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

Genome mining of lipolytic exoenzymes from Bacillus safensis S9 and Pseudomonas alcaliphila ED1 isolated from a dairy wastewater lagoon

Dairy production plants produce highly polluted wastewaters rich in organic molecules such as lactose, proteins and fats. Fats generally lead to low overall performance of the treatment system. In this study, a wastewater dairy lagoon was used as microbial source and different screening strategies were conducted to select 58 lipolytic microorganisms. Exoenzymes and RAPD analyses revealed genetic and phenotypic diversity among isolates. Bacillus safensis, Pseudomonas alcaliphila and the potential pathogens, B. cereus, Aeromonas and Acinetobacter were identified by 16S-rRNA, gyrA, oprI and/or oprL sequence analyses. Five out of 10 selected isolates produced lipolytic enzymes and grew in dairy wastewater. Based on these abilities and their safety, B. safensis S9 and P. alcaliphila ED1 were selected and their genome sequences determined. The genome of strain S9 and ED1 consisted of 3,794,315 and 5,239,535 bp and encoded for 3990 and 4844 genes, respectively. Putative extracellular enzymes with lipolytic (12 and 16), proteolytic (20) or hydrolytic (10 and 15) activity were identified for S9 and ED1 strains, respectively. These bacteria also encoded other technological relevant proteins such as amylases, proteases, glucanases, xylanases and pectate lyases.

Process design and dynamics of a series of continuously fed aerated tank reactors treating dairy manure

A 6-month trial was carried out to study operational conditions and process dynamics in a system of six continuously fed aerated tank bioreactors grouped by serial connection. Feedback was with NH3-stripped solution after biological treatment, with the purpose of lowering the NH3 content of the feedback solution in order to improve the process. The fate of carbon and nutrients during treatment were determined, as well as the ammonia stripping performance of the biological treatment. The results of the study confirmed the dynamic nature of the serial system and indicated its resistance to process disturbances. The feedback of slurry resulted in a dilution effect and significantly reduced the carbon and nutrients concentrations in the first tank, increasing the treatment efficiency. Overall, after mechanical separation, low intensity aeration treatment and ammonia stripping, up to 61%, 67%, 79% and 83% average reductions of TS, Ntot, NH4(+)-N and Ptot, respectively, were reached.