Immobilizing Microcystis aeruginosa and powdered activated carbon for the anaerobic digestate effluent treatment

The environment pollution caused by livestock anaerobic digestate effluent (ADE) is becoming increasingly severe recently. In this study, immobilized technology, embedding Microcystis aeruginosa (MA) and powdered activated carbon (PAC) with sodium alginate (SA), was employed to investigate the removal performance of nitrogen (N), phosphorus (P) and dissolved organic matter (DOM) in the treatment of ADE solution. Initially, orthogonal experiment was carried out to achieve the optimal conditions of the beads fabrication with the concentration of imbedding agents (PAC-SA) of 5% (w/w) and the ratio of microalgae and imbedding agents was 1:1 (v/v). The results indicated that the total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC) can be efficiently removed under the optimal operation conditions, with average removals of 91.88 ± 2.91% in TN, 98.24 ± 0.12 in TP and 78.31 ± 1.57% in TOC, respectively. Moreover, the fluorescence excitation-mission matrix (EEM) results illustrated that IMA-PAC beads joined system can efficiently diminish the concentrations of protein-like compounds and humic substances. Therefore, the organic contaminants and nutrients (i.e. N and P) can be efficiently removed in IMA-PAC beads joined system, which would contribute to developing new strategies for the treatment of ADE solution and nutrient recycle.