Biorreator de membranas aplicado ao tratamento de efluentes de uma indústria de processamento de frutas

Abstract

Water availability is increasingly restricted, whether as a result of the deterioration of its quality because of untreated effluents release or due to demand increase caused by population density, as well as the increase in agricultural and/or industrial activity. The need for effluent treatment to meet increasingly stringent standards, associated with the need of promoting a new water source caused market growth in technology of membrane bioreactors (MBR). One of the most attractive features of this technology is the high quality of the effluent produced, with a possibility of reuse. The aim of this research was to evaluate an effluent treatment station of a fruit processing industry using MBR in pilot scale for gauging efficiency. The tank where were the membranes had a capacity of 5,000 liters. We used ultrafiltration membranes, porous type, with pore diameter ranging from 0.035 to 0.1 µm, made by polyethersulfone (PES), with flat plate geometry type, a 25 m² area and submerged configuration. The effluent produced by the industry was from fruit, floors and machinery washing, and was characterized by chemical, physical and microbiological parameters. The MBR performance was evaluated from samples collection of three different points: crude effluent, after electroflotation and permeated. Information about pH, OD, temperature, mixed liqueur level and permeated flow were automatically collected through of a probe connected to a computer and through the ACRON Reporter program. Laboratory analyses were carried out to characterize the parameters, DQO, DBO, COT, SST, Total-Nitrate Nitrogen, Total Phosphorus, Total Coliforms and E. Coli. The crude effluent, electroflotation effluent and permeated effluent presented respectively, pH (4.94; 5.05; 8.01) temperature (31.97° C; 31.8° C; 32.49° C) and electrical conductivity (2.32 mS; 2.15 mS; 2.52 mS). The average temperature of the mixed liqueur was 29.7° C, the average OD was 3.66 mg O2/l, the average pH was 8.21, and the permeated average flow in days which the reactor operated was 1,600 l/day. The mixed liqueur level in the reactor was 91% of the useful volume. Along the operation time, the system removal efficiency was 97.93% and 98.69% for DQO and DBO respectively. The system removal average for the COT was 98.82%, Total Nitrogen presented 95.55% of average removal, while Total Phosphorus was 65.58%. The treated effluent showed reuse quality without restriction for irrigation in agriculture, according to parameters established by the World Health Organization and Resolution COEMA Number Two concerning the agricultural reuse. It answered partially the NBR 13,969 for framing in class II and answered what is treated in classes III and IV. The proposed treatment showed the effluent with a high-quality in order to reuse it in agricultural and industrial fields. Thus, the possibility of its reuse by the companies could increase the supply of water from the use of treated effluent for less noble purposes, thus stopping to consume a more noble water for less demanding purposes.