Evaluating the Performance of a Wastewater Treatment Plant of a Dairy Facility in Southern Minas Gerais, Brazil

Abstract

Dairy wastewater is highly polluting and requires treatment before being discharged into receiving surface waters or destined for reuse. This study aimed to evaluate the performance of a wastewater treatment plant (WWTP) at a dairy facility, which includes the following treatment stages: screening, grease trap, and an upflow anaerobic filter (UAF). Monitoring data from a WWTP at a dairy situated in the southern region of Minas Gerais, Brazil, were assessed based on pollutant removal efficiency in accordance with Brazilian environmental regulations. The results showed that the WWTP achieved average removal efficiencies of 96.2% for COD and 97.1% for BOD5. The BOD5/COD ratio of raw and treated wastewater averaged 0.46 and 0.30, respectively, indicating preferential removal of the biodegradable organic fraction. The treated wastewater complied with legal standards for pH, settleable solids, and total suspended solids. However, at least one sample did not meet regulatory limits for discharge into water bodies regarding surfactants and oils & greases. Strong linear correlations (R2~0.8) between COD and BOD5 data were observed for both raw and treated wastewater. While the treated wastewater was not suitable for use in the facility’s wood-fired boiler, it may be reused for agricultural irrigation.