Microbiological effects of wastewater effluent discharge into coastal waters of Puerto Rico

Microbiological effects of non-disinfected, combined chemical and domestic wastewater effluent discharge into coastal waters north of Barceloneta. Puerto Rico were investigated by membrane filter enumeration of fecal indicator bacteria and by enrichment isolation of specific pathogens. A wastewater plume was detected and delineated around the sewage outfall, located 800 m offshore and 30 m below the ocean surface. Fecal coliform and fecal streptococcus counts within the plume were significantly (F test) larger than comparable counts outside the plume. The shape and location of the plume was compatible with current patterns and prevailing winds and extended as far as 3.7 km west of the outfall, at which point the fecal coliform count was 146 100 ml⁻¹. The average non-plume fecal coliform concentration was 6.7 100 ml⁻¹. Specific pathogens isolated included Salmonella and Vibrio spp, including V. cholerae non-01 serovar isolated from a nearby river also impacted by the sewage plant.