A microbiological and chemical analysis of shrimp offloading facility effluents

Abstract

The objectives of this project included (a) characterizing microbiological and chemical parameters of the effluents from typical Texas shrimp offloading facilities, (b) determining the impact of the effluents on the quality of the contiguous waters, (c) determining what, if any, in-plant changes must be made for the effluents to meet the limitations, and (d) investigating the use of the oxidase test in monitoring for shrimp-related organisms in the offloading facility effluents. Samples were collected from April through November to cover the peak shrimping season (mid-May through mid-September). Three offloading facilities were used as sampling sites for thaw-tank, bilge, and drain samples. Samples were also collected from six harbor stations. Three were in the area receiving effluents, three in areas not receiving effluents. The chemical parameters for which the samples were tested were: biochemical oxygen demand, chemical oxygen demand, dissolved oxygen, oil and grease, total suspended solids, settleable solids, pH, temperature, and salinity. The microbiological parameters were: total aerobic count, Escherichia coli, coliforms, and oxidase reaction. The data collected were analyzed using analysis of variance, Duncan's new multiple range test, and correlation analysis. The facilities monitored were found to be in compliance with current and forthcoming limitations without implementing any in-plant changes. This compliance may be the result of several factors. One is that the shrimp are offloaded as green-headless shrimp; they have been headed at sea. This decreases the solids load of the effluents. Another reason is that the handling procedure used in the Texas facilities is less complex than the procedures used in other states. Bypassing the peeling and deveining of the shrimp decreases the effluent load. The facilities monitored currently comply. Changes in the product or the processing procedure could alter the effluents. In analyzing the water quality, the quality in the harbor area receiving the effluents was not significantly different from the quality in areas not receiving the effluents...