a century,
the solid waste processing industry is a
neophyte. Nevertheless, this manual pre-
sents the latest and best documented
theories and empirical information repor-
ted to date.
To be significantly useful to the solid
waste industry, the manual emphasizes
actual applications of available infor-
mation and the experience of equip-
ment operators. Information such as
man-hour estimates for maintenance
operations and the influence of opera-
tional variables on shredder perfor-
mance is primarily intended for those
most closely associated with equipment
operation (e.g., system designers and
plant operators). Economic data are presen-
ted in a form that enables less technical
decisionmakers to estimate the costs
associated with size reduction.
A detailed section on performance test-
ing was prepared as a guide to rational
test methods for evaluating size reduc-
tion equipment. This 'section may also
serve as an interim procedure pending
the development and consensus approv-
al of formal test standards being develo-
ped by the Committee E38 on Resource
Recovery of the American Society for
Testing and Materials (ASTM). These
methods will allow performance evalua-
tions of installed equipment and will
therefore be of practical use to plant
owners, operators, and equipment vend-
ors. They will also provide a guideline
for individuals concerned with shredder
design (e.g., researchers and develo-
pers).
A major part of the manual is ad-
dressed specifically to the design of
refuse size reduction equipment. Operat-
ing variables are related to shredder
performance and size reduction is ana-
lyzed as part of an entire electro-mechan-
ical system. This information will be
particularly useful to individuals who
are responsible for supplying and selecting
equipment and to those concerned with
the design and development of size
reduction equipment for solid waste.
Finally, the design manual provides
information on topics relating to refuse
size reduction. A review of pertinent
literature is included.
Since the main purpose of the manual
is to provide information and guidelines
for shredder design, no detailed selec-
tion criteria are given. But selection is
addressed to the degree that it overlaps
design (and the overlap is significant).
Summary of Manual Contents
The manual is divided into seven sections
on available shredding equipment, design
of refuse size reduction systems, mainte-
nance, health and safety, economics,
shredder selection, and performance
evaluation in the field. The first section
includes a brief, but adequate descrip-
tion of various types of size reduction
devices, including their basic design.
The second section addresses the desig n
of refuse size reduction systems and
begins with an explanation of the princi-
ples of refuse size reduction. These
include forces, energy, theories, and
representation of particle size distribu-
tion. Many aspects of shredder opera-
tion and performance are summarized,
including multiple-size reduction, rota-
tional velocity, condition of hammers,
hammer wear, and other necessary consid-
erations. System analysis and design
for systems of motors and shredders are
also addressed.
The section on maintenance considera-
tions focuses on maintenance cost as
the fraction of labor involved in chang-
ing and replacing parts, retipping worn
elements, cleaning out jammed shredders,
and preventive maintenance.
Dust, explosions, and projectiles are
discussed in the section on health and
safety. Causes, problems, and controls
are examined. The manual includes tables
on the economics of size reduction and
an example for cost estimates, including
costs of size reduction and hammer
maintenance.
Shredder selection is addressed by
assessing the criteria for selecting any
piece of electro-mechanical processing
equipment. In addition, the manual con-
tains a description of vertical-shaft versus
horizontal-shaft shredders. Also included
are explanations of advantages, disadvan-
tages, and relationships between machine
components, operational alternatives,
establishment of specifications, energy
requirements, maintenance, and other
more specific aspects of shredder selec-
tion.
Performance in the field is evaluated
through comparisons of size reduction
alternatives and twodifferenttest methods
for shredder performance evaluation.
Six appendices are also included in the
manual: Refuse Size Reduction Litera-
ture Reviews; Size Reduction Devices
Used in Solid Waste Processing Facil-
ities; Partial List of MSWShredder Manufac-
turers; Utilization of Selection and Break-
age Functions in Shredder Analysis;
Shredder Rotor Mass Movement of Inertia;
and Deviation of Governing Equations
for Motor Power in Terms of Motor
Characteristics.
The full report was submitted in fulfill-
ment of Contract No. 68-03-2972 by Cal
Recovery Systems, Inc., under the spon-
sorshipof the U.S. Environmental Protrec-
tion Agency.
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G. M. Savage, D. J. Lafrenz, D. B. Jones, and J. C. Glaub are with Cal Recovery
Systems, Inc., Richmond, CA 94804; the EPA authors Ihor Melnyk and C. C.
Wiles (also the EPA Project Officer, see below) are with the Municipal Environ-
mental Research Laboratory, Cincinnati, OH 45268.
The complete report, entitled "Engineering Design Manual for Solid Waste Size
Reduction Equipment," (Order No. PB 83-139 493; Cost: $16.00, subject to
change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Municipal Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
•fr U.S. GOVERNMENT PRINTING OFFICE: I9O3 099-017/0886
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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