Use of the oyster Crassostrea rhizophorae as a biological filter for effluent treatment to shrimp farm

Abstract

This study aimed to evaluate the biofiltration capacity of oyster Crassostrea rhizophorae on effluents of shrimp and check their microbiological condition after filtering process. 1.080 oysters were distributed in lanterns kept 12 fiberglass tanks (170 L) in a completely randomized design with four treatments (without oysters, 60, 120 and 180 oysters) and three repetitions. It was used the effluent from the sedimentation tank. Weekly were analyzed: ammonia nitrogen (N-NH4 +), orthophosphate (P-PO4 3-), total suspended solids (TSS) and chlorophyll-a (Cl-a) of the input and output effluent. The treatments with oysters had similar removal effect (P>0.05) in the levels of Cl-a and TSS effluent and were higher (P<0.05) to the treatment without oysters. There was no improvement in the quality of the effluent after passing through the experimental tanks to N-NH4 +. In relation to P-PO4 3-, all treatments reduced (P>0.05) the concentrations of this nutrient similarly. There were no statistical differences (P>0.05) for the values of total coliform and copper, regardless of stocking density. The samples analyzed were not found fecal coliforms and Salmonella spp. Oysters improve water quality, except to N-NH4 + and were not found organisms that prohibit its consumption.