For the purpose of this report, the Wider Caribbean Region includes states and territories within the Caribbean region as defined by the Cartagena Convention.

The WCR is divided into six sub-regions for further reference, as described in the map and list below (UNEP 1994):

Domestic sewage is a significant contributor to marine pollution in the WCR. Domestic sewage originates mostly from households, public facilities, and businesses. For wastes from communities where most homes and businesses have piped water, typical pollutant composition of domestic sewage is as follows:

The Caribbean Environmental Programme’s (CEP) Technical Report No. 33 is the best resource for a detailed distribution of pollutant loads in the WCR (UNEP 1994). The highest estimated pollutant loads into coastal waters are from Sub-regions I and V, which contribute, respectively, about 2 million and 1 million tonnes of BOD per year. BOD loads from Sub-regions II, III, and IV range from 100,000 to 400,000 tonnes per year for each region. Industrial loading of BOD is 3 to 200 times that of domestic sources in all sub-regions. More detailed information is provided in Tables 9 to 12 of CEP Technical Report No. 33, which are included in Appendix A.

Table 2-2 presents a regional summary of pollutant loads. It can be seen from Table 2-2 that industrial sources account for as much as 80 percent of the pollution load to the Wider Caribbean Basin. Even though domestic sources are a relatively small part of the total current pollution load, control of pollution from domestic sources receives considerable attention in the current report. This is because domestic sources are important in all countries of the WCR (they are ubiquitous), because pollution control from domestic sources is an important element of public education about environmental and public health issues, and because human health risk arises primarily from domestic sewage.

SEWAGE TREATMENT GOALS

The primary purpose of sewage treatment is to remove pollutants from wastewater streams before disposal into receiving waters including:

A secondary purpose of sewage treatment is to treat and dispose of the solids, or sludge, generated by the treatment processes. For sewage from industrial sources, special attention must be given to removal of toxic substances.

Resources cited in the literature review provide detailed information about current practices and the condition of sewage treatment in the WCR. UNEP-CAR/RCU, the Caribbean Environmental Health Institute (CEHI), and other organisations and governments in the WCR have funded numerous reports addressing the state of sewage collection and treatment in the region. One study concluded that less than 10 percent of the population in the Caribbean basin is served by sewage treatment.

The effectiveness of existing sewage collection and treatment facilities in the region is usually constrained by limited capacity, poor maintenance, process malfunction, poor maintenance practices, and lack of experienced or properly trained staff. Most collection and treatment facilities dispose of their effluent and wastes directly into the marine environment, resulting in high coliform concentrations and low dissolved oxygen levels in coastal waters.

In rural areas of the WCR, collection systems are rarely used, and pit privies, latrines, or septic tanks are the most common waste disposal systems. These processes can be effective, provided they are designed, installed, maintained, and used properly. The biggest problem with them is lack of maintenance. Septic tanks, pit latrines, and pit privies need to be cleaned ("desludged") periodically. Failure to desludge results in poor effluent quality. Also, septic tanks with soil absorption for effluent disposal work poorly if the soil is not very permeable, or if ground water levels are high.

In areas of higher population density, it is feasible to develop a local collection system and use a single facility to treat the community’s wastes. Lagoons, stabilisation ponds, and aerobic package plants are common treatment options for mid-size communities in the WCR. Lagoons are often appropriate, but they require a large area to provide adequate treatment. Package plants are used mostly for resort communities, hotels, and other public buildings. Many package plants in the WCR are operating improperly because of improper design and inadequate maintenance. In centralised, urban centres, lagoons, package plants, and conventional activated sludge systems are used. Many of these treatment facilities do not provide adequate treatment because of improper maintenance, and lack of skilled operators. A report by CEHI and the Pan American Health Organisation (PAHO) described the following disposal practices for systems in the WCR that collect and treat sewage (Bartone, 1984) :

The percentages do not sum to 100 in the original.

Poor sewage treatment and disposal affects the health of the local population and the environment. In St. Lucia, children have been affected by helminths. In Barbados, extremely high coliform counts have been measured. In Colombia and the United States bordering the Gulf of Mexico, sewage pollution has been identified as the cause of fish kills. And in Cuba, impacts of sewage pollution have been measured as far as 1 kilometre from sewage effluent discharge points. According to PAHO data, as of 1979, enteric and diarrhoeal diseases are the most common cause of infant mortality in many Latin America and Caribbean countries.

Problems with less severe consequences include pollution of tourist and bathing beaches and pollution impacts on the marine environment. Problems associated with poor disposal practices are high coliform counts in coastal waters, eutrophication in bays and harbours, damage to coral reefs, and fish kills or abiotic waters in the most extreme instances. Fish kills occur from oxygen depletion due to the high BOD. Table 2-2 summarises sewage collection and treatment practices in the WCR and their effects on the environment. Data in Table 2-2 were derived from a report on a seminar entitled "Monitoring and Control of Sanitary Quality of Bathing and Shellfish-Growing Waters in the Wider Caribbean," held in Kingston, Jamaica in 1991. (CEPPOL. 1991) The CEPPOL report includes the disclaimer that "the information was extracted from a variety of reports, some of which were prepared in the early 1980’s and for which no more up-to-date information was available. For some countries, information was not available at all and therefore, these have not been included in the report. As a result, the report may not accurately reflect the actual status of sewage pollution in the region, nor the existing monitoring programmes and implemented control measures." Where KCM had specific knowledge of new data, this new data was used to update the table.

Sources upon which water quality standards can be based include extensive studies on the effects of pollution in receiving waters as well as existing standards from other countries or states. Most countries in the WCR use microbiological water quality standards taken from U.S. EPA guidelines written prior to 1986. However, these standards often are too stringent and expensive for a developing nation. Planners need to account for the economic realities and development priorities of developing nations when setting water quality standards.

Three general categories of microbiological water quality standards are based on intended water uses: protection of indigenous organisms, primary contact recreation, and shellfish harvesting. For developing countries, the pollutants of greatest concern are pathogens because they pose an immediate health danger. The most stringent requirements are those for shellfish harvesting, since some shellfish tend to concentrate contaminants. The UNEP/World Health Organisation (WHO) standard for shellfish harvesting waters is a maximum of 10 faecal coliforms per 100 mL for 80 percent of samples taken. Shellfish contamination is associated with typhoid fever, cholera, viral hepatitis, and many other gastro-enteric conditions.

Currently, the UNEP-CAR/RCU, CEHI, Trinidad’s Environmental Management Authority (EMA), and other Caribbean agencies are working to develop water quality standards for other pollutants from domestic and industrial sewage. Water quality criteria have been proposed for BOD, TSS, nitrogen, phosphorus, pH, temperature, oil and grease, and bacteria. Standards from the United States and other countries are provided in Appendix B.