This report is part of an effort to assist the Governments in developing the annex on domestic wastewater. The purpose of the annex is to identify the most appropriate wastewater treatment technologies and water quality standards for the Wider Caribbean Region (WCR).

The United Nations Environment Programme (UNEP) has developed a draft protocol (Protocol to the Cartagena Convention) to reduce marine pollution in the Caribbean Sea from land-based activities. All contracting parties to the Draft Protocol commit to take steps to help reduce marine pollution. The Regional Overview of Land-Based Sources of Pollution in the Wider Caribbean Region, CEP Technical Report No. 33, identifies domestic and industrial sewage as priority sources of pollution (UNEP, 1994). This report is part of an effort by the UNEP Caribbean Regional Co-ordinating Unit (CAR/RCU) to address or identify the most appropriate wastewater treatment technologies and water quality standards for the Wider Caribbean Region (WCR).

The following excerpts from Article III of the Draft Protocol explain some of the general obligations defined:

Article I of the Draft Protocol defines "best available technology" as follows:

In this report the term "appropriate technology" is considered to be synonymous with this definition of "best available technology" from the Draft Protocol.

KCM, Inc. was contracted to prepare a report for the UNEP Caribbean Regional Co-ordinating Unit (CAR/RCU) outlining appropriate pollution control technologies for domestic and industrial sewage, both rural and urban, in the WCR. Preparation of the report included the following tasks:

• A list was prepared of experts in wastewater treatment for the WCR who could help KCM identify relevant literature, assist with site visits, and give critical comment on the draft report.

• A review was conducted of literature addressing control of urban and rural sources of domestic and industrial sewage pollution. Based on the literature reviewed, technologies appropriate for all sub-regions of the WCR were evaluated, with an emphasis on low-technology solutions.

• Site visits to the WCR were made to inspect innovative, low-cost, low-technology controls for domestic sewage pollution.

• A draft report was prepared describing the most appropriate technologies to control marine pollution caused by domestic and industrial sewage from both urban and rural sources. Technologies described in the report target pollutants such as biochemical oxygen demand (BOD), total suspended solids (TSS), oil and grease, nutrients (nitrogen and phosphorus) and toxics. Appropriate treatment alternatives have been evaluated and described in terms of practicality, capacity, ease and cost of construction, ease and cost of ongoing maintenance, environmental effectiveness, relationship to existing technologies and practices, potential for cultural and community acceptance, and other factors relevant to application in the WCR. The report includes recommendations for appropriate effluent limitations and technologies to meet those limitations.

• The draft report was submitted for review to a panel of experts selected by UNEP from the list of contacts and discussed at a workshop. This final report has been prepared based on comments from the workshop meeting.

The goals for this document are as follows:

• To identify the most appropriate technologies for domestic and industrial sewage pollution control in the WCR. Domestic sewage or wastewater is considered in this report to be the liquid waste produced by households, schools, hotels, and small commercial establishments commonly combined in town or city sanitary drainage systems. Industrial sewage is considered to be liquid waste from manufacturing plants for a variety of industrial products.

• To describe expected treatment limits for these technologies, which can help government officials develop water quality guidelines.

• To develop a reference list of relevant information that is not covered in the report or is beyond its scope.

This document is not intended to stand alone as a design manual, textbook, or reference book. It has been prepared for use by government agencies, government regulatory officials and consultants in the WCR, to help them make preliminary decisions about appropriate wastewater treatment technologies based on community size, location, hydrogeologic conditions, and other factors. Key elements include the following:

• "Decision trees" to be used in identifying appropriate pollution control technologies—Decision trees present a sequence of questions about the scenario for which pollution control is being evaluated. Each new question to be answered is determined by the answer to the preceding question. The result of the decision-tree process is identification of the treatment or disposal technologies that merit further evaluation for the scenario under review. The decision tree is a general guideline taking into account the most important criteria. Other important issues, such as social acceptance, planning, and management, are not included in the decision tree, although they are discussed separately in the report.

• Fact sheets summarising key features of each technology—The fact sheets include design criteria, expected efficiency, references for more information, a list of facilities using the technology in the WCR, and, in some cases, diagrams showing how the technology works. The references provide the information needed for a thorough evaluation of each technology and selection of the most appropriate technology. The appropriate technologies are the "recommended practices and procedures adapted to national circumstances" called for in the Draft Protocol.

• Expected treatment efficiencies for each control technology—The efficiencies are shown to give an indication of effluent discharge standards that should be achievable by the given technology when adequately designed and operated. This document has not investigated receiving water quality requirements. It is intended to support the process of standard setting by identifying the potential for sewage pollution control by different technologies, but it was not prepared to recommend specific water quality standards for the WCR.

• A review of papers, textbooks, and manuals that can be used to obtain more detailed information—The organisation of the literature review parallels that of the report, so that the reader can look up the references used in this report by topic, as well as by author.