Application of Parachlorella kessleri for treatment of poultry processing wastewater: effect of temperature on nutrient removal rate and protein production

BACKGROUND Wastewater produced from the thermal processing of poultry meat contains high levels of nitrogen and phosphorus. Thus, tertiary treatment is required to ensure that the wastewater meets Brazilian environmental regulations. Microalgae are capable of removing nutrients from wastewater and simultaneously synthesizing high‐value biomolecules, such as proteins, which perform essential functions (structuring, energy reserve and bioactivity). However, microalgae are sensitive to temperature, which affects biomass productivity and the nutrient removal rate. The southern region of Brazil – where the present study was developed – has a temperate–subtropical climate, with periods of temperatures lower than 10 °C in winter, which may affect microalgal productivity and growth. The aim of the present study was to investigate the influence of temperature on nutrient removal from wastewater produced in a thermal poultry meat processing facility using a microalga‐based process with Parachlorella kessleri . Biomass yield, nitrogen and orthophosphate removal efficiency and protein content were assessed at three temperatures (10, 20 and 30 °C) for 13 days. RESULTS A yield of 0.049 ± 0.01 g L −1 d −1 was obtained at 20 °C. On the sixth day of cultivation, the ammonia removal rate was 98.79%. Orthophosphate was removed efficiently in all treatments, with rates higher than 90%. Average protein concentration did not differ significantly among the treatments. CONCLUSION Monitoring temperature during wastewater treatment is key to understanding the underlying mechanism, especially for nutrient removal and the characterization of biomass. Further studies are needed on the ability of the microalga Parachlorella kessleri to remove orthophosphate over an ambient temperature range.