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United Nations Environment Programme
Division of Technology, Industry and Economics
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Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>

9. Wastewater reuse through aquaculture

9.1 Aquaculture

9.1.1 Introduction

Wastewater-fed aquaculture has a long history in several countries in East, South and Southeast Asia (Edwards and Pullin, 1990; Edwards, 1992). It provides food, employment and income for millions of people. Research over the past three decades has provided a scientific understanding of how these systems function. International organizations, including the World Health Organization, recommend that wastewater reuse should always be considered as an option in schemes to improve sanitation in developing countries (WHO, 1989). In reality, relatively few wastewater-fed aquaculture systems have been implemented recently. In most areas where wastewater-fed aquaculture currently exists, the practice is threatened or in decline for diverse reasons.

Key questions that need to be addressed concerning the future role of wastewater-fed aquaculture as a sustainable technology are:

  • what constitutes sound practice technically, including a consideration of public health?
  • in what social and economic contexts is wastewater-fed aquaculture an appropriate technological option ?

To attempt to answer these questions the following are presented:

  • a brief outline of current wastewater reuse systems and their relation to sanitation
  • a discussion of how wastewater-fed systems work
  • an overview of major constraints facing wastewater-fed aquaculture
  • a schema of the possible evolutionary development of wastewater-fed aquaculture as societies pass through successive stages of development
  • an outline of sound wastewater reuse practice with discussions of public health, culture systems and opportunities for wastewater-fed aquaculture.

Case studies are presented of two large fish culture systems fed with conventional sewage, in Vietnam, Case Study 1 (Vo, 1996) and India, Case Study 2 (Ghosh, 1990). Besides traditional practice, the Indian case study includes an outline of a recently introduced, improved system incorporating pretreatment of wastewater (Ghosh, 1995, 1998). A third case study from Bangladesh describes wastewater treatment and reuse with duckweed, a high-protein feed for fish. Systems involving conventional wastewater and nightsoil are outlined.

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