Piggery wastewater treatment with a Chlorella microalgae-bacteria consortium and static magnetic field

Abstract

Wastewater discharges into the environment without adequate treatment is a problem still unresolved. That is why alternative technologies, such as applying static magnetic field (SMF), are currently being sought. The objective of this research was to evaluate the effect of a 47.23 mT SMF on the removal of nitrogen (N), phosphorus (P), and the growth of a Chlorella microalgae-bacteria consortium grown in piggery wastewater under different photoperiods. SMF application increased culture productivity, with maximum values of 0.030 g/ Ld-1 in cultures exposed to SMF in a 16:8 h light/dark photoperiod and 0.038 g/ Ld-1 for the 24:0 h light/dark photoperiod. Furthermore, SMF application increased the microorganisms' photosynthetic efficiency (QY), regardless of the photoperiod used. No significant differences were observed on day 21 regarding nutrient removal between the treated and control cultures. Removal percentages of 93.41 % N and 95.56 % P were obtained for the cultures exposed to SMF in the 16:8 h light/dark photoperiod, and 94.78 % N and 95.59 % P for cultures exposed to SMF during the 24:0 h light/dark photoperiod. In general, SMF acts mainly on the growth of microorganisms.