Seasonal and wastewater stream variation of trace organic compounds in a dairy processing plant aerobic bioreactor

Removal of organic matter and nitrogen from dairy effluents in a structured bed reactor operated with intermittent aeration

The objective of this research was to evaluate the performance of a structured bed reactor (SBRIA), carried out with intermittent aeration (IA), in the removal of organic matter and nitrogen from dairy effluent, when run with different organic loading rates (OLR). The SBRIA was operated for 227 days, with 2:1 AI cycles (2 h with aeration on and 1 h off) and Hydraulic Retention Time (HRT) of 16 h. Three phases, with different OLR, were evaluated: phases A (1000 gCOD m-3 day-1 - 63 days), B (1400 gCOD m-3 day-1 - 94 days), and C (1800 gCOD m-3 day-1 - 70 days). The percentage of COD, NH4+-N removal, and nitrogen removal, respectively, were above 85 ± 7%, 73 ± 27%, and 83 ± 5, in all phases. There was no accumulation of the oxidized forms of nitrogen in the reactor. The kinetic test, performed to evaluate the nitrification and denitrification in the system, indicated that even in dissolved oxygen concentrations of 4.5 mg L-1, it was possible to obtain the denitrification process in the system. The results demonstrate that the reactor under study has positive characteristics to be used as an alternative for removing the removal of organic material and nitrogen in the biological treatment of dairy effluents.

Application of Electrocoagulation Process for Dairy Wastewater Treatment

Dairy industry wastewater is characterized by high biochemical oxygen demand (BOD5), chemical oxygen demand (COD), and other pollution load. The purpose of this study was to investigate the effects of the operating parameters such as applied voltage, number of electrodes, and reaction time on a real dairy wastewater in the electrocoagulation process. For this purpose, aluminum electrodes were used in the presence of potassium chloride as electrolytes. It has been shown that the removal efficiency of COD, BOD5, and TSS increased with increasing the applied voltage and the reaction time. The results indicate that electrocoagulation is efficient and able to achieve 98.84% COD removal, 97.95% BOD5removal, 97.75% TSS removal, and >99.9% bacterial indicators at 60 V during 60 min. The experiments demonstrated the effectiveness of electrocoagulation techniques for the treatment of dairy wastewaters. Finally, the results demonstrated the technical feasibility of electrocoagulation process using aluminum electrodes as a reliable technique for removal of pollutants from dairy wastewaters.

Physicochemical properties and trace organic compounds in a dairy processor's aerobic bioreactor

Wastewater samples were taken from an aerobic bioreactor, operated by a dairy processor in southeastern Australia to reduce nutrient and pollutant loads. Samples were taken over a two-year period, to determine whether trace organic compounds or physicochemical analyses of the wastewater could be used to discriminate the water taken before, during and after processing of the wastewater in the bioreactor. Multivariate analyses of the physicochemical data suggested that nitrate, pH and total dissolved nitrogen best described the infeed wastewater entering the bioreactor, while organic and particulate phosphorus concentrations where predominantly responsible for describing the composition of the content of the bioreactor. Gas chromatography-mass spectrometry data of organic compounds within the wastewater samples were also analysed via multivariate analyses. The analyses found that the compound 4-nitrophenol was associated with ammonia concentrations and mixed liquor wastewater. Therefore, 4-nitrophenol may possibly be used to act as an indicator of anaerobicity in aerobic bioreactors.