Evaluation of the Bardenpho system using suspended and attached biomass to treat effluent from poultry egg hatchery

Biological treatment processes utilize microorganisms to oxidize both organic and inorganic matter. The use of anoxic and aerobic chambers, in a process known as Bardenpho 4-stages, enables the removal of nitrogen and organic matter through nitrification and denitrification. This study aimed to evaluate the efficiency of two of Bardenpho’s 4-stage systems, one with attached biomass and the other with suspended biomass, for treating effluent from a poultry egg hatchery. The effluent is characterized by high chemical oxygen demand (COD) and nitrogen concentrations. Two prototypes were constructed, and during their operation, hydraulic retention times (HRTs) of the second anoxic reactor (AN2) and the second aerobic reactor (AE2), as well as the internal recirculation rate (Ri), were varied to identify opportunities for cost savings and better results. Ultimately, there were 8 variations, each lasting 18 days, totalizing a duration test of 144 days. Comparing attached and suspended systems, significant differences were found for COD removal, with median values of 92% and 84%, respectively, demonstrating that the process with support media shows better efficiency. The most outstanding results were obtained during the 8 tests in stage 2A, operated with 500% Ri, 8.1 h HRT in AN2 reactor, 4.1 h in AE2 reactor, and attached biomass. Also, a similar behavior was identified for removing other pollutants, such as nitrogen compounds. With the reduction of HRTs, it was observed that the systems could not degrade the pollutants studied, except for the second anoxic tank, which could be decreased without detriment, saving energy and space.