APPLICABILITY OF ACTIVATED SLUDGE PROCESS IN THE TREATMENT OF EFFLUENTS FROM SHRIMP PROCESSING INDUSTRY

Abstract

An activated sludge process for shrimp processing wastewater treatment had been studied. Initially, the volumetric flow of effluent per kilogram of processed shrimp was calculated; the result was 12.7 L/kg, and the average volumetric flow of discharge from the processing plant was 349250 L/d. After that, a characterization of the effluents of the plant was carried out, showing that most of the parameters analyzed don’t achieve the effluents quality parameters established by the Venezuela´s environmental requirements. Subsequently, a wastewater treatment system by activated sludge was simulated in a lab scale, using three continuous flow stirred-tank reactors with different residences times (4h, 6h and 8h), and the biokinetics constants were calculated, once pseudo-stationary conditions were reached in the continuous flow stirred-tank reactors; they were: k=0.0057 L/mgDQO.d, YT=0.3904 mgSSV/mgDQO and kd=0.1601 d-1. At last, the design of the wastewater treatment system for the shrimp processing plant was developed, and it results the following features: F/M of 0.21, biological solids retention time (θc) of 29 days, 2000 mg/L of activated sludge concentration, reactor’s volume of 171 m3 and 8 hours of residence time. With this treatment system, 85% of COD, 96% of BOD, 86.4% of nitrogen and 27% of phosphor removal efficiencies are expected, based on the simulation of the wastewater system using continuous flow stirred-tank reactors.

Key Words: wastewater, shrimp, characterization, biokinetics constants, activated sludge.