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close this book Pig waste management and recycling: The Singapore experience
View the document Foreword
View the document Preface
View the document Acknowledgments
Open this folder and view contents 1. A summary of the Singapore experience
Open this folder and view contents 2. Pig production
Open this folder and view contents 3. Pig house ventilation in the tropics
Open this folder and view contents 4. Pig housing in the tropics
Open this folder and view contents 5. Environmental impact of pig wastes
Open this folder and view contents 6. Olfaction and malodours in pig farming areas
Open this folder and view contents 7. Algae biomass recovery and utilization
Open this folder and view contents 8. Recovery of fungal and: bacterial biomass
Open this folder and view contents 9. Design and construction of the ponggol pigwaste plant
Open this folder and view contents 10. Units of treatment and unit operations
View the document Acronyms and abbreviations
View the document Sources


I arrived in Singapore in December 1975 on a 1-year leave from Ohio State University to manage a United Nations project. I stayed 15 years: 10 years in Singapore, 2 years in Malaysia, and 3 years travel throughout Southeast Asia. It was a period of extraordinary change in Southeast Asia. For me, it was a marvelous experience, the technical components of which are contained in this book.

A Decade of Change

In the 10 years from 1975 to 1985, more pivotal changes took place in Singapore than in the whole thousand-year history of the island. There was a building boom, the economy grew phenomenally, the rivers and shores were cleaned up, and sufficient capacity was added to the sewage system to collect and treat all wastewaters from homes and industry. People developed physically, socially, and culturally.

In 1975, pig rearing was a backyard activity carried out the traditional way by the Chinese, who constituted over 80% of the population of Singapore. As is humorously depicted in a cartoon in Chapter 1 (Fig. 1.1), pigs were considered part of the Chinese household. As a matter of fact, the character for "home" in the Chinese alphabet is a pig sheltered by a roof.

Within a few years, pig rearing was transformed into a substantial commercial enterprise with some of the largest farms in the world. In 1983, a world record was established for distance traveled when a Boeing 747 loaded in Chicago with sows and boars landed in Singapore. The pigs were the nucleus of the breeding stock of a projected 120 000-pig farm, the largest of its kind, to be located within a fenced area of 600 000 m² (60 ha). The first and longest barns ever built on a 1% slope and equipped with an automatic flushing system became operational in 1982. The concept was copied in several other countries in the region. A unique total recycling system was conceived, built, and tested for a decade.

The Book

I have taken a novel approach in writing this book because I wanted to accomplish two objectives: to chronicle the consequential events of that decade of change and to pass on the experience to students and consultants who will be involved in similar undertakings in the future. Thus, I wrote the book as a textbook-cum-research report.

The only sources of material for the book are the 167 reports and memos generated by project staff. It was not practical to relate in this book all the topics that were studied or to report the subject matter in the depth of coverage given in the original papers.

When editing the voluminous reports of the projects, I tried to se]ect data and papers that would present a complete picture of what happened, and at the same time, include work of universal application. There were time and space constraints in this effort. There was a 60% reduction in the size of the manuscript from the first to the last draft. Therefore, I might have omitted inadvertently or failed to even mention some crucial work in the final version of the book. If I had to do it over again, I would have started writing this book when the first project commenced and have made this book the final report. But, I did not have such foresight 15 years ago.

Although the book draws its material from work on pig excrete and pig wastewaters, the approaches and conclusions are applicable through appropriate professional judgement to all organic solid wastes and wastewaters.

This book was designed for use as a text in waste management courses for professional and graduate students, and in conjunction with other textbooks that cover the basics of animal waste management and treatment processes. If the book is used as the only reference in a university course, then the students should already have a basic course in environmental sciences and engineering and, therefore, be familiar with the basic concepts of waste treatment and with relevant terminology. The students should be upperclassmen in a professional degree program or graduate students.

The question and answer sections at the end of the first seven chapters are included to express expert opinions on some of the key issues, to serve as examples for reflection and reinforcement, and to aid in the development of professional judgement on the subject matter. There are no question and answer sections in the last two chapters because the subject matter of these chapters is highly technical and, as such, answers to all questions should be precise. It is intended that for these chapters, exercises be carried out to test the application of the formulas for sizing unit operations to the local conditions and to update the economic costs. Also, at the end of most of the chapters there is a list of forum ideas to be discussed in class or to be given as small assignments to relate the chapter contents to local situations.

The costs presented in the book must be updated and adapted to local conditions based on current unit prices and appropriate inflation factors.


For those who want to search and review the original sources, the papers are maintained in the library of the Pig and Poultry Research and Training Institute, Primary Production Department, Sambaing Road, Republic of Singapore. Copies of progress reports and of some of the technical reports can be located through the agencies that sponsored the work. To expedite the location of such reports it would be best to mention the specific projects: International Development Research Centre, Regional Office for Southeast and East Asia, Tanglin PO Box 101, Singapore 9124, Republic of Singapore (projects 3-P-85-0048, 3-A-89-4423, and others); Food and Agriculture Organization of the United Nations, Via Terme di Caracalla, Rome 00100, Italy (projects AG:DP/SIN 74/006 and AG:GCP/SIN/001/AUL); United Nations Development Programme, United Nations Plaza, New York, USA (UNDP/FAO Project SIN/74/006 and UNDP/FAO Project MAL/84/001).